title: Lightly doping Ca2+ in perovskite PrCoO3 for tailored spin states and electrical properties.
abstract: A series of Pr(1-x)Ca(x)CoO(3) samples were prepared using a novel molten salt reaction that is convenient to obtain single phases avoiding aggregates compared to conventional solid state reactions. The formation reaction was monitored by X-ray diffraction combined with thermal analysis, and all samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and alternating current impedance. It is demonstrated that all Pr(1-x)Ca(x)CoO(3) samples crystallized in a pure orthorhombic perovskite structure. By increasing the doping level, the symmetry of the orthorhombic structure was enhanced, and is followed by an increase in the population of Co(3+) in the intermediate spin state. All samples exhibited typical semiconducting behavior, showing conductivities highly dependent on the Ca(2+) doping. The conduction for x = 0 shows a simple thermal activated process, which changed into a Mott's variable range hopping mechanism for x > 0. By increasing the Ca(2+) doping level, the relevant activation energy is decreased, while the density of the localized electronic state is increased.
authors: Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, PR China.
authors: Heng
authors: H
authors: Wang
authors: Guangshe
authors: G
authors: Li
authors: Xiangfeng
authors: X
authors: Guan
authors: Minglei
authors: M
authors: Zhao
authors: Liping
authors: L
authors: Li