High-pressure Properties Research Articles

Role of Magma Oceans in Controlling Carbon and Oxygen of Sub-Neptune Atmospheres

Most exoplanets with a few Earth radii are more inflated than bare-rock planets with the same mass, indicating a substantial volatile amount. Neither the origin of the volatiles nor the planet’s bulk composition can be constrained from the mass–radius relation alone, and the spectral characterization of their atmospheres is needed to solve this degeneracy. Previous studies showed that chemical interaction between accreted volatile and possible molten rocky surface (i.e., magma ocean) can greatly affect the atmospheric composition. However, a variety in the atmospheric compositions of such planets with different properties remains elusive. In this work, we examine the dependence of atmospheric H, O, and C on planetary parameters (atmospheric thickness, planetary mass, equilibrium temperature, and magma properties such as redox state) assuming nebula gas accretion on an Earth-like core, using an atmosphere-magma chemical equilibrium model. Consistent with previous work, we show that atmospheric H2O fraction on a fully molten rocky interior with an Earth-like redox state is on the order of 10−2–10−1 regardless of other planetary parameters. Despite the solubility difference between H- and C-bearing species, C/H increases only a few times above the nebula value except for atmospheric pressure ≲1000 bar and H2O fraction ≳10%. This results in a negative O/H–C/O trend and depleted C/O below one-tenth of the nebula gas value under an oxidized atmosphere, which could provide a piece of evidence of rocky interior and endogenic water. We also highlight the importance of constraints on the high-pressure material properties for interpreting the magma–atmospheric interaction of inflated planets.

Three stable nitrogen-rich Ce-N compounds predicted from first-principles calculations at high pressure

As a new type of environmentally friendly high energy density material, metal-doped nitrogen-rich compounds have drawn much attention in recent years in the field of scientific research due to their unique high pressure properties. In this paper, a first principle computational approach has been used to conduct an extensive structural search for energetically favorable structures in the Ce-N system. We finally discovered three new structures: Ce2N3 in the P21/m phase, CeN3 in the C2/m phase, CeN5 in the P phase. Among them, the C2/m-CeN3 structure remains kinetically stable at 0 GPa and can be quenched to ambient conditions after synthesis at high temperatures and pressures. The C2/m-CeN3 and P1¯-CeN5 compounds, which have significantly higher detonation velocities and pressures than TNT and HMX, can be used as potential energy materials. Their structures of P21/m-Ce2N3, C2/m-CeN3 and P1¯-CeN5 were successfully predicted, providing valuable references for synthesizing and exploring novel stable cerium-nitrogen compounds.

High-pressure rheological properties of polyalphaolefin and ester oil blends and their impact on lubrication

Different base oils are often blended to optimize lubrication effectiveness. For blends of polyalphaolefins (PAOs) and ester oils, while their boundary lubrication performance is well-studied, studies on their rheological properties and elastohydrodynamic lubrication (EHL) are limited. This study investigates the viscosity and EHL properties of PAO 8 and pentaerythritol tetra(2-ethylhexanoate) (PEB 8) blends at various blending ratios, pressures, and temperatures. Results showed that under certain conditions, viscosities of the blends are lower than either base oil. This phenomenon was explained from a molecular perspective. The pressure–viscosity relationship was fitted using the Doolittle-Tait free-volume model. Additionally, studies of EHL performance and simulations of different oils correlate the pressure–viscosity to EHL characteristics. These findings provide insights for future lubricant formulation.

