Strength and Lattice Defects of Ceramics

本研究项目的目的是促进陶瓷材料强度研究领域内的合作，从晶格缺陷的角度对陶瓷材料的强度和力学性能有更深刻的认识，取得了如下成果：（1）硬度和脆性是陶瓷材料的一般性质。（2）对SiC、ZrO_2等陶瓷单晶的高温强度进行了系统的研究，并从位错理论的角度对它们的变形机制进行了探讨。(3)建立了离子晶体位错的光散射直接观察技术，并大大提高了其分辨率。(4)本文还研究了半导体材料的塑性，并提出了一种新的模型来解释光塑性效应。(5)用高分辨电子显微镜观察了陶瓷晶界的点阵象，发现某些陶瓷晶界处有非晶层，这对提高陶瓷材料的力学性能有很好的指导作用。

The aim of this research project is to promote the co-operative research activities on the strength of ceramics among the authorities in the various fields, and to achieve profound understandings about the strenght and mechanical properties of ceramics from the view points of lattice defects.The results obtained by this project are as follows: (1) Hardness and brittleness are th general properties of ceramic materials. They are attributed to high peierls stress and small number of slip systems, which are well understood by the crystal geometrical property (2) Strength at high temperatures of SiC, ZrO_2 and other ceramic single crystals were examined systematically, and the deformation mechanisms in them are understood on the basis of disiocation theory. (3) Direct observation technique of dislocations in lonic crystals using light scattering was estabiished and its resolution was improved greatly. (4) Plasticity of semi-conducting compounds was also investigated and photo-plstic effects was accounted for by a new model. (5) Grain bounderies in ceramics were observed by iattice images using high resolution electron microscopes and am amorphous layer was found at the boundery in some ceramics.These resuits provide good guides to improve the mechanical properties of ceramic materials.