摘要
Ⅰ. INTRODUCTION LiNbO3 is an interesting crystal in view of its piezoelectrical, electrooptical and nonlinear optical properties. It has potential applications in the laser and microwaveacoustic fields. Based on the investigations, the authors held that the anomalous birefrigence behavior along C axis of LiNb O2 near 75℃ may be attributed to the unkown phase transition instead of the cause supposed by et al. However, the change of the crystal structure involved is still open.