High-pressure synthesis, structure and physical properties of two quasi-one-dimensional compounds Ba9Nb2.54Te15 and Ba9Ta1.89Te15

Two quasi-one-dimensional compounds Ba9Nb2.54Te15 and Ba9Ta1.89Te15 were synthesized under high pressure and high temperature conditions and systematically characterized by structural, transport and magnetic measurements. Both the two compounds crystallize into a hexagonal structure with the space group P-6c2 (No. 188). The structure consists of trimeric face-sharing octahedral Nb/TaTe6 chains separated by a large distance (>10 Å), thus presenting a strong one-dimensional crystal structure. The transport properties suggest that both the two compounds are semiconductors with a band gap ∼ 0.15 eV for Ba9Nb2.54Te15 and ∼ 0.22 eV for Ba9Ta1.89Te15. Magnetic properties characterization indicates that Ba9Nb2.54Te15 displays no long-range-order above 2 K, but with an effective moment μeff ∼ 1.8 μB/f.u., while Ba9Ta1.89Te15 exhibits a diamagnetic behavior. Our results demonstrate that, in the sequence of Ba9V3Te15, Ba9Nb2.54Te15 and Ba9Ta1.89Te15, the occupation in the transition metal sites decreases, the semiconducting band gap increases, and the magnetism changes from ferromagnetism to diamagnetism.

The aging-hardening behavior of short-time in high pressure die casting AlSi9MgMnZn alloy

Short-time aging is an effective industrial technique for enhancing the mechanical properties of high pressure die cast (HPDC) aluminum alloy components. However, the evolution of precipitation behavior during short-time aging of HPDC alloys remains unclear. In this study, the short-time aging behavior of HPDC AlSi9MgMnZn alloy was investigated. The results show that the AlSi9MgMnZn alloy exhibits effective aging-hardening, with an increment in hardness of approximately 30 HV through the optimal short-time aging treatment (aged at 180 °C for 120 minutes). Higher aging temperatures led to reduced peak hardness and rapid over-aging above 220 °C. The microstructure observation indicates that the peak short-time aging promotes the simultaneous precipitation of β″ precipitates, GP zones and nano Si phases. The contribution of different strengthening mechanisms to hardness was estimated, implying that the coexistence of β″ precipitates and GP zones can provide a positive contribution to aging-hardening during short-time aging. Moreover, as the aging temperature increases, the appearance of β′ precipitates reduces the strengthening effect, leading to a decrease in hardness.

Muzzle bubble dynamics characterization of underwater launching

To comprehensively understand the dynamic behavior of muzzle bubbles during underwater launching, an emptying process aligned with the muzzle flow characteristics is established and an evaporative condensation mechanism is modeled according to the high temperature and pressure properties of the propellant gas. Utilizing the spherical bubble theory, which comprises the inflation process and evaporative condensation effects, the dynamics of muzzle bubbles and their corresponding pressure waves are investigated. The numerical simulation results well agree with the experimental observations in terms of bubble radius and near-field pressure waves. Furthermore, the influence of two key factors on the bubble dynamics is examined: underwater launching depth and initial muzzle pressures. The results illustrate that the inflation process needs to be accurately described for precise pressure wave predictions. Using the evaporation condensation model, the bubble radius and frequency can be accurately characterized. Moreover, the launching depth influences the free expansion radius and oscillation frequency mostly due to the increase in hydrostatic pressure, which decreases by 33% and increases by 150% in the 1–20 m range, respectively. The initial muzzle pressure affects the initial expansion velocity and initial shock wave mainly due to the increase in the mass flow rate, which increase by 56% and 82% in the 35–65 MPa range, respectively.

Impacts of CO2-CH4 Mixed Gas on Property of Formation Oil from the Bohai Oilfield

Mechanism analysis and technical scheme optimization on CO2 displacement and CO2 storage are based on the high-pressure physical properties of CO2-added formation oil. Oil and natural gas samples from the BZ25-1 block in the Bohai oilfield were used to conduct high-pressure physical property experiments to explore the impacts of CO2-CH4 mixed gas on the properties of formation oil. After injecting different amounts of mixed gas, the saturated pressure was measured by constant mass expansion test, the viscosity was measured by falling ball method, the expansion coefficient was measured by gas injection expansion test, and the gas–oil ratio and volume coefficient were obtained by single degassing test. The results show that with gas injection, the saturation pressure and dissolved gas–oil ratio of formation oil increase, the volume coefficient and expansion factor go up, while the oil viscosity reduces. With the increase in gas addition, the properties of formation oil continue to improve, but the increase in improvement becomes flat. With the increase in pressure, the amount of dissolved gas in the formation oil will also increase. High-purity CO2 is more helpful to change the properties of formation oil, while the gas mixed with CH4 is more beneficial to elevate the formation energy. For the BZ 25-1 block, the gas injection amount of about 80 mol% is appropriate and the CO2 purity of 60% can well balance the oil properties improvement and the formation pressure elevation.

