【摘要】 本文用室温、高温X射线衍射和差热分析等方法,研究了Mg_x/2Li_1-xIO₃晶体结构及其随成份和温度的变化。 Mg（IO₃）₂·LiIO₃二元系形成一种新型的连续固溶体。 在室温对于富LiIO₃的固溶体,晶体点阵沿x-y,平面产生畸变,其畸变开始随Mg（IO₃）₂含量的增加而加大,晶体的空间群从P6₃转变为P112.当成份为3Mg（IO₃）₂·7LiIO₃时,畸变度达最大,γ=120°22′。随着Mg（IO₃）₂含量的继续增加,畸变度又逐渐减小,当成份为Mg（IO₃）₂·LiIO₃时,晶体点阵的畸变消失,其空间群又转变为P6₃。 对于富Mg（IO₃）₂的固溶休,晶休点阵沿z轴发生畸变,晶体由具有不同c值的单胞所组成。当LiIO₃量为20—30mol％时,这一现象最为明显。随温度升高,晶体逐渐转变为单一c值的单胞。 我们认为:Mg（IO₃）₂·LiIO₃二元系固溶体,晶格发生畸变是与点阵中存在着空位密切相关的。由于空位富集,使得点阵常数c不均匀。也由于空位改变晶格场,引起IO₃^-的移动或转动,使得晶格沿x-y平面发生畸变。更多还原

【Abstract】 The variation of crystal structure types of Mgx/2Li1-xIO3 with composition and temperature has been investigated by the methods of DTA and X-ray powder diffraction both at high and room temperatures. A new type of continuous solid solutions has been found in the entire region of the binary system Mg(IIO3)2·LiI03.For the solid solutions rich in LilOs, the crystal lattice is distorted in the x-y plane with the increasing concentration of Mg(IO3)2, While the space group changes from P63 to P1121. At the composition 3Mg(IO3)2·7LiI03, the lattice distortion reaches a maximum,γ=120·22’. With further increasing of the concentration of Mg(IOs)2, the lattice distortion is reduced, and at the composition Mg(IO3)2·LiIO3) the space group turns back again to P63.For the solid solution rich in Mg(IO3)2, the lattice is distorted along the z axis, and has been found to be made of unit cells of heterogeneous parameters c (the effect is most prominent at the composition about 20-30mol% LiIO3). But with increasing temperature, the crystal lattice gradually changes back to unit cells with a uniform parameter.It seems probable that the lattice distortions in the solid solutions are caused by vacancies. The heterogeneous distribution of vacancies results in inhomogeneous parameters c, and it is also due to the presence of vacancies that alters the crystal fields around the anion group, causing the displacement and rotation of IO3 with the result that the lattice is distorted along x-y plane.更多还原