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To elucidate the epitaxial strain effect over a wide range of lattice mismatch, we investigated the structures of ∼ 25 nm thick LaNiO 3 films grown on the pseudocubic (001) surfaces of three different substrates, namely, LaAlO 3 (LAO), SrTiO 3 (STO), and DyScO 3 (DSO). Such structural information had been inferred from the intensities of a small number of Bragg reflections that relate to the NiO 6 octahedral tilting in previous studies. Here, we measured more than 100 reciprocal lattice points to derive reliable structural information. The procedure of ordinary crystal structure analysis is hampered by the multidomain structure and limited volume of measurable reciprocal space, both caused by a huge, highly symmetric substrate. To overcome this difficulty, we employed the Bayesian inference to obtain the detailed atomic positions in film samples. Octahedral tilting about the c axis was dominant for the compressively strained film grown on LAO, whereas tilting about the a and b axes was dominant for the tensile strained films grown on STO and DSO. The film lattice parameters of the samples grown on STO and DSO were nearly identical, whereas additional twofold lattice modulation, including cation displacement, was only observed in the latter. [ABSTRACT FROM AUTHOR]

A definition of structural diversity, adapted from the biodiversity literature, is introduced to provide a general characterization of structures of condensed matter. Using the favored local structure lattice model as a testbed, the diversity measure is found to effectively filter extrinsic noise and provide a useful differentiation between crystal and amorphous structures. We identify an interesting class of structures intermediate between crystals and glasses that are characterized by a complex combination of short-range ordering and long-range disorder. We demonstrate how the diversity can be used as an order parameter to organize various scenarios by structure change in response to increasing diversity. [ABSTRACT FROM AUTHOR]

In this study, Pb(Zr0.54Ti0.46)O3 films were prepared by the sol-gel method with Sm doping concentrations of 0, 0.5, 1, 1.5, 2, and 3 mol. %. Their surface morphology, density, crystal structure, piezoelectric, dielectric, and ferroelectric properties were characterized. The results indicated that, unlike Sm-doped lead zirconate titanate (PZT) ceramics, all Sm-PZT films exhibit a significant increase in the grain size compared to undoped PZT films. Moreover, Sm doping affected their crystal orientation and significantly enhanced their piezoelectric coefficient d33 and remnant polarization (Pr). Notably, the Sm-PZT film with a doping concentration of 1.5 mol. % exhibited optimal (100) orientation, achieving a high piezoelectric coefficient d33 of 279.87 pm/V, 4.55 times that of the non-doped PZT films. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are promising candidate materials for photo-driven processes. Their crystalline and tunable structure makes them well-suited for placing photoactive molecules at controlled distances and orientations that support processes such as light harvesting and photocatalysis. In order to optimize their performance, it is important to understand how these molecules evolve shortly after photoexcitation. Here, we use resonance Raman intensity analysis (RRIA) to quantify the excited state nuclear distortions of four modified UiO-68 MOFs. We find that stretching vibrations localized on the central ring within the terphenyl linker are most distorted upon interaction with light. We use a combined computational and experimental approach to create a picture of the early excited state structure of the MOFs upon photoactivation. Overall, we show that RRIA is an effective method to probe the excited state structure of photoactive MOFs and can guide the synthesis and optimization of photoactive designs. [ABSTRACT FROM AUTHOR]

Inert gases (e.g., He and Xe) can exhibit chemical activity at high pressure, reacting with other substances to form compounds of unexpected chemical stoichiometry. This work combines first-principles calculations and crystal structure predictions to propose four unexpected stable compounds of CH4Xe3, (CH4)2Xe, (CH4)3Xe, and (CH4)3Xe2 at pressure ranges from 2 to 100 GPa. All structures are composed of isolated Xe atoms and CH4 molecules except for (CH4)3Xe2, which comprises a polymerization product, C3H8, and hydrogen molecules. Ab initio molecular dynamics simulations indicate that pressure plays a very important role in the different temperature driving state transitions of CH4–Xe compounds. At lower pressures, the compounds follow the state transition of solid–plastic–fluid phases with increasing temperature, while at higher pressures, the stronger Xe–C interaction induces the emergence of a superionic state for CH4Xe3 and (CH4)3Xe2 as temperature increases. These results not only expand the family of CH4–Xe compounds, they also contribute to models of the structures and evolution of planetary interiors. [ABSTRACT FROM AUTHOR]

The development of new materials typically involves a process of trial and error, guided by insights from past experimental and theoretical findings. The inverse design approach for soft-matter systems has the potential to optimize specific physical parameters, such as particle interactions, particle shape, or composition and packing fraction. This optimization aims to facilitate the spontaneous formation of specific target structures through self-assembly. In this study, we expand upon a recently introduced inverse design protocol for monodisperse systems to identify the required conditions and interactions for assembling crystal and quasicrystal phases within a binary mixture of two distinct species. This method utilizes an evolution algorithm to identify the optimal state point and interaction parameters, enabling the self-assembly of the desired structure. In addition, we employ a convolutional neural network (CNN) that classifies different phases based on their diffraction patterns, serving as a fitness function for the desired structure. Using our protocol, we successfully inverse design two-dimensional crystalline structures, including a hexagonal lattice and a dodecagonal quasicrystal, within a non-additive binary mixture of hard disks. Finally, we introduce a symmetry-based order parameter that leverages the encoded symmetry within the diffraction pattern. This order parameter circumvents the need for training a CNN and is used as a fitness function to inverse design an octagonal quasicrystal. [ABSTRACT FROM AUTHOR]

