- 文章访问数: 3200
- PDF下载量: 553
- 被引次数: 0
摘要: 本文对LiIOO3-NaIO3赝二元系的相图,相变,非晶态的形成和稳定性,以及晶化的动力学过程等进行了仔细的研究,LiIO3-NaIO3赝二元系属共晶体系,共晶温度为325℃,共晶点成份为含50m/o LiIO3,用共晶点附近成份的试样,在超过熔点150℃的情况下首次获得碘酸盐的非晶态,非晶态的存在降低了LiIO3的表观相变温度,强X射线的辐照,各种空气湿度,细粒度等因素都加
Abstract: The phase diagram, phase transition, and formation, stability and crystallization kinetics of amorphous state in the system LiIO3-NaIO3 have been investigated. The pesudo-binary system LiIO3-NaIO3 is a eutectic one, its eutectic reaction occurs at 325℃ and the composition at eutectic point is 50 m/o LiIO3. As the melt is quenched from a temperature 150℃ higher than the melting point, an amorphous state of iodate salts is obtained for the first time. The apparent transition temperature decreases when the amorphous state exists. It is found that some factors, such as intense X-ray irradiation, various humidity and fine grain size, make the crystallization speed of amorphous state increases. Crystallization speed and perfection of LiIO3 in the amorphous state is higher than NaIO3. The process of isothermal phase transition agrees with Johnson-Mehl-Avrami equation y(t) =l-exp(- btOn), when y = 0.1-0.9, where y is the quantity of crystallization. For the sample with composition of 60 m /o LiIO3, the Avrami time exponent n = 2-3 and rate constant parameter b increases exponentially with temperature. The activation energy of crystallization from amorphous state is found to be 2.21 eV.