Simulated XRD Patterns Research Articles

Full colour luminescence tuning including white light from a mixed lanthanide activated metal-organic complex

In an attempt, metal–organic compounds of rare earth ions with 2,6-pyridinedicarboxylic acid (H2pydc) were synthesized and characterized. This paper summarizes the synthesis, characterization, and multicolour luminescence behaviour of a europium and terbium co-doped metal–organic compound (MOC) of formula [Y1.972Eu0.013Tb0.014(pydcH)6]·3H2O, 1 {H2pydc = 2,6-pyridinedicarboxylic acid}. The synthesis was performed by simple solvent evaporation method. We have also synthesized a pure yttrium based compound [Y2(pydcH)6]·3H2O, 1a following a similar procedure. The powder XRD patterns indicated that 1 and 1a were new materials; the patterns being entirely consistent with the simulated XRD pattern generated based on the structure of pure Eu compound determined using the single-crystal XRD. Compound 1 was well characterized by SEM, IR, TGA, EDX, and EDX elemental mapping analysis. Compound 1 showed different colour upon the variation of the excitation wavelength from 260 nm to 385 nm.

Combined experimental and quantum computational studies on 5-Fluorouracil salicylic acid cocrystal: Assessment on anti-breast cancer potential through docking simulation

5-fluorouracil salicylic acid (5FUSA) cocrystal was synthesised via mechanochemical and solution evaporation technique and spectroscopic experiments and theoretical research were conducted. Methods for the experiments included XRD, FTIR, and UV spectroscopy. Following that, 5FUSA was the subject of quantum chemistry investigations employing the DFT/B3LYP/6–311++G (d, p) basis level. First, the resultant simulated XRD pattern was compared to the relevant experimental pattern. The estimated FT-IR frequencies were gathered from the same level of theory and compared to the experimental data. To learn more about the reactive properties of the 5FUSA, the molecular electrostatic potential plot was generated, and Fukui function calculations were also performed. In order to examine intramolecular interactions and verify the bioactivity of the 5FUSA molecule, the natural bond orbital study was also carried out. We examined the UV–Vis absorption wavelengths (λ) via theoretical (TD-DFT) and experimental methods. The non-linear optical properties were identified, and it was discovered that it had three times the NLO activity of urea. The inter- and intramolecular interactions of the 5FUSA were explored using the Hirshfeld surface and finger print approaches. At various temperatures thermodynamic parameters were calculated and topological analyses were conducted using the (ELF, LOL, and RDG). The anticancer activity of 5FUSA cocrystal was studied using molecular docking and the docking scores ranges between -8.1 to -9.0 Kcal/mol against breast tumor proteins.

Solving the crystal structure of heterocyclic Poly(arylene benzimidazole) via model compound single crystal and theoretical calculations

Heterocyclic aramid containing benzimidazole units has demonstrated to be one of the strongest fibers. Due to positional isomerism of asymmetric benzimidazole and conformational isomerism of phenylamide, solving the crystal structure of poly(arylene benzimidazole) (PABI) aramid was a prominent challenge. Herein, we first reported the crystal structure of PABI aramid. First, the model compound: N-(4-(5-benzamido-1H-benzo[d] imidazole-2-yl) phenyl) benzamide (PBA) was cultured into single crystal: the molecules took a perfect ross-tenon-mortise interlocking conformation, in which the hydrogen bonding made a giant three-dimensional network. The PABI crystals with PBA crystal stacking feature were subsequently constructed and optimized through theoretical quantum calculation, disclosing a monoclinic unit cell with the parameters (a = 8.56 Å; b = 5.05 Å; and c = 36.78 Å; and β = 91.4°) and Pn space group. Their plausibility and validity were verified, since the simulated XRD and 2D-WAXD patterns reproduced the experimental XRD patterns. Our strategy of linking model compound PBA single crystals to obtain higher PABI crystals, paved the way to solving asymmetrical heterocyclic macromolecules crystals composed of easily isomerized chemical structures.

