Stabilisation and modification of the electrical properties of ferroelectric BaTi2O5

铁电BaTi2O5电性能的稳定和改性

• 批准号: EP/F031475/1
• 负责人: Anthony West
• 金额: $ 10.37万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FF031475%2F1
• 关键词: Stabilisation; modification; electrical; properties; ferroelectric

BaTi2O5 is a recently-discovered ferroelectric with a high Curie temperature of ~ 470oC. It has a highly anisotropic crystal structure with a permittivity in the polar direction of ~ 20,000 but a much reduced value of ~ 100 in directions perpendicular to the polar axis. Although single crystals of BaTi2O5 can be grown from the melt and it can also be synthesised as a fine powder by low temperature sol-gel routes, it appears not to be a thermodynamically stable phase and cannot be prepared using the usual high temperature ceramic routes, thereby limiting its range of applications due to inherent fabrication difficulties. We have conducted preliminary phase diagram experiments which showed that BaTi2O5 has a very limited range of stability between 1324 and 1326oC, which coincides with melting temperatures in this region of the BaO-TiO2 phase diagram. We propose to build on this result and investigate the effect of dopants on the thermodynamic stability of BaTi2O5 with a view to reducing the temperature of its lower limit of stability, thereby permitting the processing and fabrication of ceramics. Any dopants that substitute into the BaTi2O5 lattice are very likely to modify both Tc and the electrical properties: e', tan d and piezo-electric coefficients; the effect of dopants on these properties will be surveyed.

BaTi_2O_5是一种新发现的铁电材料，居里温度高达470 ℃。它具有高度各向异性的晶体结构，在极方向上的介电常数约为20，000，但在垂直于极轴的方向上的介电常数值大大降低至约100。虽然BaTi 2 O 5的单晶可以从熔体中生长，并且它也可以通过低温溶胶-凝胶路线合成为细粉末，但它似乎不是化学稳定相，并且不能使用通常的高温陶瓷路线制备，从而由于固有的制造困难而限制了其应用范围。我们已经进行了初步的相图实验表明，BaTi 2 O 5在1324和1326 oC之间具有非常有限的稳定性范围，这与BaO-TiO 2相图中该区域的熔化温度相一致。我们建议建立在这一结果和调查的影响，掺杂剂的热力学稳定性的钛酸钡，以期降低温度的下限的稳定性，从而允许加工和制造的陶瓷。任何掺杂剂，取代到BaTi_2O_5晶格很可能修改Tc和电性能：e '，tan d和压电系数;掺杂剂对这些性能的影响将进行调查。