Li_(6)Gd(BO_(3))_(3)晶体生长及热性能  

Growth and Thermal Properties of Li_(6)Gd(BO_(3))_(3)Crystals

作　　者：任伊扬 王鹏 马云峰 张明荣 张春生[3] 徐家跃 REN Yiyang;WANG Peng;MA Yunfeng;ZHANG Mingrong;ZHANG Chunsheng;XU Jiayue(School of Materials Science and Engineering,Shanghai Institute of Technology,Shanghai 201418,China;College of Materials Science and Engineering,Fujian Institute of Technology,Fuzhou 350118,China;Beijing Glass Research Institute Co.Ltd,Beijing 10111l,China)

机构地区：[1]上海应用技术大学材料科学与工程学院,上海201418 [2]福建理工大学材料科学与工程学院,福州350118 [3]北京玻璃研究院有限公司,北京101111

出　　处：《硅酸盐学报》2024年第5期1589-1596,共8页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(51802196)。

摘　　要：Li_(6)Gd(BO_(3))_(3)(LGBO)晶体具有优异的综合性能,是潜在的中子探测、激光和发光材料。但是,由于硼酸盐熔体粘度大、晶体易开裂,晶体生长非常困难。采用坩埚下降法生长出尺寸为φ20mm×30mm透明晶体,探讨了高黏度晶体的生长机理,研究了晶体的光谱和热物理性能。35℃下晶体比热容为0.898 J/(g·K),300℃时上升到1.18 J/(g·K);30℃下<100>和<020>方向热膨胀系数分别为12.768×10^(-6)K^(-1)和21.146×10^(-6)K^(-1),随温度升高表现出显著的各向异性;室温下其热导率分别为2.72 W/(m·K)和2.60 W/(m·K)。较大的比热容有利于LGBO晶体在高功率状态下稳定工作。Introduction Li_(6)Gd(BO_(3))_(3)(LGBO)crystal is an effective scintillator for neutron detection as well as a laser host and phosphor material.However,it is difficulty to grow large-size and high-quality crystals because of high viscosity of the melt and crystal cracking.Although LGBO crystals are grown by the Czochralski and other methods,the crystal size is small and the quality is poor for its practical application.The vertical Bridgman method is suitable for growing borate crystals due to its slow growth rate and small temperature gradient.This paper was to investigate the crystallization behavior of deep supercooling melt and grow LGBO crystals prepared by a modified vertical Bridgman method.In addition,the thermal properties of crystals were also analyzed to provide a reference for practical application.Methods LGBO polycrystalline materials were synthesized with high-purity chemicals(i.e.,Li_(2)CO_(3),99.99%;H3BO3,99.99%and Gd_(2)O_(3),99.99%)by a high-temperature solid-state method.LGBO crystal was grown by a modified vertical Bridgman method.The crystals were characterized by X-ray diffraction,ultraviolet excitation and emission spectroscopy,and differential scanning calorimetry.The thermal expansion coefficient of the crystals was measured by a model TMA 402 F1 thermomechanical analyzer.The thermal diffusivity coefficient of the crystals was measured by a model LFA 457 laser thermal conductivity meter,and the thermal conductivity of the crystals was calculated accordingly.Results and discussion LGBO crystal was grown in a Platinum crucible with a seed well.Seed crystal was obtained via spontaneous nucleation in advance.The DSC curves of LGBO show that the melting point is 845℃,and the crystallization temperature is 731℃.Thus,the seeding and slow growth rates are the key issues for the growth of LGBO crystal because of the deep supercooling melt.The growth parameters are optimized with a<001>-oriented seed,a slope of 30 degrees at shoulder,a small temperature gradient of 30℃/cm at solid-liquid int

关 键 词：硼酸钆锂晶体 坩埚下降法 晶体生长 热性能 

分 类 号：O482[理学—固体物理]