Investigating the differences in structure, morphology, optical properties, laser photoluminescence and dielectric properties for chitosan-doped commercial and Polycladia myrica mediated ZnO nanoparticles films combined with TD-DFT simulations

A homogeneous solution of chitosan nanoparticles in acetic acid was prepared as nano-monoblend thin film [Chit]TF. The biosynthesis ZnO nanoparticles [ZnO(b)]NPs were prepared via Polycladia myrica algal extract. A mono-nanocomposite of the chitosan nano-monoblend with commercial ZnO nanoparticles and bio ZnO nanoparticles [Chit/ZnO(c)]MNC and [Chit/ZnO(b)]MNC was synthesized using the dip casting deposition technique, respectively. Geometry optimization was achieved using TD-DFTD/Mol3 and Cambridge Serial Total Energy Bundle (TD-FDT/CASTEP) modules of the Density functional theory (TD-DFT). Molecular structure was studied and confirmed by the close matching between the experimental and simulated XRD patterns. [Chit]TF, [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC found to have an average crystallite size of 95.03 nm, 63.33 nm and 50.44 nm according to the calculations of XRD data. Optical energy gab of the direct allowed transition for [Chit]TF, [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC found to be 2.95, 2.885 and 2.705 eV, respectively. While, the simulated calculations of the isolated molecules [Chit]Iso and [Chit/ZnO]MNC/Iso by TD-DFT/DMol3 measured the energy gab as 3.217 and 2.83 eV, respectively. The suggested optical properties using CASTEP in TD-DFT agree quite well with the experimental values. A small difference in the dielectric properties between [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC was observed since [Chit/ZnO(b)]MNC found to have lower dielectric constant and conductivity values and higher electric modulus and impedance values. The wide range optical energy gab and good optical and dielectric properties of [Chit/ZnO(c)] MNC and [Chit/ZnO(b)]MNC are advantageous for various optoelectronic applications.

Preparation of NaA and NaY zeolites from kaolin and their use as adsorbent for the removal of Ni2+ and Co2+ in aqueous solution

Heavy metal ions can cause environmental problems and affect human health if they are not properly removed before waste water released into the environment. Adsorption is one of the most widely used method for removal of heavy metal ions due to its simplicity and efficiency. Among many adsorbents, NaA and NaY zeolites showed good ability to remove metal ions in aqueous solution due to their high ion exchange capacity. However, the cost of zeolites NaA and NaY, synthesized from pure chemical sources, is still quite high. Therefore, this paper presented the synthesis of NaA and NaY from kaolin, a commercial available and cheap material. Experimental results showed that kaolin calcined at 500°C was appropriate to be used as and source for synthesis of zeolite. NaA and NaY zeolites were synthesized by reaction at 100°C in 24 hours. NaA zeolite was synthesized in a gel with the molar ratio in term of 1.0 Al2O3/2.0 SiO2/1.6 Na2O/76 H2O and NaY zeolite was synthesized with the molar ratio of 1.0 Al2O3/3.7 SiO2/2.7 Na2O/76 H2O with the addition of from industrial fly ash. XRD results of both synthesized NaA and NaY zeolites showed that the diffraction peaks of these zeolites matched with simulated XRD pattern of NaA and NaY zeolite. Synthesized NaA and NaY zeolites were used as adsorbents to remove Ni2+ and Co2+ in aqueous solution. NaY zeolite showed the highest adsorption capacity of 56.5 mg/g and 58.2 mg/g for Ni2+ and Co2+, respectively. NaA zeolite showed higher metal removal efficiency than that of NaY zeolite, with the highest adsorption capacity for Ni2+ and Co2+ at 80 mg/g and 123.2 mg/g, respectively. Experimental data fit the pseudo-second-order model and Langmuir isotherm adsorption model well. The results showed that the removal of Ni2+ and Co2+ ions by NaA and NaY zeolites was of the .

