摘要
针对熔体急冷法制备的非晶硒样品,开展了压力对非晶硒玻璃化转变温度和过冷液相区影响的实验研究。在活塞圆筒高压模具上开展差热分析,测得了0.1~1700 MPa压力范围内非晶硒的玻璃化转变温度T_(g)和晶化温度T_(x),拟合出玻璃化转变中点温度T_(1/2,g)与外推起始晶化温度T_(el,x)随压力p的变化关系:T_(1/2,g)(p)=322+0.0462 p,T_(el,x)(p)=398+0.0302 p,其中,T_(1/2,g)和T_(el,x)的单位均为K,p的单位为MPa。T_(1/2,g)和T_(el,x)均随压力的增加而升高。由于T_(el,x)(p)的斜率小于T_(1/2,g)(p)的斜率,导致过冷液相区的温度范围随着压力的增加而变窄。在六面顶压机上开展差热分析,测得了2000~4500 MPa压力范围内非晶硒的晶化温度。结合活塞圆筒实验结果,发现了非晶硒的晶化温度随压力的变化规律:在0.1~1700 MPa范围内,晶化温度随压力的增加而升高;在2000 MPa以上,晶化温度的上升速率随压力的增加明显降低。当压力引起非晶硒的微观结构变化时,T_(g)(p)与T_(x)(p)曲线的斜率变化发生在相近的压力下,结合实验结果—T_(x)(p)的斜率变化出现在2 GPa左右,因此,推测T_(g)(p)的斜率变化可能出现在2 GPa左右。大腔体高压装置实验获得的转变点压力与以往报道的金刚石压砧实验结果不一致,可能与这两类实验中玻璃化转变温度、晶化温度的测量方法不同及压力测量误差有关。
The effect of pressure on the glass transition temperature and the supercooled liquid region of amorphous selenium(a-Se),which was prepared through melting quenching,was investigated.The glass transition temperature T_(g)and crystallization temperature T_(x)were determined through the differential thermal analysis(DTA)during isobaric heating.The experimental results from piston-cylinder apparatus showed that both T_(g)and T_(x)increase with the increasing pressure in the pressure range of 0.1-1700 MPa.The glass transition middle temperatures T_(1/2,g)and extrapolated crystallization onset temperatures T_(el,x)were linearly fitted to pressure.The fitting results are T_(1/2,g)(p)=322+0.0462 p and T_(el,x)(p)=398+0.0302 p,where the unit of temperature is K,and the unit of pressure is MPa.The smaller slope of T_(el,x)(p),compared with that of T_(1/2,g)(p),induces the temperature range(T_(el,x)−T_(1/2,g))in the supercooled liquid region to be narrower with the increase of pressure.DTA data in the pressure range of 2000−4500 MPa was performed by using a cubic press.A slope change in T_(x)(p)curve is found.T_(x)increases with the increasing pressure within 0.1−1700 MPa,and the rate slows down when the pressure is above 2000 MPa.In the previous diamond anvil reports,a similar pressure dependence of T_(x)and T_(g)was observed,i.e.,T_(x)and T_(g)both increase initially with the increasing pressure,and then become nearly constant above 1000 MPa.Since the slope changes in T_(g)(p)and T_(x)(p)curves occur nearly at the same pressure when the microstructure of a-Se changes,in view of the pressure of 2000 MPa corresponding to the inflection point of T_(x)(p)curve obtained in this study,it is speculated that the pressure of the inflection point of T_(g)(p)curve may be around 2000 MPa.The different pressures corresponding to the slope change obtained by the diamond anvil cell and the large-volume press may be related to the measurement method of T_(g)and T_(x),as well as the pressure measurement error.
作者
梁策
阚前华
梁文嘉
马国龙
彭放
洪时明
刘秀茹
LIANG Ce;KAN Qianhua;LIANG Wenjia;MA Guolong;PENG Fang;HONG Shiming;LIU Xiuru(School of Physical Science and Technology,Southwest Jiaotong University,Chengdu 610031,Sichuan,China;Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province,School of Mechanics and Aerospace Engineering,Southwest Jiaotong University,Chengdu 610031,Sichuan,China;Institute of Atomic and Molecular Physics,Sichuan University,Chengdu 610065,Sichuan,China)
出处
《高压物理学报》
CAS
CSCD
北大核心
2023年第5期62-70,共9页
Chinese Journal of High Pressure Physics
基金
国家自然科学基金(11004163,10774123,12074273)
中央高校基础科研业务费(2682014ZT31,2682018ZT29)。
关键词
玻璃化转变
非晶硒
高压
差热分析
glass transition
amorphous selenium
high pressure
differential thermal analysis
