General Structure Analysis System Research Articles

Crystallographic Analysis of Structural Changes in Lithium Nickel Manganese Cobalt Oxides at Different Stages of Lithiation

Mixed transition metal oxides are among the most promising cathode materials for lithium ion batteries. The high specific capacity, low cost and thermal stability makes Li(Ni1/3Mn1/3Co1/3)O2, so-called NMC, an excellent material for power tool applications. Therefore, main leading battery manufacturer focus on the combination of these three transition metals to combine the strengths of each of them [1]. The development and design of battery materials require deep understanding of the relations between chemistry, structure and its properties. Nowadays, the commercialized NMC can only reach around 60 % of its theoretical capacity when cycled up to 4.2 V. Higher specific capacities might be reached when the upper voltage limit is raised up to 4.5 V [2], but the lifetime of the cathode then decreases drastically. The deintercalation of more than 0.6 moles of lithium in the charge process of the battery leads to irreversible capacity losses. Lithium nickel manganese cobalt oxides with different transition metal ratios were successfully synthesized via coprecipitation route. The cathode materials were characterized physico- and electrochemically and the composition was confirmed via inductive coupled plasma atomic emission spectroscopy (ICP-AES). Structural changes of non-symmetric NMC compounds at different stages of lithiation were recorded using x-ray diffraction. The resulting patterns were analyzed and the structures refined using the Rietveld method implemented in the GSAS (General Structure Analysis System) package [3]. The same procedure of crystallographic characterization of the NMC structure was carried out for different transition metal ratios cycled up to 4.5 V. The results are presented and comparison between symmetric and non-symmetric lithium nickel manganese cobalt oxides will give better insight into structural changes at higher voltages and the relation to their compositions. Acknowledgement This work was financially supported by the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit) and the Austrian Research Promotion Agency (FFG). [1] N. Yabuuchi, T. Ohzuku, Journal of Power Sources 119-121 (2003): 171-174 [2] Q. Yu, Z. Chen, L. Xing, D. Chen, H. Rong, Q. Liu,W. Li, Electrochimica Acta 176 (2015): 919-925 [3] A. C. Larson, R. B. Von Dreele, Los Alamos National Laboratory Report, No. LAUR-86-748, (1987)

Rietveld refinement of X-ray powder diffraction data of Sm0.55Sr0.45MnO3 polycrystalline material

Polycrystalline Sm0.55Sr0.45MnO3 was prepared by solid-state reaction at 1300 °C. Single phase of the compound was analysed by a powder X-ray diffraction technique. The powder pattern of Sm1−xSrxMnO3 was indexed and refined using a General Structure Analysis System (GSAS) to an orthorhombic structure with space group Pnma, a = 5.4323(7), b = 7.6585(4), and c = 5.4343(7) Å.

Rietveld structure refinement of microcline

Compared with single-crystal X-ray diffraction, extracting structural data from X-ray powder diffraction (XRPD) seems meaningless for minerals with an available single crystal, such as alkali feldspar. However, alkali feldspar is highly abundant on Earth, and the feldspar structure is important in geology. Thus, the potential of extracting structural parameters from powder diffraction data collected using conventional Bragg–Brentano XRPD (BB-XRPD) with Cu K α radiation is worthy of exploration. BB-XRPD may be the most extensively used instrument in the laboratory and has a major advantage in terms of cost and convenience. Accordingly, by combining the Rietveld method with the General Structure Analysis System (GSAS) of BB-XRPD, a microcline structure in a natural feldspar sample with two minor impurities was refined for the first time. To extract high-quality structural data, a formula related to Si/Al–O bond lengths and Si/Al occupancies in terms of the crystal structure database and a new model are sequentially presented. The reliability of the structural data for such a low-symmetry phase as microcline is discussed and established by comparison with published single-crystal data.

Dual-Mode Luminescence with Broad Near UV and Blue Excitation Band from Sr2CaMoO6:Sm3+Phosphor for White LEDs

Dual-mode excitation properties were introduced in Sm3+ doped Sr2CaMoO6 prepared by a high temperature solid state reaction technique. Two ways are available to generate white light in the single-component phosphor activated by Sm3+ ions. Warm white light can be obtained from Sr1.995Sm0.005CaMoO6 phosphor pumped by 380 or 411 nm excitation energy. The full visible spectral emission of the single-phase phosphor comes from the high and low level emission lines of Sm3+ ions as well as the intrinsic luminescence of MoO6 group. It is also competitive as yellow-emitting phosphor for blue pumped white LEDs and gives three emission bands at 567, 603, and 650 nm, presenting yellow luminescence upon 466 nm radiation. The 650 nm red emission band corresponding to 4G5/2 → 6H9/2 transition of Sm3+ can make its color rendering index better. The excellent photoluminescence of Sr2CaMoO6 is related to the partial tilting CaO6 octahedral and the lowered symmetry were confirmed by General Structure Analysis System. Band gap...

