中文摘要：

分析了斜方相、四方相铌酸钾钠基无铅压电陶瓷材料的结构和X射线衍射图谱的特点.对于铌酸钾钠基压电材料斜方相结构,从构成晶胞的一个单斜原胞进行分析,计算出X射线衍射谱上每个衍射角附近的衍射峰数目和相对强度.提出了2θ在20°—60°范围内根据（1 0 2）衍射峰（52°附近）和（1 2 1）衍射峰（57°附近）劈裂的数目区分斜方和四方相的新方法.对于多晶陶瓷粉末,可以更简便的由22°（或45°）附近前后峰的相对高低来判断斜方、四方相.

英文摘要：

Characteristic of the orthorhombic and tetragonal phase of （K, Na） NbO3-based lead-free piezoelectric ceramics was analyzed in theory. X-ray diffraction differences between the orthorhombic and tetragonal phase were clarified in the 2θ range from 20° to 60°. For the orthorhombic （K, Na）NbOB-based piezoelectric ceramics, the number and relative intensity of X-ray diffraction peaks were calculated from a monoclinic primitive cell. A method distinguishing orthorhombic and tetragonal phase from the X-ray diffraction patterns was proposed. It is found that the phases of （K, Na）NbO3-based piezoelectric ceramics can be distingwished exactly from peaks of the primitive cell planes （1 0 2） and （1 2 1）. For the powder diffraction, the phases can be distinguished more easily by relative intensities of the diffraction peaks for the peak-split position at around 22° or 45°.