Crystal structure, bandgap, and the changes in the charge conduction mechanisms in ceramics are interrelated, and the underlying physics unifies all these different phenomena. The experimental and theoretical evaluation of the electronic properties of the solid solution of (1 − x)BaTiO3–(x)LaFeO3 (x = 0, 0.015, 0.031, 0.062) is attempted in this work. Bandgap was observed to be tunable with La/Fe doping from 3.2 eV (x = 0) to 2.6 eV (x = 0.06), while the lattice disorder was found to increase. A theoretical assessment confirms a considerable shift of valence band maxima and conduction band minima with an introduction of additional defect states within the bandgap. Electron localization was also confirmed theoretically with doping. Such changes in the electronic properties were experimentally confirmed from dielectric/AC - conductivity/impedance spectroscopy studies. From different transportation models, hopping is a preferred mechanism in the less distorted BaTiO3. However, a large polaron tunneling process can be justified for the doped samples at lower temperatures. Only at higher temperatures, a small polaron tunneling can be justified for the doped samples. The transportation is affected by the grain boundaries as much as the grains themselves. A complete analysis using Nyquist plots reveals the competing contributions of these regions to the transportation mechanism and is correlated to the disorder/distortions in the lattice in terms of the formation of oxygen vacancies. [ABSTRACT FROM AUTHOR]

Engineered reverse hairpin constructs containing a partial C-heptad repeat (CHR) sequence followed by a short loop and full-length N-heptad repeat (NHR) were previously shown to form trimers in solution and to be nanomolar inhibitors of HIV-1 Env mediated fusion. Their target is the in situ gp41 fusion intermediate, and they have similar potency to other previously reported NHR trimers. However, their design implies that the NHR is partially covered by CHR, which would be expected to limit potency. An exposed hydrophobic pocket in the folded structure may be sufficient to confer the observed potency, or they may exist in a partially unfolded state exposing full length NHR. Here we examined their structure by crystallography, CD and fluorescence, establishing that the proteins are folded hairpins both in crystal form and in solution. We examined unfolding in the milieu of the fusion reaction by conducting experiments in the presence of a membrane mimetic solvent and by engineering a disulfide bond into the structure to prevent partial unfolding. We further examined the role of the hydrophobic pocket, using a hairpin-small molecule adduct that occluded the pocket, as confirmed by X-ray footprinting. The results demonstrated that the NHR region nominally covered by CHR in the engineered constructs and the hydrophobic pocket region that is exposed by design were both essential for nanomolar potency and that interaction with membrane is likely to play a role in promoting the required inhibitor structure. The design concepts can be applied to other Class 1 viral fusion proteins.

Deep ultraviolet (DUV) nonlinear optical (NLO) crystals have important applications in lithography, microfabrication, and high-resolution photoelectric spectrometer. In recent years, significant progress has been made in both the theoretical design and experimental research of DUV NLO crystals. This review aims to offer a comprehensive perspective on exploring a new generation of DUV NLO materials. First, we summarize various computer-aided strategies for crystal structure design and emphasize their significant role in advancing the discovery of DUV NLO materials. Then, we outline several representative DUV crystals of experimental synthesis. Finally, we discuss the future prospects for exploring new generations of DUV NLO materials. We believe that employing data-driven, computer-aided methods to explore DUV NLO materials will help address the current challenges in the field of DUV NLO materials research. The close integration of calculation and experimentation will unlock new opportunities. [ABSTRACT FROM AUTHOR]

The surface optical (SO) phonon replica in photoluminescence (PL) spectroscopy of nitride nanowires (NWs) was theoretically investigated in this study. The dispersive relationships of SO phonon mode in anisotropic wurtzite (WZ) and isotropic zinc-blende (ZB) crystal structure NWs with circular and square cross sections (CSs) were derived within the framework of the dielectric continuum model. Based on the energy and momentum conservation laws, a constraint relationship between the frequency and wave-number was constructed for SO phonon-assisted excitonic PL spectra in the NW structure. By combining the dispersive and constraint relationships, the frequency and wave-number of the SO phonon replica in the PL spectra could be determined. The WZ and ZB crystal structures of nitride semiconductor were considered. The influences of surface factors including the CS shape, dielectric medium, and environment temperature on the frequency and photon wavelength of the band-edge emission of the SO phonon replica were studied in detail. Numerical results reveal that the crystal structure, surface factors, and environment temperature greatly affect the frequency and photon wavelength of the band-edge emission of the SO phonon replica. The calculated results for the photon wavelength agree well with the experimental values of the SO phonon replica in AlN NWs. The results of the dielectric effect obtained here are also supported by previous experimental and theoretical results for nitrides and other semiconductor NWs. The present theoretical scheme and numerical results can be used to analyze and design the SO phonon replica in PL spectra of nanostructures. [ABSTRACT FROM AUTHOR]

Ice is different from ordinary crystals because it contains randomness, which means that statistical treatment based on ensemble averaging is essential. Ice structures are constrained by topological rules known as the ice rules, which give them unique anomalous properties. These properties become more apparent when the system size is large. For this reason, there is a need to produce a large number of sufficiently large crystals that are homogeneously random and satisfy the ice rules. We have developed an algorithm to quickly generate ice structures containing ions and defects. This algorithm is provided as an independent software module that can be incorporated into crystal structure generation software. By doing so, it becomes possible to simulate ice crystals on a previously impossible scale. [ABSTRACT FROM AUTHOR]

In this report, the high-temperature transport properties of (Dy1−xCax)(Zr0.2Hf0.2Sn0.2Ti0.2Ge0.2)O7 pyrochlore oxides with x = 0, 0.05, and 0.1 are studied in dry and humid air. The phase composition and crystal structure were determined by using x-ray and neutron diffraction. The addition of calcium to the structure caused an increase in the concentration of oxygen vacancies, indicating an ionic charge compensation mechanism. Electrical studies allowed us to determine the total electrical conductivity as a function of the synthesis atmosphere and pH2O. The electrical conductivity turned out to be at the level of ∼10−3 S/cm at 800 °C, and only a slight effect of the presence of protonic defects in the structure on the total electrical conductivity was observed. In general, the samples had a low electrical conductivity with a relatively high activation energy of conduction. [ABSTRACT FROM AUTHOR]

