scholarly journals High Pressure Brillouin Spectroscopy and X-ray Diffraction of Cerium Dioxide

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3683
Author(s):  
Mungo Frost ◽  
John D. Lazarz ◽  
Abraham L. Levitan ◽  
Vitali B. Prakapenka ◽  
Peihao Sun ◽  
...  
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Cerium Dioxide ◽  
Room Temperature ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
Brillouin Spectroscopy ◽  
X Ray ◽  
Nanocrystalline Cerium Dioxide ◽  
Acoustic Velocities

Simultaneous high-pressure Brillouin spectroscopy and powder X-ray diffraction of cerium dioxide powders are presented at room temperature to a pressure of 45 GPa. Micro- and nanocrystalline powders are studied and the density, acoustic velocities and elastic moduli determined. In contrast to recent reports of anomalous compressibility and strength in nanocrystalline cerium dioxide, the acoustic velocities are found to be insensitive to grain size and enhanced strength is not observed in nanocrystalline CeO2. Discrepancies in the bulk moduli derived from Brillouin and powder X-ray diffraction studies suggest that the properties of CeO2 are sensitive to the hydrostaticity of its environment. Our Brillouin data give the shear modulus, G0 = 63 (3) GPa, and adiabatic bulk modulus, KS0 = 142 (9) GPa, which is considerably lower than the isothermal bulk modulus, KT0∼ 230 GPa, determined by high-pressure X-ray diffraction experiments.

scholarly journals The High-Pressure Structural Evolution of Olivine along the Forsterite–Fayalite Join

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 790 ◽  
Author(s):  
Martha G. Pamato ◽  
Fabrizio Nestola ◽  
Davide Novella ◽  
Joseph R. Smyth ◽  
Daria Pasqual ◽  
...  
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Room Temperature ◽  
Structural Evolution ◽  
X Ray Diffraction ◽  
Crystallographic Site ◽  
X Ray ◽  
Fe Content ◽  
Structural Mechanisms ◽  
Polyhedral Volumes

Structural refinements from single-crystal X-ray diffraction data are reported for olivine with a composition of Fo100 (forsterite Mg2SiO4, synthetic), Fo80 and Fo62 (~Mg1.6Fe0.4SiO4 and ~Mg1.24Fe0.76SiO4, both natural) at room temperature and high pressure to ~8 GPa. The new results, along with data from the literature on Fo0 (fayalite Fe2SiO4), were used to investigate the previously reported structural mechanisms which caused small variations of olivine bulk modulus with increasing Fe content. For all the investigated compositions, the M2 crystallographic site, with its bonding configuration and its larger polyhedral volume, was observed to control the compression mechanisms in olivine. From Fo100 to Fo0, the compression rates for M2–O and M1–O bond lengths were observed to control the relative polyhedral volumes, resulting in a less-compressible M1O6 polyhedral volume, likely causing the slight increase in bulk modulus with increasing Fe content.

scholarly journals High-Pressure Structural Behavior and Equation of State of Kagome Staircase Compound, Ni3V2O8

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 910
Author(s):  
Daniel Diaz-Anichtchenko ◽  
Robin Turnbull ◽  
Enrico Bandiello ◽  
Simone Anzellini ◽  
Daniel Errandonea
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Density Functional ◽  
Room Temperature ◽  
Ambient Pressure ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
A Chain

We report on high-pressure synchrotron X-ray diffraction measurements on Ni3V2O8 at room-temperature up to 23 GPa. According to this study, the ambient-pressure orthorhombic structure remains stable up to the highest pressure reached in the experiments. We have also obtained the pressure dependence of the unit-cell parameters, which reveals an anisotropic compression behavior. In addition, a room-temperature pressure–volume third-order Birch–Murnaghan equation of state has been obtained with parameters: V0 = 555.7(2) Å3, K0 = 139(3) GPa, and K0′ = 4.4(3). According to this result, Ni3V2O8 is the least compressible kagome-type vanadate. The changes of the crystal structure under compression have been related to the presence of a chain of edge-sharing NiO6 octahedral units forming kagome staircases interconnected by VO4 rigid tetrahedral units. The reported results are discussed in comparison with high-pressure X-ray diffraction results from isostructural Zn3V2O8 and density-functional theory calculations on several isostructural vanadates.

A high-pressure study of HfC and nano-crystalline TiC by X-ray diffraction and density functional theory calculations

2020 ◽  
Vol 34 (34) ◽  
pp. 2050393
Author(s):  
Lun Xiong ◽  
Bin Li ◽  
Bi Liang ◽  
Jinxia Zhu ◽  
Hong Yi ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Bulk Modulus ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Nano Crystalline

The equation of state (EOS) of HfC and nanosized TiC at high pressure has been studied by means of synchrotron radiation X-ray diffraction (XRD) in a diamond anvil cell (DAC) at ambient temperature, and density functional theory (DFT) calculations. XRD analysis showed that the cubic structure of HfC and nanosized TiC maintained to the maximum pressures. The XRD data yield a bulk modulus [Formula: see text] GPa with [Formula: see text] of HfC. In addition, the bulk modulus of nanosized TiC derived from XRD data is [Formula: see text] GPa with [Formula: see text].