Study on Foaming Agent Foam Composite Index (FCI) Correlation with High Temperature and High Pressure for Unconventional Oil and Gas Reservoirs

In the process of unconventional oil and gas reservoir exploitation, it is difficult to reduce drilling fluid lost in natural fractures, enhance the CO2 displacement effect and reduce foam drainage gas recovery costs. In most cases, foaming agents can solve these problems in a low-cost way in a short period of time. Foaming agent screening and evaluation is the key to this technology. However, there are few experimental tests used in the evaluation of foaming agent properties that match the actual unconventional oil or gas well conditions of high temperature and high pressure. Using the actual temperature and pressure conditions of a wellbore, the foaming capacity and half-life of two common foaming agents were systematically evaluated by using the high-temperature and high-pressure visual foam properties evaluation device (UPMX-500), in which the foaming agent’s volume concentration was 3‰ in a simulated formation water with a pH of 6 and salinity of 9 × 104 mg/L. The high-temperature (40 °C, 60 °C, 80 °C, 100 °C) and high-pressure (0.1 MPa, 6.0 MPa, 8.0 MPa, 10.0 MPa) effect on the foaming capacity and half-life was analyzed. Binary linear regression of pressure and temperature was carried out, taking the foam composite index as the target and using a formula with high correlation. The results showed that the foam composite index (FCI) of the two foaming agents was positively correlated with pressure and temperature. The correlation of UT-7 was FCI = 64.1196T + 735.713p − 2066.2, the correlation of HY-3K was FCI = 62.5523T + 7220.391p − 2415.6, and the coefficients of determination were 0.9799 and 0.9895, respectively, with an error of less than 10%. This correlation equation can provide a reference for accurately predicting the foaming capacity of foaming agents under high-temperature and high-pressure conditions and can also be used to optimize foaming agents or to qualitatively evaluate results for the efficient exploitation of unconventional oil and gas reservoirs.

A machine learning methodology for investigating the liquid–liquid transition of hydrogen under high-pressure

Due to its unique properties such as superconductivity and superfluidity, high-pressure properties of hydrogen attract a lot of attention. However, the Liquid–Liquid Transition (LLT) of hydrogen under high-pressure and high-temperature is of particular significance for understanding its metallization. We propose a data-driven machine learning approach based on the density functional theory data to fit the potential energy surface into a deep neural network form. This method overcomes the simulation scale limitations of first-principles approaches to investigate the dissociation behavior of hydrogen molecules under high pressure. Our findings reveal an LLT curve exhibiting a first-order continuous change along with transition zone corresponding to hydrogen molecule dissociation. This study offers valuable insights into the LLT phenomenon and the metallization of hydrogen under high pressure.

Enhanced High-Pressure Mixed-Gas Sieving Properties of Thermally Cross-Linked Polyimide Membranes

Enhanced High-Pressure Mixed-Gas Sieving Properties of Thermally Cross-Linked Polyimide Membranes

Ratio of 4:1 between ZnGeAs2 and MnAs phases in a single composite and its impact on the structure-driven magnetoresistance

