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High-temperature synthesis of the perovskite composite material i.e., 0.5(SmFeO3)-0.5(Ba0.5Sr0.5TiO3) or SFO-BST was proficiently developed through solid-state reaction technique. X-ray diffractometer was utilized to analyze the polycrystalline single stage, and Rietveld Refinement approved the development of the tetragonal phase (P4mm) in the crystalline material. The dielectric, impedance, conductivity and optical behavior of the synthesized specimen have been scrutinized. At room temperature and above, the sample shows a large dielectric constant and a small tangent loss, making it an appropriate material for microwave absorbers. The complex impedance analysis demonstrates the influences of the grain and the grain boundary. The material's efficacy to be used in a new multiferroic device is supported by its ferroelectric and ferromagnetic properties. Furthermore, the application in semiconductor photovoltaic cells is endorsed through the UV–VIS data analysis. [ABSTRACT FROM AUTHOR]

An economical sol–gel auto-combustion method aided by citric acid was used to synthesize nickel ferrite ( NiFe 2 O 4 ) nanoparticles (nickel nitrate/ferric nitrate at 1:2 and metal nitrate with citric acid at 1:1, stirring condition: 600 rpm). The impurity phase present in as-synthesized nickel ferrite was removed by sintering at 950°C in a microwave furnace. Powder x-ray diffraction of the sintered sample confirmed the removal of impurity phase and showed the spinel cubic nature of the particles. The crystallite sizes of both as-synthesized and sintered particles were calculated using the Scherrer and Williamson–Hall formulas, which confirmed the formation of nanoparticles. Further, the particle size distribution and morphology of both samples were calculated using scanning electron microscopy with the help of ImageJ software. The UV–Vis spectroscopy of the particles showed strong absorption between 200 nm and 600 nm. The room-temperature magnetic hysteresis analysis revealed that both the as-synthesized (NFO-As) and sintered (NFO-950) materials exhibited a ferromagnetic nature, with maximum saturation magnetization of 50.84 emu/g for NFO-950 and higher coercivity of 179.76 Oe for NFO-As. Specific absorption rate (SAR) values of 7.976 W/g and 11.54 W/g were determined for NFO-As and NFO-950, respectively, from induction tests, which suggests the material is a suitable candidate for hyperthermia treatment. Additionally, investigation of the particles' third-order nonlinear characteristics using a Ti-sapphire femtosecond laser showed reverse saturation absorption for NFO-950. The average nonlinear absorption coefficient of NFO-950 was found to be 1.44 times that of copper ferrite nanoparticles, rendering it a suitable candidate for optical limiting applications. [ABSTRACT FROM AUTHOR]

Cancer treatment remains a pressing global challenge, with magnetic hyperthermia emerging as a promising alternative approach. The article explores the potential of pure and doped magnetite nanoparticles for hyperthermia-based cancer treatment, aiming to enhance therapeutic efficacy while minimizing side effects. Key findings include the synthesis and characterization of NPs—Fe3O4, SnFe2O4, and CoFe2O4—using co-precipitation methods, with emphasis on their size, morphology, magnetic, structural and thermal properties confirmed through techniques like SEM, EDX, VSM, XRD and TGA. The nanoparticles' hyperthermic effects were assessed through infrared imaging, showing CoFe2O4 NPs induced the highest heating efficiency as compared to Fe3O4 and SnFe2O4 NPs. Importantly, all nanoparticles showed negligible hemolysis at a concentration of 0.2 mg/ml, indicating their compatibility with human blood. This study contributes valuable insights into optimizing MNP-based hyperthermia treatments, aiming for safer and more effective cancer therapies in the future. SnFe2O4 NPs haven't been extensively explored in the context of hyperthermia applications, making it a unique contribution to the field. The research employs an innovative and cost-effective method for evaluating the hyperthermic effect of nanoparticles using an infrared camera. This approach overcomes the potential limitations associated with probe-based temperature measurement, offering a more accurate assessment of nanoparticle-induced hyperthermia. The research thoroughly compares its findings with existing literature, highlighting the novelty of the achieved results in terms of maximum hyperthermia with minimal frequency and magnetic field strength without inducing toxicity in human blood. [ABSTRACT FROM AUTHOR]

This study explores the synthesis and characterization of Fe-doped CaTiO3 compounds via the Pechini method, focusing on their structural, magnetic, and electrical properties. Notably, a previously unreported magnetic property is observed in the Fe-doped CaTiO3 compound. Despite significant structural distortions, ferroelectric polarization is identified using the Geometrical Polarization Approach (GPA), indicating its emergent nature. These distortions are attributed to robust chemical bonds between ionic O1−2 and Ti+4 sites, as evidenced by electronic density maps. This research sheds light on the potential of these materials for various technological applications. [ABSTRACT FROM AUTHOR]

Nanocrystalline system of pristine Ho2O3 (HO) and Co-doped Ho2O3 (Ho1.9Co0.1O3-δ, HCO) were synthesized by chemical co-precipitation method. These samples were investigated by analyzing structural, morphological and magnetic data. To enhance the oxygen vacancy, both HO and HCO samples are annealed in argon atmosphere at 700 ∘ C for 6 h. Rietveld analysis of X-ray diffraction (XRD) pattern of both samples confirmed the desired crystallographic phase and successful substitution of Co-ion in Ho2O3. Microstructural analyses of prepared samples are also performed by Rietveld refinement method. Energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy (XPS) analysis confirm that impurity phases like Co3O4 and CoO are absent in HCO. Also, XPS analysis indicates that mismatch of ionic valence state of dopant ion Co2+ and host cation Ho3+ introduces oxygen vacancy in HCO. Magnetization (M) as a function of applied magnetic field (H) of both bare and doped samples are recorded at different temperatures as a function of magnetic field in the range of ~ − 5 T to 5 T. Nonlinearity in M-H loops recorded at ~ 50 K indicates the presence of magnetic ordering below ~ 50 K for both samples, but the signature of ordering in doped sample more prominent than that of the pristine. Good fitting of magnetization vs. temperature curve below ~ 50 K by the combined equation of 3D spin wave model and Curie–Weiss law and lack of saturation of M-H loop below ~ 50 K indicates coexistence of paramagnetic (PM) and ferromagnetic (FM) phases in both samples. The observed magnetic phase transition is explained by vacancy mediated bound magnetic polaron (BMP) model. Also, antiferromagnetic transition in the doped sample is observed at 3 K. [ABSTRACT FROM AUTHOR]