Elastic Properties of Calcium Oxide Perovskites

2002 ◽  
Vol 718 ◽  
Author(s):  
Nancy L. Ross ◽  
Ross J. Angel ◽  
Jennifer Kung ◽  
Tracey D. Chaplin
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Calcium Oxide ◽  
Specific Volume ◽  
Equations Of State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Threefold Increase ◽  
Volume Relationship ◽  
Brownmillerite Structure

AbstractThe equations of state and axial moduli of the CaBO3 perovskites (B=Zr,Sn,Ti,Ge) and CaFeO2.5 with the brownmillerite structure have been determined using high-pressure, singlecrystal X-ray diffraction. The bulk modulus-specific volume relationship for the Ca-perovskites is nonlinear, with CaSnO3 and CaZrO3 displaying anomalous stiffening (higher bulk moduli) than previously reported and predicted [1,2]. The axial moduli of the a- and c-axes decrease steadily by ∼30% from the least-distorted of the Pbnm perovskites, CaGeO3, to the most distorted, CaZrO3, while the b-axis shows little change. The net result is a threefold increase in the anisotropy of the axial moduli of CaSnO3 and CaZrO3 (∼21%) relative to CaGeO3 and CaTiO3 (∼4-8%). The bulk modulus of CaFeO2.5 falls significantly below the trend for the stoichiometric perovskites. The introduction of 1/6 vacancies on the oxygen positions softens the perovskite structure by 25%.

High-pressure syntheses and crystal structures of orthorhombic DyGaO3 and trigonal GaBO3

2015 ◽  
Vol 70 (4) ◽  
pp. 207-214 ◽  
Author(s):  
Daniela Vitzthum ◽  
Stefanie A. Hering ◽  
Lukas Perfler ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystal ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
High Pressure High Temperature

AbstractOrthorhombic dysprosium orthogallate DyGaO3 and trigonal gallium orthoborate GaBO3 were synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 8.5 GPa/1350 °C and 8 GPa/700 °C, respectively. Both crystal structures could be determined by single-crystal X-ray diffraction data collected at room temperature. The orthorhombic dysprosium orthogallate crystallizes in the space group Pnma (Z = 4) with the parameters a = 552.6(2), b = 754.5(2), c = 527.7(2) pm, V = 0.22002(8) nm3, R1 = 0.0309, and wR2 = 0.0662 (all data) and the trigonal compound GaBO3 in the space group R3̅c (Z = 6) with the parameters a = 457.10(6), c = 1419.2(3) pm, V = 0.25681(7) nm3, R1 = 0.0147, and wR2 = 0.0356 (all data).

Equation of state and electrical transport properties of mixture of Li1.2Mn0.54Co0.13Ni0.13O2 and LiNi0.87Co0.09Mn0.03Al0.01O2 at high pressure

2021 ◽  
pp. 2150227
Author(s):  
Lun Xiong ◽  
Pu Tu ◽  
Yongqing Hu ◽  
Xiang Hou ◽  
Shiyun Wu ◽  
...  
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Electrical Transport ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Electrical Transport Properties ◽  
X Ray ◽  
Diamond Anvil

The equation of state (EOS) of mixture of Li[Formula: see text]Mn[Formula: see text]Co[Formula: see text]Ni[Formula: see text]O2 and LiNi[Formula: see text] Co[Formula: see text]Mn[Formula: see text]Al[Formula: see text]O2 was studied by synchrotron radiation X-ray diffraction (XRD) at room-temperature in a diamond anvil cell (DAC). The results showed that the hexagonal structure is maintained to the highest pressure of 23.1 GPa. The bulk modulus and its first derivative obtained from XRD data are [Formula: see text] GPa and [Formula: see text], respectively. In addition, we have investigated the high-pressure electrical conductivity of the mixture of Li[Formula: see text]Mn[Formula: see text]Co[Formula: see text]Ni[Formula: see text]O2 and LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]Al[Formula: see text]O2 to 22.9 GPa in a DAC. It is found that the resistance decreases with the increase of pressure and changes exponentially.

Crystal Polymorphs and Multiple Crystallization Pathways of Highly Pressurized 1-Ethyl-3-Methylimidazolium Nitrate

2019 ◽  
Vol 72 (2) ◽  
pp. 87 ◽  
Author(s):  
Hiroshi Abe ◽  
Takahiro Takekiyo ◽  
Yukihiro Yoshimura ◽  
Nozomu Hamaya ◽  
Shinichiro Ozawa
Keyword(s):  
Differential Scanning Calorimetry ◽  
High Pressure ◽  
Room Temperature ◽  
Ambient Pressure ◽  
Optical Microscope ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Low Temperature Crystallization ◽  
Temperature Crystallization

Crystal polymorphs and multiple crystallization pathways of a room-temperature ionic liquid (RTIL) were observed only under high pressure (HP). The RTIL was 1-ethyl-3-methylimidazolium nitrate, [C2mim][NO3]. The HP-crystal polymorphs were related to conformations of the C2mim+ cation, and the HP-crystal pathways determined by the presence or absence of the planar′ (P′) conformation of the C2mim+ cation were switched at the bifurcation pressure (PB). Above PB, modulated crystal structures derived from the HP-inherent P′ conformer. Simultaneous X-ray diffraction and differential scanning calorimetry measurements, accompanied by optical microscope observations, confirmed the normal low-temperature crystallization of [C2mim][NO3] under ambient pressure.

HIGH-PRESSURE STRUCTURE STUDY OF CuBa2Ca3Cu4O10 + δ SUPERCONDUCTOR

2005 ◽  
Vol 19 (06) ◽  
pp. 313-316
Author(s):  
X. M. QIN ◽  
Y. YU ◽  
G. M. ZHANG ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Structure Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diamond Anvil ◽  
Murnaghan Equation

In-situ high-pressure energy dispersive X-ray diffraction measurements on CuBa 2- Ca 3 Cu 4 O 10 + δ (Cu-1234) have been performed by using diamond anvil cell (DAC) device with synchrotron radiation. The results suggest that the crystal structure of Cu-1234 superconductor is stable under pressures up to 34 GPa at room temperature. According to the Birch–Murnaghan equation of state, the bulk modulus is obtained to be ~ 150 GPa.

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