A strong influence of the lattice degree of freedom on magnetoresistance (MR) under high pressure underlies the conception of ‘structure-driven’ magnetoresistance (SDMR). In most magnetic or topological materials, the suppression of MR with increasing pressure is a general trend, while for some magnetic composites the MR enhances and even shows unusual behavior as a consequence of structural transition. Here we investigated the SDMR in the composite material based on the ZnGeAs2 semiconductor matrix and MnAs magnetic inclusions in a phase ratio of 4:1. At ambient pressure, its magnetic and transport properties are governed by MnAs inclusions, i.e. it shows a Curie temperature T C≈ 320 K and metallic-like conductivity. Under high pressure, the low-field room temperature MR undergoes multiple changes in the pressure range up to 7.2 GPa. The structural transition in the ZnGeAs2 matrix has been found at ∼6 GPa, slightly lower than in the pure ZnGeAs2 (6.2 GPa). The huge SDMR as high as 85% at 6.8 GPa and 2.5 kOe, which contains both positive and negative MR components, is accompanied by a pressure-induced metallic-like-to-semiconductor-like transition and the enhanced ferromagnetic order of MnAs inclusions. This observation offers a competing mechanism between the robust extrinsic ferromagnetism and high-pressure electronic properties of ZnGeAs2.

High-Temperature and High-Pressure Tribological Properties of Siliconized Graphite for Water-Lubricated Thrust Bearing Application in Main Coolant Pump

The effect of the microstructure of siliconized graphite on tribological properties is investigated by using a high-temperature and high-pressure water-lubricated tribometer on a self-mated ring-on-ring configuration under an applied load of 500–1500 N with a spindle speed of 100–5000 rpm in both 90 °C (5 MPa) and 25 °C (1 MPa) water environments, respectively. The Stribeck curves measurement and continuous wear tests are performed and analyzed in both water environments. The wear behaviors of the graphite, SiC, and free-silicon phases in siliconized graphite are demonstrated to explore the wear mechanism. The larger wear depths of a low-worn surface roughness on the three phases contribute to the boundary lubrication. The shallower wear depths are observed on the SiC and Si phases under the mixed lubrication, corresponding to partial contact wear of surface asperities. The wavy surface of the SiC phase and uniform flow-oriented striae of the Si phase are attributed to hydrodynamic lubrication, caused by full water film scouring the worn surface. Finally, an integrated evaluation method of G duty parameters is successfully used to identify the lubrication regimes of siliconized graphite from the boundary, mixed, to hydrodynamic lubrications for a water-lubricated thrust bearing application in the main coolant pump of a nuclear power plant.

From Insulator to Superconductor: A Series of Pressure-Driven Transitions in Quasi-One-Dimensional TiS3 Nanoribbons.

Transition metal trichalcogenides (TMTCs) offer remarkable opportunities for tuning electronic states through modifications in chemical composition, temperature, and pressure. Despite considerable interest in TMTCs, there remain significant knowledge gaps concerning the evolution of their electronic properties under compression. In this study, we employ experimental and theoretical approaches to comprehensively explore the high-pressure behavior of the electronic properties of TiS3, a quasi-one-dimensional (Q1D) semiconductor, across various temperature ranges. Through high-pressure electrical resistance and magnetic measurements at elevated pressures, we uncover a distinctive sequence of phase transitions within TiS3, encompassing a transformation from an insulating state at ambient pressure to the emergence of an incipient superconducting state above 70 GPa. Our findings provide compelling evidence that superconductivity at low temperatures of ∼2.9 K is a fundamental characteristic of TiS3, shedding new light on the intriguing high-pressure electronic properties of TiS3 and underscoring the broader implications of our discoveries for TMTCs in general.

Thermodynamic properties of rhodium—A first principle study

The high-pressure and high-temperature thermodynamic properties of rhodium (up to 2000 K and 300 GPa) are presented using the first principle approach within the quasi-harmonic approximation. The thermal Helmholtz free energy includes the contribution of both phonon vibrations and electronic excitations. The performance of three popular exchange-correlation functionals—local density approximation [Perdew et al., Phys. Rev. B 23, 5048 (1981)], Perdew–Burke–Ernzerhof generalized gradient approximation (PBE) [Perdew et al., Phys. Rev. Lett. 77, 3865 (1996)], PBE modified for dense solids [Perdew et al., Phys. Rev. Lett. 100, 136406 (2008)] are shown. The simulated thermal expansion coefficient, isobaric heat capacity, mode-Grüneisen parameter, thermodynamic average Grüneisen parameter, and bulk modulus are compared with the available experimental and theoretical reports. The contribution of thermal electronic excitations to the obtained thermodynamic parameters is significant at low pressure and high temperatures, except in bulk modulus, where it is small. The pressure-dependent elastic constant coefficient (Cij) and the Debye temperature are computed at 0 K. The Pugh ratio calculated from Cij indicates that rhodium undergoes brittle to ductile transitions at an average pressure of 7.45 GPa.