Design and Synthesis of CdWO4:Sb3+ Phosphor Based on sp Energy Level Regularities of Sb3+ Ion

Sb3+‐activated CdWO4 phosphors were designed according to sp energy levels regularities of Sb3+ ion in some inorganic compounds. The sp energy levels regularities of Sb3+ in dozens of compounds were established with the aid of the dielectric theory of the chemical bond for complex crystals: EA = 6.2187−1.7584he, EB = 7.019−1.957he, EC = 7.259−1.964he. Environmental factor he of Cd site was calculated to be 1.6583 with the refined crystal structure and refractive index of CdWO4:Sb3+. Sb3+‐doped CdWO4 was synthesized through a precipitation method and its structure was refined with the General Structure Analysis System. The transition energy of A band of Sb3+ in CdWO4 can be predicted to be 3.312 eV (374 nm), according to the relationship equation between EA and environmental factor he. By monitoring the 521 nm emission band, the excitation spectrum gives a weak excitation band peaking at 355 nm, which was assigned to the 1S0–3P1 transition of Sb3+ according to our prediction. Thus, Sb3+‐doped CdWO4 phosphor was designed and synthesized successfully based on sp energy levels regularities of Sb3+ ion. This work is a great help to understand the spectroscopy of Sb3+ ion and will be useful for the design and development of Sb3+‐doped phosphors for applications.

Chemical Synthesis and Magnetic Properties of Indium-Substituted Manganese-Zinc Nanoferrites

Nanocrystalline ferrites with composition Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2</sub> Zn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.8</sub> In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-y</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> , (y = 0.00, 0.035, 0.070, 0.100) were prepared by oxalate co-precipitation technique followed by microwave heating of precursors. The phase purity of the samples was confirmed by X-ray diffraction technique. Full profile Rietveld refinement of the powder diffraction pattern was carried out by using General Structure Analysis System II to obtain cation distribution in the spinel lattice. In <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions were distributed in tetrahedral as well as octahedral sites. Magnetization of ferrite samples was studied with vibrating sample magnetometer. In lower concentration, indium substitution increased saturation magnetization; at higher concentration of indium, saturation magnetization decreased substantially. This was due to higher fraction of indium ions occupying octahedral sites. AC susceptibility and Loria-Sinha techniques were used to study Curie temperature of nanoferrites.

Structure refinement of polycrystalline orthorhombic calcium titanate substituted by lanthanum: Ca1 − x La x TiO3 (x = 0.1–0.4)

Polycrystalline phase of composition Ca1 − x La x TiO3 (x = 0.1–0.4) has been synthesized by ceramic route at 1050°C. The material has been characterized by its typical powder X-ray diffraction pattern. The structural refinement has been carried out by step data analysis using Rietveld method and General Structure Analysis System software. The material crystallizes at room temperature in Pbnm (#62) space group with lattice parameters a = 5.2241(4) A, b = 5.7500(4) A, c = 7.9629(5) A and Z = 4. The Rietveld refinement converged to the final structure model giving profile indicator, residual parameter (R p ) = 12.27% and goodness of fit = 1.78. Major interatomic distances, bond angles, and structure factors have been calculated using General Structure Analysis Software programming a step data analysis of the compound. The metal-oxygen bond lengths are in good agreement with their standard values reported for these oxides. The crystal morphology has been examined by scanning electron microscopy. The Energy Dispersive X-ray analysis of the specimen shows that the lanthanum enters into the structural framework of CaTiO3.

