The polycrystalline samples of La 1.98‐ x Y x Sr 0.02 CuO 4 , where 0 ≤ x ≤ 0.06, have been synthesized by solid‐state reaction method, and the impact of Y cosubstitution on the thermoelectric properties of the material has been studied. Rietveld analysis of X‐ray diffraction data confirms orthorhombic structure with systematic decrease of the “c” axis on Y doping, indicating lattice strain due to the Y 3+ doping. The field‐emission scanning electron microscope analysis reveals an anisotropic grain structure with diminishing grain volume and increased grain boundaries density on yttrium doping. Electrical resistivity measurement shows weak metallic behavior with a resistivity minimum at lower temperatures. The low‐level substitution of yttrium (≈2 wt%) significantly reduces electrical resistivity, possibly due to enhanced carrier concentration. The thermopower measurement indicates hole‐type conduction across all compositions in the investigated temperature range. However, codoping of Y suppresses the thermopower at low doping concentration owing to the increased carrier concentration. A quantitative interpretation of the temperature‐dependent thermopower reveals that the two‐band model provides the closest description up to ≈220 K, corroborating the coexistence of delocalized carriers with weakly localized states. Again, the optimized composition, La 1.96 Y 0.02 Sr 0.02 CuO 4 , exhibited a peak power factor of 7.9 µW/cm·K 2 at 130 K, highlighting its potential for low‐temperature thermoelectric applications.
Saif et al. (Sun,) studied this question.