Electrical conduction in La0.85Sr0.15MnO3:Agx (0 ≤ x ≤ 0.5) ceramics with large room-temperature TCR

Abstract

Polycrystalline La0.85Sr0.15MnO3:Agx (LSMO:Agx, 0 ≤ x ≤ 0.5) ceramics were synthesized using sol-gel procedure. All specimens showed rhombohedral perovskite structures in R3‾c space group. As the amount of Ag increased, grain size of ceramics increased, and resistivity accordingly decreased. Large temperature coefficient of resistivity (TCR) of 22.9% K−1 was obtained at room temperature (289.2 K) for x = 0.4. Interestingly, analyses of resistivity-temperature (ρ-T) experimental data showed that conduction mechanism over entire temperature region perfectly matched theoretical percolation model. This reveals that electrical transport properties of LSMO:Agx ceramics are mainly affected by domains, grain boundaries (GBs), and Kondo-like spin-dependent scattering. It also demonstrates the coexistence of paramagnetic (FM) and ferromagnetic (PM) phases in LSMO:Agx ceramics. The ρ-T and scanning electron microscopy (SEM) results confirmed that the introduction of Ag weakened these scattering effects.