Structural and dielectric properties of Co doped La_0.67Ca_0.33Mn_1-xCo_xO₃ nanoparticles

Lanthanum based maganites have attracted prominent attention due to their distinguished magnetic and electronic properties. They have been subjected to strong interest primarily due to the discovery of colossal magnetoresistance effect (CMR) and magnetocaloric effect (MCE) around the ferromagnetic transition temperature (TC), which is located near room temperature. In the present work, Cobalt doped Lanthanum Calcium manganite samples with composition La_0.67Ca_0.33Mn_1-xCo_xO₃ (x=0, 0.03 and 0.05) were synthesized using chemical coprecipitation method. The prepared samples were calcined at 600 °C and then sintered at 800 °C. The structural information and pure phase formation with elemental composition were confirmed by XRD and FTIR analysis. From the XRD pattern it is observed that there is no phase change with increase in Co dopant concentration. The phase of the sample is rhombohedral r3c with a hexagonal axis setting. The FTIR studies reveal the formation of the metal oxide bonds. The intensity of vibration modes become prominent with the increase of Co concentration. The impedance analysis shows that the value of dielectric constant is high for undoped samples compared to the doped samples. This is attributed to the change in the electronic configuration of the Mn and dopant Co on coexisting in the sample, which, thereby, promotes such a feature