β-MnO_2高压相的从头计算模拟

Ab Initio Studies of High-Pressure Transformations in β-MnO_2

基于密度泛函理论(DFT),用完全势能线性缀加平面波方法(FPLAPW)计算模拟了MnO2的同质多相变体(金红石型结构、CaCl2型结构、黄铁矿型结构),通过计算,预测了β-MnO2在5 GPa时从金红石型结构转变为CaCl2型结构,在20 GPa时进一步转变为黄铁矿型结构。另外,还总结和比较了几种金红石型结构二氧化物的压致相变特点,得出第Ⅳ主族元素的金红石型结构氧化物有很好的规律性,发生的相变序列基本一致;并随着金属阳离子半径的增大,发生相变的压力值也相应地递减,各氧化物的体积模量值相应地减小。

First-principle calculations of MnO2 polymorphisms （rutile-type, CaCl2-type and pyrite-type） have been carried out with the full potential linearized augmented plane wave （FPLAPW） method. Through the calculations,we predict that the rutile-type MnO2 can transform to CaCl2-type at 5 GPa, and then transform to pyrite-type at 20 GPa. Furthermore, we summary the characteristic of several rutile-structure metal dioxide phases transformation under high pressure and conclude that the group element dioxides have similar sequence of the phase transition. In general, the pressure induced phase transformations of these group Ⅳ element dioxide take place at lower pressure with the increase of cations radii and decrease of the value of bulk moduli.