SYNTHESIS AND THERMOELECTRIC PROPERTIES OF BORON-RICH SILICON BORIDES

Boron-rich silicon borides in a boron content range 90.0 to 97.0 at% w ere prepared by are-melting and spark plasma sintering. The plasma-sin tered specimens consisted of SiBn when boron content over 93.7 at%, an d the mixture of SiBn + SiB6 when boron content below 93.7at%, while a ll the arc-melted specimens consisted of SiBn and free silicon, The th ermoelectric properties, involving electrical conductivity, thermal co nductivity as well as Seebeck coefficient were studied and the effects of the phase composition and microstructure on the thermoelectric pro perties were discussed. The dimensionless thermoelectric figure of mer it values (Z = alpha(2) sigma/kappa) of all the obtained silicon borid es; increased with increasing temperature. The plasma-sintered specime n containing 90 at% B showed the largest ZT value, which reached 0.2 a t 1100 K.