硅酸盐学报

Li₆Gd（BO₃）₃晶体生长及热性能

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任伊扬 ¹ , 王鹏 ¹ , 马云峰 ¹ , 张明荣 ² , 张春生 ³ , 徐家跃 ¹

硅酸盐学报 | 研究论文 2024,52(5): 1589-1596

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硅酸盐学报 |研究论文 2024 , 52 (5) : 1589 -1596

Li₆Gd（BO₃）₃晶体生长及热性能

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任伊扬¹, 王鹏¹, 马云峰¹, 张明荣², 张春生³, 徐家跃¹

作者信息

^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

通讯作者:

徐家跃（1965—），男，博士，教授。

作者简介:

任伊扬（1997—），男，硕士研究生。

Growth and Thermal Properties of Li₆Gd(BO₃)₃ Crystals

Yiyang REN¹, Peng WANG¹, Yunfeng MA¹, Mingrong ZHANG², Chunsheng ZHANG³, Jiayue XU¹

Affiliations

^1.School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China

^2.College of Materials Science and Engineering, Fujian Institute of Technology, Fuzhou 350118, China

^3.Beijing Glass Research Institute Co. Ltd, Beijing 101111, China

Corresponding Author:

XU Jiayue (1965-), male, Ph.D., Professor. E-mail: xujiayue@sit.edu.cn

REN Yiyang (1997-), male, Master candidate. E-mail: 978663886@qq.com

出版时间: 2024-05-20 doi: 10.14062/j.issn.0454-5648.20230653

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摘要

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Li₆Gd（BO₃）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Φ 20 mm×30 mm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。

关键词

硼酸钆锂晶体 / 坩埚下降法 / 晶体生长 / 热性能

Abstract

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Introduction

Li₆Gd(BO₃)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., Li₂CO₃, 99.99%; H₃BO₃, 99.99% and Gd₂O₃, 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 interface and a very slow descent rate of 2.4 mm/d. The transparent LGBO crystal with the sizes of 20 mm in diameter and 30 mm in length is obtained and the transmittance is close to 85% in a range of 320-800 nm. The excitation-emission spectra of the crystals are tested and the mechanism of luminescence is discussed.

The thermophysical properties of the crystal are investigated via measuring the specific heat capacity, thermal expansion, thermal conductivity and diffusion coefficient. Since the specific heat capacity of the crystal is large and changes significantly with temperature, the temperature change is relatively small when the crystal absorbs heat, and the ability to withstand thermal shock is high. The thermal expansion coefficient is an important parameter in the thermal properties of crystals, which has an important reference value for the selection of seed orientation and crystal processing in crystal growth. The gap between the thermal expansion coefficients of the two directions becomes larger with the increase of temperature. The thermal diffusivity and thermal conductivity are both physical quantities that characterize the heat transfer of materials. The thermal diffusivity of crystal phases (020) and (100) decreases with increasing temperature at 25-300 ℃. The thermal conductivity curve of LGBO crystal at 25-300 ℃ obtained by the thermal conductivity calculation formula indicates that the thermal conductivity of LGBO crystal is larger in the similar crystals.

Conclusions

Large-size LGBO crystals were grown by a modified vertical Bridgman method. The high viscosity of the melt and the extra-large supercooling determined the extremely slow growth rate of LGBO crystals. The specific heat capacity of the crystal at room temperature was 0.898 J/(g·K). The thermal expansion coefficients for the crystal phases (100) and (020) were 12.768×10^-6 K^-1 and 21.146×10^-6 K^-1, respectively. The thermal conductivities for crystal phases (100) and (020) at room temperature were 2.72 W/(m·K) and 2.60 W/(m·K), respectively. The thermal expansion had a great anisotropy as the temperature increased, and the thermal diffusivity decreased with the increase of temperature. The results indicated LGBO crystal under a high power could have a potential application due to its large specific heat.

Key words

lithium gadolinium borate crystal / bridgman method / crystal growth / thermal property

引用本文

任伊扬, 王鹏, 马云峰, 张明荣, 张春生, 徐家跃. Li₆Gd（BO₃）₃晶体生长及热性能. 硅酸盐学报, 2024 , 52 (5) : 1589 -1596 . DOI: 10.14062/j.issn.0454-5648.20230653

Yiyang REN, Peng WANG, Yunfeng MA, Mingrong ZHANG, Chunsheng ZHANG, Jiayue XU. Growth and Thermal Properties of Li₆Gd(BO₃)₃ Crystals[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (5) : 1589 -1596 . DOI: 10.14062/j.issn.0454-5648.20230653

基金

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国家自然科学基金(51802196)

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2024年第52卷第5期

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文章信息

doi: 10.14062/j.issn.0454-5648.20230653

接收时间：2023-08-29
首发时间：2026-10-22
出版时间：2024-05-20

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出版历史

收稿日期：2023-08-29
修回日期：2023-10-26

基金

国家自然科学基金(51802196)

作者信息

^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

通讯作者:

徐家跃（1965—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20230653

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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