In our study, we aimed to synthesize the Cu2Sb phase with a tetragonal structure. We achieved this by subjecting compacts (2Cu + Sb) to electrothermal explosion (ETE) with a high current density of 500 Å. To analyze the constituent phases of the alloy composite, we employed X-ray diffraction analysis with the MAUD program, which utilizes the Rietveld method, as well as scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. Furthermore, we investigated the mechanical properties through Vickers indentation and compression techniques. [ABSTRACT FROM AUTHOR]

The mechanical alloying process has been used to synthesise the nanocrystalline Fe60Al35Mg5 (wt%) powders in a high-energy planetary ball-mill Retsch PM 400. The evolution structural, microstructural and magnetic properties of ball-milled powders at different milling times (t variation from 0 to 32 h) were investigated by X-ray diffraction using the MAUD program which is based on the Rietveld method and the vibrating sample magnetometer. The XRD results reveal the formation of a bcc-Fe (Al, Mg) solid solution after 8 h of milling possessing a lattice parameter of 0.2895 nm after 32 h of milling. It is also observed a refinement of the grain size, which reaches 18.75 nm, and an increase in the microstrain after 32 h of milling. Magnetic measurements of the milled Fe60Al35Mg5 (wt%) powder mixture exhibit a soft ferromagnetic character where the magnetic parameters are found to be very sensitive to the milling time mainly due to the particle size refinement as well as the formation of the solid solutions. [ABSTRACT FROM AUTHOR]

Ni0.65Zn0.35AlxFe2−xO4 that has been synthesized using a solution-gelation method and calcined at 600 °C for 4 h was characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A single-phase cubic spinel structure belonging to the Fd-3 m space group was confirmed by Rietveld refinement. The cation distribution that was anticipated using the XRD data deviated from the preferential occupancy, and the results of the magnetization analysis supported this. The two absorption bands in the FTIR spectra corresponding to the tetrahedral and octahedral sites further support the establishment of the ferrite skeleton. Al3+ doping was found to have a considerable impact on the Debye temperature, bulk modulus, and stiffness modulus measured using FTIR data. Interatomic bonding became stronger, increasing elastic moduli. The morphology was examined using SEM, whose results showed a cluster of grains. Additionally, spherical nanoparticles with an average size of 28 nm were visible in the TEM image, which is in good agreement with the crystallite size given by the Williamson-Hall method. The Mössbauer analysis and M–H data showed a soft magnetic behavior with coercivity fluctuation. According to Arrhenius plots, all samples displayed a semiconducting characteristic. With Al3+ doping, dielectric studies revealed a declining trend. [ABSTRACT FROM AUTHOR]

In magnetron sputtering, with the simultaneous deposition of SmCo and copper, it is possible for tailoring the coercive field of SmCoCu thin films. Microstructural analysis pointed out that nanocrystalline 2:17 rhombohedral phase with diameter 10–100 nm was obtained, and coercivities in the range between 3 and 8.5 kOe. These characteristics are suitable for magnetic recording. The coercivity mechanisms are discussed. The initial magnetization curve, measured in thermally demagnetized samples, is used to discuss the coercivity mechanisms. A spring effect in the samples is observed. The spring effect is due to reversible rotation of magnetization and indicates that the coercivity mechanism is nucleation or coherent rotation of single domain size nanoscale grains. Structural data refined with X-ray diffraction Rietveld analysis for Sm2(Co,Cu)17 rhombohedral phase, Sm(Co,Cu)5 phase and cubic oxide Sm2O3 phase are provided. [ABSTRACT FROM AUTHOR]

The manganates Sm1.5–xSr1 + xBa0.5Mn2O7 for x = 0, 0.1, and 0.3 were successfully synthesized by the co-precipitation route. The compounds' crystalline structures were analyzed through powder X-ray diffraction using the refinement Rietveld method. The refined structure parameters are entirely in agreement with those expected in the case of An + 1BnO3n + 1 for n = 2 corresponding to the iso-structural Sr3Ti2O7 type. Magnetic measurements of Sm1.5–xSr1 + xBa0.5Mn2O7 (x = 0, 0.1, and 0.3) revealed the existence of a predominant antiferromagnetic ordering. Furthermore, isothermal magnetization shows that magnetization saturation is not fully attained at high fields, which can be explained by a strong super-exchange interaction of the antiferromagnetic state. The electrical resistivity at zero field shows that these compounds are electrically insulating materials, which can be explained by the predominance of the antiferromagnetic ordering. [ABSTRACT FROM AUTHOR]

CoFe2O4 nanocrystals were synthesized through chemical co-precipitation using citric acid as the capping agent. Subsequently, a green alternative was accomplished in the synthesis process by replacing the commercially purchased citric acid with naturally available lemon juice. The prepared samples were thoroughly characterized using various techniques, and the results were analyzed and the parametric variations in the two samples were compared. Using Rietveld profile refinement of the XRD patterns, the crystallographic parameters associated with both samples were explored and the cation distributions in the tetrahedral and octahedral sites were estimated. Williamson–Hall analysis of x-ray diffraction data provided the effective crystallite size and the microstrain associated with the nanocrystalline samples. The optical direct band gap and the room-temperature magnetic parameters were estimated from UV–visible spectra analysis and vibrating sample magnetometry, respectively. The coercivity, remanent magnetization, and saturation magnetization of both samples were obtained from magnetic hysteresis, and the estimated values for magnetic anisotropy energy revealed that the samples exhibited room-temperature ferrimagnetic behavior. [ABSTRACT FROM AUTHOR]

