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The temperature dependence of the structural and magnetic properties of wolframite-type FeWO4 was studied in situ by high-pressure neutron diffraction. Neutron diffraction measurements were performed with the XtremeD instrument at the Institut Laue-Langevin up to a maximum pressure of 8.7(4) GPa and a minimum temperature of 30.0(5) K. The diffraction data were analyzed via Rietveld refinements. We found that despite producing a contraction of 5% of the volume, the maximum pressure applied in this study does not modify the Shubnikov space group below magnetic order. However, the orientation of magnetic moments and the Néel temperature are slightly modified with the pressure, which is expected according to the preexistent understanding of magnetism in wolframites. We also determined a pressure–volume equation of state of FeWO4 at 300 K, which is compared with previous x-ray diffraction studies and density-functional theory calculations. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric ceramics of (1 − x)K0.5Na0.5NbO3-xCaTiO3 were fabricated, and their crystal structure, microstructure, and electrical properties were systematically studied. Rietveld refinement of the x-ray diffraction data and Raman spectroscopic analyses revealed a composition-dependent structural phase transition: three phase transitions, namely, from a pure orthorhombic phase for x ≤ 0.02 to a mixed phase of orthorhombic and tetragonal phases (0.03 ≤ x ≤ 0.08) and finally another mixed phase of tetragonal + cubic for x = 0.10 and 0.15 at room temperature (RT). The morphological study reveals a decrease in grain size along with a more uniform distribution of grains as the concentration of CaTiO3 (CT) increases; notably, a homogeneous distribution of grains is observed for x = 0.05. The temperature-dependent dielectric properties show two phase transitions, from orthorhombic to tetragonal (TO-T) and tetragonal to cubic (TC), for unmodified K0.5Na0.5NbO3 (KNN). However, both the phase transition temperatures (TO-T and TC) decrease, and the transition peaks broaden with an increase in CT substitution, and for x > 0.06, the TO-T shifted below RT. The broadening of the transition peak at TO-T may be due to the relaxation behavior. Among the prepared samples, the 5 mol. % CT-modified KNN shows the optimum electrical properties (d33 = 114 pC/N, ɛr = 412, and 2Pr = 15.25 μC/cm2) at RT. The enhanced electrical properties for x = 0.05 are due to the coexistence of orthorhombic and tetragonal phases, facilitating easy polarization rotation and flattening of the free energy profile. A phase diagram has been constructed based on the information gathered from the temperature-dependent dielectric measurements, RT x-ray diffraction, and Raman spectroscopy data and is discussed in detail. [ABSTRACT FROM AUTHOR]

(Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics were synthesized via the conventional solid-state reaction method. Structural and dielectric properties were investigated as a function of the doping concentration, considering x = 0, 2, 5, 8, 10, 12, 16, and 18 at. % Ba. The structural analyses were carried out from the x-ray diffraction technique, including the Rietveld refinement method, and Raman spectroscopy. Results confirmed the formation of the perovskite structure, revealing different crystalline symmetries, depending on the Ba2+ concentration: the single rhombohedral ferroelectric phase (R3c) for x = 0 and 2 at. %; coexistence of both rhombohedral ferroelectric (R3c) and tetragonal antiferroelectric (P4bm) phases for x = 5 at. % Ba; the single tetragonal antiferroelectric phase (P4bm) for x = 8 at. % Ba; coexistence of two tetragonal phases (antiferroelectric P4bm and ferroelectric P4mm) for x = 10 at. % Ba; and the single tetragonal ferroelectric phase (P4mm) for x = 12, 16, and 18 at. % Ba. The characteristics of the phases' transition, investigated from dielectric analysis, revealed the presence of two dielectric anomalies, which indeed have been associated to different phases' transitions, one of them showing relaxor-like characteristics. The obtained results offer new insights for a better understanding on the features of the phase diagram for the studied ceramic system, according to the different observed crystalline symmetries (ferroelectric and antiferroelectric) in a very wide doping concentration. In the light of the obtained results, a new phase diagram has been proposed considering a wider compositional range than those reported in the literature. [ABSTRACT FROM AUTHOR]

Chemical pressure is widely applied to antiferroelectrics (AFEs) as a criterion to enhance their antiferroelectricity. However, NaNbO3 (NN)-based ceramic with well-defined double polarization hysteresis (P–E) loops was rarely reported based on this strategy, and the effect of chemical pressure on antiferroelectricity remains to be understood. In this work, the Me cations (Me is Ti, Sn, Zr) with different ionic radii were introduced into the component system 0.76NaNbO3–0.20AgNbO3–0.04CaMeO3 to tune the negative chemical pressure and investigate its effect on antiferroelectricity. The enhancement of negative chemical pressure can effectively stabilize the AFE phase and reduce hysteresis, as revealed by the P–E loops and dielectric properties, which is further confirmed by the change in crystal lattice parameters and in situ Raman spectra. Rietveld refinement of x-ray powder diffraction reveals that the enhanced negative chemical pressure mainly reduces the cation off-centering displacement and [BO6] octahedral tilting angles. As a result, the 0.76NaNbO3–0.20AgNbO3–0.04CaZrO3 exhibits good reversibility of the electric field-induced antiferroelectric–ferroelectric phase transition and well-defined double P–E loops. This work reveals the underlying mechanism of chemical pressure and provides an effective way of discovering new NN-based AFEs. [ABSTRACT FROM AUTHOR]

We report an unexplored type-II multiferroic order in NiMn 2 O 4 , exhibiting strong linear magnetoelectric coupling above liquid-nitrogen (LN) temperature. The compound becomes ferroelectric at ∼ 100 K, coinciding with ferrimagnetic ordering, with a polarization value of ∼ 535 μ C/m 2 for a poling field of 5 kV/cm. At LN temperature, the polarization value increases linearly (∼ 21 %) with a magnetic field up to 30 kOe. Rietveld refinement of neutron diffraction patterns reveals a ferrimagnetic model with antiparallel moments at tetrahedral and octahedral sites, as well as a canting of octahedral moment persisting up to ∼ 100 K. Low-temperature synchrotron diffraction confirms a step-like oxygen displacement during multiferroic ordering, suggesting that the Dzyaloshinskii–Moriya interaction polarizes the intervening oxygen atoms through magnetostriction, providing a microscopic mechanism for spontaneous electric polarization in this linear magnetoelectric multiferroic compound. [ABSTRACT FROM AUTHOR]

A temperature factor is one of the main parameters in the synthesis of nanoparticles and can affect considerably the arrangement of atoms in the lattice. In the system of magnetically hard CoFe2O4 spinel ferrite, the distribution of cations directly determines the magnetic properties of the sample. It was studied, on products of co-precipitation synthesis followed by a temperature dependent sinterization, by x-ray diffraction (XRD), x-ray absorption (XAS) using synchrotron radiation, vibrating sample magnetometry, and 57Fe Mössbauer spectroscopy (MS). From the Rietveld refinement of XRD patterns, the site occupancies reveal the following trend: with a decrease in the sintering temperature, the inversion degree parameter γ, which is a fraction of Co ions residing in the octahedral sites, decreases. For the highest sintering temperature explored in this work, 1000 °C, γ ≈ 0.83 giving rise to (Co0.17Fe0.83)A[Co0.83Fe1.27]BO4 formulation. For the lowest sintering temperature explored, 500 °C, the inversion degree is approximately 0.69 giving rise to (Co0.31Fe0.69)A[Co0.69Fe1.31]BO4 formulation. The propensity for the cationic arrangement was also confirmed by MS. Qualitative analysis of XAS at Co L3,2 edges strongly supports the tendency observed by XRD: the lower the sintering temperature, the more Co ions tend to occupy the tetrahedral sites. The magnetic behavior of the samples is consistent with the particle size which was determined by transmission/scanning electron microscopies. The particle size is the product of different sintering temperatures after the primary synthesis. [ABSTRACT FROM AUTHOR]

