Temperature dependence of transport behavior and thermochromic property of spark plasma-sintered (La,Sr)MnO3 bulk ceramics

Abstract

Dense (La,Sr)MnO3 bulk ceramics were prepared by spark plasma sintering to study the temperature dependence of transport behavior and thermochromic property in these materials as a function of Sr concentration. The measurement of transport property showed an improvement in electron mobility and electrical conductivity as increasing Sr doping content. The doping of Sr2+ led to the increasing in Mn4+ amount, which enhanced the Mn3+–O–Mn4+ double exchange and reduced the Jahn–Teller effect, and as a result improved the electrical properties of the samples. Concentrating on the variation of temperature-dependent resistivity, it is noted that all the samples exhibited metal–insulator transition temperature (denoted by Tp), showing metallic behavior for T Tp. We then fitted the resistivity data in the semiconducting region by the small polaron hopping (SPH) model and found that the transport behavior in this regime could be described by the SPH mechanism. The infrared emissivity (e) of the (La,Sr)MnO3 ceramics changed with testing temperature, and a shape increase in the emittance value was observed near Tp, which was considered to be associated with the metal–insulator transition. The La1−xSrxMnO3 (x = 0.1−0.2) bulk ceramics exhibited a significant transition in emissivity around Tp, indicating good variable-emittance by appropriate Sr doping.