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首页> 外文学位 >Ferroelectric-paraelectric phase transitions in the lead(x) calcium(1-x) titanium trioxide and the lead(x) barium(y) strontium(1-x-y) titanium oxide perovskite systems.
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Ferroelectric-paraelectric phase transitions in the lead(x) calcium(1-x) titanium trioxide and the lead(x) barium(y) strontium(1-x-y) titanium oxide perovskite systems.

机译：铅（x）钙（1-x）三氧化钛和铅（x）钡（y）锶（1-x-y）氧化钛钙钛矿体系中的铁电-顺电相变。

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摘要

The paraelectric-ferroelectric phase transformations in the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} and the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}rm y{rcub}{dollar}Sr{dollar}sb{lcub}1-rm x-rm y{rcub}{dollar}TiO{dollar}sb3{dollar} systems are analyzed. Studies on the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}rm y{rcub}{dollar}Sr{dollar}sb{lcub}1-rm x-rm y{rcub}{dollar}TiO{dollar}sb3{dollar} system were focussed on the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}0.5-rm x{rcub}{dollar}Sr{dollar}sb{lcub}0.5{rcub}{dollar}TiO{dollar}sb3{dollar} and the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Sr{dollar}sb{lcub}0.5-rm x{rcub}{dollar}Ba{dollar}sb{lcub}0.5{rcub}{dollar}TiO{dollar}sb3{dollar} compositions. X-ray studies indicate that both Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} and Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}rm y{rcub}{dollar}Sr{dollar}sb{lcub}1-rm x-rm y{rcub}{dollar}TiO{dollar}sb3{dollar} form a solid solution in the entire composition range studied. Transmission electron microscopy studies combined with dielectric measurements reveal that lead and calcium atoms order on alternate {dollar}{lcub}111{rcub}{dollar} planes for the x {dollar}>{dollar} 0.2 compositions, in the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} system, but, the ordering is less than perfect. No structural ordering was observed in the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}rm y{rcub}{dollar}Sr{dollar}sb{lcub}1-rm x-rm y{rcub}{dollar}TiO{dollar}sb3{dollar} system for the compositions studied. Dielectric constant as function of temperature was measured to study the paraelectric-ferroelectric phase transitions in these systems. Addition of calcium titanate was found to broaden the width of the ferroelectric-paraelectric transition region in the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} system. Hysteresis measurements reveal that Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} is ferroelectric at room temperature for the x {dollar}ge{dollar} 0.5 compositions. A similar behavior was observed for the x {dollar}>{dollar} 0.2 compositions in Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}0.5-rm x{rcub}{dollar}Sr{dollar}sb{lcub}0.5{rcub}{dollar}TiO{dollar}sb3{dollar} and for the x {dollar}>{dollar} 0.1 compositions in the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Sr{dollar}sb{lcub}0.5-rm x{rcub}{dollar}Ba{dollar}sb{lcub}0.5{rcub}{dollar}TiO{dollar}sb3{dollar} system. Diffuse phase transitions in solid solutions are primarily attributed to statistical fluctuations in compositions on a microscopic scale. The size of the ferroelectric nucleus determines the fluctuations in compositions and is of paramount importance in determining the nature of the paraelectric-ferroelectric phase transformation in solid solutions. A mathematical model based on probability distribution functions was used in this study to quantitatively establish the size of such fluctuations in composition for the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} and the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}rm y{rcub}{dollar}Sr{dollar}sb{lcub}1-rm x-rm y{rcub}{dollar}TiO{dollar}sb3{dollar} systems. The size of the ferroelectric nucleus was determined to be 15A for the Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ca{dollar}sb{lcub}1-rm x{rcub}{dollar}TiO{dollar}sb3{dollar} system and for the ternary system it was determined to be between 15-30A for Pb{dollar}sb{lcub}rm x{rcub}{dollar}Ba{dollar}sb{lcub}0.5-rm x{rcub}{dollar}Sr{dollar}sb{lcub}0.5{rcub}{dollar}TiO{dollar}sb3{dollar} and between 10-20A for the Pb{do