Prediction of a series of superhard BC4N structures

Six novel superhard BC4N-x (x = a, b, c, d, e, f) structures with low energies are determined by ab-initio evolutionary methodology using crystal structure analysis by particle swarm optimization (CALYPSO) code. These BC4N polymorphs employ a sp3-hybrid network with BN and C layers connected alternatively, and with low energies close to those of the previously proposed lowest energy c-BC4N. The possible precursors and phase transition paths from hBC4N-x to novel BC4N-x (x = a, b, c, d, e, f) are also determined, and the energies of the hBC4N-x are close to each other under ambient pressure. Moreover, simulated XRD patterns of these novel BC4N structures show agreement with experimental data. The Raman main peak positions and intensities of these structures are also consistent. All indications point out the experimentally synthesized samples likely contain various BC4N structures.

Molecular dynamics simulations of microstructural evolution of irradiated (U,Pu)O[formula omitted] studied via simulated XRD patterns

Molecular dynamics simulations of microstructural evolution under irradiation of (U,Pu)O2 solid solutions have been carried out with the Frenkel pair accumulation method with two empirical potentials. Simulated X-Ray diffraction patterns have been systematically generated along the irradiation pathway from the computed atomistic configurations. Description of the X-Ray diffraction patterns for each of these well characterized damage microstructure snapshots is discussed. Attempt to correlate the features of the X-Ray diffraction peaks with the microstructural evolution with irradiation dose is also provided. Special attention is dedicated to the swelling effect.

Theoretical and experimental study of the microstructure of a metallic melt in an In50Bi50 alloy based on the Wulff cluster model

In this paper, the Wulff cluster model which has been proved to successfully describe the melt structure of pure metals, homogenous alloys and eutectic alloys has been extended to an alloy with intermetallic compounds (In50Bi50). According to the cohesive energy and the solid-state XRD patterns, the most possible types of clusters in the melt are Bi and InBi. At relatively high temperatures, the superimposed XRD (simulated) patterns of Bi and InBi clusters are in good agreement with the experimental HTXRD patterns in terms of the position and intensity of the peaks. With the decrease of temperature, there is an obvious deviation in the simulated XRD value at the second peak caused by the nucleation process of Bi clusters, which would be modified by adding simulated XRD patterns of the Bi bulk. The proportion of the superimposed Bi bulk XRD pattern increases with the decrease of temperature suggesting that the nucleation process of the Bi cluster begins at 160 °C.

Illite-Age-Analysis (IAA) for the Dating of Shallow Faults: Prerequisites and Procedures for Improvement

Fault age determination using the illite-age-analysis (IAA) method for fault gouges has played a key role in providing absolute age information in tectonic evolution studies for the last 20 years. The accuracy and precision of the IAA method depend on (1) how to reasonably quantify the relative content of 1M/1Md illite generated from fault activity compared to detrital 2M1 illite in the size fractions of the fault gouge, and (2) how to minimize the error factors in K-Ar or Ar-Ar dating analysis. XRD-based quantitative analysis of illite polytype has made great progress in accuracy by generating a simulated XRD pattern of 1M/1Md polytype using WILDFIRE© and full-pattern-fitting it with the XRD pattern measured from size fractions of the fault gauge. Nevertheless, the results of quantitative analysis of illite polytypes may vary depending on the sample state of the size fractions for XRD analysis, especially the preferred orientation due to the layered crystal structure of illite. In addition, the radiometric dating results may be distorted depending on the error factor of the dating method itself and on the mineral composition of the size fractions, that is, the presence of K-containing minerals such as biotite and K-feldspar other than illite. In this study, we reviewed previous studies that determined fault activity ages by applying IAA to fault gouges. From this, the prerequisites and recommendations for each of the five steps (particle size separation process, XRD analysis process, polytype quantification, radiometric dating, IAA plot) for improving the IAA method are summarized and presented. The continuous application of the improved IAA is expected to greatly contribute to the study of tectonic evolution through geological time.

