Dissolution of Impurities Difficult to Solve in Ceramics and the Defect Structures Induced by the Dissolution

为了改善和发展新型陶瓷材料的化学、物理和机械性能，有必要弄清这些材料中特定杂质的作用。陶瓷在高温下的固有缺陷也被认为是难以溶解的杂质。MgO和NiO在<Al_2> <O_3>中的溶解度用纯单晶<Al_2> <O_3>和多晶<Al_2> <O_3>与尖晶石分散（<MgAl_2> <O_4>或<NiAl_2> <O_4>）的扩散偶联测定。测定了镁离子在<Al_2O_3>中的杂质扩散系数，并澄清了MgO溶解引入的缺陷结构。本文提出了一种利用x射线衍射技术测定MgO在<Li_2O>中的低溶解度的新方法。通过比较<Li_2O>中的离子电导率和自扩散系数，可以明确mgo溶解<Li_2O>中的离子电导率。澄清了Th <O_2> - <UO_2>和<ZrO_2> - mgo体系的扩散控制汽化。讨论了<ZrO_2> - <CeO_2>体系中组成离子的扩散与晶粒快速长大的关系。

In order to improve and develop chemical, physical, and mechanical properties of new ceramic materials, it is necessary to clarify the functions of specified impurities in those materials. The intrinsic defects in ceramics at high temperatures are also considered as impurities which are difficult to dissolve.1. Dissolution of MgO and NiO in <Al_2> <O_3>The solubilities of MgO and NiO in <Al_2> <O_3> have determined using a diffusion couple of a pure single-crystal <Al_2> <O_3> and polycrystalline <Al_2> <O_3> dispersed with spinel( <MgAl_2> <O_4> or <NiAl_2> <O_4> ). The impurity diffusion coefficient of magnesium ions in <Al_2O_3> has determined and also defect structure introduced by the dissolution of MgO has clarified.2. Defect Structure in <Li_2O>A new method to determine the low solubility of MgO in <Li_2O> by using an X-ray diffraction technique has been developed. Ionic conductivity in MgO-dissolved <Li_2O> could be clarified by comparing the ionic conductivity with self-diffusion coefficients in <Li_2O> .3. Other CeramicsDiffusion-controlled vaporization for the system Th <O_2> - <UO_2> and <ZrO_2> -MgO has been clarified. The relation between the rapid grain growth and the diffusion of the constituent ions in the system <ZrO_2> - <CeO_2> has been discussed.