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以Na_2O-TeO_2玻璃系统中发现的一个新晶相Na_2O·8TeO_2(NT_8)为研究对象,通过热分析和X-射线衍射等分析手段,着重探讨了该晶相的形成条件和分解条件,分析了该晶相发生转变的过程和机理。结果发现该晶相在330℃下能够稳定存在,而在330～340℃之间则会分解成Na_2O·4TeO_2(NT_4)和TeO_2两种晶体。在由NT_8向NT_4和TeO_2的转变过程中出现了两个热效应,先是一个吸热反应,然后是一个放热反应,这说明在NT_8向NT_4和TeO_2的转变过程中,出现了一个中间相,该中间相为一种非晶相。作者认为,NT_8向NT_4和TeO_2的转变分为两个步骤,第一步是由NT_8向中间非晶相的转变,第二步是中间非晶相向NT_4和TeO_2的转变,而且由NT_8向中间相转变的过程与由中间相向NT_4和TeO_2转变的过程是同时进行的。
A new crystal phase named Na_2O · 8TeO_2 (NT_8) was found in the Na_2O-TeO_2 glass system. The formation and decomposition conditions of the crystal phase were investigated by means of thermal analysis and X-ray diffraction. The crystal phase transformation process and mechanism. The results show that the crystalline phase can be stable at 330 ℃, and decomposed into two kinds of crystals of Na_2O · 4TeO_2 (NT_4) and TeO_2 at 330 ~ 340 ℃. During the transition from NT_8 to NT_4 and TeO_2, two thermal effects, first an endothermic reaction and then an exothermic reaction, show that during the transition from NT_8 to NT_4 and TeO_2, an intermediate phase The mesophase is an amorphous phase. The author believes that NT_8 to NT_4 and TeO_2 transition is divided into two steps, the first step is from NT_8 to the intermediate amorphous phase transition, the second step is the intermediate amorphous phase NT_4 and TeO_2 transition, and from NT_8 to the intermediate phase The process of transformation is in parallel with the transformation from the intermediate phase NT_4 and TeO_2.