Tailoring the crystal structure, spin, and charge state of perovskite oxides through fluorine ion doping is an attractive and effective strategy, which could significantly modify the physical and chemical properties of base oxides. Here, BaFe1−xMnxO3−δ (x = 0, 0.1, 0.2, 0.3) and BaFe1−xMnxO2.9−δF0.1 (x = 0.1, 0.2, 0.3), belonging to 6H-type BaFeO3−δ, are prepared and investigated to evaluate the impact of F− doping. The distortion of crystal structure and the reduced average valence of Mn and Fe confirm the preference for F− substitution in the hexagonal layer, which are found as the key factors for the improved magnetic properties, including ferromagnetic ordering temperature, coercive force, and remanent magnetization. Moreover, the valence reduction of B-site ions and the increased resistance distinctly indicate the expense of electron hole via fluorine doping. This work describes the adjustment of crystal structure, electronic configuration, and ferromagnetic performance by simple F− doping, which provides a prospect for practical magnetic materials. [ABSTRACT FROM AUTHOR]

Tailoring the crystal structure, spin, and charge state of perovskite oxides through fluorine ion doping is an attractive and effective strategy, which could significantly modify the physical and chemical properties of base oxides. Here, BaFe1−xMnxO3−δ (x = 0, 0.1, 0.2, 0.3) and BaFe1−xMnxO2.9−δF0.1 (x = 0.1, 0.2, 0.3), belonging to 6H-type BaFeO3−δ, are prepared and investigated to evaluate the impact of F− doping. The distortion of crystal structure and the reduced average valence of Mn and Fe confirm the preference for F− substitution in the hexagonal layer, which are found as the key factors for the improved magnetic properties, including ferromagnetic ordering temperature, coercive force, and remanent magnetization. Moreover, the valence reduction of B-site ions and the increased resistance distinctly indicate the expense of electron hole via fluorine doping. This work describes the adjustment of crystal structure, electronic configuration, and ferromagnetic performance by simple F− doping, which provides a prospect for practical magnetic materials. [ABSTRACT FROM AUTHOR]

The high-pressure synthesis of double-core nanothreads derived from pseudo-stilbene crystals represents a captivating approach to isolate within the thread chromophores or functional groups without altering its mechanical properties. These entities can be effectively utilized to finely tune optical properties or as preferential sites for functionalization. Bibenzyl, being isostructural with other members of this class, represents the ideal system for building co-crystals from which we can synthesize double-core nanothreads wherein bridging chromophores, such as the azo or ethylene moieties, are embedded in the desired concentration within a fully saturated environment. To achieve this, a critical step is the preliminary characterization of the high-pressure behavior of crystalline bibenzyl. We report here an accurate investigation performed through state-of-the-art spectroscopic techniques, Raman and Fourier transform infrared spectroscopy, and x-ray diffraction up to 40 GPa. Our findings reveal a strongly anisotropic compression of the crystal, which determines, at pressures between 1 and 2 GPa, consistent modifications of the vibrational spectrum, possibly related to a torsional distortion of the molecules. A phase transition is detected between 9 and 10 GPa, leading to a high pressure phase where, above 24 GPa, the nanothread formation is observed. However, the observed reaction was limited in extent and required significantly higher pressures in comparison to other members of the pseudo-stilbene family. This comprehensive study is imperative in laying the foundation for future endeavors, aiming to synthesize double-core nanothreads from pseudo-stilbene crystals, and provides crucial insights into the high-pressure behavior and phase transitions of crystalline bibenzyl. [ABSTRACT FROM AUTHOR]

We study epitaxial growth, crystal structures, and magnetic properties of Fe–As compound thin films grown on GaAs (111)B substrates at various values of the As4:Fe flux ratio γ, using molecular beam epitaxy. The samples grown at low As4 flux (γ = 0.3, sample A) show mainly a body-centered-cubic (bcc) crystal structure, exhibiting ferromagnetic properties similar to bcc Fe. Meanwhile, the Fe–As samples grown at medium γ (2.7–4.5, sample group B) comprise regions of Ni2In-type FeAs (a hexagonal crystal with lattice constants of a = 0.399 nm and c = 0.536 nm), which are grown at the bottom and interface with the GaAs buffer layer, and a layer of non-stoichiometric FeAs with a DO3 structure (a = 0.522 nm) formed on the top. The DO3-structure FeAs phase contains partially transformed regions, which are characterized by thin stripes in a scanning transmission electron microscopy image. Furthermore, in the sample grown with high γ = 8.5 (sample C), a hexagonal Fe–As crystal with a large in-plane lattice constant (a = 0.691 nm and c = 0.542 nm) and threefold screw axes are observed. None of these crystal structures of Fe–As compounds has ever been reported. While sample C shows no ferromagnetism, the samples in group B exhibit strong ferromagnetism with high Curie temperature TC above 400 K. These new ferromagnetic Fe–As compounds are promising for spintronic device applications. [ABSTRACT FROM AUTHOR]

Inspired by the single-bonded nitrogen chains stabilized by tetravalent cerium, pentavalent tantalum, and hexavalent tungsten atoms, we explored the possibility of single-bonded nitrogen polymorphs stabilized by trivalent lanthanum ions. To achieve this, we utilized the crystal structure search method on the phase diagram of binary La–N compounds. We identified three novel thermodynamically stable phases, the C2/c LaN3, P-1 LaN4, and P-1 LaN8. Among them, the C2/c phase with infinite helical poly-N6 chains becomes thermodynamically stable above 50 GPa. Each nitrogen atom in the poly-N6 chain acquires one extra electron, and the spiral chain is purely single-bonded. The C2/c phase has an indirect band gap of ∼1.6 eV at 60 GPa. Notably, the band gap exhibits non-monotonic behavior, decreases first and then increases with increasing pressure. This abnormal behavior is attributed to the significant bonding of two La–N bonds at around 35 GPa. Phonon spectrum calculations and AIMD simulations have confirmed that the C2/c phase can be quenched to ambient conditions with slight distortion, and it exhibits excellent detonation properties. Additionally, we also discovered armchair-like nitrogen chains in LaN4 and the armchair and zigzag-like mixed nitrogen chains in LaN8. These results provide valuable insights into the electronic and bonding properties of nitrides under high pressure and may have important implications for the design and development of novel functional materials. [ABSTRACT FROM AUTHOR]

