scholarly journals Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

2018 ◽  
Vol 101 (8) ◽  
pp. 3357-3371 ◽  
Author(s):  
Oliver L. G. Alderman ◽  
Chris J. Benmore ◽  
Alex Lin ◽  
Anthony Tamalonis ◽  
J. K. Richard Weber
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Melt Structure ◽  
X Ray ◽  
Coordination Numbers ◽  
Bond Lengths

scholarly journals Structure of bismuth tellurite and bismuth niobium tellurite glasses and Bi2Te4O11 anti-glass by high energy X-ray diffraction

RSC Advances ◽  
2020 ◽  
Vol 10 (22) ◽  
pp. 13237-13251 ◽  
Author(s):  
Nupur Gupta ◽  
Atul Khanna ◽  
Hirdesh ◽  
Ann-Christin Dippel ◽  
Olof Gutowski
Keyword(s):  
High Energy ◽  
Tellurite Glasses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths

Te–O, Bi–O and Nb–O bond lengths, co-ordinations in bismuth tellurite, bismuth niobium tellurite glasses and Bi2Te4O11 anti-glass by HEXRD, RMC and Riteveld analysis.

Structure of Zinc Phosphate Glasses of 75 and 80 mole% ZnO Content Studied by X-Ray Diffraction and Reverse Monte Carlo Simulations

2005 ◽  
Vol 60 (7) ◽  
pp. 517-526 ◽  
Author(s):  
Uwe Hoppe ◽  
Yanko Dimitriev ◽  
Pal Jóvári
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
High Energy ◽  
Phosphate Glasses ◽  
Strong Increase ◽  
Reverse Monte Carlo ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coordination Numbers ◽  
Q Factors

X-Ray diffraction, using high-energy photons from a synchrotron, was used to extend the investigation of (ZnO)x(P2O5)1−x glasses to samples of ZnO content close to x = 0.8 which were obtained by roller-quenching. The isolated PO4 tetrahedra are surrounded by ZnOn polyhedra, where Zn−O coordination numbers of ∼ 4.5 are determined. The small increase of NZnO from ∼ 4 at metaphosphate composition (x = 0.5) to ∼ 4.5 is not sufficient to explain the strong increase of the packing density beyond the minimum at x = 0.5. The medium-range order was analyzed on the basis of partial SPP(Q) and SZnZn(Q) factors obtained from Reverse Monte Carlo simulations of glasses with 0 ≤ x ≤ 0.8. The positions of the first peaks in these factors, the number densities of P and Zn atoms and knowledge of definite P-P and Zn-Zn distances were used to check the applicability of simple models such as the dense packing of uniform P- and Zn-centered spherical environments for glasses with x=0.8 and 0.5, the packing of corrugated sheets for vitreous P2O5 and the packing of phosphate chains for Zn metaphosphate glass.

Ternary Antimonides RE2Ir3Sb4 (RE = La, Ce, Pr, Nd)

2011 ◽  
Vol 66 (8) ◽  
pp. 777-783
Author(s):  
Konrad Schäfer ◽  
Wilfried Hermes ◽  
Ute Ch. Rodewald ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen
Keyword(s):  
High Frequency ◽  
Three Dimensional ◽  
Magnetic Ordering ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Static Disorder ◽  
X Ray ◽  
Coordination Numbers ◽  
Arc Melting ◽  
Covalently Bonded

