TCR and MR room-temperature enhancing mechanism of La0.7K0.3−Sr MnO3 ceramics for uncooling infrared bolometers and magnetic sensor devices

Abstract During the last decades, significant improvements of both the magnetoresistance (MR) and the temperature coefficient of resistivity (TCR) of ceramics (at room temperature) have opened new opportunities to build uncooled infrared bolometers and magnetic sensor devices. Herein, polycrystalline La0.7K0.3−xSrxMnO3 ceramics, with 0.00 ≤ x ≤ 0.25 were prepared by a facile sol–gel method. TCRmax increased from 6.4% K−1 at 270.2 K (for x = 0.00) to 11.9% K−1 at 291.2 K (for x = 0.05), and the low-field (1 T) MRmax reached 30.5% at 294.5 K. The phenomenological percolation (PP) model, the Jahn–Teller (JT) effect, and the double exchange (DE) mechanism were used for the comprehensive understanding of the nature of electromagnetic transport properties. Another interesting finding is that the TCR characteristic can be calculated by using the PP model. The JT effect, DE mechanism, and PP model clearly modified both the TCR and MR of the prepared ceramics. The relationship between the proposed TCR/MR dependency and several scattering factors opens up new avenues to enhance TCRmax and MRmax of manganite ceramics.