Synthesis, Characterization, and Crystal Structure Refinement of Lanthanum and Yttrium Substituted Polycrystalline 2M Type Zirconolite Phases: Ca1-xMxZrTi2O7(M = Y, La andx= 0.2)

Solid phases of zirconolite-2M with composition Ca0.8M0.2ZrTi2O7(M = La, Y) have been synthesized through ceramic route and their structures refined to a satisfactory convergence using Rietveld analysis. Zirconolites crystallize in space group C2/c withZ= 8. The powder diffraction data of Ca0.8Y0.2ZrTi2O7(CZTY) and Ca0.8La0.2ZrTi2O7(CZTLa) have been subjected to General Structural Analysis System software to arrive at a satisfactory structure fit with Rp = 0.1128 and Rwp = 0.1805 for CZTY and Rp = 0.1178 and Rwp = 0.1874 for CZTLa, respectively. The unit cell parameters area= 10.1708 (6) Ǻ,b= 6.2711 (4), andc= 11.2779 (6) Ǻ for CZTY anda= 11.2548 (6) Ǻ,b= 6.2601 (4), and c=11.2606 (7) Ǻ for CZTLa. Calculated interatomic distances and bond angles are in good agreement with their standard values. Particle size along prominent reflecting planes calculated by Scherrer’s formula ranges between 67 and 107 nm. The polyhedral (CaO8, ZrO7, and TiO6/TiO5) distortions and valence calculation based on bond strength analysis have been reported. The compositions of the zirconolites were determined using energy dispersive X-ray (EDAX) analysis. Cation site occupancies were determined by applied compositional constraints which were found consistent with the expected zirconolite-2M cation site occupancies.

Crystal Chemistry of Immobilization of tetravalent Ce and Se in ceramic matrix of sodium zirconium phosphates

Sodium zirconium phosphate (here after NZP) is a typical host material capable of converting the intermediate level waste resulting from light water reactor (LWR) fuel reprocessing into a single-phase material with good stability, high integrity and long durability. The crystal chemistry of NaZr1.9Ce0.1P3O12 and NaZr1.9Se0.1P3O12 phases has been investigated using general structure analysis system programming. The Se/CeNZP phases crystallize in the space group R-3c and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The Phosphate counter ions stretching and bending vibrations in the infrared (IR) region have been assigned. SEM and EDAX analyses provide evidence of Ce and Se in the matrix.

Fabrication and Characterization of Ferroelectric Thin Film Ba&lt;sub&gt;x&lt;/sub&gt;Sr&lt;sub&gt;1-x&lt;/sub&gt;TiO&lt;sub&gt;3 &lt;/sub&gt;for Application in Light Intensity Detector

Ferroelectric thin film devices have been demonstrated using BaxSr1-xTiO3 (BST) as a light intensity detector. Various compositions of BST (x=0.7, 0.8 and 0.9) were prepared using Chemical Solution Deposition method. Solution of barium acetate, strontium acetate, titanium (IV) iso-propoxide in a mixture of acetic acid and ethylene glycol was spin-coated onto a silicon substrate. The BST film was annealed at 800°C. The microstructure and the crystalline characterization of BST were studied using X-Ray Diffraction (XRD) pattern with General Structure Analysis System (GSAS) refinement. The film thickness was measured using Scanning Electron Microscopy (SEM). The response of BST film to source of light intensity was investigated with IRC meter and resonator coupling. The results show that the resistance of a thin BST film decrease as the intensity of light increase. On resonator coupling, VOUT shows a slight increases as the intensity of light increases.

Effects of Iron Dopants on Barium Strotium Titanate (Ba&lt;sub&gt;0.8&lt;/sub&gt;Sr&lt;sub&gt;0.2&lt;/sub&gt;TiO&lt;sub&gt;3&lt;/sub&gt;) Thin Films

BST thin films have been grown by Chemical Solution Deposition (CSD) method on the substrate of Pt/Si. The fabrication of BST doped by Fe have been successfully using spin coater with 4000 rpm during 30 second. Annealing process use the holding time at 3 hours, the heating rate at 5°C/min and temperature at 800°C. The ratio of Ba0.8Sr0.2TiO3 molar and Fe variant dopant (0%, 1%, 3%, and 5%) were characterized by X-Ray Diffraction (XRD) and obtaining results that show the peak shift due to variations dope. The peak shifted to the right for each increment Fe dopant. Results of addition Fe dopant also cause a differences in the magnitude of Full Width at Half Maximum &lt;em&gt;(&lt;/em&gt;FWHM) and lattice parameters on BST ferroelectric materials. Other characterize that has been done by Scanning Electron Microsopy (SEM), it is show the thickness of the material. The resulting lattice parameters with the General Structure Analysis System (GSAS) software analysis showed that a thin films of BST and BSTF have a tetragonal structure because it has a value of a=b≠c and α=β=γ=900. Based on SEM characterization, the thickness of thin film is about 330 nm.

