新型铁电晶体铌镥酸铅-钛酸铅的生长与性能

Growth and Characterization of a New Lead Lutetium Niobate with Lead Titanate Ferroelectric Crystal

采用顶部籽晶法生长了一系列不同组分的高居里温度铌镥酸铅-钛酸铅[（1-x）Pb（Lu1/2Nb1/2）O3-xPbTiO3 （PLN-xPT）]铁电晶体。该晶体在三方相区域表现出典型的介电弛豫特性, 不同组分的晶体表现出了较高的居里温度; 基于介电和结构测试结果, 得到了该体系的低温二元体系相图, 在相图中存在一个准同型相界区域（MPB）, 其组分位于x = 0.49~0.51; 利用偏光显微镜分析晶体电畴结构得到和X射线粉末衍射测试结果吻合的相结构; 电学性能测试结果表明不同组分的晶体性能差异较大。组分位于MPB附近的晶体表现出优异的压电性能, 如x = 0.49时, 居里温度Tc = 360℃, 压电常数d33 〉 1600 pC/N。处于MPB附近的晶体存在较大的矫顽Ec 〉10kV/cm, 一些组分晶体的三方–四方相变温度TRT 〉 200℃。结果表明高的居里温度及优异的压电性能使二元铌镥酸铅-钛酸铅晶体具有更大的温度应用范围及更广阔的应用前景。

A series of new lead lutetium niobate with lead titanate （1-x）Pb（Lu1/2Nb1/2）O3-xPbTiO3 （PLN-xPT） ferroelectric crystals were grown successfully by the top-seed solution growth technique. Structural analysis and electrical properties measurement showed that the crystals have high Curie temperatures and each composition had different performances. The temperature dependences of permittivity showed typical relaxor behavior in the rhombohedral phase region. Based on the measurement result, a solid state phase diagram in the low temperature range was established, which revealed a morphotropic phase boundary （MPB） in the composition of x = 0.49 to 0.51. Electric domains on （001） surface were observed by the polarizing microscope, in agreement with the X-ray diffraction data. Those compositions within MPB exhibited good piezoelectric properties, such as high coercive field Ec （〉10 kV/cm） and high rhombohedral-tetragonal phase transition temperature TRT （〉 200℃）. For PLN-0.49PT, it had a high Curie temperature Tc = 360℃ and a piezoelectric coefficient of d33 〉 1600 pC/N. High Curie temperature and excellent piezoelectric property make this material a promising candidate which can operate in a wider temperature range.