SrTiO3 is a well-known photocatalyst with various applications, such as antibacterial agents, self-cleaning surfaces, and water and air conditioning. With the increased environmental pollution, SrTiO3 is one of the most studied perovskite photocatalysts, exhibiting pronounced photocatalytic activity for removing chemical pollutants and water splitting. In the present work, pure Strontium titanate (ST) nanoparticles were successfully prepared using high-energy ball milling and Pechini techniques and characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), scanning and transmission electron microscopy, respectively. Structural parameters were evaluated by Rietveld refinement analysis from XRD data, which confirmed the cubic system of SrTiO3 with Pm-3 m space group. Scanning electron microscope results showed that ST1 samples consisted of agglomerated and irregular-shaped structures between 20 and 40 nm, and in ST2, the particles were round-shaped and had an average size of 150 nm. The obtained nanoparticles were used for photocatalytic methylene blue (MB) degradation, and synthesis methods' influence on catalytic activity was investigated. The photocatalytic studies examining the decoloration of MB dye reveal the function of smaller particles in increasing the rate of reactions. The degradation rate constant of MB on the ST1 (Pechini-synthesized sample) and ST2 (high energy ball milled sample) is 0.0145 and 0.0112 min−1, respectively. The better photocatalytic activity of the ST1 demonstrated 93% degradation of dye under the solar light simulator. The photocatalytic reaction data provided well a first-order kinetic model. [ABSTRACT FROM AUTHOR]

This work reports the magnetic phase transition in the polycrystalline La0.90Pr0.10Mn0.8Co0.2O3 perovskite sample. The solid-state reaction was used for the synthesis of the polycrystalline sample. The detailed study of this polycrystalline sample includes the structural characterization by Rietveld refinement. The surface morphology by FESEM demonstrates a well-prepared sample. The EDAX spectra show the elemental confirmation in the prepared sample. For the detailed magnetic study, M–T and M–H measurements were performed by applying various external magnetic fields at various temperatures. The ZFC and FC curves have been measured under variable temperatures and they show the magnetic phase transition from ferromagnetic to paramagnetic. Also, the splitting between ZFC and FC curves depicts the relaxation mechanism in the sample. The scaling law suggests the orientation, strain effects, and domain structures. The FWHM of the peaks of both (ZFC & FC mode) is increasing with the applied field. This may be due to the magnetic relaxation in the sample. The M–H loops also confirm the ferromagnetic to a paramagnetism phase transition; however, the non-saturating appearance of M–H curves of all three systems is indicative of high magnetic anisotropy. [ABSTRACT FROM AUTHOR]

In this work, the magnetoelectric composites (1 – x)PbZr0.52Ti0.48O3–xCoFe2O4 ((1 – x)PZT–xCFO) have been synthesized using the combination of sol-gel (for PZT ceramic) and the solid-state (for CFO material) methods. X-ray powder diffraction results and Rietveld refinement have shown that the PZT compound crystallizes in two tetragonal and rhombohedral structures with P4mm and R3m space groups, respectively, while the CFO material has shown a spinel cubic structure with Fd3m space group. The (1 – x)PZT–xCFO composites, for x = 0.10 to 0.50, have been fitted and matched very well to the phases corresponding to PZT and CFO materials. The effect of sintering temperature on the structural and dielectric properties of these composites has been also studied (for x = 0.20). It has been found that the phase is stable for 900°C for 4 h while for 1000 and 1100°C we obtain many secondary phases. On the other hand, the pellet sintered at 900°C shows a low dielectric permittivity value and high relaxation behavior. The scanning electron micrographs (SEM) reveal multigrain agglomerations for all the samples and the grain size is maximal (about 2 µm) for x = 0.10 of CFO content and minimal (about 0.7 µm) for pure CFO. The dielectric properties of the composite samples have been also investigated as a function of temperature and showed one phase transition at 410°C for PZT ceramic. This phase transition has shifted to the lower temperature and present a relaxation phenomenon with the increase of CFO content. The dielectric permittivity decreases with the increase of CFO rate related to the CFO ceramic which has a low dielectric permittivity value. The magnetic properties of these magnetoelectric (ME) composites have been also studied by measuring the magnetization as a function of temperature. The obtained results show one maximum of around 427°C related to the phase transition temperature of CFO. In addition, the magnetization value is found to increase when CFO content increases indicating an intrinsic ME coupling. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3 or BFO), is an extremely promising multiferroic material having broad range of applications. In the present study, we investigated the optimization of annealing temperature for the preparation of pure phase bismuth ferrite using quantitative Rietveld analysis of XRD patterns. The rhombohedral structure was confirmed by X-ray diffraction with R3c space group as a primary phase (pure BFO) along with a cubic secondary phase (Bi25FeO40) having space group I23. The quantitative analysis of refine data shows the decrease in the values of fitting parameters in case of double refinement and hence convergence towards the best fitting. Also, with the increase in annealing temperature, very nominal decrease in phase percentage of secondary phase was observed. At annealing temperature of 780 °C, the intensity of (110) planes suddenly becomes more in comparison to (104) planes. The average crystallite size of samples was calculated using Scherrer formula, W–H plot method, and Rietveld method, and lattice strain was derived from the W–H plot method. Overall, the crystallite size increases with the increase in annealing temperature. It has been also observed that the strain, lattice parameters, unit cell volume, and effective bond lengths decrease with the increase in annealing temperature, but no significant change was observed in bond angles with the variation in annealing temperature. [ABSTRACT FROM AUTHOR]

