CRYSTAL-STRUCTURE OF THE HIGH-PRESSURE PHASE OF BAFCL

The structural stability of the layered matlockite compound BaFCl has been studied under pressure to similar to 35 GPa. BaFCl is observed to undergo a reversible structural transition at about 22 GPa and the hi gh-pressure phase has been identified to be monoclinic with space grou p P2(1)/m. The structural identification of the high-pressure phase wa s carried out by taking into account the fact that the interlayer bond ing between the two similar Cl- layers is relatively weak compared to those between the other layers and intralayer bondings, thereby render ing the low-pressure structure unstable against the deformation under pressure. [S0163-1829(98)50226-3].