Thermoelectric properties of CeNi2Al3 compound: an experimental and theoretical study

We present thermoelectric properties of the CeNi2Al3 compound in the temperature range from 4 to 300 K. The electrical resistance (ρ) exhibits a metallic-like character reaching approximately 50 μΩ cm at room temperature. The temperature dependence of the Seebeck coefficient (S) is typical for mixed valence compounds having positive values with a broad maximum (~ 46 μV/K) over a wide temperature range from 200 to 300 K. The thermal conductivity (κ) value reaches 15 W/(m K) at T = 300 K. The power factor (PF = S2/ρ) at 150 K is high (~ 70 μW/cm K2), larger than for conventional thermoelectric materials based on Bi2Te3. The dimensionless figure of merit (ZT) has a broad maximum over a wide temperature range, which reaches the value of 0.1 around 220 K. The experimental results are supported by calculations within the density functional theory (DFT) performed on the basis of the full-potential local-orbital minimum-basis scheme (FPLO). The coherent potential approximation (CPA) is used to simulate the chemical disorder. The calculations are focused on the site preference of Ni and Al atoms. Investigations of the energetic stability have shown that in CeNi2Al3 the aluminum atoms prefer the 3g sites and the nickel ones the 2c sites.