The antimonides RE2Ir3Sb4 (RE = La, Ce, Pr, Nd) were synthesized by arc-melting of the elements and subsequent annealing or via high-frequency melting. The samples were characterized by X-ray powder diffraction, and the four structures were refined from single-crystal X-ray diffraction data: Pr2Ir3Sb4 type, Pnma, Z = 4, a = 1621.9(2), b = 458.60(8), c = 1099.8(1) pm, wR2 = 0.036, 1558 F2 values for La2Ir3Sb4, a = 1616.6(8), b = 456.5(2), c = 1094.8(5) pm, wR2 = 0.092, 1080 F2 values for Ce2Ir3Sb4, a = 1613.0(5), b = 454.9(2), c = 1094.1(5) pm, wR2 = 0.057, 1428 F2 values for Pr2Ir3Sb4, and a = 1609.8(6), b = 452.9(2), c = 1092.3(5) pm, wR2 = 0.052, 1472 F2 values for Nd2Ir3Sb4, with 56 parameters per refinement. The Sb1 atoms show enhanced displacement off the mirror planes at y = 1/4 and y = 3/4. A series of temperature-dependent structure refinements of Pr2Ir3Sb4 down to 90 K are indicative of static disorder. The iridium and antimony atoms build up covalently bonded three-dimensional [Ir3Sb4] networks with Ir-Sb distances ranging from 256 -269 pm (Nd2Ir3Sb4). The two crystallographically independent rare earth sites fill cavities of coordination numbers 17 (8 Ir + 9 Sb) and 15 (6 Ir + 9 Sb) within the [Ir3Sb4] polyanions. Temperature-dependent magnetic susceptibility measurements indicate a stable trivalent ground state for the cerium compound. No magnetic ordering was evident down to 3 K.

The Structure of Gallium Phosphate Glasses by High-energy X-ray Diffraction

2002 ◽  
Vol 57 (8) ◽  
pp. 709-715 ◽  
Author(s):  
U. Hoppe ◽  
D. Ilieva ◽  
J. Neuefeindb
Keyword(s):  
Coordination Number ◽  
Short Range ◽  
High Energy ◽  
Phosphate Glasses ◽  
X Ray Diffraction ◽  
Strong Decrease ◽  
X Ray ◽  
Coordination Numbers ◽  
Tetrahedral Sites ◽  
Gallium Phosphate

X-ray diffraction experiments are used to obtain short-range order information of gallium phosphate glasses of meta- and pyrophosphate compositions. Parameters of the first-neighbor peaks, such as coordination numbers and distances, are obtained. A strong decrease of the Ga-O coordination number from 6.0±0.2 to 4.6±0.2 upon Ga2O3 addition is found, which is accompanied by a shortening of the Ga-O distances. Only GaO6 octahedra exist at the metaphosphate composition. Close to the pyrophosphate composition, the majority of Ga atoms occupies already tetrahedral sites. The Ga-O coordination number behaves equivalent with the ratio MTO = n(OT)/n(Ga), thus, with the number n(OT) of terminal oxygen atoms (OT) in phosphorus-OT bonds which are available for the coordination of each Ga atom. Thus, P-OT-Ga bridges are formed for all OT atoms. The GaOn polyhedra neither share OT atoms nor form Ga-O-Ga bridges. With increasing fraction of GaO4 tetrahedra and decreasing lengths of the phosphate chains the network expands.

Properties of Mbe Grown Heterostructures of GaAs/InSb and InP/InSb.

1989 ◽  
Vol 145 ◽  
Author(s):  
M. T. Asom ◽  
E. A. Fitzgerald ◽  
F. A. Thiel ◽  
R. People ◽  
D. Eaglesham ◽  
...  
Keyword(s):  
Hall Effect ◽  
Lattice Mismatch ◽  
High Energy ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Energy Position ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Peaks

AbstractWe have employed molecular beam epitaxy in the growth of InSb on GaAs and InP. The transport, optical and structural properties of the films were investigated by in-situ reflection high energy electron diffraction, Hall effect and temperature dependent Hall effect, photoluminescence, transmission electron microscopy and X-ray diffractometry techniques. We report mobilities of up to 32,000 cm2/volt-sec and free electron concentrations of 3x1016/cm3 at room temperature. We have discovered a new defect state in InSb with an energy position of Ec - 0.05 ± 0.006eV. Optical and structural measurements reveal that the differences in thermal expansion and lattice mismatch between the substrates and films results in the broadening of the X-ray diffraction peaks and the near gap photoluminescence linewidths. Furthermore, we observe band gap shifts to higher energies of 10meV and 20meV for growth on GaAs and InP, respectively.

scholarly journals Structure of strontium tellurite glass, anti-glass and crystalline phases by high-energy X-ray diffraction, reverse Monte Carlo and Rietveld analysis