In this work, an attempt is made for improving the piezoelectric properties of a lead-free (Na 0. 5 K 0. 4 8 5 Li 0. 0 1 5) (Nb 0. 9 8 V 0. 0 2) O3 ceramic system by doping manganese in it. The Rietveld analysis of XRD micrographs of the ceramics indicates the samples crystallizing into 99.86% of orthorhombic phase and very small traces of tetragonal phase around room temperature. The Curie temperature ( T c ) is hardly affected by the incorporation of Mn 4 + into the system. At the manganese concentration of 0.02 wt.%, the ceramic system attains the peak values in its density, dielectric constant at room temperature ( ε RT ), planar electromechanical coefficient ( k p) , piezoelectric coefficient ( d 3 3 ), and remnant polarization ( P r ). The optimum piezoelectric properties of k p = 4 3 % and d 3 3 = 1 9 3 pC/N are observed for this composition. The study reveals that the modification of (Na 0. 5 K 0. 4 8 5 Li 0. 0 1 5 ) (Nb 0. 9 8 V 0. 0 2) O3 with an appropriate quantity of Mn 4 + can produce the desired changes in the crystallographic properties and densification so as to eventually improve its piezoelectric properties. [ABSTRACT FROM AUTHOR]

In the present investigations, Gd3+ ions were substituted at the Sr2+ site through conventional solid state reaction technique. The influence of Gd3+ ion substitution on the physical attributes of Sr2FeTiO6 (SFTO) was meticulously examined. The basic structure of Sr2 − xGdxFeTiO6 (SGFTO) (x = 0.2 to 0.8), was employed to start the Rietveld structural refinement of the powder X-ray diffraction patterns. This process confirmed the presence of a cubic structure with a space group of Pm3m. The replacement of Gd3+ ions, noted for their larger ionic radii, led to a minor increase in the lattice parameters and the volume of the unit cell. The identity of the elements within the compound was determined by examining their oxidation states through X-ray photoelectron spectroscopy. The SEM images reveal that as Gd content increases in the SGFTO samples, the structure becomes denser and more agglomerated, with reduced porosity and less uniform particle sizes. This suggests that higher Gd content leads to a more compact morphology, potentially impacting the material's electrochemical performance and mechanical stability. The use of diffuse reflectance measurements confirmed that the band gap values decreased slightly from 2.95 eV to 2.24 eV for the Sr2 − xGdxFeTiO6 (x = 0.2–0.8) materials, indicating that these synthesized samples exhibit semiconductor nature. The study investigated how often the dielectric constant and its behavior change with temperature, and these measurements proved that as the amount of Gd3+ in the material increased from 0.2 to 0.8, the dielectric constant also increases. The research on magnetization showed that the prepared materials had a stronger magnetic property and displayed a antiferromagnetic behavior. All synthesized materials made in this way has the possibility to be used in today's electronic devices, magneto-optical storage devices, and magneto-dielectric technologies. Highlights: • The study investigates the substitution of Gd3+ ions at the Sr2+ site in Sr2FeTiO6 using the solid-state reaction method, examining its impact on the material's physical properties. • Rietveld refinement of X-ray diffraction patterns confirmed that Sr2-xGdxFeTiO6 (x = 0.2–0.8) maintains a cubic symmetry with a Pm3m space group, with Gd3+ ion substitution causing a slight increase in lattice parameters and unit cell volume. • X-ray photoelectron spectroscopy and EDAX pattern analysis confirmed the presence and uniform distribution of Sr, Gd, Fe, Ti and O elements, indicating a homogeneous and uniform structure. • Diffuse reflectance measurements showed a reduction in band gap values from 2.95 eV to 2.24 eV with increasing Gd3+ substitution, indicating a semiconductor-like nature of the synthesized samples. • Dielectric constant measurements revealed a progressive increase with higher Gd content, while magnetization analysis indicated an enhanced magnetic nature with antiferromagnetic character, highlighting potential applications in electronic technologies, magneto-optical storage systems, and optoelectronic and sensor devices. [ABSTRACT FROM AUTHOR]

Optical characteristics and microstructure of multilayered zirconia with different yttria contents in each layer can be influenced differently with a layer after speed sintering. The layer-wise translucency and opalescence of dental zirconia (E.max, E.max ZirCAD prime; Cercon, Cercon ht ML) after conventional (control) and speed sintering were analyzed using a spectrophotometer (n = 5). Specimens were subjected to microstructural analyses (n = 2) using field-emission scanning electron microscopy (FE-SEM) and phase analyses (n = 1) using high-resolution X-ray diffraction (HRXRD) and Rietveld refinement. The translucency parameter (TP) and opalescence parameter (OP) were analyzed using a 3-way ANOVA, followed by Scheffé's post hoc test (α = 0.05). The average grain size was analyzed using the Welch's t-test and Kruskal–Wallis test, followed by the Bonferroni–Dunn post hoc test (α = 0.05). Changes to the TP and OP after speed sintering were only observed in the dentin layers. Although the TP of E.max increased (p < 0.05), the difference was below the 50:50% perceptibility threshold (ΔE00 = 0.8). The OP of E.max decreased slightly, whereas that of Cercon increased slightly (p < 0.05). The microstructure and phase fraction of both zirconia barely changed. Therefore, speed sintering is considered to have a negligible clinical impact on the optical characteristics and microstructure. [ABSTRACT FROM AUTHOR]

High‐entropy spinel‐type oxides are synthesized by a modified Pechini process, wet chemistry approach, and solid‐state synthesis method and characterized as anode materials for Li‐ion batteries. The Pechini process that involves chelation and polyesterification reactions facilitates the formation of high‐entropy spinel‐type oxides without compositional segregation at ≈600 °C as confirmed by in situ and ex situ XRD. XAFS analysis and the Rietveld refinement of room‐temperature neutron diffraction data suggest the composition (Mn0.05Fe0.48Co0.47, tetrahedral)(Cr0.61Mn0.52Fe0.11Co0.09Ni0.68, octahedral)O4 for phase‐pure specimens. Compared to high‐entropy spinel‐type oxides synthesized by the solid‐state method, the precursor‐derived materials demonstrate higher specific capacity as anodes, in which the materials without citric acid addition exhibit low capacity fading at high current densities and maintained a capacity of ≈200 mAh g−1 after 1000 cycles. The generation of a rock‐salt‐type phase during cycling is confirmed for the first time by in situ charging–discharging XRD. The charging–discharging of this anode material is achieved mainly through the embedding–disembedding of lithium ions in the lattice of the generated rock‐salt‐type phase. [ABSTRACT FROM AUTHOR]

In powder diffraction, lattice symmetry relaxation causes a peak to split into several components which are not resolved if the degree of desymmetrization is small (pseudosymmetry). Here the equations which rule peak splitting are elaborated for the six minimal symmetry transitions, showing that the resulting split peaks are generally broader and asymmetric, and suffer an hkl‐dependent displacement with respect to the high‐symmetry parent peak. These results will be of help in Rietveld refinement of pseudosymmetric structures where an exact interpretation of peak deformation is required. [ABSTRACT FROM AUTHOR]

We present the synthesis (solid-state reaction) and characterization of an iron-modified lanthanum silver manganate ceramic, La0.85Ag0.15Mn0.8Fe0.2O3. XRD investigation at room temperature using Rietveld refinement indicates rhombohedral crystal symmetry (#R 3 ¯ c) with a crystallite size of 30 nm. Scanning electron micrographs demonstrate a homogeneous distribution of well-grown grains with defined grain boundaries, which is critical for understanding the conductivity mechanism. The compactness of the grains verifies the creation of a dense sample, which could be one of the factors contributing to the observed physical attributes. The purity and uniform distribution of all constituent elements were confirmed using the energy-dispersive X-ray analysis spectrum and color mapping, respectively. The Maxwell–Wagner polarization effect is observable at low frequencies. The analysis of impedance and modulus plots indicates the existence of a negative temperature coefficient of resistance and a non-Debye relaxation process, respectively. The existence of a thermally activated conduction mechanism in the investigated sample is supported by the analysis of AC conductivity as a function of temperature and frequency. The semiconducting nature is supported by the existence of semicircular arcs in both the Nyquist's and Cole–Cole plots, suggesting that they would be good candidates for energy storage devices. The presence of NTC thermistor character for temperature sensor applications is suggested by the resistance versus temperature investigation. [ABSTRACT FROM AUTHOR]

