Acoustic shock wave-induced superheating-assisted dynamic recrystallization - a case study of D-tartaric acid.

Superheating-assisted melting and crystallization are prominent subjects in condensed matter physics. However, understanding the superheating concepts under acoustic shocked conditions remains a mystery. Herein, we demonstrate superheating on the basis of dynamic recrystallization in a D-tartaric acid powder sample, which nearly attains an ideal crystal structure and morphology under the 100-shocked conditions compared to the control sample and the obtained results are evaluated by conventional diffraction, spectroscopic and microscopic techniques.

Acoustic Shock Wave-Induced Rutile to Anatase Phase Transition of TiO Nanoparticles and Exploration of Their Unconventional Thermodynamic Structural Transition Path of Crystallization Behaviors.

Titanium dioxide (TiO) is one of the most well-known and long-standing polymorphic materials in the transition metal oxide group of materials. The transition from rutile to anatase is one of the long-standing fundamental questions among materials science researchers because seeking the nucleation site at the beginning of the phase transition is highly challenging. Until now, there have been no studies on the unconventional structural phase transition of TiO nanoparticles by acoustic shock waves.

Acoustic Shock Wave-Induced Amorphous to Crystalline Phase Transitions of LiSO─Raman Spectroscopic and Thermal Calorimetric Approach.

In this context, we have reexamined the acoustical shock wave-induced amorphous-glassy-crystalline-amorphous phase transitions in the LiSO sample under 0, 1, 2, and 3 shocked conditions by implementing the detailed Raman spectroscopic approach. The recorded Raman spectroscopic data clearly reveal that the transition from the amorphous-glassy-crystalline state occurs because of a significant reduction of the translational disorder of lithium cations, particularly [Li (2)] ions wherein a slight reduction of the librational disorder of SO anions takes place, whereas the crystalline to amorphous transition occurs only at the third shocked condition because of the librational disorder of SO anions. The double degenerate υ and υ Raman modes provide a clear indication of the occurrence of the librational disorder of SO anions at the third shocked condition.

Pressure-driven structural phase transitions and metallization in the two-dimensional ferromagnetic semiconductor CrBr.

High-pressure structural, magnetic and electrical transport characteristics of CrBr were synthetically investigated using Raman scattering, electrical conductivity, high-resolution transmission electron microscopy (HRTEM) and first-principles theoretical calculations during compression and decompression under different hydrostatic conditions. Upon pressurization, CrBr underwent a second-order structural transition at 9.5 GPa, followed by the semiconductor-to-metal and magnetic switching at 25.

Pressure-induced coupled structural-electronic transition in SnS under different hydrostatic environments up to 39.7 GPa.

A series of high-pressure Raman spectroscopy and electrical conductivity experiments have been performed to investigate the vibrational and electrical transport properties of SnS under non-hydrostatic and hydrostatic environments. Upon compression, an coupled structural-electronic transition in SnS occurred at 30.2 GPa under non-hydrostatic conditions, which was evidenced by the splitting of the E mode and the discontinuities in Raman shifts, Raman full width at half maximum (FWHM) and electrical conductivity.

An Overview of the Experimental Studies on the Electrical Conductivity of Major Minerals in the Upper Mantle and Transition Zone.

In this paper, we present the recent progress in the experimental studies of the electrical conductivity of dominant nominally anhydrous minerals in the upper mantle and mantle transition zone of Earth, namely, olivine, pyroxene, garnet, wadsleyite and ringwoodite. The main influence factors, such as temperature, pressure, water content, oxygen fugacity, and anisotropy are discussed in detail. The dominant conduction mechanisms of Fe-bearing silicate minerals involve the iron-related small polaron with a relatively large activation enthalpy and the hydrogen-related defect with lower activation enthalpy.

Characterization of metallization and amorphization for GaP under different hydrostatic environments in diamond anvil cell up to 40.0 GPa.

