Pressure Dependence Of Properties Research Articles

Amorphous to amorphous phase transformation in boron-rich amorphous silicon borides: an ab initio study

ABSTRACT This study employs a constant-pressure ab initio approach to investigate the high-pressure behavior of five distinct boron-rich amorphous silicon borides. A unique amorphous-to-amorphous phase transition is exposed, providing insights into the structural resilience of these materials under extreme conditions. Our results reveal a gradual increase in the coordination number of both B and Si atoms under pressure, with subsequent densification upon pressure release. Yet the recovered amorphous phases closely resemble the uncompressed states, highlighting the reversibility of these phase changes. Significant structural modifications around Si atoms are observed, emphasizing their pivotal role in the observed phase transitions. Additionally, pressure-induced metallization is witnessed in these materials, indicating their distinctive electronic behavior under high pressure. This work significantly contributes to a deeper understanding of the high-pressure behavior of boron-rich amorphous silicon borides and opens avenues for exploring their potential applications in fields requiring exceptional structural stability and unique pressure-dependent properties.

Isotope effects in supercooled H2O and D2O and a corresponding-states-like rescaling of the temperature and pressure.

Water shows anomalous properties that are enhanced upon supercooling. The unusual behavior is observed in both H2O and D2O, however, with different temperature dependences for the two isotopes. It is often noted that comparing the properties of the isotopes at two different temperatures (i.e., a temperature shift) approximately accounts for many of the observations-with a temperature shift of 7.2K in the temperature of maximum density being the most well-known example. However, the physical justification for such a shift is unclear. Motivated by recent work demonstrating a "corresponding-states-like" rescaling for water properties in three classical water models that all exhibit a liquid-liquid transition and critical point [Uralcan et al., J. Chem. Phys. 150, 064503 (2019)], the applicability of this approach for reconciling the differences in the temperature- and pressure-dependent thermodynamic properties of H2O and D2O is investigated here. Utilizing previously published data and equations-of-state for H2O and D2O, we show that the available data and models for these isotopes are consistent with such a low temperature correspondence. These observations provide support for the hypothesis that a liquid-liquid critical point, which is predicted to occur at low temperatures and high pressures, is the origin of many of water's anomalies.

Pressure-dependent large-scale seismic anisotropy induced by non-Newtonian mantle flow

Summary Observations of large-scale seismic anisotropy can be used as a marker for past and current deformation in the Earth’s mantle. Nonetheless, global features such as the decrease of the strength of anisotropy between ∼150–410 km in the upper mantle and weaker anisotropy observations in the transition zone remain ill-understood. Here, we report a proof of concept method that can help understand anisotropy observations by integrating pressure-dependent microscopic flow properties in mantle minerals particularly olivine and wadsleyite into geodynamic simulations. The model is built against a plate-driven semi-analytical corner flow solution underneath the oceanic plate in a subduction setting spanning down to 660 km depth with a non-Newtonian n = 3 rheology. We then compute the crystallographic preferred orientation (CPO) of olivine aggregates in the upper mantle (UM), and wadsleyite aggregates in the upper transition zone (UTZ) using a viscoplastic self-consistent (VPSC) method, with the lower transition zone (LTZ, below 520 km) assumed isotropic. Finally, we apply a tomographic filter that accounts for finite-frequency seismic data using a fast-Fourier homogenization algorithm, with the aim of providing mantle models comparable with seismic tomography observations. Our results show that anisotropy observations in the UM can be well understood by introducing gradual shifts in strain accommodation mechanism with increasing depths induced by a pressure-dependent plasticity model in olivine, in contrast with simple A-type olivine fabric that fails to reproduce the decrease in anisotropy strength observed in the UM. Across the UTZ, recent mineral physics studies highlight the strong effect of water content on both wadsleyite plastic and elastic properties. Both dry and hydrous wadsleyite models predict reasonably low anisotropy in the UTZ, in agreement with observations, with a slightly better match for the dry wadsleyite models. Our calculations show that, despite the relatively primitive geodynamic setup, models of plate-driven corner flows can be sufficient in explaining first-order observations of mantle seismic anisotropy. This requires, however, incorporating the effect of pressure on mineralogy and mineral plasticity models.

