Formation Characteristics of the Commensurate Fluorite-Type Bi2O3−Nb2O5 Solid Solution
Formation Characteristics of the Commensurate Fluorite-Type Bi2O3−Nb2O5 Solid Solution
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相应萤石型Bi2O3−Nb2O5固溶体的形成特征
DOI：
10.1021/cm0509025
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
D. Suvorov
中科院分区：
文献类型：
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作者：
U. Pirnat;M. Valant;and Boštjan Jančar;D. Suvorov
利用X射线粉末衍射和透射电子显微镜研究了萤石型Bi 2 O3 − Nb 2 O 5固溶体的四元结构的形成特征和稳定范围。结果表明，这种四阶调制相的形成是通过中间形成的无公度调制立方萤石相，然后是无公度-公度转变。这种转变可以被描述为具有温度依赖性诱导时间和生长动力学的均质成核，其由在诱导时间期间成核的四畴的生长速率确定。对于通式Bi 3-yNb 1 + yO 7 +y，四方相的均匀性范围在−0.2 ≤ y ≤ 0.04之间。四元Bi 3-yNb 1 + yO 7 +y相在转变温度以下是热稳定的，在该转变温度下它转变回立方无公度相。转变温度随Nb含量的增加而升高。
X-ray powder diffraction and transmission electron microscopy were used to investigate the formation characteristics and stability range of the tetragonal modification of a fluorite-type Bi2O3−Nb2O5 solid solution. The results showed that this tetragonal, commensurately modulated phase forms through the intermediate formation of the incommensurately modulated cubic fluorite phase followed by the incommensurate−commensurate transformation. This transformation can be described as a homogeneous nucleation with a temperature-dependent induction time and growth kinetics, which is determined by a growth rate of the tetragonal domains nucleated during the induction time. The homogeneity range of the tetragonal phase was found to extend between −0.2 ≤ y ≤ 0.04 for the general formula Bi3-yNb1+yO7+y. The tetragonal Bi3-yNb1+yO7+y phase is thermally stable up to the transition temperature where it transforms back to the cubic incommensurate phase. The transition temperature increases with Nb concentration from 750 ...