Ionic conductors with the composition SrTi1−xCexO3 (x = 0, 0.02, and 0.04) were synthesized by a high-temperature conventional ceramic route, and their electrical properties were analyzed for use as solid electrolytes in intermediate-temperature solid oxide fuel cells (IT-SOFCs). Scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM-EDX) was used to analyze the compositional homogeneity and morphology of the samples. The phase analysis was performed using X-ray diffraction (XRD), followed by Rietveld refinement, confirming the cubic crystal structure under the space group P m 3 ¯ m . The bands at 462 cm−1 and 449 cm−1 in the Raman spectrum confirmed the incorporation of Ce at the Ti-site of SrTiO3. The presence of a negative charge was found from zeta potential analysis, supporting the presence of Ce3+ at the Ce4+site, denoted by C e C e 4 + 3 + ′ , and Ti3+ at the Ti4+ site, denoted by T i T i 4 + 3 + ′ , in X-ray photoelectron spectroscopy (XPS) analysis. The total conductivity of samples showed thermal-dependent Arrhenius behavior with two different activation energy values. The activation energy ≥ 1 eV in high-temperature regions indicated the migration of doubly ionized oxygen vacancy and ≤ 0.50 eV reflecting the migration of electrons between the degenerate sites of Ti4+/Ce4+. The impedance spectroscopy studies suggested the presence of bulk contribution in the electrical properties, and similar charge carriers were responsible for both processes. The impact of oxygen vacancy on electrical conduction was also supported by the magnetic properties, which displayed diamagnetic to paramagnetic phase transition with Ce doping. The highest value of total conductivity was obtained around 0.003 S cm−1 at 610°C, making it a potential candidate for solid electrolytes in IT-SOFC applications. [ABSTRACT FROM AUTHOR]

This work examined the impact of Mg doping on the sintering, hydration, and chloride-binding capacity of C4AF minerals and elucidated the role of Mg doping on reactivity mechanisms by experiments and calculations. Rietveld analysis determined the solid solubility limit of Mg in C4AF is 1.6% by weight. By the density functional theory (DFT), it revealed Mg preferentially substitutes Fe sites, followed by Ca sites in C4AF. Increasing Mg doping up to 4% by weight enhanced the chloride-binding capacity of hydrated C4AF pastes by more than 50%, attributed to the increased formation of Friedel's salt. The introduction of Mg in C4AF promoted clinker sintering upon hydration and produced katoite, which reacted with chloride. Additionally, Mg facilitated the formation of layered double hydroxides that adsorb chlorides. The changes imparted by Mg doping served to increase microstructure porosity and optimize pore size distribution. The results provide insight into the role of Mg in high-Mg, high-Fe cement, demonstrating that C4AF phase change improves resistance to chloride intrusion. This has implications for the use of high-Mg limestone and the application of this cement in marine environments. [ABSTRACT FROM AUTHOR]

The present study reveals the synthesis of Iron oxide nanoparticles (IONPs) by varying the molar ratio of ferric (Fe3+) to ferrous (Fe2+) ions via chemical coprecipitation method for the study of cationic distribution of Fe‐ions and its potential application for magnetic hyperthermia therapy (MHT). X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS), were used to characterize the physicochemical properties. Several structural parameters were estimated using the Rietveld refinement, resulting in structural modelling verified by magnetic characteristics. A vibrating sample magnetometer (VSM) assessed the magnetic hysteresis loop at room temperature in a field range of ±15 kOe, revealing superparamagnetic behavior for the ratio Fe2+/Fe3+ 1:2. The saturation magnetization (Ms) of IONPs increased with the increasing Fe2+ concentration and attained a maximum value of 60.21 emu g−1 at a molar ratio of 2:1. The potential of the inductive heating capability of IONPs in an alternating current magnetic field (AMF) was studied to treat localized MHT. The changes in magnetic properties and inductive heating properties of IONPs are associated with the cationic distribution of Fe2+ at the tetrahedral (A) and octahedral (B) sites of crystal structure. The variation in cationic properties at the A and B sites may result in varying/tuneable magnetic properties, affecting the overall heating profiles of hyperthermia. [ABSTRACT FROM AUTHOR]

This study presents the development of eco-friendly cementitious materials for soil stabilization, based on alkaline multi-industrial waste (AMIW), using steel slag (SS), blast furnace slag (BFS), carbide slag (CS), fly ash (FA) and flue gas desulfurization gypsum (FGDG) as the raw materials. The optimal AMIW-based cementitious material composition determined through orthogonal experiments was SS:CS:FGDG:BFS:FA = 15:10:15:44:16. Central composite design (CCD) in response surface methodology (RSM) was employed to optimize the curing process parameters. The maximum 7-day unconfined compressive strength (7d UCS) was achieved under the optimal conditions of 18.51% moisture content, 11.46% curing agent content and 26.48 min of mix-grinding time. The 7d UCS of the AMIW-stabilized soil showed a 24% improvement over ordinary Portland cement (OPC)-stabilized soil. Rietveld refinement results demonstrated that the main hydration products of the stabilized soil were C-S-H and ettringite. After curing for 7 days to 28 days, the C-S-H content increased from 3.31% to 5.76%, while the ettringite content increased from 1.41% to 3.54%. Mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) analysis revealed that with the extension of curing time, the pores of the stabilized soil become smaller and the structure becomes denser, resulting in an improvement in compressive strength. [ABSTRACT FROM AUTHOR]

This work investigated the structure, microstructure, and ferroelectric and dielectric behavior of (Pb0.97Ba0.03)(Zr0.98Ti0.02)1−xSnxO3 (PBZT_xSn) solid solution with variable tin content in the range x = 0.00–0.08. Synthesis was carried out using the powder calcination method, and sintering was carried out using the hot-pressing method. For all the PBZT_xSn samples at room temperature, X-ray diffractograms confirmed the presence of an orthorhombic (OR) crystal structure with space group Pnnm, and the microstructure is characterized by densely packed and properly shaped grains with an average size of 1.36 µm to 1.73 µm. At room temperature, PBZT_xSn materials have low permittivity values ε′ ranging from 265 to 275, whereas, at the ferroelectric–paraelectric phase transition temperature (RE–C), the permittivity is high (from 8923 to 12,141). The increase in the tin dopant in PBZT_xSn lowers permittivity and dielectric loss and changes the scope of occurrence of phase transitions. The occurring dispersion of the dielectric constant and dielectric loss at low frequencies, related to the Maxwell–Wagner behavior, decreases with increasing tin content in the composition of PBZT_xSn. Temperature studies of the dielectric and ferroelectric properties revealed anomalies related to the phase transitions occurring in the PBZT_xSn material. With increasing temperature in PBZT_xSn, phase transitions occur from orthorhombic (OR) to rhombohedral (RE) and cubic (C). The cooling cycle shifts the temperatures of the phase transitions towards lower temperatures. The test results were confirmed by XRD Rietveld analysis at different temperatures. The beneficial dielectric and ferroelectric properties suggest that the PBZT_xSn materials are suitable for micromechatronic applications as pulse capacitors or actuator elements. [ABSTRACT FROM AUTHOR]

The BiFe1-xNdxO3 (x = 0.00, 0.03, 0.06, 0.09, 0.12) (BFNO) nanoparticles have been synthesized successfully through the chemical coprecipitation technique. The effect of neodymium (Nd) doping on structural, dielectric, magnetic, and magnetodielectric properties of BiFeO3 (BFO) multiferroic nanoparticles has been reported here. The Rietveld refinement of X-ray diffraction (XRD) data confirms the formation of rhombohedral crystal structure (R3c space group) of the prepared nanomaterials. The average crystallite size obtained from XRD is in the range of 54 to 21 nm for pure and doped materials. The transmission electron microscope (TEM), high-resolution TEM (HRTEM), and energy dispersive X-ray (EDX) of the samples indicate the particle size, high crystallinity, and incorporation of Nd3+ ions respectively. The dielectric parameters and real-imaginary part of impedance behavior point out the transport mechanism of the doped samples. The magnetic and magnetodielectric properties of the doped nanomaterials have been enhanced than the pure BFO. The magnetic moment of BFNO samples increases due to the suppression of oxygen vacancies in accordance with the reduced super-exchange interaction of Fe2+-O-Fe3+. The leakage current and the multiferroic properties have been checked for all the samples at room temperature. [ABSTRACT FROM AUTHOR]