Pressure-induced ferroelectric and electronic transitions in two-dimensional ferroelectric semiconductor of NbOCl2 up to 41.7 GPa

NbOCl2, a representative van der Waals ferroelectric (FE) semiconductor, has become the research frontier due to its peculiar appeal in both fundamental research studies and potential applications. In the present work, the high-pressure structural, vibrational, and electrical transport properties of NbOCl2 under different hydrostatic environments were systematically investigated over a wide pressure range of 1.7–41.7 GPa using a diamond anvil cell coupled with in situ Raman spectroscopy, electrical conductivity, and high-resolution transmission electron microscopy (HRTEM) observations. Upon non-hydrostatic compression, NbOCl2 underwent a FE-to-antiferroelectric phase transition at 3.4 GPa, followed by a semiconductor-to-metal transformation at 15.7 GPa. Under hydrostatic compression, the FE transformation and metallization of NbOCl2 were postponed by ∼2.0 and ∼4.0 GPa due to the effect of helium pressure-transmitting medium. Upon decompression, the phase transition was demonstrated to be reversible under different hydrostatic environments, which was well corroborated by HRTEM analyses. In addition, the linear relations between electrical current and sinusoidal voltage with the nonlinearity factors of ∼1.0 reflect the Ohmic response of NbOCl2 before and after the FE transition. Our findings on NbOCl2 provide a guideline for exploring other layered FE materials under high pressure and establishing a design paradigm for new generations of FE-based devices.

Pressure-induced phase transitions and decompositions of Sr–S compounds

The processes involved in the high-pressure phases of Sr–S compounds and the pressure-induced decomposition into strontium and sulfur are investigated using a structure prediction approach combined with first-principles calculations. The compression of Sr–S compound leads to its decomposition into strontium and sulfur at 794 GPa, which contradicts the general intuition that pressure stabilizes and densifies materials. With increasing pressure, the combined effect of the ΔPV and ΔU term increases the enthalpy difference, ultimately leading to the decomposition of the Sr–S compound. Moreover, the analysis based on molecular orbital theory reveals that pressure induces an increased population of antibonding states, consequently reducing the stability of the compound and promoting its decomposition. Furthermore, the analysis of atomic interactions reveals that under pressure, the reduction of charge transfer between atoms causes a decrease in electrostatic interactions, thereby weakening the stability of the compound and resulting in its decomposition into strontium and sulfur atoms. This work not only demonstrates the high-pressure properties of Sr–S compounds but also provides insight into understanding other high-pressure alkaline-earth sulfides.

Study on optimization and mechanism of CO2 injection to enhance oil recovery in mid-deep heavy oil reservoirs

In order to improve the oil recovery of mid-deep heavy oil reservoirs, this study investigates the efficiency of enhanced oil recovery and the mechanisms of oil displacement in mid-deep heavy oil reservoirs using different injected gases (N2, CH4, CO2) and development approaches (gas flooding and gas huff-n-puff) through a series of experiments. These experiments include high-pressure physical properties tests of crude oil after gas injection, displacement efficiency tests of gas injection, and displacement efficiency tests of gas huff-n-puff. The results indicate that for mid-deep heavy oil reservoirs, the preferred optimal injection gas is CO2, with gas huff-n-puff being the most effective development method. Furthermore, a numerical simulation study was conducted to explore the adaptability parameters of CO2 huff-n-puff development in different well patterns, encompassing variables such as the amount of gas injected per cycle, crude oil viscosity, reservoir permeability, and oil layer thickness.

