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As a typical representative of Ga-based III-V compound semiconductor material, the pressure-induced structural phase transition of gallium phosphide (GaP) has received more attention, while the present work explains the electronic structure and photoconductivity properties under high pressure, especially. The paper focuses on the high-pressure electronic structure and photoconductivity properties up to 50.0 GPa in GaP, along with the ZB (zinc-blende structure) to RS (rock salt structure) phase structural transition using enthalpy calculation. The discontinuous thermal expansion coefficient and unit cell volume collapse by 15.0–15.5% are observed at around 39.2 GPa due to reversible structural phase transition under compression and decompression conditions, which is also reflected in the measured discontinuous Hall coefficient and conductivity at approximately 39.0 GPa. The computed semiconductor-to-metal transition is determined to occur at 24.5 GPa by band-gap closure in good agreement with the experimentally determined transition pressure. The light illumination provides a potential way to reduce conductivity without effect on pressure of phase transition. [ABSTRACT FROM AUTHOR]

The electrical transport properties of As 2 Te 3 were studied under high pressure using theoretical and experimental methods. The structural phase transition was observed at around 25 GPa using first-principles calculations, which was reflected in the collapse of the cell volume and the calculation of the enthalpy. The pressure-induced metallization was confirmed at approximately 7 GPa from closed energy bands and density of states, and the resistivity of variable temperature also shown a piece of evidence for metallization at 7.1 GPa. The curves of the electrical parameters at 7 GPa are consistent with the theoretical calculations. In addition, discontinuous changes in carrier parameters were observed at around 15 GPa, which is attributed to the isostructural phase transition of As 2 Te 3. Studying the electrical transport properties of As 2 Te 3 under high pressure, especially its pressure-induced metallization properties, can provide a theoretical basis for its application in storage devices and thermoelectric materials, and help to understand the properties of other A 2 B 3 -type compounds under high pressure. [Display omitted] [ABSTRACT FROM AUTHOR]

The investigation of the electrical transport properties of ZrS 2 is conducted up to 30.7 GPa using first-principles calculation and electrical experimental methods. The electrical parameters of ZrS 2 are investigated under high pressure conditions using the thin film integrated microcircuit technology on a diamond anvil cell. The structural phase transitions occur at approximately 2.0 GPa and 6.0 GPa, as evidenced by changes in the energy band structure and discontinuities in electrical parameters. At around 12.3 GPa, the pressure-induced metallization is observed by temperature-induced resistivity and the closing of the band gap. The sudden decrease in resistivity can be attributed to the combined contribution of an increase in carrier concentration and mobility. Similarly, the abrupt decrease in Hall coefficient is attributed to the increase in carrier concentration. [Display omitted] • ZrS 2 undergoes two phase transitions by theoretical calculation. • The reversible structural phase transitions causes changes in electronic properties. • Metallization occurs at around 12.3 GPa via temperature-induced resistivity. • The measured electrical parameters confirm the generation of phase transitions. [ABSTRACT FROM AUTHOR]

The high-pressure electronic structure and electrical properties of Mg 2 Pb are investigated from ambient pressure to 42 GPa by first-principles calculation. Mg 2 Pb undergoes reversible structural transitions from F m 3 ‾ m structure to Pnma structure and then to P6 3 /mmc structure. The structural phase transitions are determined respectively at around 6 GPa and 28 GPa using pressure-dependent enthalpy calculations, which are also reflected from the cell volume collapse and discontinuous axial ratios of lattice constants. The sliding of Mg and Pb atomic layers is revealed via the Mg 1 –Pb–Mg 2 atom pair during structural phase transitions, corresponding to abrupt decrease of c/b and a/b. The semimetal-to-metal transition is also observed at approximately 28 GPa owing to energy-band closure, whilst metallic character is strengthened with increasing pressure. The paper is prone to theoretically explore the structural phase transition and metallization of Mg 2 Pb-type family under extreme conditions. [Display omitted] • The reversible twice structural phase transitions are observed for Mg2Pb. • The structural phase transitions are found at around 6 GPa and 28 GPa for Mg2Pb. • The semimetal-to-metal transition transition is determined at approximately 28 GPa. • The sliding of Mg and Pb atomic layers is revealed via the Mg1-Pb-Mg2 atom pair. • The extreme high-pressure behavior of Mg2X-type (X=carbon group) family is disclosed. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of WTe 2 are studied from ambient pressure to 30.0 ​GPa. The pressure-induced structural phase transition is found from T d phase to 1T′ phase above 10.0 ​GPa by lattice offset, which is also reflected at approximately 11.2 ​GPa based on the discontinuous electrical parameters. A pair of hole wave and electron wave packets of T d phase gradually overlap revealing the reversible T d -to-1T′ phase structural transition. WTe 2 is observed to undergo semimetal-to-semiconductor transition owing to the calculated energy band up to 15 ​GPa, which is also observed at 11.2 ​GPa according to the resistivity-temperature curves under compression and decompression conditions. The electronic density of states at the Fermi level is mainly contributed by the d orbital of W and the p and s orbital of Te. The photoconductivity property is shown by the theoretical and experimental methods. [Display omitted] • The structural transition of WTe 2 is shown from T d phase to 1T′ phase above 10.0 ​GPa by lattice-offset. • The pressure-induced semimetal-to-semiconductor transition is obtained caused by Td-to-1T′ structural phase transition. • A pair of hole and electron wave packets of T d -WTe 2 gradually overlap and finally disappear due to lattice-offset. • The photoconductivity property of WTe 2 is observed and the phase transition pressure can be reduced by photoconductivity. [ABSTRACT FROM AUTHOR]