Abstract
In this study, La0.7Ca0.3-xKxMnO3 (LCKMO) polycrystalline ceramics were synthesized by sol–gel method. Their structures, surface morphologies, and electromagnetic transmission characteristics were studied and discussed. X-ray diffraction results showed that all prepared specimens highly crystalized as single phase with orthorhombic perovskite structure and Pnma space group. Characterization by scanning electron microscopy revealed that grain size increased with the increase in the K+ content. Electrical resistivity as function of temperature (ρ-T) was investigated through standard four-probe method. With the increase in the K+ content, metal–insulator transition temperature (Tp) and the Curie temperature (TC) shifted to higher temperatures, while the resistivity (ρ) reduced. Careful analysis of data indicated that peak temperature coefficient of resistance (TCR) and magnetoresistance (MR) were affected by K+ substitution. At x = 0.02, peak TCR and MR values reached 6.03%·K−1 and 30.26%, respectively. Characteristics of resultant ceramics were explained based on double exchange interaction. Overall, LCKMO materials act as promising candidates for broad range of applications in magnetic devices and infrared detectors at room temperature.
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