Combined theoretical and experimental study of the electronic and optical property of Sb2WO6

Both theoretical and experimental analysis are carried out to understand the physical properties of the fascinating electronic and optical properties of antimony tungstate (Sb2WO6). The nanosized (~40–80 nm) material is produced using hydrothermal method followed by the SEM and XRD analysis to find the structural properties. The present calculations using PBEsol and PBE approximations for exchange-correlation potential are compared with the experimental structural parameters and in the case of the calculations using PBEsol approach the predicted crystal parameters and simulated XRD pattern are in excellent agreement with experimental results. The experimental absorption spectra measured in the ultraviolet-visible range provide the bandgap of 2.42 eV, while the most intense peak of photoluminescence spectra is found at 468 nm (2.65 eV). Using density functional theory (DFT) technique, the band structure and density of states for Sb2WO6 are calculated and the calculated bandgap of 2.62eV is in agreement with the experimental finding. From theoretical partial density of states calculations we identify that the bandgap is formed between the O−2py orbitals bonded with Sb at valence band maxima and the W−5dx2−y2 orbital at conduction band minima. The atomic level transitions responsible for the peaks of absorption spectra are identified as well by means of DFT calculations. Following the matching of theoretical and experimental observations, the calculations of optical properties reveal the plasma frequency to be equal to 13.36 eV.

Polymeric copper(II) diethylenetriaminepentaacetates for gas adsorptions

A series of copper(II) diethylenetriaminepentaacetates [Cu(H4dtpa)Cl]·KCl·3.5H2O (1), Kn[Cu(H2dtpa)]n·2nH2O (2), K3[Cu(dtpa)]·3H2O (3) and Kn[Cu2(dtpa)]n·4nH2O (4) (H5dtpa = N,N,N′,N″,N″-diethylenetriamine-pentaacetic acid) have been obtained from the direct reactions of copper(II) chloride with diethylenetriaminepentaacetic acid in acidic or weak acidic solutions. pH values show obvious impacts for the coordination modes of DTPA with the formations of monomer, one dimensional (1D) and three dimensional (3D) structures respectively. The four complexes are well characterized by elemental analysis, IR, X-ray structural analyses and theoretical bond valence calculations. There exist free carboxy and amino groups in 1, which indicates that strong acidity can weaken the coordination of DTPA. Complex 4 is a 3D metal organic framework with small holes of diameter 3.3 Å, which can adsorb oxygen for 12.83 mg/g under 29.9 bar. It is thermal stable up to 150 °C based on simulated and experimental XRD patterns.

2D Trimetal-organic framework derived metal carbon hybrid catalyst for urea electro-oxidation and 4-nitrophenol reduction

Because of the abundance of transition metals, their enhanced electrochemical/chemical efficiency on par with the benchmark catalysts, long-term stability, etc., the expansion of transition metal/metal oxide-based electrocatalysts for oxygen evolution, urea oxidation reactions and 4-nitrophenol reduction becomes indispensable. In particular, the abundant availability along with improved electrochemical performance is crucial for fuel cell applications when it comes to large scale commercialization. In this work, we report the synthesis of a trimetallic metal-organic framework based on Ni, Co and Zn using BTC as a linker and the preparation of its metal oxide - carbon composites at different temperatures, 600, 700 and 800 °C (TM-MOF-600, TM-MOF-700, and TM-MOF-800) by carbonization under an inert atmosphere. The PXRD pattern of TM-MOF complemented well with the simulated XRD patterns of Co–Ni-BTC MOF as well as Zn-BTC MOF, whereas the PXRD pattern of the carbonized samples indicated the presence of three types of metal oxides i.e., CoO, NiO, and ZnO. TEM indicated spherical morphology of TM-MOF, upon calcination, an irregular agglomeration occurred and the average particle size was found to be 60–110 nm. The as-prepared TM-MOF and its carbon composites were tested for their electrocatalytic as well as catalytic activities towards oxygen evolution, urea oxidation and 4-nitrophenol reduction reactions. Electrochemical results indicate the better performance of TM-MOF-800 in both OER and UOR reactions with an onset potential of 1.66 V (OER) and 1.37 V (UOR) at a current density of 10 mA cm−2. The long-term stability of these catalysts under alkaline conditions indicates excellent stability. Besides, the urea electrolyzed products were analyzed by gas chromatography to get clear insights on the formed products. Catalytic reduction of 4-nitrophenol in the presence of excess NaBH4 showed excellent conversion to 4-amino phenol in short duration.