A semi-analytical rate-transient analysis model for fractured horizontal well in tight reservoirs under multiphase flow conditions

Abstract Rate-transient analysis (RTA) has been widely applied to extract reservoir/fracture properties using analytical and semi-analytical methods with simplifying assumptions. However, current RTA models may lead to misdiagnosis of flow regimes and incorrect estimates of reservoir/fracture information when complex fracture network, multiphase flow, and pressure-dependent properties occur in tight reservoirs simultaneously. A semi-analytical model is developed to account for multiphase flow, complex fracture network, and pressure-dependent properties. The technique uses the black oil formulation and butterfly model to determine three nonlinear partial differential equations (PDEs) that describe the flow of oil, gas, and water in the reservoir with complex fracture network. A modified Boltzmann variable considering the heterogeneity of complex fracture network is proposed to convert the fluid flow PDEs to a set of ordinary differential equations (ODEs) that can be solved through the Runge-Kutta method. A new rate-transient analysis workflow is also developed to improve flow regime identification (ID) and the accuracy for tight oil reservoirs with complex fracture network. It is applied to a synthetic case with equivalently modeled complex fracture network and multiphase flow. The estimated fracture properties are in excellent agreement with model inputs.

Comprehensive computational investigation of structural and mechanical characteristics of crystalline C3N4 under high pressure based on experimental data

This study presents a comprehensive investigation of the structural and mechanical characteristics of crystalline C3N4, encompassing seven distinct phases within the pressure range of 0–150 GPa, employing the GGA-PBE method. The analysis reveals significant insights, including the phase transitions of C3N4 from g-C3N4 of P-6m2 at 0 GPa to α-C3N4 of P31c at 9.1 GPa, culminating in c-C3N4 of I-43d at 95.3 GPa. Moreover, the minimal enthalpy difference observed between the gr-C3N4 and g-C3N4 at 0 GPa suggests the potential coexistence of these phases, indicating the likelihood of multiple graphitic carbon nitride structural coexistences at this pressure. The enthalpy difference between α-C3N4 and β-C3N4 structures also indicates the possibility of their coexistence. Furthermore, the study explores the pressure-dependent mechanical properties of C3N4, including changes in elastic constants and major elastic moduli with pressure, though it raises concerns regarding the potential instability of g-C3N4 under high-pressure indicated by calculated stability conditions.

Pressure-dependent mechanical properties of thin films under uniaxial strain via the layer compression test

Pressure-dependent mechanical properties of thin films under uniaxial strain via the layer compression test

Electronic, magnetic, half-Metallic, pressure-induced elastic and curie temperature predictions of Zr2RhTl Heusler alloy: DFT and EFT studies

ABSTRACT The DFT method investigated the total and partial magnetic moments, half-metallic characters, and pressure-dependent elastic properties of Zr2RhTl alloy. According to the ground state properties, the FM phase is more stable in energy than the AFM and NM phases. The Curie temperature value was obtained as 897.43 K with the help of the energy differences of the AFM and FM phases. The total magnetic moment of Zr2RhTl alloy was obtained as 2.00 µB/f.u. Partial magnetic moment values were obtained as 0.810, 0.506, 0.032, and 0.009 µB for Zr1, Zr2, Rh, and Tl atoms, respectively. All these total and partial magnetic moment values and Curie temperatures were supported by the Effective Field Theory (EFT) method. In addition, partial Curie temperatures of Zr2RhTl alloy were calculated by EFT separately for each element. The up-spins of Zr2RhTl alloy show metallic character in both the GGA and GGA + mBJ approximations, while the down-spins have band gaps of 0.698 and 0.699 eV, respectively. Electronic properties were also supported by GGA + U (U = 1, 2, 3 eV) interactions. Therefore, Zr2RhTl alloy is a true half-metallic ferromagnetic material. Zr2RhTl alloy was elastically stable, and the Debye temperature was calculated as 221.496 K at 0 GPa. All calculations obtained using two different methods (DFT and EFT) and two different approximations (GGA and GGA + mBJ) support each other. Therefore, Zr2RhTl alloy proved to be a very suitable material to be used as an alternative for spintronics.