Piezoceramics with the formula Pb0.93Sr0.06Ba0.01(Mg1/3Nb2/3)0.035(Ni1/3Nb2/3)0.2 (Sb1/2Nb1/2)0.015(ZrxTi1−x)0.75O3 + 0.5 wt. % Li2CO3, where x = 0.51, 0.50, 0.49, 0.48, 0.47, and 0.46, have been made using the one-step solid-state method. The phase structure and electrical properties were systematically investigated in the quinary system. Here, the crystalline structure transformed gradually from the rhombohedral to tetragonal phase with decreasing Zr content. More importantly, the effective piezoelectric coefficient d33* of the ceramics demonstrates an excellent thermal stability below the Curie temperature. Meanwhile, piezoelectric ceramics with x = 0.49 exhibited the extraordinary electrical properties near the morphotropic phase boundary. A huge piezoelectric coefficient d33 = 853 pC/N, high Curie temperature TC = 152 °C, and the electromechanical coupling coefficients kp = 67.4%, kt = 63.5%, and k33 = 67.4% were obtained at the composition of x = 0.49, which may lead a promising future for the transducer applications. [ABSTRACT FROM AUTHOR]

In situ temperature-dependent crystal structure of lead-free ferroelectric perovskite Ba0.798Ca0.202Zr0.006Ti0.994O3 single crystal was characterized using x-ray diffraction from 170 to 380 K. Three phases were identified at different temperatures of 170, 220, and 298 K, revealing rhombohedral (R3m), orthorhombic (Pmm2), and tetragonal (P4mm) crystal structures, respectively. The change in the bond length and its distortion are reported for both AO12 and BO6 polyhedrons, allowing for the estimation of the spontaneous polarization. The Debye–Waller factor is reported as a function of temperature for A and B-sites. Density-functional theory calculations on the tetragonal phase were performed to obtain information on the distribution of the Ca ions, the local atomic displacements, and the ideal value of the spontaneous polarization of a defect-free crystal at 0 K. We find that Ca prefers to arrange in columnar 2D plates oriented along the tetragonal axis. The Ca ions avoid being next neighbors of Zr; however, the specific arrangement of Ca has only a minor impact on the spontaneous polarization. [ABSTRACT FROM AUTHOR]

The interplay between crystal nucleation and the structure of the metastable fluid has been a topic of significant debate over recent years. In particular, it has been suggested that even in simple model systems such as hard or charged colloids, crystal nucleation might be foreshadowed by significant fluctuations in local structure around the location where the nucleus first arises. We investigate this using computer simulations of spontaneous nucleation events in both hard and charged colloidal systems. To detect local structural variations, we use both standard and unsupervised machine learning methods capable of finding hidden structures in the metastable fluid phase. We track numerous nucleation events for the face-centered cubic and body-centered cubic crystals on a local level and demonstrate that all signs of crystallinity emerge simultaneously from the very start of the nucleation process. We thus conclude that we observe no precursor for the crystal nucleation of hard and charged colloids. [ABSTRACT FROM AUTHOR]

Photonic topological insulators have been widely studied due to the robustness of energy transport via supported edge modes immune to structural disorder. In this work, a topological gap waveguide is constructed by introducing line defect into a topological photonic crystal structure and combining it with a gap waveguide structure, the design of which, therefore, combines the advantages of both topological and gap waveguides. Not only does it give high transmission efficiency but it also enables high robustness for energy transmission under structural defects and sharp bends. Our proposed topological waveguide design can be implemented with conventional semiconductor technology and integrated into optical circuits for communication systems. [ABSTRACT FROM AUTHOR]

Thermoelectric materials can directly convert between thermal energy and electrical energy, and their efficiency is determined by the average dimensionless figure of merit ZT. The crystal SnSe has been discovered with unique transport features and ultra-high ZT values. Considering the high production cost, long processing time, and poor mechanical properties of crystal SnSe, it is important to achieve mass production and commercial applications in polycrystal SnSe with good processability and low cost. This perspective summarizes the strategies to improve the thermoelectric properties of polycrystal SnSe, including composition control to tune the carrier concentration and modify the band structure, and process control to texture the grains and remove oxides, which all mainly focused on enhancing the peak ZT values of polycrystal SnSe. Recently, a novel structure control strategy was implemented to modulate the crystal structure of SnSe. By alloying proper ternary compounds, the cubic-structure polycrystal SnSe was obtained with completely different thermoelectric transports and high-ranged overall ZT values. This structure control strategy offers an effective way to enhance the wide-range thermoelectric performance of polycrystal SnSe and provides a new research idea for the development of highly efficient thermoelectric materials, especially for those with low-dimensional structures. [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]

