Preparation of Two Series of materials with Perovskite Structure and Investigation of their Physical Properties
Hanan Saber refai Mohamed;
Abstract
Two series with nominal compositions La 0.7Cao.3Mno.96(InxAio-x)o.o403 (AI I In doped Ca-series) and Lao.7Sro.3Mno.96(InxAlo-xJ)o.o403 (AI /In doped Sr-series) with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 of perovskite manganites were synthesized by conventional solid state reaction techniques. The starting materials were spectroscopically pure oxides. Energy dispersive x-ray (EDX) technique is used for the elemental analysis and shows no significant differences between the analytical and nominal compositions. So, the nominal composition is used throughout the text
Scanning electron microscope (SEM) Model JEOL JSM-5400 was used to examine the microstructures of the fracture surfaces of samples. (SEM) micrographs showed that the microstructure of the present samples is homogeneous with particle size in the range of( IOO nm) for (AI I In) doped Ca-series and ( 40 nm) for (AI I In) doped Sr-series.
Infrared transmission spectroscopy of the (AI I In) doped Ca and (AI I In) doped Sr manganites at room temperature in the range from 200 to 600 cm-1 were performed. In the present manganites, the orthorhombic distortion in (AI I In) doped Ca-series results in a splitting of the non - degenerate modes of the IR spectra which shift to lower frequency with increasing In content. The splitting is attributed to the reduction in the crystal symmetry of this series compared to the ideal perovskite structure. For (AI I In) doped Sr-series which has rhombohedral distortion the vibrational modes of ir spectroscopy show further splitting than found for (AI I In) doped Ca-series.
Room temperature step scanned x-ray diffraction (XRD) patterns collected using CuKa radiation confirmed the presence of single-phase perovskite like structure with orthorhombic unit cell (space group Pnma) for (AI I In) doped Ca-series and rhombohedral unit cell (space group R3C) for (AI I In) doped Sr-series.
All XRD data were analyzed with Rietveld method_. The refined lattice parameters and cell volume of the two series indicate that, a linear relation between the lattice parameters and the In content is obtained, where Vegard's law is obeyed. The increase
Scanning electron microscope (SEM) Model JEOL JSM-5400 was used to examine the microstructures of the fracture surfaces of samples. (SEM) micrographs showed that the microstructure of the present samples is homogeneous with particle size in the range of( IOO nm) for (AI I In) doped Ca-series and ( 40 nm) for (AI I In) doped Sr-series.
Infrared transmission spectroscopy of the (AI I In) doped Ca and (AI I In) doped Sr manganites at room temperature in the range from 200 to 600 cm-1 were performed. In the present manganites, the orthorhombic distortion in (AI I In) doped Ca-series results in a splitting of the non - degenerate modes of the IR spectra which shift to lower frequency with increasing In content. The splitting is attributed to the reduction in the crystal symmetry of this series compared to the ideal perovskite structure. For (AI I In) doped Sr-series which has rhombohedral distortion the vibrational modes of ir spectroscopy show further splitting than found for (AI I In) doped Ca-series.
Room temperature step scanned x-ray diffraction (XRD) patterns collected using CuKa radiation confirmed the presence of single-phase perovskite like structure with orthorhombic unit cell (space group Pnma) for (AI I In) doped Ca-series and rhombohedral unit cell (space group R3C) for (AI I In) doped Sr-series.
All XRD data were analyzed with Rietveld method_. The refined lattice parameters and cell volume of the two series indicate that, a linear relation between the lattice parameters and the In content is obtained, where Vegard's law is obeyed. The increase
Other data
| Title | Preparation of Two Series of materials with Perovskite Structure and Investigation of their Physical Properties | Other Titles | تحضير مجموعتين من مواد ذات تركيب بيرفسكيتى وفحص خواصهما الفيزيائية | Authors | Hanan Saber refai Mohamed | Issue Date | 2010 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.