Electrical and thermal properties of single crystalline Mo5X3 (X=Si, B, C) and related transition metal 5-3 silicides

High purity single crystals of Mo5SiB2(D8l), Mo5Si3(D8m), Mo5Si3C(D88) and Ti5Si3(D88) and polycrystals of Nb5SiB2(D8l) and V5SiB2(D8l) have been grown and their electrical and thermal properties have been measured. The resistivity of all transition metal 5-3 silicides exhibit a negative curvature with a tendency towards saturation when it is plotted as a function of temperature. The resistivity of Mo5SiB2, Mo5Si3 and Mo5Si3C is saturated at a lower value than that of Ti5Si3, Nb5SiB2 and V5SiB2. In Mo5Si3C where room temperature resistivity is large because of large residual resistivity, resistivity saturation is pronounced and results in almost temperature independent resistivity. Thermal conductivities for Mo5SiB2, Mo5Si3, Mo5Si3C and Ti5Si3 are about 27, 19, 8.5 and 11 W/mK, respectively. Mo5Si3C exhibits almost temperature independent thermoelectric power along [112̄0]. On the other hand, thermoelectric power of Mo5Si3C along [0001] and Mo5SiB2 decreases monotonically with increasing temperature.