一、引言随着近代科学技术的迅速发展,对压电材料的数量和特性的要求也日益增加。人们在探求新的压电材料方面进行着大量的工作,一方面想找到新的可用压电材料,另一方面想在大量工作的基础上探讨压电晶体化学规律。晶体的压电性不仅依赖于宏观对称的必要条件还取决于晶体中自发偶极子(spontaneous dipoles)的存在及其微观对称的充分条件。影响其压电特性的因素是极为复杂的,在理论上尚不能加以預计。因此,无论是想肯定一种晶体的压电性或是估计其技术应用的可能性仍需通过 I. INTRODUCTION With the rapid development of modern science and technology, the requirements on the quantity and characteristics of piezoelectric materials are also increasing day by day. There is a great deal of work going on in search of new piezoelectric materials, both on the one hand in finding new usable piezoelectric materials and on the other hand on the basis of extensive work on the principles of piezoelectric crystals chemistry. The piezoelectricity of a crystal depends not only on the necessary conditions for macroscopic symmetry but also on the existence of the spontaneous dipoles in the crystal and the sufficient conditions for its microscopic symmetry. The factors that affect its piezoelectric properties are extremely complex and can not be predicted theoretically. Therefore, whether it is to confirm the piezoelectricity of a crystal or to estimate the possibility of its technical application,