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The pressure-induced structural phase transition of rhenium monocarbon (ReC) is investigated via the projector augmented wave (PAW) method with the generalized gradient approximation (GGA). Using the first-principles calculations, the equilibrium structural parameters of ReC in rocksalt (NaCl), cesium chloride (CsCl), zinc blende (ZB), wurtzite (WZ), nickel arsenide (NiAs) and tungsten carbide (WC) types are successfully obtained, and the results are well consistent with other theoretical data. It is firstly noted that WC-ReC translates into CsCl-ReC at 510.50 GPa by analyzing the enthalpy difference versus pressure. From the calculated elastic constants, the aggregate elastic modulus ( B , G , E ), the Poisson's ratio ( σ ) and the Debye temperature Θ D of WC-type are also derived. It is observed that all the data of WC-ReC obtained increase monotonically with increasing pressure. Meanwhile, the thermodynamic properties of WC-ReC under high temperature and high pressure are investigated applying nonempirical Debye model in the quasi-harmonic approximation.

The temperature dependence of oxygen ion behavior in Zn 2 GeO 4 has been studied from 78 to 873 K. As the temperature increases, the oxygen ions undergo positional disordering along the oxygen vacancies, with the oxygen related modes (ORMs) at 751 cm − 1 and 775 cm − 1 broadening and weakening dramatically. The temperature dependence of the bandwidth of oxygen ion mode is particularly interesting and a model suggested by Andrade and Porto is used to describe the linewidth of a phonon. The activation energy calculated from the ORM is 0.46 eV. Moreover, the motion of oxygen ion in Zn 2 GeO 4 is described in terms of the conventional fast-ion conductor.

SiC nanoparticles reinforced magnesium matrix composites were fabricated by ultrasonic method. The AZ91 alloy and SiC nanoparticles with the average diameter of 50 nm were used as the matrix alloy and the reinforcement, respectively. The addition of nanoparticles was 0.1%, 0.3%, and 0.5% (mass fraction) of the composites. The results of microstructural evaluation and mechanical properties indicate that the nanoparticles can be dispersed into magnesium alloys efficiently and uniformly with the aid of ultrasonic vibration. As compared with the matrix alloys, the grains of composites were refined and the mechanical properties of composites were improved significantly. The SEM and DSC analyses show that the SiC nanoparticles can act as the heterogeneous nucleation of a-Mg. Also, the strengthening mechanism responsible for the composites reinforced with SiC nanoparticles was discussed.