The crystal structures of both Pb2PbO4 (Pb3O4) and Pb2SnO4 at room temperature can be described using mullite-type setting in the space groups P42/mbc and Pbam, respectively. At what chemical extend the crystal structure prefers either of the space groups would be an excellent playground in the Pb2(Pb1−xSnx)O4 solid solution. Members of the solid solutions have been prepared by solid-state reactions carried out in sealed quartz tubes. Each sample has been found to be phase pure confirmed by X-ray powder diffraction data Rietveld refinement. Samples with higher tin content require higher synthesis temperatures, and controlled decomposition of Pb3O4 serves as the source for both Pb2+ and Pb4+ cations. Since the Pb4+ cation is larger than Sn4+, the MO6 polyhedral volume decreases with increasing Sn-content. As such, each metric parameter shows a linear trend following Vegard's rule. The concomitant contraction of the MO6 octahedra and the high stereo-chemical activity of the 6s2 lone electron pairs of lead in the Pb2+O4 distorted pyramid results in symmetry reduction. DFT suggests dynamical instability of the tetragonal Pb3O4 while Pb2SnO4 keeps orthorhombic symmetry at low temperatures, which agrees well with the experimental findings. The global blue shift of the vibrational mode frequencies is explained by the quasi-harmonic approach. The indirect band-gap linearly increases from 2.1(1) eV (x = 0) to a maximum value of 2.5(1) eV for x = 0.8 followed by a sharp drop towards Pb2SnO4. Thermogravimetric analysis demonstrates higher thermal stability with increasing Sn-content, which is explained in terms of higher bond strength of Sn–O than that of Pb–O in the MO6 octahedra. [ABSTRACT FROM AUTHOR]

The effect of specimen displacement in X‐ray powder diffraction experiments with laboratory diffractometers has been revisited and new expressions have been derived for several commonly used experimental configurations, including Bragg–Brentano parafocusing geometry and flat‐plate transmission geometry. The results presented in this work allow the analysis of data from samples with relatively large displacements. This may open the possibility to study samples with dimensions that are difficult to accommodate with the sample‐handling capabilities of standard laboratory diffractometers. [ABSTRACT FROM AUTHOR]

High‐pressure neutron powder diffraction data from PbNCN were collected on the high‐pressure diffraction beamline SNAP located at the Spallation Neutron Source (SNS) of Oak Ridge National Laboratory (Tennessee, USA). The diffraction data were analyzed using the novel method of multidimensional (two dimensions for now, potentially more in the future) Rietveld refinement and, for comparison, employing the conventional Rietveld method. To achieve two‐dimensional analysis, a detailed description of the SNAP instrument characteristics was created, serving as an instrument parameter file, and then yielding both cell and spatial parameters as refined under pressure for the first time for solid‐state cyanamides/carbodiimides. The bulk modulus B0 = 25.1 (15) GPa and its derivative B′0 = 11.1 (8) were extracted for PbNCN following the Vinet equation of state. Surprisingly, an internal transition was observed beyond 2.0 (2) GPa, resulting from switching the bond multiplicities (and bending direction) of the NCN2− complex anion. The results were corroborated using electronic structure calculation from first principles, highlighting both local structural and chemical bonding details. [ABSTRACT FROM AUTHOR]

FullProfAPP is a software tool for data processing, refinement and visualization of large collections of powder diffraction patterns. Featuring an intuitive graphical user interface, it seamlessly facilitates a variety of tasks. These include conducting full‐profile phase searches, sequential and high‐throughput Rietveld refinements, and managing background (and peak) detection. FullProfAPP also provides convenient interaction with crystallographic databases and supports the visualization and export of high‐quality pixel and vector graphics depicting the refinement results, among other functionalities. FullProfAPP wraps around the refinement program FullProf [Rodríguez‐Carvajal (1993), Physica B, 192, 55–69] and offers the flexibility of user‐defined workflows by accessing and editing FullProf's input files and triggering its execution as necessary. FullProfAPP is distributed as open‐source software and is presently available for Windows and Linux operating systems. [ABSTRACT FROM AUTHOR]

Iodine eluent is a type of secondary waste that adsorbs radioactive iodine during the reprocessing of used nuclear fuel. To better deal with it, Na2SiO3 and NaAlO2 were used to immobilize iodine eluents by synthesizing iodosodalite via a hydrothermal method. Orthogonal experiments were designed to investigate the effects of four factors: mass ratio of iodine eluent, Al/Si ratio, temperature, and aging time. Powder X-ray diffraction with Rietveld refinements was performed to characterize the structures and phases of the samples, of which iodosodalite and hydrosodalite are the primary phases that immobilize iodine effluents. Fourier-transform infrared spectroscopy and scanning electron microscopy results demonstrated a cage-like sample structure. Energy-dispersive X-ray spectroscopy revealed a homogeneous distribution of Na, Al, Si, O, and I on the sample surfaces. X-ray photoelectron spectroscopy indicated the presence of both iodide and iodate in the synthesized products. The optimal synthesis process is a reaction temperature of 190 ℃, NaI + NaIO3:Na2SiO3 + NaAlO2 ratio of 1:5, Si/Al ratio of 1:1, and aging time of 7 d. The leaching rate of iodine (including I− and IO3−) indicates considerable chemical durability of the optimized sample. [ABSTRACT FROM AUTHOR]

High‐nickel cathode materials are widely used in lithium‐ion batteries because of their advantages of high energy density and high safety. High‐nickel cathode materials need to further improve cycling stability because they are prone to structural changes and capacity degradation. This paper proposes a method to improve high‐nickel cathode materials by Mg doping. XRD proves that Mg‐doped high‐nickel materials still have R‐3 m spatial structural characteristics; Rietveld refinement confirms that the c‐axis gradually increases with the increase of Mg content. Combined with DFT calculations, the presence of Mg can inhibit structural collapse during charge and discharge, reduce Li/Ni antisite defects, improve the electronic conductivity of the material, and improve the cyclic stability of the material. The 0.6 mol % Mg‐doped sample has an initial discharge capacity of 233 mAh g−1 at 0.1 C in the range of 2.7–4.3 V, a capacity retention rate of 91.0 % after 50 cycles at 1 C, still retains 79.9 % after 100 cycles. The dQ/dV curves further indicate that the presence of Mg improves the structural stability of the material. [ABSTRACT FROM AUTHOR]

The ternary material Mn2SiTe4 was synthesized by direct fusion using the annealing method. X-ray powder diffraction analysis indicated that this material crystallizes in the olivine-type structure, space group Pnma, Z = 4, with unit cell parameters: a = 13.905(2) Å, b = 8.128(1) Å, c = 6.526(1) Å, V = 737.6(2) Å3. This olivine structure can be described from a hexagonal close-packing of selenium atoms where manganese atoms occupy ½ of the octahedral sites while silicon atoms lay in ⅛ of the tetrahedra. The magnetic susceptibility curve indicate a possible antiferromagnetic behavior for this material. This compound is related to the ternary layered Mn3Si2Te6 recently studied as possible two-dimensional (2D) magnetic material. [ABSTRACT FROM AUTHOR]