Single-phase spinel Mn0.05Zn0.95Fe2O4 was synthesised by auto combustion method using metal nitrates and Glycine via various mediators (a) Aloe vera, (b) ethylene glycol, and (c) egg white represented as (a) MZF-AV, (b) MZF-EG, and (c) MZF-EW respectively. The experimental characterisation was done using XRD, vibration sample magnetometer (VSM), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and UV–Visible spectrometer. The structural parameters and electron density distribution, hence bonding, were analysed using the computational techniques of Rietveld and the maximum entropy method (MEM). The estimated minimum crystallite size of the sample by x-ray method is 16 ± 0.72 nm for the sample grown via the Aloe vera. VSM results show superparamagnetism in MZF-AV was further confirmed by magnetization vs temperature with zero field cooled (ZFC)/field cooled (FC) protocol. The ZFC/FC curve reveals the blocking temperature of 57.7 K and single domain superparamagnetic particle size of 9.4 nm for the sample MZF-AV. The samples MZF-EG and MZF-EW show little ferromagnetism with small coercivity and retentivity. SEM results show hexagonal-shaped crystal formation for the sample grown via egg white, while others show non-spherical highly agglomerated particles. EDX results are convincing without any impurity addition. MEM electron density analysis favours superparamagnetism with maximum tetrahedral A–O and octahedral B–O covalent bonding. Electron density distribution analysis based on MEM shows a significant variation in type and strength of inter bonding between A–O, B–O, and super exchange bonding between A–A, A–B, and B–B. [ABSTRACT FROM AUTHOR]

Pristine Antimony tungstate nanoparticles prepared via a simple hydrothermal process showcase interesting photocatalytic efficiency, degrading Methylene Blue (MB) completely in 180 min under visible light. In this study, the impact on crystalline quality and related optical properties as well as photocatalytic efficiency of antimony tungstate due to temperature variation during hydrothermal synthesis are explored. While X-ray diffraction (XRD) shows the polycrystalline nature of all synthesized samples; however, a systematic increase in crystallite size is revealed by analysing the XRD peak broadening. XRD spectra are further examined by Rietveld analysis showing a change in unit cell volume. Additionally, the overall changes in the corresponding grain size and micro-strain developed in the crystals are determined using the Williamson-Hall plot. Moreover, significant variations in few Raman modes are observed with increasing synthesis temperature. A notable modification in the optical band gap as determined from the absorbance of the UV–Vis spectra is perceived with the change in synthesis temperature within the range of ~ 2.38–2.57 eV. Further, the photoluminescence measurement indicates that the synthesized antimony tungstate is weak luminescent material with a band-to-band emission at ~ 468 nm. Finally, photocatalytic efficiencies of the samples are ascertained to change with the synthesis parameter, estimated by decomposing methylene blue (MB), highest degradation rate constant (k) value is observed as 0.015 min−1 for the sample prepared at 180 °C. While the sample with the highest efficiency is also applied for degrading the Rhodamine B (RhB) and Potassium Dichromate (K2Cr2O7) under visible light irradiation. [ABSTRACT FROM AUTHOR]

Mx-Bi2O3 (M = None, Ni2+, Ce3+, Eu3+ and Yb3+) nanomaterials were fabricated by a facile and low temperature solid state method using a basic bismuth nitrate, nickel nitrate, cerium nitrate, europium trioxide and ytterbium trioxide raw compounds at 400 ˚C and 24 h. Rietveld analysis data showed that α-Bi2O3 was crystallized well in monoclinic crystal system with the space group of P121/c1. The data revealed that some of the crystallographic parameters of the synthesized materials were changed by doping the metal ions into Bi2O3 crystal system. The morphology of the synthesized materials was studied by field emission scanning electron microscope (FESEM) images. Direct band gap energy (Eg) values were calculated by ultraviolet – visible (UV-Vis) spectra. The data showed that the Eg of the synthesized materials were in the range of about 2.4 to 2.75 eV. Vibrating-sample magnetometer (VSM) analysis data confirmed that the synthesized samples had ferromagnetic behavior. The highest Ms value was obtained for Yb3+-doped Bi2O3 (0.025 emu/g). Electrochemical property of the synthesized Bi2O3 nanomaterial was studied by cyclic voltammetry (CV) analysis. The data confirmed that Bi2O3 can be used in energy storage applications. Impedance spectroscopy (EIS) plot of Bi2O3 revealed that the Z value was about 15–20 Ω/cm2. The slope of the curve was near to 90° representing the good capacitor behavior of Bi2O3. [ABSTRACT FROM AUTHOR]

Single-phase, nanocrystalline Zn2+ substituted cubic spinel CaFe2O4 with the composition ZnxCa1-x Fe2O4 (x = 0.0, 0.05, 0.1, 0.15) was prepared by solvothermal method. The magnetic properties of the prepared samples were analysed by vibration sample magnetometer (VSM), which reveals a switching from soft ferromagnetic behaviour to super-paramagnetic for an increase in Zn2+ doping concentration. The maximum coercivity of 405.54 G and squareness ratio of 35.8% is obtained for pure CaFe2O4, and the doping of nonmagnetic Zn2+ ions gradually loses the ferromagnetism. Neel's two sublattices' collinear model well explains the overall magnetic property. The surface morphology and elemental composition were analysed using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. An optical bandgap analysis was carried out using UV–Visible spectroscopy, revealing a random variation of the optical energy gap with composition. X-ray peak analysis reveals the single-phase cubic spinel structure with Fd-3 m space group. The estimated crystallite sizes range from 22 to 39 nm, and lattice parameter varies in random fashion with the increase of Zn2+ doping concentration. Mixed cubic spinel structure is revealed from cation distribution analysis. Rietveld refinement technique is utilised for structural refinements. The maximum entropy method (MEM) is used for the experimental electron density analysis and hence bonding. The 3D, 2D and 1D MEM analyses reveal the weakest tetrahedral A–tetrahedral A bonding and the alteration in tetrahedral A–octahedral B and octahedral B–octahedral B bond strength with doping. Moderate A–O and B–O covalent bonding favours maximum saturation magnetism of 83.59 emu/g for the composition Zn0.05Ca0.95Fe2O4. [ABSTRACT FROM AUTHOR]