Sr 2 V 2 O 7 (SVO) microwave dielectric ceramics were fabricated through a conventional solid-state synthesis method and sintered at 900–1000 °C for 10 h. The crystal structures and morphologies of the SVO samples were examined via X-ray diffraction and scanning electron microscopy. These analyses revealed that the SVO sample sintered at 950 °C exhibited high crystallinity and a triclinic crystal system. Through the lens of lattice dynamics, the phonon characteristics of the SVO samples were investigated via Raman spectroscopy and far-infrared spectroscopy to elucidate the dielectric response mechanics and microstructural origins of these responses. Raman spectra were classified into three sections corresponding to the vibration of Sr2+ ions, the V–O or V–O–V telescopic vibration, and the internal elongation of the tetrahedral structure composed of V–O, respectively. The inherent dielectric properties obtained from the far-infrared spectra were analyzed using a four-parameter semi-quantum model with the assistance of the Focus software. This analysis aligned with the measured property values. The relationships between the crystal structures and the dielectric properties were established using the Raman modes. Particularly, the SVO sample sintered at 950 °C exhibited excellent dielectric properties, characterized by a dielectric constant (ε r) of 9.49, a quality factor (Q × f) of 35,189 GHz, and a resonant frequency (f) of 12.48 GHz. [ABSTRACT FROM AUTHOR]

Dy3+, Eu3+ co-doped glass ceramics (GCs) containing SrMoO 4 crystalline phase were prepared by melt-curing-crystallization method. The most favorable heat treatment conditions for the glass ceramics were found to be 610 °C/2 h by differential scanning calorimetry (DSC), ultraviolet spectrophotometer (UV–Vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The best doping concentrations of Dy3+ and Eu3+ in this glass ceramic were 0.8 % and 0.6 %, concentration quenching caused by dipole-dipole interactions occurs when the content of rare earth ions in GCs continues to increase. The chromaticity coordinates of the Dy3+- Eu3+ co-doped glass ceramics changed from cool white light to warm white light with the addition of Eu3+ concentration. At the optimal doping concentration (0.8 % Dy3+-0.6 % Eu3+), the chromaticity coordinate of glass ceramics is (0.3972, 0.3331), and the related color temperature is 3047 K. The luminescence intensity can still reach about 80 % of room temperature at 180 °C, and its thermal quenching activation energy is 0.233 eV. This suggests that glass ceramics have excellent thermal stability. After adding an appropriate amount of Li+, the crystalline phase of the glass ceramics remained unchanged and the luminous intensity of the glass ceramics increased by a factor of about 1.4 in the same environment. The thermal quenching activation energy of the glass ceramic doped with 0.2 % Li+-0.8 % Dy3+-0.6 % Eu3+ was 0.344 eV. The experimental results indicate that GCs has potential application prospects in the field of solid-state lighting. [ABSTRACT FROM AUTHOR]

Crystal structure, microstructure, static and dynamic magnetic properties of Ba 3-x Nd x Co 2 Fe 24 O 41 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were investigated. Samples were prepared via sintering at 1250 °C for 4 h, and XRD results revealed their crystal structure after Nd substitution. With the increase in Nd3+ ion dopant content, particle porosity increased, leading to slight decrease in volume density. Static magnetic data showed the weak effect of Nd-substitution on saturation magnetization strength and a slight increase in coercivity (from 52 Oe to 75 Oe at x = 0–0.5), while out-of-plane magnetic anisotropy rose significantly (from 10.1 kOe to 14.5 kOe at x = 0–0.5). Dynamic magnetic tests demonstrated noticeable decrease in permeability (from 17 to 8), whereas cutoff frequency increased from 0.8 GHz to 1.9 GHz and the maximum Snoek product reached 18.8 GHz for the sample with x = 0.4. The fitting of real part of permeability using domain wall resonance and natural resonance models revealed that resonance frequency and out-of-plane anisotropy both increased with Nd-substitution. Moreover, despite Nd doping, samples maintained low magnetic loss and high Q value within higher frequency range. Therefore, findings of this study provide a pathway to development of substituted Z-type barium (Co 2 Z) ferrites for high frequency applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) oxides are paid great attention due to their good thermal stability, but the high lattice thermal conductivity (κ L) largely impedes their further development. In this paper, a Hollandite-type structure and multiple dopants in K x Ti 8 O 16 -based oxides are studied to seek for an ultralow κ L. Benefited from the complex crystal structure, a relatively low κ L (2.13 W m−1 K−1 at 373 K) is obtained in K 1.78 Ti 8 O 16. The Ba dopant can make the [TiO 6 ] octahedra undistorted and increase the Ti3+ amount, leading to a doubled power factor. Meanwhile, the dual-doping effect of Ba and Nb dopants can further decrease the κ L to 0.85 W m−1 K−1. Thus, a competitive zT value of 0.18 is obtained in Ba 1.15 Ti 7.2 Nb 0.8 O 16 at 1073 K. This work demonstrates that the TE performance of Hollandite-type oxides deserves to be further studied and a complex crystal structure can be designed to achieve a high zT value. [ABSTRACT FROM AUTHOR]

Entropic stabilization of the crystal structure of solids was demonstrated for various systems, starting with metals and continuing with oxides, nitrides, borides, and more complex structures. The influence of additional thermodynamic driving forces sometimes allow to stabilize the material in a crystalline configuration that is unusual for it. In this paper, we focused on the HfZrCeYMgO system, which has shown excellent mechanical properties and a stable crystal structure. We added different concentrations of aluminum oxide, but found that even in significant quantities, it was embedded in the lattice without separating into separate phases. At the same time, we found that the addition of aluminum significantly increases the crystallinity of the coating as well as its mechanical characteristics. We associate the increase in coating crystallinity with a consistent increase in the entropy of mixing in the HfZrCeYMgAlO system. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) substituted for CrCd x Fe 1-x O 3 (x = 0.0, 0.025, 0.050, 0.075) nanocrystallites were prepared using the sol-gel technique. The synthesized materials were sintered at 700 °C for 4 h to obtain the CrCd x Fe 1-x O 3 phase. The XRD analysis evidenced the formation of a single-phase rhombohedral structure of all the synthesized materials. The crystallite size values of prepared samples lie in the nanoscale range (37–42 nm). Rietveld refinement endorsed materials' pure-phase rhombohedral structure. Cationic distribution and the Wykoff position are also derived from Rietveld refinement results. A 3D crystal structure was drawn using a CIF file from refinement results. The vibrational band ν 1 oscillates from 492 to 502 cm−1 due to substituting Cd2+ at the tetrahedral site, while ν 2 remains unaltered. XPS results verified the existence of all metal ions and their related electronic state. The electrical transport features were evaluated at microwave frequency. The values of dielectric parameters were optimized with frequency and Cd2+ substitution. Grain boundary contribution was elucidated by impedance Cole-Cole plots. The minimum reflection loss of −57 dB suggested the potential use of these materials in microwave absorption applications. [ABSTRACT FROM AUTHOR]

