Pb(Mg_(1/3)Nb_(2/3))O_3弛豫铁电晶体的生长形貌和生长机理

Growth Morphology and Mechanism of Pb(Mg_(1/3)Nb_(2/3))O_3 Relaxor Ferroelectric Crystals

以PbO作助熔剂采用高温溶液法生长出Pb(Mg1/3Nb2/3)O3弛豫铁电晶体,利用X线衍射仪(XRD)和扫描电子显微镜(SEM)分析了晶体相结构和生长形貌。研究结果表明,采用高温溶液法生长出纯钙钛矿相结构的Pb(Mg1/3Nb2/3)O3弛豫铁电晶体,晶体多为淡黄色,较小的呈赝立方形态,较大晶体逐渐趋于不规则形态,最大尺寸达4mm×4mm×3mm。晶体中存在位错蚀坑和PbO包裹等生长缺陷,生长过程中的温度波动和成分起伏等因素导致这些缺陷的出现。晶体{100}面生长速率最慢能成为热力学上稳定存在的自然显露晶面,晶体的生长机制为二维成核层状生长。

Pb（Mg1/3Nb2/3）O3 （PMN） relaxor ferroelectric crystals were prepared with PbO as additive by high temperature flux method. Phase structure and growth morphology were characterized by X-ray diffraction analysis （XRD） and scanning electron morphology （SEM）. It is indicated that most crystals showed color of light yellow and maximum size of 4 mm × 4 mm × 3mm. The smaller ones had a pseudo-cubic shape and the larger ones had not. The light yellow crystals were pure perovskite phase structure. Some growth defects such as dislocations and PhO packages were observed in the crystal surface, which was attributed to the composition and temperature fluctuation in the process of crystal growth. The slowest growth rate face { 100} was the free exposing planes with thermodynamics stability. The growth mechanism of the crystals was a layer growth mechanism controlled by two-dimensional nucleation.