铌锌酸铅-钛酸铅单晶的生长及性能

Growth and Properties of Lead Zinc Niobate-LeadTitanate Single Crystals

本文系统地研究了(1-x)Pb(Zn 1/3 Nb_(2/3))O_(3) -xPbTiO_(3)(PZN-PT)单晶的光学透过率与结晶取向和组分的关系,发现四方相单晶的透过率明显大于三方相和准同型相界(MPB)。[001]方向极化的四方相PZN-12%PT单晶在0.5~5.8μm的波段范围内,未镀增透膜的晶片透过率约为65%;准同型相界处PZN-8%PT单晶沿[011]方向极化的单晶透过率高于[001]和[111]方向。随着PT含量变高,单晶带隙逐渐变小。本文中还测量不同组分单晶的折射率,和大多数ABO 3型钙钛矿结构化合物相似,PZN-PT单晶的折射率较大,随着波长的减小其值迅速增大。晶体的色散现象明显,拟合得出各组分晶体的色散方程。利用塞纳蒙补偿法和双光束干涉法测量了电光系数,PZN-PT单晶的电光系数较大,在准同型相界附近其值达到极大,[001]方向极化PZN-8%PT单晶有效电光系数为460 pm/V,比广泛应用的铌酸锂高出20倍。四方相PZN-12%PT单晶有效电光系数为138 pm/V,在20~80℃范围内其值变化不大。良好的透光性能和优异的电光性质,使PZN-PT单晶可以满足高速低功耗电光器件的要求。

Transmittance of(1-x)Pb(Zn 1/3 Nb_(2/3))O_(3) -xPbTiO_(3)(PZN-PT)single crystals was systematically characterized with respect to crystallographic orientation and composition.The results show that the transmittance of tetragonal single crystal is evidently larger than that of rhombohedral and morphotropic phase boundary(MPB)single crystals.Transmittance spectrum of tetragonal PZN-12%PT single crystal poled along[001]direction ranges from 0.5μm to 5.8μm,its transmittance without antireflective film is roughly 65%.After poled along[011]direction,the transmittance of PZN-8%PT single crystal in MPB is much higher than that poled along[001]or[111]direction.As the PT content increases,optical band gap of single crystals decreases.Refractive indices of PZN-PT single crystals with different PT content were measured.Just as most compounds with ABO 3 perovskite structure,the refractive indices of PZN-PT single crystals are very large,which decrease rapidly with the increasing wavelength.Refractive index dispersion is obvious,and dispersion equations were fitted.Electro-optic(EO)coefficients were measured by Sénarmont compensator and two-beam interference methods.The EO coefficients of PZN-PT single crystals are very large,which reach maximum in the MPB.The effective EO coefficient of PZN-8%PT single crystal is 460 pm/V after poled along[001]direction,which is higher than 20 times that of widely used LiNbO 3.The effective EO coefficient of PZN-12%PT single crystal is 138 pm/V,which is nearly invariant from 20℃to 80℃.Because of the excellent transmittance and outstanding EO properties,PZN-PT single crystals allow of smaller size and lower operating voltage for EO devices.