Abstract Direct solid state synthesis by hot pressing has been applied in order to produce high efficiency bulk specimens. Single phase with 98.5% of theoretical density was successfully produced by direct hot pressing of elemental powders containing 1.2 at.% excess Zn. Thermoelectric properties as a function of temperature were investigated from room temperature to 600 K and compared with results of other studies. Transport properties at room temperature were also evaluated. Thermoelectric properties of single phase materials produced by direct synthesis were measured and are comparable to the published data. Direct solid state synthesis by hot pressing provides a promising processing route in this material