Novel yellow-emitting Ca 2 Gd(Sb,Nb)O 6 :Pr3+ phosphors were prepared via a conventional solid-state reaction. Their crystal structure, chemical composition, and photoluminescence (PL) emission properties were comprehensively studied. In this work, the same phase structure (monoclinic in the space group of P 21/c (14) in both Ca 2 GdSbO 6 :Pr3+ and Ca 2 GdNbO 6 :Pr3+ phosphors confirmed that the B′ site composition (Sb5+ and Nb5+) of the Ca 2 GdB'O 6 double-perovskite structure slightly affected the phase structure while the Pr3+ was going to substitute the Gd3+ site. Moreover, the concentration quenching mechanism for both Ca 2 GdSbO 6 :Pr3+ and Ca 2 GdNbO 6 :Pr3+ phosphors was an electric dipole-dipole interaction. The emission spectrum of Ca 2 GdNbO 6 :Pr3+ phosphors appeared to red-shift because of structure distortion. Afterward, the chromaticity coordinates of the optimal Ca 2 GdSbO 6 :Pr3+ and Ca 2 GdNbO 6 :Pr3+ phosphors were determined as (0.462, 0.473) and (0.499, 0.453) in the yellow-emitting region. Finally, under the blue-green (BG) light excitation, the emission intensity, thermal stability, and decay curves of the optimal Ca 2 GdSbO 6 :Pr3+ and Ca 2 GdNbO 6 :Pr3+ phosphors were compared as well. [ABSTRACT FROM AUTHOR]

Europium-hydroxyapatite (Eu-HA) nanocomposite was developed via continuous hydrothermal synthesis. Eu+3 ions partially replaced the Ca+2 ions within hydroxyapatite molecular structure. High quality Eu-HA nanorods of 20 nm width and 6 μm lengths were verified via TEM micrographs. Eu-HA maintained the crystalline structure of HA with minimum change; material studio software confirmed the partial replacement of Ca+2 by Eu+3. XPS analysis demonstrated Eu+3 content of 6.91 atom %. Ca/P ratio was found to be 1.405 and 0.118 for virgin HA and Eu-HA respectively; this was ascribed to the partial replacement of Ca+2 with Eu +3. The EDAX mapping verified the uniform dispersion of Eu ions within Eu-HA structure. Eu-HA nanocomposite was uniformly distributed in silica sol-gel matrix; subsequently it was applied on AZ31 magnesium alloy. The corrosion performance of Eu-HA sol-gel coating nanocomposite (Eu–S) was evaluated using different electrochemical techniques including Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscope (EIS), and Electrochemical Noise (EN) in aerated 0.1 M NaCl solution. Corrosion protection was assessed to that of neat silica sol-gel coating (NSG). Pitting was detected over the whole NSG coated sample, after few hours of immersion in the corrosive solution. EuS coated AZ31 withstand up to 144 h without any sign of corrosion or delamination. EIS analysis with PDP parameters suggested the formation of protective layer; that is responsible for the corrosion resistance. Europium has unique ability to form a protective oxide layer acting as a barrier layer that could prevent the penetration of corrosive electrolyte to the underlying metal substrate. [ABSTRACT FROM AUTHOR]

Hypothesis: The physical and mechanical properties of triacylglycerols (TAGs), or 'fats', depend on their composition and thermal history which, in turn, impact crystal structure and morphology. We examine whether thermal history can be mechanistically related to film removal by a surfactant solution. Experiments: Model TAG mixtures, comprising triolein:tripalmitin:tristearin 0.5:0.3:0.2, were subjected to a range of cooling profiles from the melt (0.5-80 °C/min, Newtonian and annealed), and the resulting solid films characterised by microscopy, X-ray diffraction, infrared spectroscopy, and contact angle measurements. Film removal from a model glass substrate by an aqueous surfactant solution of sodium dodecylsulphate and dodecyldimethylamine oxide at room temperature fixed at 25 °C was examined under quiescent flow conditions. Findings: Quantitative relations are established between TAG cooling profile, crystal structure and morphology, surface energy γ S F E , and removal (or 'cleaning'). In general, films cooled slowly from the melt yield heterogeneous morphologies with predominantly β 1 ′ phase, higher polar γ S F E , and faster removal timescales. By contrast, rapid cooling results in homogeneous films, rich in β 2 ′ phase, low polar γ S F E , and long removal times. Our results elucidate the non-trivial impact of TAG thermal history, connecting the multiscale semi-crystalline structure to surface energy, and eventually to film delamination by micellar solutions. [ABSTRACT FROM AUTHOR]