The first principle calculation of elemental-vacancy-assisted modifications on structural properties and optical responses of ZnO system

The structural properties and optical responses of ZnO0.94 and Zn0.94O systems as the possible models of ZnO system containing elemental defect states were studied using the plane-wave method within the generalized gradient approximation. The pristine ZnO system was used as the reference. The simulated XRD patterns showed the three highest intensity for (100), (002), and (101) orientations for all the systems. Compared to O vacancy, Zn vacancy mostly provided higher structure factor shifts of ZnO system. Moreover, the strongest local-symmetry distortion at ZnO4 tetrahedra was implied in Zn0.94O system. The optical responses showed that all the systems exhibited the optical dichroism based on the extinction coefficient spectra. Interestingly, Zn0.94O system showed the lowest energy levels of absorption and high-reflectance edges. Additionally, the highest saturation threshold energy of the effective number of valence electrons was obtained for this system. The result emphasizes the importance of Zn vacancy in providing the significant effect on the optical responses of ZnO system.

A sol-gel synthesis to prepare size and shape-controlled mesoporous nanostructures of binary (II-VI) metal oxides.

A base-catalyzed sol–gel approach combined with a solvent-driven self-assembly process at low temperature is augmented to make manganese oxide (Mn3O4), copper oxide (CuO), and magnesium hydroxide (Mg(OH)2) nanostructures with size- and shape-controlled morphologies. Nanostructures of Mn3O4 with either hexagonal, irregular particle, or ribbon shape morphologies with an average diameter ranged from 100 to 200 nm have been prepared in four different solvent types. In all morphologies of Mn3O4, the experimental XRD patterns have indexed the nanocrystal unit cell structure to triclinic. The hexagonal nanoparticles of Mn3O4 exhibit high mesoporocity with a BET surface area of 91.68 m2 g−1 and BJH desorption average pore diameter of ∼28 nm. In the preparation of CuO nanostructures, highly nanoporous thin sheets have been produced in water and water/toluene solvent systems. The simulated XRD pattern matches the experimental XRD patterns of CuO nanostructures and indexes the nanocrystal unit cell structure to monoclinic. With the smallest desorption total pore volume of 0.09 cm3 g−1, CuO nanosheets have yielded the lowest BET surface area of 18.31 m2 g−1 and a BHJ desorption average pore diameter of ∼16 nm. The sol of magnesium hydroxide nanocrystals produces highly nanoporous hexagonal nanoplates in water and water/toluene solvent systems. The wide angle powder XRD patterns show well-defined Bragg's peaks, indexing to a hexagonal unit cell structure. The hexagonal plates show a significantly high BET surface area (72.31 m2 g−1), which is slightly lower than the surface area of Mn3O4 hexagonal nanoparticles. The non-template driven sol–gel synthesis process demonstrated herein provides a facile method to prepare highly mesoporous and nanoporous nanostructures of binary (II–IV) metal oxides and their hydroxide derivatives, enabling potential nanostructure platforms with high activities and selectivities for catalysis applications.

Experimental and ab initio study of the Ag–Li system for energy storage and high-temperature solders