This work aims to understand the magnetic behaviour in the La0.70Pr0.30Mn0.8Co0.2O3 perovskite sample. The sample was prepared by a solid-state reaction. The Rietveld refinement gives orthorhombic crystal structure with lattice constants, i.e. a = 5.4928(5) Å, b = 7.7683(7) Å, and c = 5.5148(5) Å. The magnetization shows the ferromagnetic to paramagnetic transition. The blocking temperature (TB = 151 K) and paramagnetic Curie temperature (θp = 189 K) have been found by the magnetization versus temperature (M-T) curves. The blocking temperature indicates the interaction between internal magnetic energy and thermal energy. This interaction can also be clearly seen in the coinciding temperature (Tcon). The scaling law also supports the paramagnetic Curie temperature. The derivative of M-T curves shows a magnetic phase transition at 163 K temperature. The M-H loops show the ferromagnetic nature at a lower temperature and paramagnetic at room temperature which supports our M-T results. The Tg (spin-glass transition) decreases with increasing field. The Kneller's fitting gives the TB = 176 K. The loop squareness value is decreasing with increasing temperatures. The peak width (2Hm) suggests that magnetic domains exist in the sample at lower temperature. [ABSTRACT FROM AUTHOR]

This research work aims to investigate the mechanical alloying of Fe15Co2P3 powder mixture in terms of phases' formation, microstructural parameters, and magnetic properties as function of milling time. Parametric Rietveld refinement method, of the obtained X-ray patterns, was performed for qualitative and quantitative phase analysis alongside the determination of structural, microstructural, and mechanical properties. The ball-milled powder mixture crystallized within the face-centered cubic α-Fe(P) solid solution in equilibrium with Co75Fe25 phase. The crystallite size decreases reaching 100 and 200 nm respectively after 3 h of milling. The highest values of the dislocation density, microstrain, and stored energy are registered for the α-Fe(P) solid solution. The studied mechanical properties manifest the brittle nature of the α-Fe(P) solid solution compared to the Co75Fe25 phase. The squareness ratio Mr/Ms and the coercivity values of the milled powders increase with increasing milling time and reach steady state after 2 h. The hysteresis loss energy and maximum permeability reach minimal values of 45 × 10−4 W/m3 and 49 × 10−3 H/m respectively, after 1 h of milling at the opposite of the switching field distribution. The obtained results demonstrate the formation of nanostructured Fe15Co2P3 ternary alloy with optimum characteristics as promising candidate for diverse applications primarily in the biomedical field for diagnostics and therapeutics such as magnetic hyperthermia and vector probes for future imaging technologies. [ABSTRACT FROM AUTHOR]

This study deals with improving the properties of lightweight aggregate by the addition of Ca-bentonite mineral to expandable clays. The addition of bentonite can result in advanced lightweight aggregate materials which meet international standards. Besides bentonite material, twelve different clays (from Egyptian and Hungarian mines) were studied by X-ray fluorescence (XRF), X-ray powder diffraction (XRD, Rietveld method), and a heating microscope (HM). Aggregates were produced and their physical and mechanical properties were measured. The structure and the chemical composition of the clay-Ca bentonite aggregates were studied by scanning electron microscope (SEM) and with energy dispersive spectroscopy (EDAX). The results showed that the addition of 10 wt% bentonite can reduce the bulk density by up to 20%, can increase the compressive strength by up to 180%, and can increase the height of expansion by up to 68% in some samples. It was found that the high kaolinite content of the clay samples was not beneficial for expanding and decreasing the bulk density of aggregates. According to the Rietveld method from XRD and a statistical correlation model shown, the amorphous contents have a reciprocal relationship with the bulk density and a direct relationship with the height expansion. Bentonite, as a natural additive, to some clays, was suitable for producing lightweight aggregates with far better properties, as well as a more economical means of production. [ABSTRACT FROM AUTHOR]

Present work describes the synthesis of Sr3Al2O6 nano powders by one-step solid state reactions using Al﴾NO3)3.6H2O, Sr﴾C2H3O2)2 and Sr﴾NO3)2 at 800 and 900 ̊C for 8 h. For the synthesis of Sr3MxAl2O6 + δ ﴾M = Sm3+, Eu3+, Ho3+ and Yb3+) nano powders, Al﴾NO3)3.6H2O, Sr﴾NO3)2, Eu2O3, Ho2O3 and Yb2O3 were used at 800 ̊C for 8 h. Characterization of the as-synthesized materials was performed by X-ray powder diffraction (XRPD) technique. The rietveld analyses data were studied to investigate the reaction conditions on the crystal phase growth and purity of the obtained materials. According to the rietveld analyses data, it was found that reaction temperature and raw materials type had important role on the crystal phase growth and purity. The data indicated that doping the lanthanide ions into Sr3Al2O6 crystal phase improved the purity of the final products. The morphologies of the synthesized materials were studied by field emission scanning electron microscopy (FESEM) technique to study the effect of the reaction conditions on the morphology of the obtained materials. As shown by the FESEM measurements, Sr3Al2O6 nanomaterials had almost particles and porous morphology. However, the type and homogeneity of the porous structures were different. BET data revealed that the reaction time and temperature, and the raw materials type had important roles on the textural properties. The data showed that the highest specific surface area value was 5 m2/g. Vibrating-sample magnetometer (VSM) analysis showed that the as-synthesized nanomaterials had ferromagnetic property. Ultraviolet–visible spectra indicated that the nanostructured Sr3Al2O6 powder had absorption in the ultraviolet and visible light regions and the direct optical band gap energies were in the range of 3.4 to 3.8 eV. The data indicated that when Eu3+ was doped into the crystal system, a sharp absorption peak was observed in the visible light region suggesting the visible light region active property. [ABSTRACT FROM AUTHOR]

Ce1-xSmxO2-δ (x = 0.0, 0.1, 0.2, 0.3) samples were prepared by sucrose and pectin–assisted auto combustion method. The phase identification, morphology, spectroscopic properties, and electrical properties of the samples are studied by XRD, FESEM, Raman spectrometer, and impedance spectroscopy. Rietveld refinement was carried on XRD samples for structural properties. Samples showed a single phase with the cubic fluorite structure. The average crystallite size was in the range of 10–17 nm. The sample Ce0.8Sm0.2O2−δ exhibits improved conductivity with low activation energy in comparison with pure ceria. [ABSTRACT FROM AUTHOR]

