研究晶体材料(在此通常指单晶)的宏观性质及其应用的学科——晶体物理学——有着悠久的历史,是固体物理领域中最古老的分支之一。人们早在18世纪就已发现晶体是有着规则外形的固体,这样就将固体分为晶体与非晶体。1912年德国科学家劳埃发现晶体对X射线的衍射现象后,人们就能准确地通过X射线实验测定出晶体中原子的周期性排列以及原子间的键长、键角等,从而产生了定量的晶体物理学。 随着现代科学技术的发展,晶体材料及器件在激光、微电子学、红外、超声和信息存储与显示等技术中所获得的广泛应用使人们对晶体材料宏观性质的研究有了新的认识并更加重视,从而也得到不少新成就。本文将就此作些基本知识及应用的介绍。 一、晶体及其宏观性质都是各向异性的。 由于晶体宏观性质的测量不会受到大小为晶胞基矢长度(埃的量级)分数的影响,因此所讨论的晶体材料宏观性质只与晶体的点对称性有关,而不必深究其平移对称性。 晶体的点对称操作可分为真旋转和非真旋转两大 The study of the macroscopic properties of crystalline materials (usually referred to herein as single crystals) and their applications - crystal physics - has a long history and is one of the oldest branches of solid state physics. As early as the eighteenth century, it was discovered that crystals are solids with a regular appearance, which divides solids into crystals and non-crystals. In 1912 German scientist Laaye discovered the diffraction phenomenon of X-ray crystal, people could accurately determine the periodic arrangement of atoms in the crystal by X-ray experiment and the bond length, bond angle and so on between atoms, so as to produce a quantitative Crystal Physics. With the development of modern science and technology, the wide application of crystalline materials and devices in the fields of laser, microelectronics, infrared, ultrasonic and information storage and display has brought new understanding on the macroscopic properties of crystalline materials. Pay more attention and thus get a lot of new achievements. This article will be some basic knowledge and application of this introduction. First, the crystal and its macroscopic properties are anisotropic. Since the measurement of macroscopic properties of crystals is not influenced by the size of the length of the unit cell’s fundamental length (the order of angstroms), the macroscopic nature of the crystal material in question is only related to the point symmetry of the crystal without having to study its translational symmetry . Crystal point-symmetric operation can be divided into true rotation and non-true rotation of the two