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

Abstract

Dense (La,Sr)MnO 3 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 Sr 2? led to the increasing in Mn 4? amount, which enhanced the Mn 3? -O-Mn 4? double exchange and reduced the JahnTeller 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 T p ), showing metallic behavior for T \ T p and semiconducting character for T [ T p . 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)MnO 3 ceramics changed with testing temperature, and a shape increase in the emittance value was observed near T p , which was considered to be associated with the metalinsulator transition. The La 1-x Sr x MnO 3 (x = 0.1-0.2) bulk ceramics exhibited a significant transition in emissivity around T p , indicating good variable-emittance by appropriate Sr doping.

Effect of oxygen partial pressure on epitaxial growth and properties of laser-ablated AZO thin films

“…It is generally believed that better electrical conductivity could be attributed to the finer microstructure [18] , including grain size and crystallinity. With increasing oxygen partial pressure, especially when P O2 = 10 Pa and P O2 = 13 Pa, the AZO grains are more crystallized and the film's surface is denser, which will improve the interconnectivity between grains and thus lead to a higher Hall carriers concentration.…”