Perovskite type lanthanum manganite：Morpho-structural analysis and electrical investigations  

作　　者：Paula Sfirloaga Maria Poienar Iosif Malaescu Antoanetta Lungu Paulina Vlazan Paula Sfirloaga;Maria Poienar;Iosif Malaescu;Antoanetta Lungu;Paulina Vlazan(Institute for Research and Development in Electrochemistry and Condensed Matter, P. Andronescu Street, No.1, 300224, Timisoara, Romania;West University of Timisoara, Vasile Parvan 4, 300223, Romania)

机构地区：[1]Institute for Research and Development in Electrochemistry and Condensed Matter, P. Andronescu Street, No.1, 300224, Timisoara, Romania [2]West University of Timisoara, Vasile Parvan 4, 300223, Romania

出　　处：《Journal of Rare Earths》2018年第5期499-504,共6页稀土学报（英文版）

基　　金：Project supported by the Experimental Demonstrative Project 48PED/2017-Executive Unit for Financing Higher Education,Research,Development and Innovation(UEFISCDI)

摘　　要：Perovskite-type oxides of LaMnO3 were synthesized by means of the sol-gel method, in the presence of citric acid as gelling agent. The precursors used were Mn（NO3）2·H2O, La2O3, and NaOH,mixed in the stoichiometric ratio to obtain perovskite materials. The obtained gel was heat-treated at 400, 600 and 800 ℃ respectively, for 6 h. X-ray diffraction and FT-IR spectroscopy were used to analyze the phase transformation as a function of temperature, and the Rietveld refinement was used in order to characterize the materials obtained structurally. The average crystallite size of the products was calculated from XRD data and the average particle size was measured from the TEM micrographs. At 600 ℃, the synthesized compound is well-crystallized, showcases a perovskite structure（Pm-3m space group）, and exhibits uniform and homogeneous hexagonally-shaped particles, with sizes in the 20-50 nm range.Complex impedance measurements in the 20-2 × 10^6 Hz frequency range were carried out at different temperatures（26-115 ℃）, and the electrical conduction mechanism is discussed.Perovskite-type oxides of LaMnO3 were synthesized by means of the sol-gel method, in the presence of citric acid as gelling agent. The precursors used were Mn（NO3）2·H2O, La2O3, and NaOH,mixed in the stoichiometric ratio to obtain perovskite materials. The obtained gel was heat-treated at 400, 600 and 800 ℃ respectively, for 6 h. X-ray diffraction and FT-IR spectroscopy were used to analyze the phase transformation as a function of temperature, and the Rietveld refinement was used in order to characterize the materials obtained structurally. The average crystallite size of the products was calculated from XRD data and the average particle size was measured from the TEM micrographs. At 600 ℃, the synthesized compound is well-crystallized, showcases a perovskite structure（Pm-3m space group）, and exhibits uniform and homogeneous hexagonally-shaped particles, with sizes in the 20-50 nm range.Complex impedance measurements in the 20-2 × 10^6 Hz frequency range were carried out at different temperatures（26-115 ℃）, and the electrical conduction mechanism is discussed.

关 键 词：Rare earths Sol-gel method Physico-chemical properties Electrical investigations 

分 类 号：TB383.1[一般工业技术—材料科学与工程] TQ133.3[化学工程—无机化工]