La1−xCaxMnO3:Ag0.2 (0.25 ≤ x ≤ 0.31) Ceramics with high temperature coefficient of resistivity under magnetic field

Abstract The polycrystalline La1−xCaxMnO3 ceramics exhibit good electromagnetic performance, i.e., high temperature coefficient of resistivity (TCR), which can be tuned flexibly with respect to structures. Unfortunately, the magnetic field applied to these materials causes a massive decrease in TCR, which hinders their practical applications. In this study, polycrystalline ceramic La1−xCaxMnO3:Ag0.2 was fabricated by sol–gel and solid–phase doping methods, and subsequently vast TCR was obtained in the magnetic field for ceramic with x = 0.2. For this polycrystalline material, high value of TCR (58.65 %·K−1, 62.00 %·K−1) could be maintained with or without magnetic field with metal–insulator (M–I) transition temperature near room temperature range. Extremely high value of TCR in the presence of magnetic field is attributed to the spin–spin coupling effect, which is beneficial to the sensitivity of M–I transition, generating vast TCR in the magnetic field. Overall, these findings provide new prospects for future applications in infrared bolometers.