No abstract

The earlier high-pressure stndy of Cw concenmted on the orientational transition and mom-temperature transformations observed in diamond anvils. This work presents a parl of the T-P phase diagram for solid Cw at pressures up to 20 kbar in the temperahlre range extended to 700 K. A new phase region is outlined herein. The new phase is retained to ambient conditions and preliminarily characterized. The new phase is more dense than the initial Cm by al least 8.5% and less compressible by -1.5 times. Its crystal svucmre is very different from the well known face-centred cubic and simple cubic phases, and its recovely to a cubic phase is associated with an endothermal heat effect of -23 I g-', The nature and the lhemcdynamic stability of the new phase are discussed in connection with polymerization of & molecules, which seem likely.

No abstract

No abstract

The crystal structure of the equiatomic TiZr alloy is studied in the pressure range up to 57 GPa using the diamond anvils and synchrotron radiation. It is found that this alloy follows the ␣→→␤ transition series earlier observed on Zr and Hf. Superconductivity measurements on the same alloy to 47 GPa show that the transition to the bcc ␤ phase is connected with an increase in the superconducting transition temperature to 15 K. The pressure dependence of the atomic volume is fitted to an equation of state. Low values of the pressure derivative of the bulk modulus as well as the increase in the superconducting transition temperature are discussed in terms of a pressure-induced s -d electron transfer.