Unprecedented analysis of the impact of high-level Al3+ substitution on the structural and magnetic properties of low-coercivity Co0.5Zn0.5AlxFe2−xO4 (0.3 ≤ x ≤ 0.8) nanoferrites prepared via autocombustion method is presented. Single-phase cubic structure has been assured for all samples using XRD patterns and FTIR spectra. Due to the notable difference in the ionic radii of Fe3+ and Al3+, structural defects are created for high substitution levels, which is to be balanced by cation redistribution and/or the appearance of Fe2+ and Co3+ cations. Rietveld analysis and size-strain plots were used to explain the non-monotonic change of the lattice parameter, microstrain and crystallite size. For the as-prepared samples, the estimated size ranged from 9 to 19 nm, which was confirmed by HRTEM images. Magnetic properties were deduced from M–H loops traced at room temperature. Saturation magnetization (MS) decreased with increasing Al3+ content while coercivity (Hc) was fluctuating. Based on the experimental data of XRD, FTIR, and VSM, a cation distribution has been proposed and tightly correlated with the structural and magnetic properties. The significant reduction of the lattice parameter and coercivity for the sample with x = 0.8 upon sintering process has been explained in the light of the cation distribution. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3 or BFO in short), one of the very promising multi-ferroic materials possessing a rhombohedrally distorted perovskite structure, has been synthesized using conventional solid-state reaction method. Eight sets of samples were prepared by varying initial synthesis parameters. Effects of precursors' grinding time, heating rate, quenching rate and sintering temperature on the phase, structural and spectral properties of obtained materials were systematically studied using XRD, FTIR and Rietveld methods. The results revealed that the optimal condition to obtain pure-phase BiFeO3 is using preheated furnace with sintering at 1073 K and then quenching in air for rapid cooling with intermediate grinding time of 3 h. Rietveld analysis applied on the X-ray diffraction data via Fullprof software indicated around 97% purity of the sample with the above-mentioned conditions. Deviation from the above temperature or grinding time or quenching rate leads to an increase in the phase fractions of Bi2Fe4O9 and Bi25FeO40 which are the major secondary phases formed during the synthesis of bismuth ferrite. [ABSTRACT FROM AUTHOR]

Hydrochloric acid hydrolysis in its gas form was used to produce cellulose nanoparticles from flax shives with a very high yield (> 90%). The efficiency of the transformation was examined by gravimetry, atomic force microscopy and transmission electron microscopy. A novel purpose-built anisotropic line-broadening X-ray diffraction model was used. This XRD method uses a parametric shape in order to address the issue of strongly broadened and overlapping Bragg rays that are characteristic of nano-sized crystallites. This method demonstrated the remarkable stability of the crystallite shapes during hydrolysis and its sensibility was sufficient to detect a minor co-crystallization along the hydrophilic faces. The presence of amorphous material strictosensu in the form of individual and randomly oriented chains was not necessary to describe the diffractograms accurately. Thermal FTIR with isotopic exchange was also performed using deuterium oxide to characterize the accessibility of the materials between 20 and 260 °C. Further, back-exchange experiments were performed in order to quantify the hysteretic amount of deuterium that was trapped by microstructural reorganization. These experiments showed that hydrolysis cancelled any form of deuterium trapping (water-induced co-crystallization). For the first time, thermal FTIR demonstrated that isotopic labelling of cellulose sources can produce false positives when conducted at room temperature and thermal FTIR can unambiguously distinguish between labelled cellulose groups and free deuterium oxide, which is paramount when measuring the higher accessibility of the nanocelluloses. It was also demonstrated that the high-temperature hydrogen bond reorganization and thermal degradation of the cellulose chains strongly depend on the hydrolysis and on the microstructure of the substrate. [ABSTRACT FROM AUTHOR]

In this study, pure barium zirconium titanate Ba(Zr0.5Ti0.5)O3 (BZT) powders were successfully synthesized via the mechanochemical route using barium carbonate and titanium oxide as precursors. Structural properties of BZT are characterized by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscope, energy dispersive X-ray spectrometry, thermogravimetric analysis, and FT-IR spectroscopy. It was observed that the ball milling operation has a significant influence on sintering temperature. Single-phase BZT was obtained under sintering conditions at 1350 °C. XRD and Rietveld refinement studies revealed that BZT composition has a cubic structure with a space group of Pm-3m (#221). As estimated by the Scherrer formula, the average crystallite size was determined as 79.2 nm for sintering temperature at 1350 °C. [ABSTRACT FROM AUTHOR]

Microwave (MW) assisted synthesis of hydroxyapatite (HAP) nanopowders (NPs) is an efficient and eco-friendly contemporary technique. This paper discusses the influence of two MW parameters i.e., microwave power (MWP) and irradiation time (MWIT) on structural and physicochemical properties of HAP NPs. MWP and MWIT settings had little effect on phase constitution of NPs as suggested by XRD analysis. HAP was a major phase in all NPs. Rietveld refinement suggested that with the increase in MWP and changes in MWIT settings, bond length, and Ca/P molar ratio increased, whereas, crystal size, crystallinity, and microstrain of NPs decreased. Also, HAP unit cell contracted along a-axis and expanded along c-axis with the increase in MWP and changes in MWIT settings. FTIR corroborated XRD phase analysis and suggested bone-like apatitic formation in all NPs. FESEM indicated agglomerated state of NPs constituted of nano-dimensional elongated particles. TEM suggested the rod shaped particles having aspect ratio varied between 2 and 3. EDX results corroborated with XRD and FTIR results. By analysis of all results, properties of NPs irradiated at 900 and 1200 W were relatively more promising. Hence, this study systematically and minutely examined the overall effect of MW parameters on various properties of HAP NPs. Graphical abstract: [ABSTRACT FROM AUTHOR]