High-pressure phase stability of gallium phosphide was explored under different hydrostatic environments up to 40.0 GPa in a diamond anvil cell. Two irreversible phase transitions from the semiconductor to metal to an amorphous state appear at 19.

Effect of Temperature, Pressure, and Chemical Composition on the Electrical Conductivity of Schist: Implications for Electrical Structures under the Tibetan Plateau.

The experimental study on the electrical conductivities of schists with various contents of alkali ions ( = K₂O + Na₂O = 3.94, 5.17, and 5.

Phase Transition and Metallization of Orpiment by Raman Spectroscopy, Electrical Conductivity and Theoretical Calculation under High Pressure.

The structural, vibrational, and electronic characteristics in orpiment were performed in the diamond anvil cell (DAC), combined with a series of experimental and theoretical research, including Raman spectroscopy, impedance spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), and first-principles theoretical calculations. The isostructural phase transition at ~25.0 GPa was manifested as noticeable changes in the compressibility, bond lengths, and slope of the conductivity, as well as in a continuous change in the pressure dependence of the unit cell volume.

Pressure-induced metallization in MoSe under different pressure conditions.

In this study, the vibrational and electrical transport properties of molybdenum diselenide were investigated under both non-hydrostatic and hydrostatic conditions up to ∼40.2 GPa using the diamond anvil cell in conjunction with Raman spectroscopy, electrical conductivity, high-resolution transmission electron microscopy, atomic force microscopy, and first-principles theoretical calculations. The results obtained indicated that the semiconductor-to-metal electronic phase transition of MoSe can be extrapolated by some characteristic parameters including abrupt changes in the full width at half maximum of Raman modes, electrical conductivity and calculated bandgap.

Evidence of the pressure-induced conductivity switching of yttrium-doped SrTiO3.

The electrical transport properties of undoped and yttrium-doped strontium titanate (Sr(Ti1 - x Y x )O3 - δ , x  =  0, 0.02) under high pressure were investigated with in situ impedance spectroscopy measurements. A pressure-induced conductivity switching for undoped and 2 mole% Y-doped strontium titanate is observed at around ~10.

[Review on Application of Optical Scattering Spectroscopy for Elastic Wave Velocity Study on Materials in Earth's Interior].

In-situ experimental results on the elastic wave velocity of Earth materials at high pressure and high temperature in combination with data from seismic observation can help to inverse the chemical composition, state and migration of materials in Earth's interior, providing an important approach to explore information of deep earth. Applying the Brillouin scattering into the Diamond Anvil Cell (DAC) to obtain the in situ elastic wave velocities of minerals, is the important approach to investigate elastic properties of Earth's Interior. With the development of DAC technology, on the one hand, the high temperature and high pressure experimental environment to simulate different layers of the earth can be achieved; on the other hand, the optical properties of DAC made many kinds of optical analysis and test methods have been widely applied in this research field.

Electrical conductivity of orthopyroxene: implications for the water content of the asthenosphere.

Electrical conductivity of minerals is sensitive to water content and hence can be used to infer the water content in the mantle. However, previous studies to infer the water content in the upper mantle were based on pure olivine model of the upper mantle. Influence of other minerals particularly that of orthopyroxene needs to be included to obtain a better estimate of water content in view of the high water solubility in this mineral.

Novel technique to control oxygen fugacity during high-pressure measurements of grain boundary conductivities of rocks.

This paper describes the development and application of a novel method for the measurement of grain boundary electrical conductivity of rock at high temperature and pressure. In this method, the metal electrodes, the corresponding metal shielding case, and the sleeves are altered in order to appropriately adjust and monitor the oxygen fugacity in a sample cavity in a high-pressure apparatus. As an example, a series of oxygen buffers including Fe(3)O(4) + Fe(2)O(3), Ni + NiO, Fe + Fe(3)O(4), Fe + FeO, and Mo + MoO(2) was selected and tested, and the oxygen fugacity was confirmed as adjusted during the process of electrical conductivity measurements.