Understanding layered compounds under high pressure

This Tutorial focuses on the physics of layered compounds under high pressure. We have chosen h-BN and III–VI layered materials as representative materials. h-BN layers are strictly two-dimensional. Layers in III–VI compounds are more complex, and subtle details in their structural behavior play an important role in the evolution of high pressure properties. They are also interesting because they contain a different number of layers in their primitive unit cell and/or have a different ionic character. We begin describing the structural evolution. We discuss the experimental challenges encountered as well as the main findings related to intra- and interlayer compressibility, polytype influence, and geometrical modifications induced by pressure inside the layers. We then describe lattice vibrations. The origin of the modes is reviewed, paying attention to the relationships between atom motions in different layers. We discuss the convenience of redefining the Grüneisen parameter and describe the behavior of rigid layer modes, soft modes, and Davidov pairs. The last section is devoted to the electronic properties. We show that the changes observed when passing from a single layer to a three-dimensional BN are qualitatively similar to those induced by high pressure. The pressure behavior of electronic transitions in III–VI layered compounds is very rich, revealing the subtle balance between intra- and inter-layer interactions. Finally, we take advantage of high pressure studies to explain the formation of the Mexican hat type of valence band at ambient conditions in single layers of InSe and GaSe, but not in three-dimensional compounds.

Effects of high hydrostatic pressure on the functional properties of soy protein isolate

AbstractIn this study, functional properties of high hydrostatic pressure (HHP)‐treated soy protein isolate (SPI) samples including protein solubility, emulsification activity (EA), and water holding capacity (WHC) were studied. Fourier transform infrared spectroscopy (FTIR), viscosity, and nuclear magnetic resonance (NMR) relaxometry experiments were performed. Three pressure (300, 400, and 500 MPa), two pH (5.0 and 7.0), and two temperature levels (25 and 40°C) were used to prepare SPI samples. Solubility of SPI was more pH‐dependent than HHP‐dependent, whereas WHC was more sensitive to pressure. Samples processed at 300 MPa, pH 5.0, and 40°C demonstrated higher EA (p < .05) than the untreated samples. Pressure application significantly reduced the viscosity of SPI dispersions (p < .05). Samples processed at 300 MPa, pH 5.0, and 40°C and at 400 MPa, pH 5.0, and 40°C attained the longest transverse relaxation time (T2) values reflecting their low solubility profiles. Thus, results indicated that HHP was able to modify the functional properties of SPI at different temperature and pH conditions.Practical ApplicationsHigh hydrostatic pressure (HHP) is an emerging technology with its diverse range of applications in food industry. Modification of functional properties of food ingredients is one of the latest applications of HHP treatment. This study demonstrated that HHP treatment was able to modify some functional properties of soy protein isolate (SPI) samples including water holding capacity, solubility, and emulsification activity. Pressure level, pH, and temperature affected the functional properties of SPI samples. The parameter type/range and results of this study could be used in model HHP studies to improve some functional properties of SPI for different purposes.

SYNTHESIS AND RESEARCH OF NEW DERIVATIVES OF ALKYLXANTHATATE ACETIC ACID AS ADDITIVES WITH TRIBOLOGICAL PROPERTIES

The work is devoted to the synthesis and study of new derivatives of alkylxanthateacetic acid, obtained by the interaction of potassium alkylxanthates with allyl ester of monochloroacetic acid. The structure of the synthesized compounds was confirmed by IR and 1H NMR spectroscopy data, as well as by the study of their physicochemical properties, including the determination of the refractive indices and specific gravity and the calculation of molecular refraction based on them, followed by their comparison. It has been established that the synthesized compounds have high extreme pressure properties in transmission oils, while esters of alkylxanthate acetic acid have anticorrosion properties, so they can be used to make prototypes of transmission oils used in various friction units. Using the example of allyl ester of ethylxsanthateacetic acid, the dependence of the yields of the synthesized compounds on the nature of the solvent was revealed. The dependence of the effectiveness of the lubricating properties of the synthesized compounds on the length of alkyl radicals has been revealed