Ultra-sensitive pressure sensing capabilities of defective one-dimensional photonic crystal

Present research work deals with the extremely sensitive pressure-sensing capabilities of defective one-dimensional photonic crystal structure (GaP/SiO2)N/Al2O3/(GaP/SiO2)N. The proposed structure is realized by putting a defective layer of material Al2O3 in the middle of a structure consisting of alternating layers of GaP and SiO2. The transfer matrix method has been employed to examine the transmission characteristics of the proposed defective one-dimensional photonic crystal in addition to MATLAB software. An external application of the hydrostatic pressure on the proposed structure is responsible for the change in the position and intensity of defect mode inside the photonic band gap of the structure due to pressure-dependent refractive index properties of the materials being used in the design of the sructure. Additionally, the dependence of the transmission properties of the structure on other parameters like incident angle and defect layer thickness has also studied. The theoretical obtained numeric values of the quality factor and sensitivity are 17,870 and 72 nm/GPa respectively. These results are enough to support our claim that the present design can be used as an ultra-sensitive pressure sensor.

Phase transition, mechanical and electronic properties of Ti3B4 under high pressure

We explore the crystalline structures for Ti3B4 in the 0–200 GPa pressure range via first-principles calculations based on density functional theory and advanced crystal structures prediction method using an evolutionary algorithm. The low-pressure-stable Immm phase of Ti3B4 gives way to a newly predicted orthorhombic phase (Pmmm) at 136 GPa. The B six-membered rings in the Immm phase transform to linked B zigzag chains in the Pmmm phase. Based on the electronic band structures, both Immm and Pmmm are metallic from 1 atm to 200 GPa; pressure-induced charge transfer promotes this phase transition. The simulated Vickers hardness values of Immm and Pmmm at ambient pressure are 41.5 and 34.9 GPa, respectively. The hardness of the Immm phase reduces with pressure while the opposite trend is observed for the Pmmm phase. These findings on the pressure-dependent properties of Ti3B4 yield insights into the intriguing high-pressure behaviors of the titanium-boron system.

A comparative study of structural, electronic, magnetic, and pressure-dependent properties of Full-Heusler Fe2XSi (X=Mn and Co): first-principles calculation and Monte Carlo Simulation

This study investigates the structural, electronic, magnetic, and pressure-dependent properties of Fe2XSi (X=Mn and Co) full-Heusler alloy through a comprehensive computational approach. The structural stability of these alloys confirmed L21 and XA prototypes as favorable structures for Fe2MnSi and Fe2CoSi, respectively. In addition, Fe2MnSi exhibits 100% spin polarization suggesting its potential suitability for spintronics applications. Conversely, Fe2CoSi does not exhibit similar behavior. The calculated magnetic moments of these alloys revealed an increase due to Coulomb interaction (U). The magnetic moments satisfy the Slater-Pauling relation, with calculated values of 3 for Fe2MnSi and 5 for Fe2CoSi. Heisenberg exchange interaction parameters are calculated to illustrate distinct magnetic interactions within the alloys. The study further explores thermomagnetic properties through Monte Carlo simulations, including thermal magnetization, thermal magnetic susceptibility, and Curie temperature The calculated were found to be 294 K for Fe2MnSi and 1029 K for Fe2CoSi, showing close agreement with experimental data. We additionally investigate the pressure-dependent properties of these alloys, revealing a non-linear dependence of the band gap on pressure for Fe2MnSi, with values decreasing from 0.668 eV to 0.259 eV as pressure increased from −15.917 to 23.712 GPa. For Fe2CoSi, the band gap remained zero across varying pressure conditions, indicating its metallic conducting behavior.