The development of new electrocatalysts for the oxygen evolution reaction (OER) is fundamental for water-splitting devices. In this work, a novel composite based on Ca3Co4O9 (C349) and Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF) was synthesized and characterized using XRD with Rietveld refinement, SEM, EDX, and FTIR. The electrochemical properties were evaluated in a KOH alkaline medium. The composite exhibited exceptional OER electrocatalytic activity, showing an overpotential of 389 mV at 10 mA cm−2, which is lower than the pristine BSCF and C349 samples. Tafel slope of 77 mV dec−1 and double-layer capacitance (Cdl) of 4.37 mF were obtained, indicating an ECSA of 109.25 cm2. The composite also demonstrated a high turnover frequency (TOF) of 1.9 × 10−3 mol O2 s−1, underscoring its superior catalytic efficiency. Impedance spectroscopy revealed that the C349 and BSCF samples exhibited greater limitations in charge transfer compared to the composite. These results highlight the composite's potential as a highly effective OER electrocatalyst, leveraging the synergistic effects of C349 and BSCF. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive inquiry into the structural refinement and Raman spectroscopy of natural barium strontium sulfate, characterized as Sr0.967(2)Ba0.030(2)U0.0022(6)Y0.0012(6)SO4. The crystal structure of orthorhombic sulfate celestine is meticulously refined using Rietveld methods with conventional powder X-ray diffraction data, optimizing the structural model within space group Pnma (Z = 4). The ultimate reliability factors, namely χ2 = 5.6, RF = 3.6, and RBragg = 4.65, confirm the outstanding quality of the refinement process. These factors serve as indicators of the degree to which the refined crystal structure in alignment with the experimental data. In this case, the values suggest a high level of accuracy and precision in the refinement, reinforcing the reliability of the obtained structural model for the celestine crystal. The resulting unit cell parameters are reported as a = 8.372(9) Å, b = 5.357(6) Å, c = 6.877(7) Å, and V = 308.42(7) Å3. The average Vinograd et al. (Appl. Geochem. 89, 59–74, 2018) distance is 2.832(6) Å, while the corresponding average Baker and Bloomer (Geochim. Cosmochim. 52, 335–339, 1988) distance is 1.497(4) Å. This investigation confirms the isostructural nature of the celestine solid solution with pure SrSO4 and barite (BaSO4). Chemical analysis through X-ray fluorescence provides the empirical formula for celestine as (Sr0.979Ba0.013U0.001Y0.005)SO4. Additionally, the application of Vegard’s law for unit cell parameters consistently aligns with the chemical formulas obtained from Rietveld refinement and X-ray fluorescence analysis, underscoring the reliability of Vegard’s law in predicting compound composition. Distinctive vibrational modes in natural celestine are unveiled through Raman spectroscopy, revealing a composition diverging from typical celestine. The observed shift in Raman bands is ascribed to the incorporation of Ba, U, and Y into the celestine lattice, resulting in a solid solution denoted as Sr1-x (Ba, U, Y)ₓSO4. The chemical formula derived through the application of Vegard’s law for ν1(SO4) is reported as Sr0.977 Ba0.023SO4. This formula closely corresponds to the formulation presented earlier. [ABSTRACT FROM AUTHOR]

The embedded call to a special version of the web‐based Bilbao Crystallographic Server tool k‐SUBGROUPSMAG from within GSAS‐II to form a list of all possible commensurate magnetic subgroups of a parent magnetic grey group is described. It facilitates the selection and refinement of the best commensurate magnetic structure model by having all the analysis tools including Rietveld refinement in one place as part of GSAS‐II. It also provides the chosen magnetic space group as one of the 1421 possible standard Belov–Neronova–Smirnova forms or equivalent non‐standard versions. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the changes in the physicochemical properties of hydroxyapatite (HAp) extracted from horse humerus bones of different ages (1, 3, 6, and 8 years) subjected to low temperature calcination (600°C). Thermal analysis revealed significant mass loss due to water, collagen, organic compounds, carbonates, and age‐related magnesium out‐diffusion. Higher fat content in older bones contributed to increased mass loss. Phosphorus content remained constant across age groups, while calcium and sodium showed age‐related fluctuations. Magnesium levels decreased with age, emphasizing its importance for early bone development. The Ca/P ratio deviated from the stoichiometric values due to additional ions from biogenic sources. Infrared spectroscopy identified functional groups in carbonated HAp, with changes observed before and after calcination. The full width at half maximum (FWHM) of the 961 cm−1 band decreased with age, indicating improved crystalline quality. The molar absorption coefficients provided information on the changes in molecular concentration and emphasized the differences between the age groups. X‐ray analysis revealed nanocrystalline HAp in all samples, with crystallite size increasing with age. Rietveld analysis showed that the lattice parameters were affected by the presence of organic material, but the lattice constants remained stable, confirming high crystallinity independent of age. TEM analysis confirmed nanocrystalline structures, with crystallite size increasing with age. SEM images showed the characteristic porosity of calcined HAp, with particle size correlating positively with age. Calcination at 600°C preserved the nanoscale properties and microcrystal formation. Raman spectroscopy confirmed the identity of HAp, with FWHM variations indicating age‐related changes in crystalline quality. EHAp1 showed increased FWHM, indicating lower crystalline quality and increased trace element content. [ABSTRACT FROM AUTHOR]

Recent research in solid-state physics and materials engineering focuses on the development of new dielectric materials, with bismuth-based pyrochlores being already extensively applied in communications technology for their excellent dielectric properties and relatively low sintering temperatures. Herein, the structural, morphological, electrical, and magnetic properties of Bi1.34Fe0.66Nb1.34O6.35 ceramic, prepared by the sol–gel method and sintered at 500 °C, are investigated. The Rietveld refinement of the XRD pattern showed a cubic phase belonging to the space group Fd-3m and a crystallite size of 42 nm. Transmission electron microscopy further confirmed the crystallite size and the homogeneous distribution of Bi, Fe, Nb, and O elements, as evidenced by high-angle annular dark field imaging and STEM-EDX mapping. The morphology of the sample, assessed by scanning electron microscopy, is characterized by submicron-sized spherical particles. Dielectric spectroscopic studies revealed that the dielectric properties, strongly influenced by frequency and temperature, indicate the material's potential for energy storage due to lower dielectric loss compared to the dielectric constant. The observed relaxation phenomena, confirmed through variations in dielectric loss and loss tangent, highlight the influence of grain boundaries and temperature on electron hopping and charge carrier dynamics. Using SQUID magnetometry, we identified two distinct magnetic phases. The primary phase, corresponding to the Bi1.34Fe0.66Nb1.34O6.35 ceramic, exhibits an antiferromagnetic behavior below its Néel temperature at around 8.8 K. A secondary high-Curie temperature ferrimagnetic phase, likely vestigial maghemite and/or magnetite, was also detected, indicating an estimated fraction below 0.02 wt.%. [ABSTRACT FROM AUTHOR]

In this work, the synthesis of Ho3+-doped calcium titanate perovskite (CaTiO3) revealed significant photoluminescence (PL) properties, predominantly displaying a distinct green emission. The investigation explored Ho3+-doped CaTiO3 perovskite synthesized via the sol–gel method. Structural analysis confirmed an orthorhombic crystal structure through powder x-ray diffraction (XRD) and Rietveld refinement, while Fourier transform infrared (FT-IR) spectroscopy confirmed the presence of functional groups in Ho3+-doped CaTiO3. Diffuse reflectance spectroscopy (DRS) revealed a charge transfer band between O2− and Ho3+ ions in the range of 250–350 nm, supported by photoluminescence excitation (PLE) spectra. A bandgap of 3.39 eV was found for Ho3+-doped CaTiO3. At 0.03 mol Ho3+, the PLE band intensity was saturated, indicating optimal excitation efficiency. Emission spectra revealed distinct intra 4f–4f transitions, particularly a green emission at 545 nm under 454 nm excitation corresponding to 5F4 + 5S2 → 5I8 transition. The PL intensity reached its peak at 0.03 mol Ho3+ and then decreased due to concentration quenching. Color purity reached ~90%, highlighting its potential in applications requiring precise green emission. The results of the study suggest that this perovskite is well suited for optoelectronics, lighting, displays, or industries that require specific green light emission properties. [ABSTRACT FROM AUTHOR]

In this study, BiFeO3 (BFO) and Er3+-, La3+-, and Nd3+-substituted BFO were synthesized using Pechini's modified sol–gel auto-combustion route. Comprehensive investigations were conducted on the structural, magnetic, and optical properties of the samples. X-ray diffraction and Rietveld refinement analysis provided insights into the crystal structure, which was found to be distorted rhombohedral for all the samples except for BEFO (Bi0.95Er0.05FeO3), which was orthorhombic. The crystallite size and strain were calculated by strain-size plots. Fourier transform infrared spectroscopy confirmed the crystallinity and characteristic FeO6 peaks of perovskites in all the samples. Microstructural investigations using field-emission scanning electron microscopy imaging revealed the morphological features and particle size distribution. The magnetization–hysteresis (M–H) loop demonstrated that the Ms and Mr values decreased after the incorporation of rare earth (RE) ions in the BFO lattice, while electron paramagnetic resonance analysis elucidated the magnetic interactions within the materials. In addition, UV direct reflectance spectroscopy coupled with Kubelka–Munk plot analysis facilitated the determination of band gap energy values, which were in the range of 2.11–2.22 eV. The integration of these diverse characterization techniques offers a holistic understanding of the structural, morphological, magnetic, and optical properties of BFO and its RE-substituted variants. This multifaceted approach not only enriches our knowledge of these materials but also paves the way for their diverse applications in sensors, spintronics, actuators, and photocatalysts for environmental remediation. [ABSTRACT FROM AUTHOR]