2020 ◽  
Vol 76 (1) ◽  
pp. 108-121 ◽  
Author(s):  
Rajinder Kaur ◽  
Atul Khanna ◽  
Hirdesh ◽  
Ann-Christin Dippel ◽  
Olof Gutowski ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Rietveld Refinement ◽  
Short Range ◽  
Bond Angle ◽  
High Energy ◽  
Reverse Monte Carlo ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths ◽  
Atomic Pair

The structures of xSrO–(100 − x)TeO2 (x = 5, 7.5, 8.5 and 10 mol.%) glass, anti-glass and crystalline samples were studied by high-energy X-ray diffraction (HEXRD), reverse Monte Carlo (RMC) simulations, atomic pair distribution function analysis and Fullprof Rietveld refinement. The atomic pair distributions show the first peak at 1.90 Å due to the Te—O equatorial bonds and the Te—O peak is asymmetrical due to the range of Te—O bond lengths in glass, anti-glass and crystalline samples. The short-range structural properties of glasses such as Te—O bond lengths, Te–O speciation, Te–Te distances and O—Te—O bond angle distributions were determined by RMC simulations. The average Te–O coordination number (N Te–O) for 5SrO–95TeO2 glass is 3.93 which decreases to 3.59 on increasing the SrO concentration to 10 mol.%. The changes in N Te–O revealed that the glass network predominantly contains TeO4 units with a small amount of TeO3 units and there is a structural transformation TeO4 → TeO3 with an increase in SrO concentration. The O—Te—O bond angle distributions have a peak at 79° and reveal that the Oequatorial—Te—Oequatorial bonds are the most abundant linkages in the tellurite network. Two glass samples containing 7.5 and 8.5 mol.% of SrO were annealed at 350°C for 1 h to produce anti-glass phases; they were further annealed at 450°C for 4 h to transform them into crystalline phases. The anti-glass samples are disordered cubic SrTe5O11 and the disordered monoclinic SrTeO3 phases, whereas the crystalline samples contain monoclinic SrTeO3 and the orthorhombic TeO2 phases. The unit-cell parameters of the anti-glass and crystalline structures were determined by Fullprof Rietveld refinement. Thermal studies found that the glass transition temperature increases with an increase in SrO mol.% and the results on the short-range structure of glasses from Raman spectroscopy are in agreement with the RMC findings.

Effect of cerium substitution on structural and impedance properties of 0.8Ba0.2(Bi0.5K0.5)TiO3lead free ceramic system

2016 ◽  
Vol 30 (06) ◽  
pp. 1650056
Author(s):  
M. N. V. Ramesh ◽  
K. V. Ramesh
Keyword(s):  
Impedance Analysis ◽  
Solid State Reaction Method ◽  
High Energy ◽  
Dielectric Studies ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Lead Free Ceramics ◽  
A Site

Cerium-doped 0.8BaTiO3-0.2Bi[Formula: see text]K[Formula: see text]TiO3with composition 0.8Ba0.2(Bi[Formula: see text]K[Formula: see text])Ti[Formula: see text]Ce[Formula: see text]O3where x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.06 lead free ceramics were prepared by conventional solid state reaction method followed by high energy ball milling. X-ray diffraction studies confirm the tetragonal structure at room temperature for all the Ce-doped samples. Lattice parameters and density were increasing with increase of Ce doping. Frequency and temperature dependent dielectric studies were carried out and indicate that the dielectric constant and Curie temperature are decreasing with increasing of Ce doping. All the Ce-doped samples exhibiting diffused and dispersive phase transitions with degree of diffuseness ranging from 1.4 to 2 calculated from the modified Curie–Weiss law. Impedance studies confirms the temperature dependent non-Debye kind of relaxation process in the material. From the Cole–Cole plots measured at high temperatures, reveals that the grain effect in the all Ce-doped samples. Impedance analysis studies also support the X-ray diffraction and dielectric studies that occupation of Ce both at A-site and B-site for small values of Ce doping.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

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