A 10(9) PA HIGH-PRESSURE-CELL FOR X-RAY AND OPTICAL MEASUREMENTS

The construction of a new high-pressure cell is presented. It is a piston-cylinder type of apparatus. The entrance and exit of X-rays or light are possible through two parallel diamond-plate windows placed on V-shaped slits covering almost the whole range of reflection angles. This makes the cell particularly suitable for X-ray diffraction examinations of monocrystals. The potential accuracy of absolute-bulk-modulus determination by lattice-constant measurements using the Bond method [Bond (1960). Acta Cryst. 13, 814-816] at pressures of 10(8)-10(9) Pa can be estimated at 1-2%. The cell enables the simultaneous examination of two samples, which makes possible the comparison of their compressibilities with an accuracy of 0.01-0.1%. As examples, the results of compressibility measurements on GaAs and GaN are given.