High-entropy carbides with tunable crystallization and growth have been demonstrated using single-source precursor derived ceramic route. The in situ nanocrystallization of high-entropy carbide phases, (Ta 0.2 W 0.2 V 0.2 Mo 0.2 Nb 0.2)Si δ C and (Ta 0.167 W 0.167 V 0.167 Mo 0.167 Nb 0.167 Si 0.167)C in amorphous Si-based ceramic matrices was achieved by using polysiloxanes and polycarbosilanes as polymer precursors respectively. The results exemplify a prominent role of the architectures of the polymeric precursors in controlling the structural features of these ceramics at various length scales. In particular, it was observed that high-entropy carbides with rock salt and zinc blende crystal structures were formed when polysiloxanes and polycarbosilanes with different backbone structure were used as polymeric precursors respectively. This is attributed to the thermodynamics of nucleation of the carbidic phases in these nanocomposites. Furthermore, the precursor architecture that dictates free carbon content, influenced nanostructural features and porosity in the material. Therefore, engineering such compositionally complex phases is feasible by selecting suitable polymeric precursors. • Precursor architecture influenced the crystal structure of high-entropy carbides. • Crystal structure dependent on earliest nucleated carbidic phase. • Free carbon played a key role in controlling crystallite size and porosity. [ABSTRACT FROM AUTHOR]

The structural and various electrical properties of (1-x)Pb(Zr 1-z Ti z)O 3 -xPb(Zn 0.4 Ni 0.6) 1/3 Nb 2/3 O 3 [(1-x)P(Z 1-z T z)-xPZNN] piezoceramics have been systematically investigated to ascertain the compositions that manifest a rhombohedral-pseudocubic-tetragonal (R-PC-T) multistructure. Rietveld refinement results indicate that the pseudocubic (PC) structure observed in the (1-x)P(Z 1-z T z)-xPZNN piezoceramics closely resembles the Pm3m cubic structure. Nonetheless, the PC structure cannot be classified as cubic, given that piezoceramics exhibiting the PC structure also demonstrate ferroelectric and piezoelectric properties. The R-PC-T multistructure was detected in (1-x)P(Z 1-z T z)-xPZNN piezoceramics for compositions where 0.335 ≤ x ≤ 0.44, across various z values. Compositions exhibiting the R-PC-T multistructure are identified as particularly promising. Notably, the piezoceramic with the composition 0.58 P(Z 0.41 T 0.59)-0.42PZNN (x = 0.42 and z = 0.59) displayed remarkable piezoelectric properties, including a high piezoelectric charge constant, d 33 , of 825 pC/N, a coupling coefficient, k p , of 0.7, and a strain of 0.185% at 3.0 kV/mm, alongside a high Curie temperature (T C) of 240 °C. • (1-x)P(Z 1-z T z)-xPZNN piezoceramics with R-PC-T multistructure were identified. • The PC structure of (1-x)P(Z 1-z T z)-xPZNN ceramics is close to the Pm3m C structure. • Most piezoceramics with R-PC-T multistructure exhibit excellent piezoelectricity. • 0.58 P(Z 0.41 T 0.59)-0.42PZNN piezoceramic shows a large d 33 (825 pC/N) and k p (0.7). [ABSTRACT FROM AUTHOR]

Based on crystal engineering, three Zn/Cd-based metal--organic frameworks (MOFs) (FUM-153(Zn--H), FUM-167(Cd--H), and FUM-176(Cd--NH2)) were successfully prepared from rigid O-donor/flexible N-donor linkers (H2bdc (terephthalic acid) (L(O) H) or NH2-H2bdc (2-aminoterephthalic acid) (L(O) NH2) and bpfb (N,N'- 1,4-(phenylene) diisonicotinamide) (L(N))) with Zn/Cd ions. Structurally, the major difference among the FUMs is the various behaviors of the DMF solvent in the lattice or the coordination environment of the structures. This study investigated the effect of hydrogen bonding of NH2 substitution in 2-D layer linkers and its effect on the layer architecture. The results showed that hydrogen bonding indirectly affects the coordination of DMF solvent to the metal center and the porosity. To investigate the effect of the NH2 substitution in the presence or absence of the DMF solvent in the FUMs, the Cambridge Structural Database (CSD) was surveyed for similar structures with the L(O) H and L(O) NH2 linkers. Remarkably, the obtained data suggested that the existence of NH2 substitution may reduce the probability of the coordination of DMF to the metal centers. Theoretical studies were carried out to explore the gas adsorption performance of the title FUMs. A better CH4 adsorption compared to CO2 for all FUMs was observed. It is worth noting that CH4 and CO2 gas adsorption in FUM-176(Cd--NH2) is higher than that in FUM-153(Zn--H) and FUM-167(Cd--H). It can be deduced that the NH2 substitution in 2-D layer linkers prevented the entering of DMF molecules into the framework (lattice or coordinated solvent). Consequently, more accessible pores are provided for gas molecules. The work demonstrates the role of linker functionality in the crystal structure, pore size, and gas adsorption properties. [ABSTRACT FROM AUTHOR]

A high-temperature synthetic approach is used to prepare a series of pseudo-binary phases- Co2-xNixZn11. In the structures of Co2-xNixZn11, the statistical distribution between Co and Ni that is suggested by compositional analysis is confirmed by combined refinements of X-ray and neutron powder diffraction (NPD) experimental data. The aforementioned phases adopt a body-centered cubic lattice with a noncentrosymmetric space group I43m (217). Their crystal structures comprise two 26-atom γ-brass clusters. Each γ-cluster is made of four sequential polyhedral shells: inner tetrahedron (IT), outer tetrahedron (OT), octahedron (OH), and distorted cuboctahedron (CO). Diffraction experiments and the computations endorse that the OT site is statistically distributed by Co and Ni atoms, while the other three sites (IT, OH, and CO) are occupied by Zn atoms. The density of states (DOS) curve for Co1.5Ni0.5Zn11 displays a similar feature as binary Co2Zn11, whereas the wide pseudo-gap is formed near EF as Ni-concentration increases in Co2-xNixZn11. Bonding analysis shows that this specific atomic distribution nearly optimizes heteroatomic Co/Ni--Zn contacts in the Co1.0Ni1.0Zn11 and Co0.5Ni1.5Zn11. The Co1.7Ni0.3Zn11 exhibit paramagnetic behavior, whereas Co0.5Ni1.5Zn11 shows distinct diamagnetic behavior. With the increase in Ni concentration in the structure of Co2-xNixZn11, Ni atoms gradually substitute the Co atoms at OT sites; hence, magnetic characteristics change from para- to diamagnetism. [ABSTRACT FROM AUTHOR]

