PREPARATION AND ELECTRICAL TRANSPORT-PROPERTIES OF PYRITE (FES2) SINGLE-CRYSTALS

Pyrite single crystals have been prepared by chemical vapour transport. An investigation of the Hall effect showed n-type conduction in most crystals with a fairly preparation-independent carrier concentration n = 10(16) cm-3. An exception was observed for crystals pulled over a temperature gradient, where n = 2 X 10(17) cm-3 was measured. A high temperature growth experiment as well as an annealing study, both under high sulphur pressure, led to crystals showing a positive sign in the Hall measurement. The Seebeck coefficient was S = -11-mu-V K-1 in this case, which compares with S= -320-mu-V K-1 measured on Hall n-type samples. A phosphorus-doped pyrite crystal showed S = 22-mu-V K-1.