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Title: Phase transitions in A-site substituted perovskite compounds: The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) solid solution

Abstract

The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) A-site substituted perovskite compounds have been synthesized and characterized by XRD and Raman spectroscopy at room temperature. The XRD powder diffraction study suggests that the end-member Na{sub 1/2}La{sub 1/2}TiO{sub 3} crystallizes in the tetragonal space group I4/mcm. The phase transition from Pbnm to I4/mcm is located between x=0.34 and 0.39 and is driven by the variation of ionic radii at the A-site. The observed Raman modes are in agreement with group theory analysis, and the relationships between the behavior of structural parameters (e.g. Ti-O-Ti bond angle), indicated by long-range order, and the corresponding Raman frequency shifts and intensity evolution, indicated by short-range order, are established and discussed in terms of the radius effect and the mass effect.

Authors:
 [1];  [2];  [3]
  1. Department of Geology, Peking University, Beijing 100871 (China)
  2. Department of Geology, Peking University, Beijing 100871 (China), E-mail: sqin@pku.edu.cn
  3. Bayerisches Geoinstitut, Universitaet Bayreuth, D-95440 Bayreuth (Germany)
Publication Date:
OSTI Identifier:
21015717
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 3; Other Information: DOI: 10.1016/j.jssc.2006.12.012; PII: S0022-4596(06)00636-0; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATOMIC RADII; BOND ANGLE; CALCIUM COMPOUNDS; GROUP THEORY; ORTHORHOMBIC LATTICES; PEROVSKITE; PHASE TRANSFORMATIONS; RAMAN SPECTROSCOPY; SODIUM COMPOUNDS; SOLID SOLUTIONS; SPACE GROUPS; TEMPERATURE RANGE 0273-0400 K; TETRAGONAL LATTICES; TITANATES; X-RAY DIFFRACTION

Citation Formats

Li Yuan, Qin Shan, and Seifert, Friedrich. Phase transitions in A-site substituted perovskite compounds: The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) solid solution. United States: N. p., 2007. Web.
Li Yuan, Qin Shan, & Seifert, Friedrich. Phase transitions in A-site substituted perovskite compounds: The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) solid solution. United States.
Li Yuan, Qin Shan, and Seifert, Friedrich. Thu . "Phase transitions in A-site substituted perovskite compounds: The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) solid solution". United States. doi:.
@article{osti_21015717,
title = {Phase transitions in A-site substituted perovskite compounds: The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) solid solution},
author = {Li Yuan and Qin Shan and Seifert, Friedrich},
abstractNote = {The (Ca{sub 1-2x}Na{sub x}La{sub x})TiO{sub 3} (0=<x=<0.5) A-site substituted perovskite compounds have been synthesized and characterized by XRD and Raman spectroscopy at room temperature. The XRD powder diffraction study suggests that the end-member Na{sub 1/2}La{sub 1/2}TiO{sub 3} crystallizes in the tetragonal space group I4/mcm. The phase transition from Pbnm to I4/mcm is located between x=0.34 and 0.39 and is driven by the variation of ionic radii at the A-site. The observed Raman modes are in agreement with group theory analysis, and the relationships between the behavior of structural parameters (e.g. Ti-O-Ti bond angle), indicated by long-range order, and the corresponding Raman frequency shifts and intensity evolution, indicated by short-range order, are established and discussed in terms of the radius effect and the mass effect.},
doi = {},
journal = {Journal of Solid State Chemistry},
number = 3,
volume = 180,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
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  • Li{sub (1-2x)}Ni {sub x}TiO(PO{sub 4}) oxyphosphates with 0 {<=} x {<=} 0.10 crystallize in the orthorhombic system with the space group Pnma, those with 0.10 < x {<=} 0.25 crystallize in the monoclinic system with the space group P2{sub 1}/c and compositions with 0.25 < x < 0.50 present a mixture of the limit of the solid solution Li{sub 0.50}Ni{sub 0.25}TiO(PO{sub 4}) and Ni{sub 0.50}TiO(PO{sub 4}). The structure of the compositions 0 {<=} x {<=} 0.25 is based on a three-dimensional anionic framework constructed of chains of alternating TiO{sub 6} octahedra and PO{sub 4} tetrahedra, with the lithium and nickelmore » atoms in the cavities in the framework. The dominant structural units in the compositions are chains of tilted corner-sharing TiO{sub 6} octahedra running parallel to one of the axis. The oxygen atoms of the shared corners, not implied in (PO{sub 4}) tetrahedra, justify the oxyphosphate designation. Titanium atoms are displaced from the geometrical center of the octahedra resulting in alternating long ({approx}2.25 A) and short ({approx}1.71 A) Ti-O(1) bonds. The four remaining Ti-O bond distances have intermediate values ranging from 1.91 to 2.06 A.« less
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