Mechanical Stability and Energy Gap Evolution in Cs-Based Ag, Bi Halide Double Perovskites under High Pressure: A Theoretical DFT Approach.

Due to their intrinsic stability and reduced toxicity, lead-free halide double perovskite semiconductors have become potential alternatives to lead-based perovskites. In the present study, we used density functional theory simulations to investigate the mechanical stability and band gap evolution of double perovskites Cs2AgBiX6 (X = Cl and Br) under an applied pressure. To investigate the pressure-dependent properties, the hydrostatic pressure induced was in the range of 0-100 GPa. The mechanical behaviors indicated that the materials under study are both ductile and mechanically stable and that the induced pressure enhances the ductility. As a result of the induced pressure, the covalent bonds transformed into metallic bonds with a reduction in bond lengths. Electronic properties, energy bands, and electronic density of states were obtained with the hybrid HSE06 functional, including spin-orbit coupling (HSE06 + SOC) calculations. The electronic structure study revealed that Cs2AgBiX6 samples behave as X-Γ indirect gap semiconductors, and the gap reduces with the applied pressure. The pressure-driven samples ultimately transform from the semiconductor to a metallic phase at the given pressure range. Also, the calculations demonstrated that the applied pressure and spin-orbit coupling of the states pushed VBM and CBM toward the Fermi level which caused the evolution of the band gap. The relationship between the structure and band gap demonstrates the potential for designing lead-free inorganic perovskites for optoelectronic applications, including solar cells as well as X-ray detectors.

Post-impact squeeze-out behavior of oils with different pressure-dependent rheological properties

The rapid approach of surfaces significantly increases pressure and viscosity of lubrication oil, trapping it in a dimple at the contact zone that requires time to be squeezed out. In this study, a measuring system was developed that utilized a ball-disk impact device and light interference technology to investigate the post-impact squeeze-out behavior of oils. Dimple shape evolution varied depending on the pressure-dependent rheological properties of the oils. Specifically, higher pressure–viscosity coefficients resulted in greater reduction in dimple radius, whereas lower pressure–viscosity coefficients led to quicker collapse in dimple height, providing a qualitative criterion for comparing pressure-dependent rheological properties of oils. Additionally, effect of initial dimple height and external load on the squeeze-out behavior were investigated.

Pressure-dependent mechanical properties, optical phonon frequencies, and acoustic velocity of the gallium arsenide semiconductor

Pressure-dependent mechanical properties, optical phonon frequencies, and acoustic velocity of the gallium arsenide semiconductor

Piezochromism in Dynamic Three-Dimensional Covalent Organic Frameworks.

Piezochromic materials with pressure-dependent photoluminescence tuning properties are important in many fields, such as mechanical sensors, security papers, and storage devices. Covalent organic frameworks (COFs), as an emerging class of crystalline porous materials (CPMs) with structural dynamics and tunable photophysical properties, are suitable for designing piezochromic materials, but there are few related studies. Herein, we report two dynamic three-dimensional COFs based on aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ) chromophores, termed JUC-635 and JUC-636 (JUC = Jilin University China), and for the first time, study their piezochromic behavior by diamond anvil cell technique. Due to the various luminescent groups, JUC-635 has completely different solvatochromism and molecular aggregation behavior in the solvents. More importantly, JUC-635 with AIE effect exhibits a sustained fluorescence upon pressure increase (~3 GPa), and reversible sensitivity with high-contrast emission differences (Δλem = 187 nm) up to 12 GPa, superior to other CPMs reported so far. Therefore, this study will open a new gate to expand the potential applications of COFs as exceptional piezochromic materials in pressure sensing, barcoding, and signal switching.