Luminescence properties of nano and bulk ZnWO4 and their charge transfer transitions

We here investigated the photoluminescence properties of nano and bulk ZnWO4 phosphors with the aim to understand the observed altered properties of nanoparticles as compared to their bulk counterparts. Their excitation bands were decomposed into three components by Gaussian fitting. The influence of crystalline defects that are present due to the low synthesis temperature of ZnWO4 nanoparticles on the excitation spectra was studied. The structures of ZnWO4 samples were refined with the General Structure Analysis System. Making use of the estimated refractive indices and the refined lattice parameters, four chemical bond parameters of W–O bonds were calculated and integrated to give the environmental factor he, which can to some extent explain the broadened excitation band in bulk ZnWO4. A new factor H of every W–O bond was calculated, and based on the results, three components of the excitation band at about 250, 280 and 300 nm were assigned to be from W–O1, W–O2(2) and W–O2(1) charge transfer transitions, respectively.

Crystallographic evaluation of titanate ceramics as a host structure for immobilization of samarium

In order to simulate the mechanism of rare earth fixation in perovskite, Ca1−x Sm2/3x TiO3 (x = 0.1–0.5) was synthesized via ceramic route at 1050°C. Up to ∼4 mol % Sm could be loaded into calcium titanate formulations without significant changes of the three-dimensional framework structure. Their crystal structures were refined by Rietveld analysis of powder X-ray diffraction data. The structure refinement converged to satisfactory values of the Rietveld parameters (R p and R wp ) and goodness of fit. The lattice parameters, structure factors, bond lengths, and bond angles were calculated from General Structure Analysis System software (GSAS). The M-O stretching and bending vibrations in the IR region were assigned. The crystal morphology was examined by scanning electron microscopy. Energy-dispersive X-ray (EDX) analysis of the specimens shows that samarium enters into the structural framework of CaTiO3.

Diffusion of lanthanum into single-phase sodium zirconium phosphate matrix for nuclear waste immobilization

Sodium zirconium phosphate (NZP) is a potential material for immobilization of nuclear effluents. Up to ∼2.17 mol % (10.71 wt %) lanthanum could be loaded into NZP formulations without significant changes in the three-dimensional framework structure. The crystal chemistry of Na1+x Zr2−x La x P3O12 (x = 0.1−0.5) phases was investigated using General Structure Analysis System programming. The LaNZP phases crystallize in space group $$R\bar 3c$$ with Z = 6. Powder diffraction data were subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The PO4 stretching and bending vibrations in the IR region were assigned. SEM and EDAX analysis provide evidence of La in the matrix.

Synthesis and crystallographic study of cation substituted NZP materials: Na1+xZr2−xMxP3O12(M = Sb, Al, Cr andx = 0.1)

A novel concept of immobilization of light water nuclear reactor fuel reprocessing waste effluent through interaction with sodium zirconium phosphate (NZP) has been established. It was found that a large number of hazardous cations could be loaded in the NZP-based matrix without significant change of three-dimensional framework structure. Starting from the raw powder diffraction data of polycrystalline solid phases, crystal structure of substituted NZP phases has been investigated using the General Structure Analysis System (GSAS) package. Cation(s) substituted NZP phases crystallize in rhombohedral symmetry (space groupR-3candZ = 6). Powder diffraction data have been subjected to Rietveld refinement to reach satisfactory structural convergence ofR-factors. Unit cell parameters, inter atomic distances, bond angles, reflecting planes (h,k,l), structure factors, polyhedral (ZrO6and PO4) distortion, and particle size have been reported. PO4stretching and bending vibrations in the Infra red (IR) region have been assigned. SEM and EDAX analysis provide analytical evidence of fixation of cations in the matrix.

Solid state synthesis and structural refinement of polycrystalline phases: Ca1−2xZr4M2xP6−2xO24 (M[dbnd]Mo, x = 0.1 and 0.3)

The structure of molybdenum substituted Polycrystalline calcium zirconium phosphate (CZP) was determined on the basis of crystal data of solid solutions. It was found that up to ∼5.81wt.% (∼1.74mol%), molybdenum could be loaded into CZP formulations without significant changes of the three-dimensional framework structure. The crystal chemistry of Ca1−2xZr4M2xP6−2xO24 (MMo, x=0.1 and 0.3) phases has been investigated using General Structure Analysis System (GSAS) programming. The Mo substituted CZP phases crystallize in the space group R-3 and Z=6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The PO4 stretching and bending vibrations in the Infra red (IR) region have been assigned. Morphology and compositional analysis have been carried out by scanning electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) of the specimens.

