The high-pressure behaviour of CdSe up to 3 GPa and the orientation relations between its wurtzite- and NaCl-type modifications

The high-pressure behaviour of wurtzite-type CdSe up to the transition pressure of about 3 GPa was studied using single-crystal X-ray diffraction techniques. The axial ratio c/a increases slightly with increasing pressure. The fit of the Birch-Murnaghan equation of state gave a bulk modulus K = 53.3(5) GPa with a fixed pressure derivative K' = 4. During the phase transformation the single crystals were destroyed but the obtained material showed a pronounced preferred orientation that enabled the determination of the orientation relations between the low-pressure wurtzite-and the high-pressure NaCl-type phase. While the diffraction pattern corroborates a known transition mechanism the observed macroscopic changes are in disagreement with it. (c) 2005 Elsevier SAS. All rights reserved.