Enhancement of Optical, Electrical, Magnetic, and Thermopower Properties of LaMnO3 by Potassium‐Doping

Optical, magnetoresistance, and thermoelectric properties of La1−xKxMnO3 (x = 0.05, 0.15, and 0.25) compounds have been investigated. The crystallography demonstrates that the samples x = 0.05 and 0.15 are a single‐phase rhombohedral ( R3¯C$R \overset{\cdot}{3} C$ ) structure, while x = 0.25 is near to a single rhombohedral phase with a minor amount of Mn3O4 (with a ratio of ≈2%). The optical properties manifest that the reflectivity decreases slightly with increasing x‐doping, where the sample of x = 0.05 has the lowest reflection value, making it a promising material for photovoltaic applications. Electrical resistivity measurements show that the samples have a metal–semiconductor transition, and the transition temperature Tms decreases with the K content. The thermoelectric data show a remarkable coincidence behavior of the ρ–T relationship, which has a peak at a transition temperature (TS). Magnetic susceptibility data show that the samples undergo ferro‐paramagnetic transition at a certain temperature (Curie temperature).