Ba3Ca2(PO4)3F, having been proven beneficial for ancient geological surveys, was also found to be an efficient fluorescence emitter when doped with various rare-earth and transition ions. Advancing the respective properties further, dysprosium (Dy3+) was added as an activator into the Ba3Ca2(PO4)3F host lattice. The Dy ion in its trivalent form possesses emission in two regions, blue at 481 nm and green at 575 nm, opening a new window towards its plausible use in white-light-emitting diode (LED) lighting appliances. Subsequent analyses including x-ray diffraction, Rietveld refinement, photoluminescence, and lifetime observed in milliseconds (ms) revealed a similar nature of the decay curves as given in the literature. Further, a CIE coordinate calculation predicted near-ideal white light emission. [ABSTRACT FROM AUTHOR]

This article describes the synthesis of CoFe2O4 nanoparticles, which can be used to form an anode for supercapacitor applications. The CoFe2O4 nanoparticles were synthesized via a hydrothermal route. The structural parameters of the prepared samples were characterized by x-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), and the supercapacitive behavior was evaluated by cyclic voltammetry plots, galvanostatic charge–discharge plots, and electrochemical impedance spectroscopy (EIS). Rietveld refinement confirmed the spinel structure of the CoFe2O4 nanoparticles with space group Fd3m. The FE-SEM micrographs confirmed the spherical shape of the CoFe2O4 nanoparticles, with a mean particle size of 58 nm. The electrochemical performance of the samples was checked in different aqueous electrolytes: Na2SO4 and KOH. The nanoparticles exhibited differences in capacitive behavior in different aqueous electrolytes, with higher specific capacitance (362 F/g) in the KOH electrolyte due to its greater molar ionic conductivity in comparison to the Na2SO4, and a low resistance value obtained from impedance measurements was observed for CoFe2O4 nanoparticles. The cyclic stability of CoFe2O4 in KOH electrolyte, with 82.16% retention after 2000 cycles at current density of 1 A/g, evidenced its outstanding performance, with exceptionally high specific capacitance of 314 F/g. [ABSTRACT FROM AUTHOR]

The environmentally friendly plant-based green synthesis approach provides a fabulous opportunity to produce versatile zinc oxide powders with multifarious morphology and/or size. In this study, it was mainly aimed at using Polygonum cognatum Meisn. extract to synthesize zinc oxide powder via a simple green synthesis route. For this purpose, zinc nitrate solution was mixed with an aqueous extract of fresh Polygonum cognatum Meisn. plant leaves to obtain a zinc-based precursor, and then zinc oxide powder was synthesized by means of calcination conducted at 400°C for 2 hours in air. Phase, spectroscopic, and microstructural analysis techniques, as well as Rietveld refinement method and Williamson-Hall analysis, were performed to investigate the powder characteristics. It was found that the synthesized high-purity zinc oxide powder had a hexagonal wurtzite crystal structure. Zinc oxide powder was observed to have a particularly large amount of nano-sized equiaxed particles (~25 nm in average diameter) together with micron- sized hourglass-like particles consisting of two hexagonal prisms (each <1 μm in height). All in all, the main implication of our research is that the Polygonum cognatum Meisn. plant can be potentially used as a biomass source for the green synthesis of zinc oxide nano/microparticles. [ABSTRACT FROM AUTHOR]

In most of the chemical methods, the as-prepared NPs have a metal hydroxide form. The calcination temperature is very important to prepare the metal oxide from metal hydroxide. Thus, in this work, the chemical precipitation and sol–gel routes were employed to produce the Nickel hydroxide nanoparticles and analyze their functional, structural, thermal, and morphological behavior of prepared NPs. The formation of Ni(OH)2 is confirmed by FTIR analysis including both techniques. Rietveld refinement techniques were used to diffraction patterns by the program FullProf. The well-matched XRD patterns reveal that prepared NPs have β -Ni(OH)2 phase and hexagonal structure (HCP) with a space group of P3m1 for both the methods. The kinetic factors were calculated using different models. The Phadnis–Deshpande model is employed to identify the mechanism of solid state kinetic reaction. Solid state kinetic model observes nucleation and nuclei growth (Avrami–Erofeev nuclei growth) and 2D diffusion mechanism for chemical precipitation and sol–gel, respectively. From the FESEM analysis, flower-shaped architectures and nanosheet morphology are presented in the prepared sample by chemical precipitation and sol–gel, respectively. From the kinetic parameters, we conclude that the decomposition of Ni(OH)2 to NiO is thermally stable, has slow reaction and spontaneous process at 300∘C. The results show that the chemical precipitation method is more suitable for energy storage application compare to the Sol–gel method. [ABSTRACT FROM AUTHOR]

This study investigates the potential of utilizing industrial by-products—mill scale (MS) and aluminum dross (AD)—as sources of Fe2O3 and Al2O3, respectively, for hercynite (FeAl2O4) production. Through combustion of MS-AD-graphite systems at 1550 °C under air atmosphere, hercynite-based refractory materials were synthesized. Results confirm the viability of this upcycling approach for hercynite synthesis. During the formation of hercynite, the development of a dendritic structure can be observed, which subsequently fuses into a grain shape. XRD phase analysis using the Rietveld method revealed that the major components of the product with a C/O ratio of 1 were 85.11% FeAl2O4, 10.99% Al2O3, and 3.9% C. For the product with a C/O ratio of 2, the composition was 82.4% FeAl2O4, 13.0% Al2O3, and 4.6% C. The combustion of raw pellets with a C/O ratio of 1 at 1550 °C for 1 h in a normal air atmosphere is economically viable for producing hercynite, yielding 85.11 wt%. This approach presents a sustainable and eco-friendly alternative to using commercial raw materials, potentially eliminating the need for virgin alumina and iron ore. By repurposing waste materials from the steel and aluminum industries, this study contributes to the circular economy and aligns with the goal of zero waste. [ABSTRACT FROM AUTHOR]

Complex oxides La 0. 9 7 Ba 0. 0 3 MnO3, La 0. 7 3 Ba 0. 2 7 MnO3 and La 0. 5 Ba 0. 5 MnO3 were synthesized and their structural properties were studied. The structural investigation of the samples is done by incorporating X-ray diffraction (XRD) and scanning electron microscope (SEM) technique at room temperature. The Rietveld method was successfully used for the analysis of the obtained diffraction spectra. It was determined that these compounds have a perovskite structure. Partial substitutions La→Ba do not disturb the ideal perovskite structure and the cubic crystal structure with the space group Pm-3m is preserved. Crystallographic parameters, lattice parameters and interatomic distances were determined for each compound. As a result of SEM studies, it was determined that the size of crystallites in LaxBa 1 − x MnO3 solid solutions ranged from 2 to 10 μ m. [ABSTRACT FROM AUTHOR]

Crystals of Ca10.5−xTMx(VO4)7 (TM = Co, Cu), belonging to the whitlockite family, were synthesized by solid-state reaction and studied as a function of the TM content (x) for the first time. The structure was refined at ambient conditions and at high temperatures up to 1200 K using the Rietveld method. The unit cell size significantly decreases with increasing TM content up to the solubility limit, xlim, which is 0.78(3) for TM = Co and 0.75(4) for TM = Cu. Occupancy factors show a preference for the M5 site by Co/Cu. The unit cell size varies smoothly with temperature, while the axial ratio exhibits nonlinear behaviour above approximately 800 K. The thermal expansion coefficient was determined from 300–1100 K. Atomic arrangement modifications at higher temperatures are indicated by changes in the axial ratio, the thermal expansion coefficient, and the reduction of fractional TM occupancy at the M5 site at specific temperatures. [ABSTRACT FROM AUTHOR]

