Elastic softening of bulk modulus of monoclinic HfO2 under high pressure

2020 ◽  
Vol 117 (18) ◽  
pp. 182903
Author(s):  
Yuichi Akahama ◽  
Saori Kawaguchi ◽  
Naohisa Hirao ◽  
Yasuo Ohishi
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Elastic Softening

Deformation of polyiodides in Cs2I8 crystals at high pressure

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Tomasz Poreba ◽  
Gaston Garbarino ◽  
Davide Comboni ◽  
Mohamed Mezouar
Keyword(s):  
High Pressure ◽  
Electron Transfer ◽  
Bulk Modulus ◽  
Electronic Properties ◽  
Supramolecular Architecture ◽  
Ambient Conditions ◽  
Electron Transfer Mechanism ◽  
Covalently Bonded ◽  
Potential Sources ◽  
High Bulk

Dicaesium octaiodide is composed of layers of zigzag polyiodide units (I8 2−) intercalated with caesium cations. Each I8 2− unit is built of two triiodides bridged with one diiodine molecules. This system was subjected to compression up to 5.9 GPa under hydrostatic conditions. Pressure alters the supramolecular architecture around I8 2−, leading to bending of the triiodide units away from their energetically preferred geometry (D ∞h). Short I2...I3 − contacts compress significantly, reaching lengths typical for the covalently bonded polyiodides. Unlike in reported structures at ambient conditions, pressure-induced catenation proceeds without symmetrization of the polyiodides, pointing to a different electron-transfer mechanism. The structure is shown to be half as compressible [B0 = 12.9 (4) GPa] than the similar CsI3 structure. The high bulk modulus is associated with higher I—I connectivity and a more compact cationic net, than in CsI3. The small discontinuity in the compressibility trend around 3 GPa suggests formation of more covalent I—I bonds. The potential sources of this discontinuity and its implication on the electronic properties of Cs2I8 are discussed.

scholarly journals Thermal properties of cubic zincblende thallium-phosphide from quasi-harmonic Debye model approximation

2017 ◽  
Vol 5 (1) ◽  
pp. 14 ◽  
Author(s):  
Salah Daoud
Keyword(s):  
High Pressure ◽  
Thermal Properties ◽  
Bulk Modulus ◽  
Unit Cell Volume ◽  
Theoretical Data ◽  
Debye Model ◽  
Zero Temperature ◽  
Isothermal Bulk Modulus ◽  
Model Approximation ◽  
First Order

The thermal properties of cubic zincblende (B3) thallium - phosphide (TlP) compound under high pressure up to 12 GPa have been studied using the quasi-harmonic Debye model approximation. The relative unit cell volume, the isothermal bulk modulus, the first order derivative isothermal bulk modulus, the Debye temperature and the Grüneisen parameter are studied at zero-temperature and at standard ambient temperature (298 K) respectively. Our obtained values of the different previous quantities are in general in agreement compared to other theoretical data of the literature.

scholarly journals Elastic Behaviour of Diborides Under High Pressure

2009 ◽  
Vol 1 (2) ◽  
pp. 275-280
Author(s):  
Seema Gupta ◽  
S. C. Goyal
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Statistical Model ◽  
Bulk Modulus ◽  
Electron Gas ◽  
Elastic Behaviour ◽  
Pressure Derivative ◽  
First Order ◽  
Elastic Data ◽  
Quantum Statistical

The present study deals with the elastic behaviour of diborides (BeB2, MgB2 and NbB2) under high pressure with the help of equation of state (EOS) using the elastic data reported by Islam et al. It is concluded that EOS, which are based either on quantum statistical model or  pseduopotential model, only are capable of explaining high pressure behaviour of the solids under study.  Moreover the value of first order pressure derivative of bulk modulus at infinite pressure (Kinfinity) is greater than 5/3 and thus the diborides under study do not behave as Thomas-Fermi electron gas under high compression. Keywords: Equation of state; High Pressure; Diborides. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i2.1189 

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].

The Study of High Pressure and Bulk Modulus of Metals by Equations of State

2016 ◽  
Vol 5 (3) ◽  
pp. 397-400
Author(s):  
R. S. Singh ◽  
Deepti Sahrawat
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Equations Of State

A Numerical Study of High Pressure Flow Through a Hydraulic Pressure Relief Valve Considering Pressure and Temperature Dependent Viscosity, Bulk Modulus and Density

2016 ◽  
Author(s):  
Sven Osterland ◽  
Jürgen Weber
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Hydraulic Pressure ◽  
Temperature Dependent ◽  
Relief Valve ◽  
Temperature Dependent Viscosity ◽  
Pressure Region ◽  
Flow Through ◽  
The Mean ◽  
Dependent Viscosity

This paper investigates the flow through a hydraulic pressure relief valve at high levels of operating pressure up to 700 bar (10000 Psi). Following the flow path from the cold high pressure region before the metering edge to the warm low pressure region behind, the mean viscosity decreases by a factor of 16, the mean bulk modulus decreases by a factor of 2 and the mean density decreases by 6 %. Based on this preliminary considerations, a turbulent single phase flow considering pressure and temperature dependent viscosity, bulk modulus and density is modelled and steady state as well as transient calculations are performed. The results of this study show that a pressure and temperature dependent viscosity reduces the pressure drop and the spool force by 10 % compared to a simulation with constant fluid parameters. Moreover, it is shown that compressible flow modelling has negligible influence on pressure drop and spool force — nevertheless, it is required to describe the temperature correctly. Due to the effect of volumetric work an incompressible model approach predicts the mean temperature rise 20 % too high. Finally, it was found that the temperature on the spool exceeds 400 °C. Afterwards, this fact is experimentally validated obtaining tempering colors in high pressure tests.

scholarly journals High-pressure Synthesis and Bulk Modulus of Non-centrosymmetric Superconductor Mo3Al2C

2017 ◽  
Vol 950 ◽  
pp. 042028
Author(s):  
C Sekine ◽  
U Sai ◽  
J Hayashi ◽  
Y Kawamura ◽  
E Bauer
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
High Pressure Synthesis ◽  
Pressure Synthesis
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