Numerical Simulation of Palm Biodiesel Droplet Evaporation at Various Temperatures and Pressures

This study uses numerical simulations to determine the evaporation characteristics of palm biodiesel droplets under normal gravity at temperatures ranging from 473 to 873 K and pressures ranging from 0.2 to 5 bar. A transient, two-phase, axisymmetric volume of fluid (VOF) model is employed to model transport processes across phases. The palm methyl ester is modelled as a single-component fuel with temperature- and pressure-dependent thermophysical properties. The study compares the obtained evaporation rates with those available in the literature and presents the effects of external parameters in experimental setups. Additionally, the study investigates the effects of changing the oxygen/nitrogen composition of the environment at elevated temperatures. The results show that elevated temperatures enhance the evaporation rate at all pressures and oxygen contents due to significantly enhanced thermal conductivity and droplet surface temperatures, while elevated pressures decrease the evaporation rates. Across the pressure range, evaporation rates decrease by 219%, 213%, and 196% for temperatures of 473, 673, and 873 K, respectively. Furthermore, increasing oxygen concentration in the environment can also increase the evaporation rate; however, the effect is less noticeable with a 6.4% increase at 473 K and more significant with a 27.8% increase at 873 K across the selected oxygen composition range.

Data for manuscript "Period- and pressure-dependent hydraulic properties of a fractured granite inferred from periodic pumping tests". Barbosa et al. submitted to JGR:Solid Earth.

Data for manuscript "Period- and pressure-dependent hydraulic properties of a fractured granite inferred from periodic pumping tests". Barbosa et al. submitted to JGR:Solid Earth.

Giant piezoresistivity in a van der Waals material induced by intralayer atomic motions

The presence of the van der Waals gap in layered materials creates a wealth of intriguing phenomena different to their counterparts in conventional materials. For example, pressurization can generate a large anisotropic lattice shrinkage along the stacking orientation and/or a significant interlayer sliding, and many of the exotic pressure-dependent properties derive from these mechanisms. Here we report a giant piezoresistivity in pressurized β′-In2Se3. Upon compression, a six-orders-of-magnitude drop of electrical resistivity is obtained below 1.2 GPa in β′-In2Se3 flakes, yielding a giant piezoresistive gauge πp of −5.33 GPa−1. Simultaneously, the sample undergoes a semiconductor-to-semimetal transition without a structural phase transition. Surprisingly, linear dichroism study and theoretical first principles modelling show that these phenomena arise not due to shrinkage or sliding at the van der Waals gap, but rather are dominated by the layer-dependent atomic motions inside the quintuple layer, mainly from the shifting of middle Se atoms to their high-symmetric location. The atomic motions link to both the band structure modulation and the in-plane ferroelectric dipoles. Our work not only provides a prominent piezoresistive material but also points out the importance of intralayer atomic motions beyond van der Waals gap.

Cryogenic liquid nitrogen stimulation-induced cracking in gas-enriched shale reservoirs: A numerical investigation

Cryogenic shock-induced brittle cracking has promising application prospects in reservoir stimulation. In this paper, a fully coupled thermo-hydro-mechanical (T-H-M) model combined with the statistical meso-damage theory is proposed to investigate the trans-scale progressive cracking process of shale gas reservoirs stimulated by liquid nitrogen (LN2). In this theoretical framework, shale meso-heterogeneity in both thermo-mechanical and hydraulic properties is characterized by two independent statistical distribution functions; temperature-dependent rock properties and temperature- and pressure-dependent fluid thermodynamic properties are described using some experimental and theoretical formulas. The numerical model is implemented in a finite element context and subsequently validated against existing classical coupling results. Numerical results demonstrate that LN2 fracturing accompanied by the unique cryogenic shock effect leads to a complex cracking process involving multiple-point fracture initiation, asymmetric macrofracture propagation, and primary fracture bifurcation. Sensitivity analysis indicates that approximately equidistant or equilength radial fractures may be generated at a lower stress difference, lower permeability, or higher elastic modulus; both fracture initiation pressure and induced fracture morphology are more sensitive to injected fluid temperature relative to initial reservoir temperature; a larger thermal expansion coefficient is beneficial for inducing more fractures, but not applicable to the thermal conductivity. Preferable candidates for LN2 stimulation to generate multiple fractures in shale reservoirs are recommended. It is also found that compared with H2O and supercritical CO2, fracturing using LN2 can generate fractures with lower initiation pressure and greater complexity. Preliminary results confirm the potential of using LN2 fracturing to improve the stimulation effect of shale reservoirs.

