High pressure synthesis of platinum metal pyrochlores of the type Pb2M2O6–7

The cubic pyrochlore-type phases Pb2Rh2O7 (a = 10.112Å), Pb2Pt2O6.7 (a = 10.291Å), Pb2Os2O7 (10.347Å), Pb2Ir2O6.5 (a = 10.284Å), and Pb2Ru2O6.5 (a = 10.271Å) have been prepared at 700°C under 3000 atm of pressure. Electrical resistivity measurements indicate that the Ir, Ru and Os compounds are metallic whereas the Rh and Pt compounds are semiconductors.