机译：Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ca {dollar} sb {lcub} 1-rm x {rcub} {dollar} TiO {dollar} sb3 {dollar}中的顺电-铁电相变和Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} rm y {rcub} {dollar} Sr {dollar} sb {lcub} 1-rm x-rm y {分析了rcub} {dollar} TiO {dollar} sb3 {dollar}系统。关于Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} rm y {rcub} {dollar} Sr {dollar} sb {lcub} 1-rm x-rm y的研究{rcub} {dollar} TiO {dollar} sb3 {dollar}系统的重点是Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} 0.5-rm x {rcub} {dollar} Sr {dollar} sb {lcub} 0.5 {rcub} {dollar} TiO {dollar} sb3 {dollar}和Pb {dollar} sb {lcub} rm x {rcub} {dollar} Sr {dollar} sb { lcub} 0.5-rm x {rcub} {dol} Ba {dollar} sb {lcub} 0.5 {rcub} {dollar} TiO {dollar} sb3 {dollar}的组成。 X射线研究表明，Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ca {dollar} sb {lcub} 1-rm x {rcub} {dollar} TiO {dollar} sb3 {dollar}和铅{dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} rm y {rcub} {dollar} Sr {dollar} sb {lcub} 1-rm x-rm y {rcub}在所研究的整个组成范围内，{TiO2} {sb3}形成固溶体。透射电子显微镜研究与介电测量结果相结合，发现铅和钙原子在x {dollar}> {dollar} 0.2成分的交替{dollar} {lcub} 111 {rcub} {dollar}平面上以Pb {dollar}排列sb {lcub} rm x {rcub} {dollar} Ca {dollar} sb {lcub} 1-rm x {rcub} {dollar} TiO {dollar} sb3 {dollar}的系统，但是订购并不完美。在Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} rm y {rcub} {dollar} Sr {dollar} sb {lcub} 1-rm中未观察到结构有序x-rm y {rcub} {dollar} TiO {dollar} sb3 {dollar}体系用于研究的组合物。测量介电常数作为温度的函数，以研究这些系统中的顺电-铁电相变。发现添加钛酸钙可加宽Pb {dollar} sb {lcub} rm x {rcub} {dol} Ca {dollar} sb {lcub} 1-rm x {rcub}中铁电-顺电转变区的宽度{dollar} TiO {dollar} sb3 {dollar}系统。磁滞测量表明，Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ca {dollar} sb {lcub} 1-rm x {rcub} {dollar} TiO {dollar} sb3 {dollar}在房间是铁电的x {geol} ge {dollar} 0.5成分的温度。在Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} 0.5-rm x {rcub} {中，x {dollar}> {dollar} 0.2组成观察到类似的行为{美元} Sr {dollar} sb {lcub} 0.5 {rcub} {dollar} TiO {dollar} sb3 {dollar}和x {dollar}> {dollar} 0.1的成分在Pb {dollar} sb {lcub} rm x中{rcub} {dollar} Sr {dollar} sb {lcub} 0.5-rm x {rcub} {dollar} Ba {dollar} sb {lcub} 0.5 {rcub} {dollar} TiO {dollar} sb3 {dollar}系统。固溶体中的扩散相变主要归因于微观尺度上成分的统计波动。铁电核的大小决定了成分的波动，并且对于确定固溶体中顺电-铁电相变的性质至关重要。在这项研究中使用了基于概率分布函数的数学模型来定量地确定Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ca {dollar} sb {lcub} 1的这种成分波动的大小-rm x {rcub} {dollar} TiO {dollar} sb3 {dollar}和Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} rm y {rcub} {dollar } Sr {dollar} sb {lcub} 1-rm x-rm y {rcub} {dollar} TiO {dollar} sb3 {dollar}系统。对于Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ca {dollar} sb {lcub} 1-rm x {rcub} {dollar} TiO {dollar}，铁电核的大小确定为15A } sb3 {dollar}系统，对于三元系统，Pb {dollar} sb {lcub} rm x {rcub} {dollar} Ba {dollar} sb {lcub} 0.5-rm x { rcub} {dollar} Sr {dollar} sb {lcub} 0.5 {rcub} {dollar} TiO {dollar} sb3 {dollar}和10-20A之间的Pb {do

著录项

  • 作者

    Ganesh, Ramaratnam.;

  • 作者单位

    University of Southern California.;

  • 授予单位 University of Southern California.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1995
  • 页码 119 p.
  • 总页数 119
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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