The standard enthalpies of formation of the Ag30Li70 and Ag20Li80 gamma phases (cubic, sg. I-43 m) were measured using the solution calorimetry method; the standard enthalpy of formation of the Ag10Li90 alloy, corresponding to a hypothetical γ phase, was determined using the same method. All the measured and literature values of the standard enthalpies of formation of the Ag–Li intermetallic phases were compared with the data calculated using ab initio for stable and unstable phases and Miedema’s model. The XRD pattern for a sample with Ag30Li70 was obtained and it was verified that it contained the γ phase, as expected. Moreover, the structure of the γ-phase for the Ag4Li9 disordered phase was minimized and the vibrational heat capacity at constant volume and the thermal coefficient of linear expansion were calculated using ab initio methods. The simulated XRD pattern of the latter phase was compared with the experimental pattern. It was determined that only one gamma phase, with a homogeneity range not wider than 0.69 ≤ x(Li) ≤ 0.73, is stable for T ≥ 298 K. Furthermore, besides AgLi-β with a homogeneity range of 0.50 ≤ x(Li) ≤ 0.60 at 298 K, a cubic Ag15Li49-β is stable for x(Li) = 0.77. The entropy term stabilizes the cubic structure of the AgLi-β which can be tetragonal at 298 K. The enthalpies and Gibbs energies of formation were calculated at 298, 320, 425, and 600 K. A new “map” of the phases in equilibrium at different temperatures is proposed.

Layered Ionic Conductor Na2Zn2TeO6: Crystal Structure and Stacking Faults

Na-ion batteries (NIBs) are considered the most attractive and cost-effective alternative to Li-ion batteries (LIBs), due to the widespread abundance of sodium and its chemical similarity with Li, facilitating the conversion of battery technologies. Meanwhile, replacing the liquid electrolyte in traditional batteries with a super-ionic conductor material in the solid-state presents additional advantages in terms of safety and stability. The research for solid-state electrolytes (SSE) is consequently a very active field. Layered tellurates with formula Na2 M 2TeO6 (M = Co, Mg, Zn, Ni) have been reported to exhibit high Na-ion conductivity, around 10-4 S/cm, and crystallize into two distinct P2-layered modifications, structurally related to Na-deficient Na xMO2 (x < 0.7; M = Co, Fe, Mn) materials. Na2Ni2TeO6 (NNTO) adapts an AA stacking of hexagonal Ni-Te layers (P63/mcm), while Na2 M’ 2TeO6 (M’ = Zn, Co) adapts an alternative AB stacking (P6322) [1]. However, the structure of the Na2 M’ 2TeO6 compounds is not yet fully resolved, because the refinements reported in literature do not account for the broadening of a low-angle peak in the X-ray diffraction pattern which could be ascribed to the presence of stacking faults [1,2]. In this study, Na2Zn2TeO6 (NZTO) was synthesized via conventional solid-state methods. Synchrotron X-ray diffraction (SXRD) experiments were performed to verify the presence and quantify the amount of stacking faults in the structure. The standard Rietveld refinement against SXRD data shows that NZTO crystallizes into the P6322 structure (a = 5.289 Å, c = 11.244 Å), consistent with previous reports. The refinement exhibits a poor fit of Bragg intensity and could not describe the significant broadening of the (0 1 1) reflection, as shown in Figure 1. We performed density functional theory (DFT) calculations to verify the nature of these faults. We modeled two different NZTO modifications, the standard one (space group P6322) and the one obtained by substituting Zn for Ni in the NNTO structure. The energy difference is smaller than 10 meV, indicating the possible coexistence of these phases at room temperature or, indeed, the presence of the associated stacking faults in the P6322 structure. The latter hypothesis was directly tested by simulating the effect of NNTO-type stacking faults in NZTO and subsequent refinement against SXRD data employing the FAULTS software [3]. The simulated XRD patterns reveal that only the (0 1 1) reflection is drastically broadened and its intensity decreases as the fraction of NNTO-type stacking faults increases. Notably, the other peaks remain largely unchanged. The FAULTS-refined profiles exhibit a better fitting of the Bragg intensity and peak broadening of the (0 1 1) reflection, revealing 3% NNTO-type stacking faults in NZTO. In conclusion, a more accurate structural model of the NZTO compound is proposed and validated. Figure 1: Rietveld refinement (without stacking faults) and FAULTS refinement (with stacking faults) against SXRD data (λ = 0.3149 Å) for NZTO.

