Crystallographic modeling and impedance studies of gadolinium modified La_1−xGd_xMnO₃ (x = 0.1-0.3) ceramics

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• 作者：Rashmi Chourasia^a ; ^{dr.rchourasia@gmail.com} ; Vijay Varma^a ; Shivendra Chaurasiya^b ; O.P. Shrivastava^a
• 关键词：X-ray diffraction ; Nanoceramics ; Rietveld refinement ; Electrical properties ; Electron microscopy
• 刊名：Polyhedron
• 出版年：2017
• 出版时间：10 January 2017
• 年：2017
• 卷：121
• 期：Complete
• 页码：269-277
• 全文大小：2429 K
• 卷排序：121

文摘

The crystal chemistry of perovskite structured ceramic phases: La0.9Gd0.1MnO3 (LMGd-1), La0.8Gd0.2MnO3 (LMGd-2) and La0.7Gd0.3MnO3 (LMGd-3) have been investigated using General Structure Analysis System (GSAS) programming. The LMGd phases crystallize in the space group R-3c and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of Rietveld parameters: Rp, Rwp and goodness of fit. Lattice parameters, bond lengths and bond angles have been calculated from GSAS software. Their electrical behaviour investigated by impedance spectroscopy in the frequency range 42 Hz–5 MHz at temperatures between 50 ° and 300 °C. Nyquist plots show the dominance of grain contribution and Debye – like relaxation in the materials. Conductivity data as a function of temperature and frequency suggest semiconductor behavior of the materials.