The decomposition pressure,congruent melting point and electrical resistivity of cerium nitride

The melting point of CeN in nitrogen was determined at pressures between 10⁻² and 21 atmospheres. Congruent melting was observed at T = 2575 ± 20°C and P = 5 ± 1 atmospheres. With lower nitrogen pressures, the melting point was related to the applied (or decomposition) pressure by the equation log P_atmos(N₂) = 18·5 − 5·1 × 10⁴/T. The electrical resistivities of samples prepared from these melts were measured at temperatures between 150–900°K. The room temperature resistivity of congruently melted samples was 21 μΩ-cm, which may be compared with the value of 75 μΩ-cm for cerium metal at this temperature. These samples had a positive (metallic) temperature dependence of resistivity of 0·11 μΩ-cm/°C at room temperature and increased with temperature to a value of 0·22 μΩ-cm/°C at a temperature of 700°K. The noncongruently melted samples had a similar behavior, but with somewhat higher values of resistivity. The room temperature Seebeck coefficients for both types of samples were approximately + 5 μV/°C, relative to platinum.