Nitridophosphates are in the focus of current research interest due to their structural versatility and properties, such as ion conductivity, ultra‐incompressibility and luminescent properties when doped with suitable activator ions. Multinary representatives often require thorough investigation due to the competition with the thermodynamically more stable binary and ternary compounds. Another point of concern is the synthetic control of structural details, which is usually limited by conventional bottom‐up syntheses. In this study, we report on the synthesis and characterization of the quaternary nitridophosphate CaLi2PN3. Various synthesis protocols were used for the preparation of CaLi2PN3, including the novel nitridophosphate double salt approach. The crystal structure was solved and refined from single‐crystal X‐ray diffraction data and confirmed by Rietveld refinement, solid‐state NMR spectroscopy, EDX measurements and low‐cost crystallographic calculations. The experimental results were corroborated by DFT calculations, which revealed the electronic band structure. Formation energy calculations allowed conclusions to be drawn about the stability in comparison to the initial ternary nitridophosphates. The synthesis of CaLi2PN3 exemplifies the enormous potential of medium‐pressure syntheses in the field of nitridophosphate research. Furthermore, the presented new synthesis route allows a certain degree of structural control, which is a promising addition to previous synthesis strategies in nitridophosphate chemistry. [ABSTRACT FROM AUTHOR]

In this work, non-ordered and ordered CeO2-based catalysts are proposed for CO2 conversion to dimethyl carbonate (DMC). Particularly, non-ordered mesoporous CeO2, consisting of small nanoparticles of about 8 nm, is compared with two highly porous (635–722 m2/g) ordered CeO2@SBA-15 nanocomposites obtained by two different impregnation strategies (a two-solvent impregnation method (TS) and a self-combustion (SC) method), with a final CeO2 loading of 10 wt%. Rietveld analyses on XRD data combined with TEM imaging evidence the influence of the impregnation strategy on the dispersion of the active phase as follows: nanoparticles of 8 nm for the TS composite vs. 3 nm for the SC composite. The catalytic results show comparable activities for the mesoporous ceria and the CeO2@SBA-15_SC nanocomposite, while a lower DMC yield is found for the CeO2@SBA-15_TS nanocomposite. This finding can presumably be ascribed to a partial obstruction of the pores by the CeO2 nanoparticles in the case of the TS composite, leading to a reduced accessibility of the active phase. On the other hand, in the case of the SC composite, where the CeO2 particle size is much lower than the pore size, there is an improved accessibility of the active phase to the molecules of the reactants. [ABSTRACT FROM AUTHOR]

This research investigates the mechanical activation of kaolin as a supplementary cementitious material at the laboratory scale, aiming to optimize milling parameters using the response surface methodology. The study evaluated the effects of rotation speed and milling time on the amorphous phase content, the reduction in crystalline kaolinite, and impurity incorporation into the activated clay through the Rietveld method. The results demonstrated that adjusting milling parameters effectively enhanced clay activation, which is crucial for its use in low-carbon cements. High rotation speeds (300/350 rpm) and prolonged grinding times (90/120 min) in a planetary ball mill increased the pozzolanic activity by boosting the formation of amorphous phases from kaolinite and illite and reducing the particle size. However, the results evidenced that intermediate milling parameters are sufficient for reaching substantial degrees of amorphization and pozzolanic activity, avoiding the need for intensive grinding. Exceedingly aggressive milling introduced impurities like ZrO2 from the milling equipment wear, underscoring the need for a balanced approach to optimizing reactivity while minimizing impurities, energy consumption, and equipment wear. Achieving this balance is essential for efficient mechanical activation, ensuring the prepared clay's suitability as supplementary cementitious materials without excessive costs or compromised equipment integrity. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of speed sintering and glazing on the flexural strength and microstructure of multilayered 5 mol% yttria-stabilized (5Y-) zirconia, which remains unknown. Bar-shaped specimens (N = 600) were fabricated from 5Y-zirconia (FX; Ceramill Zolid FX ML, ST; Katana STML) by cutting, polishing, sintering (conventional and speed sintering), and then glazing. A flexural strength test (n = 30/group), field emission scanning electron microscopy (FE-SEM) observation (n = 2/group), and an X-ray diffraction (XRD) study with Rietveld refinement (n = 1/group) were performed. The flexural strength was analyzed using three-way ANOVA and a post hoc Scheffé test. The grain size was analyzed using the Kruskal–Wallis H test and Bonferroni–Dunn post hoc test. Flexural strength slightly decreased in the nonglazed FX after speed sintering (p < 0.05). Glazing with and without glazing paste did not affect flexural strength at both sintering speeds (p > 0.05). Speed sintering and glazing minimally changed the Weibull modulus and phase fraction, and did not affect grain size (p > 0.05). ST had a larger grain size and lower tetragonal phase content than FX and had a lower flexural strength than FX in most groups (p < 0.05). Overall, the multilayered 5Y-zirconia is considered suitable for dental application using speed sintering and glazing. [ABSTRACT FROM AUTHOR]

This article summarizes the impact of the Ti ion at the Mn site of polycrystalline Sm0.5Sr0.4Nd0.1MnO3 samples, exploring the correlation between the structural, microstructural, magnetic, and magnetocaloric properties through the solid‐state route. The Rietveld refinement pattern divulges that all samples are crystallized predominantly in the orthorhombic phase with the Pnma space group. Temperature‐dependent magnetic studies of Sm0.5Sr0.4Nd0.1Mn1‐xTixO3 (x=0, 0.1, 0.2) expose phase separation phenomena in the field cooling curve, where the first peak at 42 K corresponds to the antiferromagnetic charge ordering or spin orientation of spontaneous magnetization, and the second peak at 87 K, 75.91 K, and 74.28 K corresponds to the paramagnetic to ferromagnetic transition. The maximum magnetic entropy changes (ΔSM) at T=110 K are discerned to be 2.5 J Kg−1 K−1, 1.65 J Kg−1 K−1, and 1.31 J Kg−1 K−1, respectively. Normalization of ΔS values in Sm0.5Sr0.4Nd0.1Mn1‐xTixO3 (x=0, 0.1, 0.2) does not overlap the universal behavior at magnetic fields (1T ‐ 7T), confirming the existence of field‐induced second‐order magnetic transitions. The relative cooling power (RCP) values are found to be 777.96 J Kg−1, 255.28 J Kg−1, and 190.58 J Kg−1 respectively. Further, the enhancement of the working span temperature and the broadening of specific heat capacity peaks in Sm0.5Sr0.4Nd0.1Mn1‐xTixO3 (x=0.1, 0.2) samples make these materials a promising candidate to serve as operating substances in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

In this study, Ce2[Zr1−x(Ba1/3Nb2/3)x]3(MoO4)9 (0.02 ≤ x ≤ 0.1, CZ1−xNx) ceramics were sintered at 600 °C and 700 °C using the traditional solid-state method. An analysis conducted through XRD and Rietveld refinement confirmed that all the CZ1−xNx ceramics displayed a single phase with a trigonal structure (space group R-3c). The observed increases in cell volume with increasing x values indicate the successful substitution of (Ba1/3Nb2/3)4+. The high densification of the synthesized phase was validated by the density and SEM results. Additionally, the P-V-L theory demonstrates a strong correlation between the Ce-O bond and εr, as well as τf, and between the Mo-O bond and Q×f. Notably, the CZ0.98N0.02 ceramics demonstrated superior performance at 675 °C, exhibiting εr = 10.41, Q×f = 53,296 GHz, and τf = −23.45 ppm/°C. Finally, leveraging CZ0.98N0.02 ceramics as substrate materials enabled the design of a patch antenna suitable for the 5G communication band, demonstrating its significant potential in this field. [ABSTRACT FROM AUTHOR]