The equimolar reaction between 1,9-bis(N,N-dimethylaminomethyl)-5,5′-diphenyldipyrromethane, H2L1 or 1,9-bis(3,5-dimethylpyrazolylmethyl)-5,5′-diethyldipyrromethane, H2L2 and [NiCl2(DME)] in the presence of KH yielded the neutral mononuclear nickel(II) complexes [Ni(L1)-κ4N,N,N,N], 1 and [Ni(L2)-κ4N,N,N,N], 2, respectively. Their X-ray structures revealed the formation of triple chelation by the ligand in both structures with quite different nickel(II)-surrounded square planar geometries owing to the steric difference between –NMe2 and 3,5-dimethylpyrazolyl groups. While the –NMe2 group substituted ligand L1 afforded nickel complex 1 with a plane of symmetry, 3,5-dimethylpyrazole substituted L2 rendered helical chirality in the structure of complex 2. Both the enantiomers (Δ and Λ) of complex 2 were observed in the crystal lattice. Their solution state behaviors were consistent with the solid-state structures as monitored by 1H NMR spectroscopy. Both the enantiomers of complex 2 were present in a dynamic equilibrium in solution and studied by variable temperature 1H NMR spectroscopy. Similar to the chiral complex, the corresponding ligand H2L2 also exhibited chirality as shown by its crystal structure and the two ligand enantiomers participated in a very fast dynamic interconversion, which became slower upon metalation. [ABSTRACT FROM AUTHOR]

IRMOF-10, derived from biphenyl-4,4′-dicarboxylic acid and zinc, is a prototype for an open cubic structure prone to interpenetration. Interpenetration can compromise MOF pore volume and surface area which drives the need to develop strategies to synthesize non-interpenetrated MOFs. In this work, an additive design strategy was employed to suppress interpenetration of IRMOF-10. The presence of the additive during traditional solvothermal synthesis yielded an activated material with the highest surface area reported to date and enabled the determination of the single crystal structure. In situ monitoring of the nucleation of crystals under polarized light provided insights into the mechanism behind interpenetration in the IRMOF-9/10 system. This work provides a roadmap to suppress interpenetration more generically in other MOFs and achieve improved surface areas and pore volumes for this prominent class of porous sorbents. [ABSTRACT FROM AUTHOR]

In recent years, notable progress in computational density functional theory (DFT) has facilitated the collection of extensive datasets in the field of materials science. Machine learning is a crucial technique for effectively processing and analyzing these large datasets and accelerating the creation of new compounds. In this work, we employ the Extreme Gradient Boosting (XGBoost) classification algorithm to predict the crystal structure of 381 halides and oxide perovskites using 78 features. We achieved a classification accuracy of 76.62% for these materials. Subsequently, we utilized the Random Forest and XGBoost algorithms to investigate a dataset comprising 761 perovskite materials from the material project database to predict the band gap energy (best accuracy = 84.78%, mean absolute error(MAE) = 0.410 eV, root mean square error (RMSE) = 0.594 eV) and formation energy (best accuracy = 94.81%, MAE = 0.083 eV/atom, RMSE = 0.157 eV/atom), all of these prediction results based on the chemical formulas. Notably, the feature importance analysis shows the significant influence of the number of d electrons in the d orbit of the B atom on both band gap (Eg) and formation energy (EF) properties. Finally, we applied our prediction model to identify stable perovskite solar cells, achieving an accuracy of 85.18%. These findings provide valuable guidelines for the discovery of stable perovskite solar cells and help researchers tailor the composition of perovskite materials to optimize their light-harvesting capabilities, leading to higher-power conversion efficiencies. [ABSTRACT FROM AUTHOR]

In the presented work, the structure dependence as well as luminescence features of a wide range of hybrid crystals based on lead halides and a homologous series of alkyl diamines from 1,4-diaminobutane to 1,8-diaminooctane are investigated. The structure of several previously undescribed hybrid crystals has been established. The even–odd effect of alkanes and its influence on the structure of such hybrid crystals have been demonstrated for the first time. The luminescence properties of the crystals and their dependence on the type of anion as well as the length and oddity of the organic cation are described in detail. The obtained data expand our knowledge of the relationship between the structure of the organic cation, including its parity and structure, and the electronic and optical properties of the hybrid crystals. [ABSTRACT FROM AUTHOR]

The synthesis of amides holds great promise owing to their impeccable contributions as building blocks for highly valued functional derivatives. Herein, we disclose the design, synthesis and crystal structure of a mixed-ligand ruthenium(II) complex, [Ru(η6-Cym)(O,O-PLY)Cl], (1) where Cym = 1-isopropyl-4-methyl-benzene and O,O-PLY = deprotonated form of 9-hydroxy phenalenone (HO,O-PLY). The complex catalyzes the aerobic oxidation of various primary amines (RCH2NH2) to value-added amides (RCONH2) with excellent selectivity and efficiency under relatively mild conditions with common organic functional group tolerance. Structural, electrochemical, spectroscopic, and computational studies substantiate that the synergism between the redox-active ruthenium and π-Lewis acidic PLY moieties facilitate the catalytic oxidation of amines to amides. Additionally, the isolation and characterization of key intermediates during catalysis confirm two successive dehydrogenation steps leading to nitrile, which subsequently transform to the desired amide through hydration. The present synthetic approach is also extended to substitution-dependent tuning at PLY to tune the electronic nature of 1 and to assess substituent-mediated catalytic performance. The effect of substitution at the PLY moiety (5th position) leads to structural isomers, which were further evaluated for the catalytic transformations of amine to amides under similar reaction conditions. [ABSTRACT FROM AUTHOR]