Bioinert cum bioactive titania reinforced hydroxyapatite (T-HAP) nanopowders (NPs) have been receiving great attention in load-bearing orthopedic and dental implant applications. This study comprehensively evaluated the in vitro performance of T-HAP NPs immersed in SBF for different durations for 7 and 30 days. Duration of immersion had little effect on phase constitution of phase pure and T-HAP NPs as suggested by XRD analysis. Rietveld refinement suggested that with the increase in duration of immersion, inter-atomic distance between atoms of HAP phase and crystallinity of NPs decreased, whereas lattice parameters, cell volume, crystal size, and microstrain in T-HAP NPs increased. FTIR supported XRD phase analysis and suggested bone-like apatitic formation in all NPs. SEM indicated the agglomeration of NPs composed of particles of irregular shapes and sizes. EDX results corroborated with XRD and FTIR results. Hydrodynamic diameter measured using DLS were compared to be significantly bigger than crystal sizes (Rietveld and Scherrer) calculated using XRD data. During in vitro study, pH measurement of SBF suggested the bioactive nature of all NPs and also revealed the higher rate of solubility of T-HAP NPs. All T-HAP NPs gained weight after respective days of immersion in SBF. Hence, this study systematically and minutely evaluated the in vitro performance of T-HAP NPs immersed for different durations in SBF. [ABSTRACT FROM AUTHOR]

This work deals with the drying kinetics of three red clays with different mineralogical composition and grain size distribution used for the production of clay bricks. The kinetic study was performed using thermo-gravimetry (TG) in both non-isothermal and isothermal mode in the 50-200 °C range. To the knowledge of the authors, this is the first time that the drying process of clay bricks is studied using the TG method to present a general model at molecular scale of the phenomenon. The observed drying mechanism is composed of a fast initial step and a slow final step. The former is characterized by an Avrami-like mechanism with an Avrami coefficient n comprised between 1 and 2. This kinetic parameter indicates a diffusive control in three dimensions with instantaneous or deceleratory nucleation and refers to desorption of adsorbed water from the surface of all mineral phases. The second step is also characterized by an Avrami-like mechanism with n = 1 and points to a diffusion-controlled reaction in two dimensions, with instantaneous nucleation. This step involves dehydration of plastic clay minerals such as illite, smectite and IS through diffusion of water molecules within the two-dimensional interlayer. The apparent activation energies related to the first fast mechanism have similar values (<32 kJ mol) for all samples. The apparent activation energy E for the second slower step is dependent upon the mineralogical composition and is >35 kJ mol. The dependency of the apparent activation energies on grain size distribution and sample mass was also assessed. [ABSTRACT FROM AUTHOR]

The Rietveld method is a versatile tool to parameterize the fine structure of crystallites analyzed by diffraction. The method relies on a crystallographic model representing what is known a priori, and free coefficients determined from fits to experimental data. This article provides an introduction to Rietveld analysis of celluloses from higher plants that are adequately described by the cellulose Iβ crystal structure. Possibilities of Rietveld analysis have been recently enhanced by a tailored crystallographic model and computational algorithm, named Cellulose Rietveld Analysis for Fine Structure (CRAFS). From each two-dimensional diffraction pattern, CRAFS automated analysis outputs unit cell parameters, crystallite sizes, peak profile functions, integrated crystalline intensity (proportional to cellulose degree of crystallinity), and crystallite orientation distribution function. Two of the major hurdles for analysis of plant cellulose-overlapping of diffraction peaks and preferred crystallite orientation-are consistently treated by the two-dimensional Rietveld analysis. Hence, the method is a unique tool to explore cellulose fine structural variability, with differences arising from specimen conditioning, processing, and biological origins. [ABSTRACT FROM AUTHOR]

Bismuth titanate (BiTiO) was developed by means of titanium oxide (TiO) suspension in auto-combustion process at 220 °C to get nanosized (20 ± 5 nm) bismuth titanate (BiTiO) powder. Complete piezoelectric phase (tetragonal) was obtained after calcination at 700 °C. Dilatometery of compacts was performed to find out sintering temperature. On the basis of shrinkage results, compacts were sintered at 750, 800, and 850 °C for 2 h. After sintering single phase was obtained with orthorhombic structure analyzed by X-ray diffraction and also investigated by Rietveld method. High-resolution scanning electron microscopy revealed that fine plate-like structure which is a characteristic of BIT powder can be obtained at 850 °C. Sintering results indicate that density and average grain size increase with the increasing temperature. A maximum of about 90 % of the theoretical density was achieved for the sintered product at 850 °C. [ABSTRACT FROM AUTHOR]

Two morphological types of the synthetic analogue of the mineral natisite NaTiSiO have been prepared in the system NaO-TiO-SiO-HO. The crystal structures of the obtained pillow ( A)- and coin ( B)-shaped particles have been refined with similar parameters by the method of Rietveld, compared to each other and to the available single crystal X-ray diffraction data. Sample B showed bigger unit cell with longer a = b and shorter c-axis when compared with phase A. The shorter a = b axes in phase A led to compensative elongation of the c-axis and notably longer terminal bond distance in the TiO semi-octahedra. Analysis of the refined structural parameters showed that Ti-O bond of the unshared apical oxygen is the most responsive to the lattice strain. Additionally, the overall mechanism of structural response to the observed microstructural distortions is discussed. Graphical Abstract: The possible influence of different particle morphology on the Rietveld refinement results of synthetic natisite has been evaluated[Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

Neutron powder diffraction (NPD) offers many advantages in the analysis of battery materials. Understanding the relationship between the structural transformations of electrode materials and their electrochemical performance within lithium-ion batteries is crucial for further development of these technologies and is the overall goal of in situ NPD experiments. In this work, we present NPD data of electrode materials within batteries that are collected in situ during electrochemical cycling, including the commercially available materials LiCoO, LiMnO, LiFePO and graphite and the YFe(CN) and FeFe(CN) materials that are not commercially available. Using these data, we illustrate the experimental approach and requirements for the collection of in situ NPD data of sufficient quality for detailed structural analyses of the electrode components of interest within batteries. [ABSTRACT FROM AUTHOR]