Frequency dependent linear and nonlinear optical properties of compositionally tuned inorganic CsSnX (X = Br, I) composites

Structural, electronic and optical properties of CsSnX (X = Br, I) system have been thoroughly investigated by means of an unbiased crystal structure screening, density functional theory and perturbation approach. Crystallography of known parent structures, CsI and CsBr were well replicated compared to experimental observations. Experimentally verified cubic Cs2SnI6 phase was operatively reproduced. Its computed crystal class and simulated XRD pattern match the available experimental data, hence signifying the robustness of methodology applied. Other energetically and dynamically stable structures include cubic Cs2SnBr6, triclinic Cs2Sn2Br6 and Cs2Sn2I6. These phases are direct semiconductors which exhibit non-monotonic association between GW corrected band gap and halogen type or atomic mass. Instead, their energy gap is determined by the structure of CsSn halide compounds, and span an energy range from mid infrared to near ultraviolet region. The GW-raised gap was incorporated as scissor shift to ensure good reliability of optical calculations. Dynamical dielectric function, adsorption coefficient, energy-loss and refractive index spectrum of aforementioned phases were acquired. Both novel Cs2Sn2Br6 and Cs2Sn2I6 phases have impressive zero limit second-order susceptibility ranging from 3.1 p.m. V−1 to 22.8 p.m. V−1.

“DistorX” program for analysis of structural distortions affecting X-ray diffraction patterns

For the purposes of research on strongly correlated electronic systems (SCES), a computer program, DistorX (Distortion or X-ray diffraction patterns), was created. The program is an interactive Jupyter notebook for simulating the effects of structural distortions on X-ray diffraction patterns. The program is designed to be universal, in that it may be successfully applied to a variety of structures. In previous reports, a structural transition from a cubic phase of Yb3Rh4Sn13 – type to the superlattice variant was been observed at 160 K for a series of skutterudite-related Ce3M4Sn13 compounds, where M = Co, Ru or Rh. In this work, we use a specialized build of DistorX to simulate the low-temperature X-ray diffraction patterns of a distorted unit cell. The method described here obtains simulated XRD patterns from the atomic positions and permits investigation of crystal structure without imposed symmetry operations. We further indicate the crystallographic plane in which the distortion occurs, and explain the possible origin of CDW in these materials.

Holistic Study of Doped Layered Titanate Nanofibers

Layered titanate nanostructures are uniquely suited to large-scale application in energy science due to their inexpensive processing, ease of synthesis, and their versatility to be ion-exchanged with specific elements. The quantity and scope of experimental literature that exists for these porous, ion-exchangeable nanostructures is not matched in the computational studies available; we have expanded the boundaries of both by combining the experiment and the computation to answer questions about how dopant atoms are integrated into the layered titanate nanofiber crystal lattice during synthesis. We simulated doped hydrogen trititanate (H2Ti3O7) with and without magnetic substitutional doping for a variety of dopant sites. Predicted structural energies, band structure, charge distribution, and magnetic properties were examined. Simulated XRD patterns are comparable to experimental results from synthesized doped nanofibers. Finally, EDX scans confirmed the presence of dopants in the titanates. We found that this combined computational/experimental collaboration provided strong evidence for one interpretation of the dopant integration, and we expect to generalize this work on different dopants.

Tin-tellurium-phosphide: Investigation of composition dependent band structure and its experimental realization

The experimental discernment of TCIs (topological crystalline insulators) and other Dirac materials in recent times, has opened a new platform for their applications in spin-electronics and quantum computing. A very promising material in thermoelectric and photovoltaic applications, namely SnTe, has been increasingly investigated by band engineering, however, there is not sufficient verification of any band-crossing characteristics or evolution of Weyl nodes yet. In this present study, we investigate a novel class of possible substitutional solid solutions of Sn, Te, and P of varying compositions by density functional theory, where specific crystal symmetry elements may allow the existence of robust topological states. With fine tuning of chemical composition, one can also locate the existence of Dirac-like nodes at certain points of the Brillouin zone from preliminary first-principle calculations. Apart from simulations, synthesis and structural examinations of Sn-Te-P, were also conducted. The structural analysis of a representative member of this system was also carried out with the help of the simulated XRD patterns, to indicate the existence of a new phase during synthesis in a condensed system combustion.