The susceptibility of either oxidation into Sn(IV) or disproportionation into Sn(IV) and Sn(0) limits the study of metal tin‐(II)‐borate ceramics. We report mullite‐type SnCrBO4 and SnVBO4 synthesized in sealed quartz tubes by conventional solid‐state method. X‐ray powder diffraction data Rietveld refinements confirm that both compounds are isostructural to PbMBO4 phases for M = Al, Ga, Cr, Mn, and Fe. The end‐members show a complete miscibility within the Sn(Cr1−xVx)BO4 solid solution. Both the microstructural (average crystallite size, microstrain, and degree of crystallinity) and crystal structural (metric parameters, bond lengths, polyhedral volume, and polyhedral distortion) parameters are observed with respect to the compositional x‐value. The stereochemical activity of the 5 s2 lone electron pairs of Sn2+ cations has been measured by using the Wang–Liebau eccentricity parameter. The structural features are complemented by 119Sn Mössbauer, Raman, and Fourier‐transformed infrared spectroscopy. The 119Sn Mössbauer isomer shifts and the quadrupole splitting values confirm the SnO4 coordination and an Sn(II) valence state. The electronic band gap has been calculated from the UV/Vis diffuse reflectance spectra, which slightly increases with successive decrease of the cationic radius from V to Cr. Temperature‐dependent inverse DC magnetic susceptibility suggests that SnCrBO4 and SnVBO4 are antiferromagnetic and ferromagnetic (FM) with a Néel temperature of 17.2(1) K and a Curie temperature of 29.8(1) K, respectively. Alike the end‐member SnVBO4, Sn(Cr0.5V0.5)BO4 is also found to be a rare FM insulator. The thermal stability decreases with increasing vanadium content in the solid solution. [ABSTRACT FROM AUTHOR]

High‐temperature piezoelectric sensing is usually used in the aerospace, automotive, and power plant fields. High temperature piezoelectric ceramics are considered the key materials in these fields. In this paper, Ca1−x(Ba1/2Sr1/2)xBi2Nb1.985(W3/4Mn1/4)0.015O9 (x = 0.05, 0.10, 0.15 and 0.20) (C1−xBSxBNWM) has been synthesized by a traditional solid state reaction method. The effects of substitution of calcium at the A‐site by barium and strontium on phase evolution and piezoelectric properties of the CaBi2Nb2O9 orthorhombic Aurivillius phases were investigated. The crystal structure of piezoelectric ceramics was characterized by XRD, Rietveld refinement, and Raman spectroscopy. Co‐substitution of barium/strontium (Ba2+/Sr2+) and tungsten/manganese (W6+/Mn4+) resulted in lattice distortion of C1−xBSxBNWM ceramics. The results induce that the tetragonal crystal structure increase with increasing the co‐substitution cations. Isothermal impedance spectroscopy confirmed intrinsic thermally activated conduction in the system. The C1−xBSxBNWM ceramics with x = 0.15 exhibit a very high Curie temperature (TC ∼ 923°C), a reasonable piezoelectric coefficient (d33 = 13.3 pC/N). Remarkably, even after thermal annealing at temperatures up to 800°C, it still retains a high d33 of 13 pC/N. In addition, the C0.85BS0.15BNWM ceramic had a relatively high resistivity (3.82 × 106 Ω·cm, 500°C). The Ca0.85(Ba1/2Sr1/2)0.15Bi2Nb1.985(W3/4Mn1/4)0.015O9 ceramics make possible their application in high‐temperature acceleration transducers. [ABSTRACT FROM AUTHOR]

Advancing the development of high‐temperature piezoelectric devices requires high‐performance piezoelectric materials with high Curie temperature, where charge signals can be efficiently collected at elevated temperatures. Recent investigations indicate that bismuth titanate‐ferrite (Bi5Ti3FeO15) is a good high‐temperature piezoelectric material because of its high Curie temperature (TC > 760°C). However, the piezoelectric performance of Bi5Ti3FeO15‐based compounds has not been extensively studied because of their extremely poor piezoelectric performance and low direct current electrical resistivity at elevated temperatures. Herein, we reported the strong piezoelectric performance enhancement in Bi5Ti3FeO15, with the nominal compositions of Bi5‐xEuxTi3FeO15 (BTF‐100xEu). X‐ray diffraction Rietveld refinements and Raman spectra reveal an enhanced lattice distortion in europium‐substituted Bi5Ti3FeO15, which is mainly dominated by rotation distortion. The increased domain wall density that detected by out‐of‐plane piezoelectric force microscopy is in favor of domain wall movement and polarization reversal. Both of the enhanced lattice distortion and the increased domain wall density contribute to the piezoelectric enhancement in Bi5Ti3FeO15, as a result, the optimal composition of BTF‐8Eu exhibits a large piezoelectric constant d33 of 24 pC/N, three times higher than that of Bi5Ti3FeO15. Importantly, BTF‐8Eu exhibits high TC of 782°C, excellent in‐situ piezoelectric response (>94% that of the initial value at room temperature), and stable electromechanical coupling properties up to 400°C. This work reveals the origin of strong piezoelectric enhancement in europium‐substituted Bi5Ti3FeO15 results from the intrinsic contribution of structure distortion and the extrinsic contribution of ferroelectric domain. [ABSTRACT FROM AUTHOR]

Erionite is the name for a zeolite mineral series originating from diagenesis or hydrothermal alteration of volcanic rocks. The particular erionite "species" is based on the dominant extra-framework cation, erionite-Ca, erionite-K, or erionite Na. Irrespective of the species, erionite can display a fibrous/ asbestiform morphology and has been linked with cases of malignant mesothelioma, a disease typically associated with asbestos exposure. Characterization of new discoveries of erionite is therefore important to assess any potential exposure hazards. This study describes a new asbestiform erionite from vesicles within the Upper Cretaceous Mt. Somers Volcanics Group (MSVG), Canterbury, New Zealand. The erionite is within the Hinds River Dacite, the youngest unit within the MSVG at Gawler Downs, ~100 km west of Christchurch, in the foothills of the Southern Alps. A multi-analytical approach was taken to analyze the sample which included micro-Raman spectroscopy, thermogravimetric analysis, electron microscopy, electron microprobe analysis, and X-ray powder diffraction with the Rietveld method. Results confirmed the mineral as fibrous erionite-K. The chemical composition of the mineral is unique due to the presence of higher levels of Mg. While Fe was also identified, this was due to smectite flakes occurring on the surface of the erionite fibers. According to the World Health Organization (WHO) respirable mineral fiber definition, where length ≥5 μm. width ≤3 μm, and aspect ratio (L/w) ≥3:1, the Gawler Downs erionite fibers are respirable, while the fibers themselves exceed respirable thickness. In addition to morphology. a value for the potential toxicity model was computed to be 2.28 for the Gawler Downs erionite. This is similar to those of other carcinogenic erionites from Karain. Turkey (2.33). and Nevada. U.S.A. (2.28). Taken together. results indicate Gawler Downs erionite represents an environmental hazard. Nevertheless. further investigation is required to determine potential environmental exposure pathways by which erionite may become airborne and assess the actual environmental risk in the Gawler Downs area. [ABSTRACT FROM AUTHOR]

Lithium‐rich layered oxides (LRLOs) are one of the most attractive families among future positive electrode materials for the so‐called fourth generation of lithium‐ion batteries (LIBs). Their electrochemical performance is enabled by the unique ambiguous crystal structure that is still not well understood despite decades of research. In the literature, a clear structural model able to describe their crystallographic features is missing thereby hindering a clear rationalization of the interplay between synthesis, structure, and functional properties. Here, the structure of a specific LRLO, Li1.28Mn0.54Ni0.13Co0.02Al0.03O2, using synchrotron X‐ray diffraction (XRD), neutron diffraction (ND), and High‐Resolution Transmission Electron Microscopy (HR‐TEM), is analyzed. A systematic approach is applied to model diffraction patterns of Li1.28Mn0.54Ni0.13Co0.02Al0.03O2 by using the Rietveld refinement method considering the R3¯$\bar{3}$m and C2/m unit cells as the prototype structures. Here, the relative ability of a variety of structural models is compared to match the experimental diffraction pattern evaluating the impact of defects and supercells derived from the R3¯$\bar{3}$m structure. To summarize, two possible models able to reconcile the description of experimental data are proposed here for the structure of Li1.28Mn0.54Ni0.13Co0.02Al0.03O2: namely a monoclinic C2/m defective lattice (prototype Li2MnO3) and a monoclinic defective supercell derived from the rhombohedral R3¯$\bar{3}$m unit cell (prototype LiCoO2). [ABSTRACT FROM AUTHOR]