Thermoelectric properties and spark plasma sintering of doped YB₂₂C₂N

YB₂₂C₂N is one of a series of rare earth borocarbonitrides and is potentially the long awaited n-type counterpart to boron carbide. We conducted studies on YB₂₂C₂N spark plasma sintered with additions of YB₄ and YB₂₅C, including the investigations of the densification process and the thermoelectric properties of the material. We discovered that a small amount of dopants can lower the starting temperature of densification during spark plasma sintering (SPS). Variations of pressure and temperature during the sintering process are also found to have an effect. Electrical conductivity of the dense samples has increased due to insertion of metal borides and also because of the improvement of the relative density. At the same time, only a slight reduction was observed for the Seebeck coefficient leading to an important improvement of power factor. The highest density of more than 95% was achieved with 5 wt% of YB₂₅(C) dopant.