A semi-analytical rate-transient analysis model for light oil reservoirs exhibiting reservoir heterogeneity and multiphase flow

Rate-transient analysis (RTA) has been widely applied to extract estimates of reservoir/hydraulic fracture properties. However, the majority of RTA techniques can lead to misdiagnosis of reservoir/fracture information when the reservoir exhibits reservoir heterogeneity and multiphase flow simultaneously. This work proposes a practical-yet-rigorous method to decouple the effects of reservoir heterogeneity and multiphase flow during TLF, and improve the evaluation of reservoir/fracture properties. A new, general, semi-analytical model is proposed that explicitly accounts for multiphase flow, fractal-based reservoir heterogeneity, anomalous diffusion, and pressure-dependent fluid properties. This is achieved by introducing a new Boltzmann-type transformation, the exponent of which includes reservoir heterogeneity and anomalous diffusion. In order to decouple the effects of reservoir heterogeneity and multiphase flow during TLF, the modified Boltzmann variable allows the conversion of three partial differential equations (PDE's) (i.e., oil, gas and water diffusion equations) into ordinary differential equations (ODE's) that are easily solved using the Runge-Kutta (RK) method. A modified time-power-law plot is also proposed to estimate the reservoir and fracture properties, recognizing that the classical square-root-of-time-plot is no longer valid when various reservoir complexities are exhibited simultaneously. Using the slope of the straight line on the modified time-power-law plot, the linear flow parameter can be estimated with more confidence. Moreover, because of the new Boltzmann-type transformation, reservoir and fracture properties can be derived more efficiently without the need for defining complex pseudo-variable transformations. Using the new semi-analytical model, the effects of multiphase flow, reservoir heterogeneity and anomalous diffusion on rate-decline behavior are evaluated. For the case of approximately constant flowing pressure, multiphase flow impacts initial oil rate, which is a function of oil relative permeability and well flowing pressure. However, multiphase flow has a minor effect on the oil production decline exponent. Reservoir heterogeneity/anomalous diffusion affect both the initial oil production rate and production decline exponent. The production decline exponent constant is a function of reservoir heterogeneity/anomalous diffusion only. The practical significance of this work is the advancement of RTA techniques to allow for more complex reservoir scenarios, leading to more accurate production forecasting and better-informed capital planning.

Pressure-dependent joint elastic-electrical properties of calcite-cemented artificial sandstones

Understanding the correlations between the elastic and electrical properties of various types of rocks is the key to the successful joint interpretation of seismic and electromagnetic survey data to provide petrophysical parameters to better assess the subsurface earth. However, the pressure-dependent joint elastic-electrical properties of calcite-cemented sandstones remain poorly understood, even though such rocks are widely distributed in nature and are all experiencing pressures. To obtain such knowledge, a new method has been developed for the manufacture of calcite-cemented artificial sandstones and investigated comprehensively the effects of porosity and cementation content on the confining pressure-dependent joint elastic-electrical properties of the synthetic samples made using the new recipe. Confining pressure is found to more significantly affect the P- and S-wave velocities and electrical resistivity in the samples with higher and lower porosity, respectively, when their cementation content remains the same. On the other hand, cementation content impacts the pressure-dependent elastic and electrical properties more complexly, and the effects of cementation content can be influenced by the minor fluctuation of porosity in the samples, especially at low confining pressures. More interestingly, P- and S-wave velocities are found to approximately linearly correlate with electrical resistivity as confining pressure varies, and the slopes of the linear joint correlations are demonstrated to vary distinctly with porosity and cementation content. The experimental data are interpreted in terms of the competing effects of porosity and cementation content on the microstructure of the samples. The results have helped to reveal the nature that porosity and cementation content find on affecting the joint elastic-electrical properties with varying pressure and have important practical implications for discriminating the porosity and cementation effects that will pave the way to a more successful interpretation of the joint seismic and electromagnetic survey data.