热处理引起3C-ZnS结构转变的X-射线衍射分析

为了论证层错是硫化锌晶体中交流电致发光的一个必要条件,我们把3C-ZnS单晶体在1100℃热处理后引入了层错.同时,我们对热处理前后的结构,用劳埃背反射法和文献8、13]推导的公式进行了分析.结果表明,沿3C-结构<111>四个等价方向都可以产生无序、孪晶和2H-结构,而且当热处理时间足够长时,结构转变趋向于一个<111>方向.这些实验结果,在有关的文献中尚未见到.

X-RAY DIFFRACTION ANALYSIS OF 3C-ZnS STRUCTURE TRANSFORMATIONS CAUSED BY HEAT TREATMENT

Zinc sulphide has a high-temperature stable structure at T>1024℃,i.e.wurtzite(2H)and a low-temperature stable structure at T<1024℃,i.e.sphalerite(3C).Much x-ray diffraction study of 2H→3C structure transformations were reported,but the study of 3C→2H structure transformations are little.Especially,the experimental investigations about the orientations of 3C→2H transformations by Laue diffraction haven''t been seen as yet.In the present work,the stacking faults were introduced into 3C-ZnS single-crystals by heat treatment,the orientated relation of 3C→MT(micro-twin)→2H transformations was then investigated with Laue back reflection method.Specimens of ZnS single-crystals were prepared with vapour-grown method.It was found by means of x-ray diffraction that the crystallinity of the specimens is fine,and there is no stacking faults in ZnS crystals.The heat treatment condition.1100℃,S vapour protecting the specimens,keeping crystals at high temperature 10 minutes to 5 hours,cooling the specimens in air.The x-ray condition.Cu radiation,35kV,D=37mm,taking Laue back reflection photographs of each specimen in fixed position before and after each heat treatment respectivly.After that,a lot of new Laue diffracted patterns which have not been reported in the literature were observed.In order to interpret these patterns,simple and suitable formulas to index Laue photographs and calculate "anomalous diffracted spots" have been derived,and the stereographic projections corresponding to some crystal planes also have been plotted.All of Laue diffracted spots and streaking in the Laue photographs were indexed and analysed.