The core mathematics, goodness-of-fit parameters of Rietveld refinement technique is introduced for structural analysis of crystalline materials not available as single crystals. X-ray diffraction (XRD) patterns of PbTiO compound prepared by following solid-state route, suggests it to be in single crystal form. All the observed peaks could be indexed to P4 mm space group with tetragonal symmetry. XRD pattern is analysed by employing Rietveld method. The unit cell parameters are found to be a = b = 38987 (0.0008) Å and c = 4·1380 (0·0009) Å. The axial ratio c/a and unit cell volume are found to be 1·0614 and 62·896 (0.023) Å. Bond lengths and angles are calculated using the cell parameters. Using the Rietveld refinement parameters a stable PbTiO structure is suggested. [ABSTRACT FROM AUTHOR]

This article studied the thermal behavior and the evolution of the crystalline phases with temperature of the red mud (bauxite tailing) from an aluminum industry at Maranhão, North-Northwestern Brazil. The experiments were carried out by Field Emission Scanning Electron Microscopy (FE-SEM), Simultaneous Thermal Analysis (TG-DSC), Optical Dilatometry up to 1623 K, and X-ray diffraction (XRD) of previously heated samples between 523 and 1523 K. The crystalline phases and the amorphous contents were quantified on raw and heated samples (at 1523 K) according to the Rietveld Quantitative Analysis (RQA) method. The data obtained showed that the raw red mud is composed by a mixture of seven different phases (hematite, goethite, sodalite, anatase, gibbsite, calcite, and amorphous). Finally in the interval of 1023-1523 K the following crystalline phases: hematite, nepheline, sodalite, anatase, perovskite, and pseudobrookite have been observed. [ABSTRACT FROM AUTHOR]

A recently developed synchrotron-based imaging technique, X-ray diffraction microtomography (XRD-CT), has been applied here for the first time to a complex system, the hydrating Portland cement paste, in order to monitor the evolution of microstructure and phase formation with a 3D non-invasive imaging approach. The ettringite-XRD-peak-based image reconstructions, combined with transmission microtomography (X-μCT) images, allowed to assess the ubiquitous distribution of this phase, which appears early in the hydration process and showed its preferential concentration in the relatively less compact regions of the paste. The comparison of greyscale histograms for cement pastes after 9 and 58 h from hydration showed an increase of ettringite content with age, in agreement with the quantitative Rietveld analysis of the sum patterns. By renormalizing the greyscale histograms to the relative weight fraction, as obtained from Rietveld refinements, a new technique which allows estimation of phase contents with spatial resolution has been developed. The results achievable by combining XRD-CT, X-μCT and Rietveld appear very promising to provide experimental snapshots of the cement hydration process to be compared with results obtained from computer simulations. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The crystal structure of alunite (K0.72,Na0.28) Al3(SO4)2(OH)6 from El Gnater, central Tunisia, is refined by the Rietveld method. Raman and infrared data of this mineral are also given in order to provide some further information about the mineralogy and chemistry of this alunite. The crystal system is trigonal, space group R $$ \bar 3 $$ m, with a = 6.9834(4) Å and c = 17.0899(11) Å. Final Rietveld refinement converges to R p = 0.16, R wp = 0.16, and R Bragg = 0.07. In the alkalic site, the occupancy of potassium and sodium is refined to 72 and 28%, respectively. The Raman and infrared spectra are investigated in order to improve previous assignments of the observed frequencies, especially for tetrahedral and octahedral vibration and OH group, which are discussed on the basis of unit-cell group analysis and by comparison with previously observed wavenumbers of natrojarosite and synthetic alunite. [ABSTRACT FROM AUTHOR]

Nanostructured α-Fe2O3 powders were prepared by high-energy ball milling. The milling process spans grinding times from 30 min to 24 h. The as-milled samples were characterized by means of 57Fe Mössbauer spectrometry, Rietveld analysis of X-ray diffraction data and particle size analysis. The obtained results evidence the presence of disordered hematite characterized by a hyperfine field distribution with a well-behaved dependence on the mean crystallite size for which the mean hyperfine field decreases asymptotically as the grain size decreases. A new relationship is proposed in order to describe such behavior. Finally the presence of superparamagnetic grains, the occurrence of a partial topotactic phase transformation into a spinel phase and tool induced contamination are also presented and discussed. [ABSTRACT FROM AUTHOR]

The structure of the orthorhombic phase in the MoVNbTeO propane ammoxidation catalyst system has been characterized and refined using a combination of TEM, synchrotron X-ray powder diffraction (S-XPD), and neutron powder diffraction (NPD). This phase, designated as M1 by Ushikubo et al. [1], crystallizes in the orthorhombic space group Pba2 (No. 32) with a = 21.134(2) Å, b = 26.658(2) Å, and c = 4.0146(3) Å. The formula unit is Mo7.5V1.5NbTeO29. Bond valence sum calculations indicate the presence of d1 metal sites neighbored by d0 metal sites. The d1 sites are occupied by a distribution of Mo5+ and V4+, whereas the d0 sites are occupied by a distribution of Mo6+ and V5+. Out-of-center distortions in d0 octahedra are consistent with the second-order Jahn–Teller effect and lattice effects. We argue that the V5+–O–V4+/Mo5+ moieties adjacent to Te4+ and Mo6+ sites in the [001] terminal plane provide a spatially isolated active site at which the selective ammoxidation of propane occurs. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the structural and magnetic properties of the GdHoRuO (0≤ x≤2) pyrochlores. X-ray diffractograms of all samples studied presented a cubic pyrochlore type crystal structure with lattice parameters varying linearly in accordance to Vegard's law. It is shown that by substituting Gd by Ho one can tune the magnetic order of this system moving from antiferromagnetic (in the absence of Ho) to ferromagnetic (in the absence of Gd). [ABSTRACT FROM AUTHOR]