Crystal chemistry of immobilization of divalent Sr in ceramic matrix of sodium zirconium phosphates

Sodium zirconium phosphate (NZP) is a potential material for immobilization of nuclear effluents. It was observed up to ∼1.98mol% (6.07wt%), of strontium could be loaded into NZP formulations without significant changes of the three-dimensional framework structure. The crystal chemistry of Na1−xSrx/2Zr2P3O12 (x=0.1–1.0) phases has been investigated using General Structure Analysis System programming. The SrNZP phases crystallize in the space group R-3c and Z=6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The PO4 stretching and bending vibrations in the Infra red (IR) region have been assigned. SEM and EDAX analysis provide evidence of Sr in the matrix.

Crystallographic Evaluation of Sodium Zirconium Phosphate as a Host Structure for Immobilization of Cesium and Strontium

Sodium zirconium phosphate (NZP) is a potential material for immobilization of nuclear effluents. It was observed up to ~7.16 wt% (~2.67 mol%) of strontium and ~14.46 wt% (~3.56 mol%) of cesium could be simultaneously loaded into NZP formulations without significant changes in the three‐dimensional framework structure. The crystal chemistry of Na1−x(Cs1.33Sr1)xZr2P3O12 (x = 0.1–1.0) has been investigated using General Structure Analysis System programming. The CsSrNZP phases crystallize in the space group R‐3c and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R‐factors.

Fully activated Li2MnO3 nanoparticles by oxidation reaction

Fully activated Li2MnO3 nanoparticles were prepared by a chemical based oxidation reaction. All of the diffraction peaks of the prepared samples were well matched to a monoclinic phase (space group: C2/m) with no impurity peaks and refined using the General Structure Analysis System (GSAS) program. The activated Li2MnO3 sample showed homogeneously well-dispersed nanoparticles with a size of ∼10 nm. The oxidation state of Mn was confirmed by XPS. The activated Li2MnO3 nanoparticles delivered a high charge capacity of 302 mA h g−1 above 4.5 V and discharge capacity of 236 mA h g−1 during the first cycle. Interestingly, the cycle performance of the activated Li2MnO3 nanoparticles during extended cycles exhibited somewhat stable discharge capacities without any drastic capacity fading, even when cycled in the high voltage range of 2.0–4.9 V and after the phase transition to spinel. In terms of the rate performance, the activated Li2MnO3 sample exhibited significantly superior properties compared to the bulk Li2MnO3 sample, probably due to the nano-size particles with high crystallinity.

Structure refinement of polycrystalline orthorhombic yttrium substituted calcium titanate: Ca $_{\bf 1-\boldsymbol x}$ Y $_{\boldsymbol x}$ TiO $_{\bf 3+\boldsymbol\delta }$ ( ${\boldsymbol x}$ = 0·1–0·3)

The perovskite ceramic phases with composition Ca $_{\boldsymbol 1-x}$ Y $_{\boldsymbol x}$ TiO $_{\boldsymbol 3+\delta}$ (where $\boldsymbol x$ = 0·1, 0·2 and 0·3; hereafter CYT-10, CYT-20 and CYT-30) have been synthesized by solid state reaction at 1050°C. The structure refinement using general structure analysis system (GSAS) software converges to satisfactory profile indicators such as Rietveld parameters: Rp, R wp , RF 2 and goodness of fit. The title phases crystallize at room temperature in the space group Pbnm (#62) with ${\boldsymbol a}$ = 5·3741(4) A, ${\boldsymbol b}$ = 5·4300(4) A, ${\boldsymbol c}$ = 7·6229(5) A and ${\boldsymbol Z}$ = 4. Major inter-atomic distances, bond angles and structure factors have been calculated from the step analysis data of the compound. The crystal morphology has been examined by scanning electron microscopy. Energy dispersive X-ray (EDX) analysis of the specimens show that yttrium enters into the structural framework of CaTiO 3 . The particle size of the ceramic phases along major reflection planes ranges between 12 and 40 nm. The polyhedral (CaO 8 and TiO 6 ) distortions and valence calculations from bond strength data are also reported.