Thermoelectric Properties and Electronic Density of States of Transition Metal Monoborides, FeB, CoB, NiB and there Solid Solutions

Abstract

Monoboride of iron, cobalt and nickel, and there solid solutions having FeB crystal structure were prepared by solid state reaction at 950°C in vacuum, and then HIPed using hydrothermal water as fluid at 900°C for 2h under a pressure of 100MPa. Electrical conductivity and Seebeck coefficients of the specimens were measured to evaluate thermoelectric properties. Electrical conductivities were more than 10⁵Sm^-1 and Seebeck coefficients range from +20 to -30 μVK^-1 as metal atoms changed. On the other hand, electrical densities of states of those borides were calculated by the first principle (DV-Xα) methods. The Felmi level of those borides was near the 3d orbital of metal atom and this seemed to be a reason of relatively high Seebeck coefficients of the borides.