期刊
JOURNAL OF ALLOYS AND COMPOUNDS
卷 671, 期 -, 页码 226-233出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jallcom.2016.02.087
关键词
Pyrochlore; Defect-fluorite; Holmium titanate; Order-disorder transition; Ionic conductivity
资金
- NAS (USA)
- HEC (Pakistan) [131]
- HEC under the International Research Support Initiative Program (IRSIP) [PGA - P280420]
- Khyber Pakhtunkhwa Government through DoST, Peshawar [130314]
Compounds in the pyrochlore systemHo(2)(ZryTi1-y)(2)O-7 exhibit an order-disorder transition from pyrochlore to a defect-fluorite type structure. Compositions in this system were prepared via mechanical milling, followed by a two-step sintering process. Structural characterization was carried out via Rietveld refinements using neutron powder diffraction data, supported by X-ray diffraction to determine the phase and location of the pyrochlore-fluorite transformation. Unit-cell parameters were determined for the whole series using Rietveld refinements as well as the Nelson-Riley function. The neutron refinement results confirmed that the cation disorder was independent of the anion Frenkel disorder. The relation between the x-parameter in the oxygen 48f position and anion Frenkel disorder was found to be linear for the pyrochlore structure. The ionic conductivity studies were undertaken via AC impedance analysis to determine the electronic behaviour and its relation to the structural change in the temperature range 300 degrees C-700 degrees C. The trends in ionic conductivity and activation energy were explained structurally via neutron powder diffraction and X-ray diffraction data. The pyrochlore-fluorite boundary composition (at y = 0.5) exhibited the lowest activation energy and highest ionic conductivity. (C) 2016 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据