Spontaneous polarization in ultrasmall lithium niobate nanocrystals revealed by second harmonic generation
Spontaneous polarization in ultrasmall lithium niobate nanocrystals revealed by second harmonic generation
复制标题
DOI：
10.1103/physrevb.86.195428
复制
发表时间：
2012-11-26
影响因子：
3.7
通讯作者：
Mader, Werner
中科院分区：
文献类型：
--
作者：
Knabe, Bastian;Buse, Karsten;Mader, Werner
采用溶胶-凝胶法和湿法化学腐蚀相结合的方法制备了直径为5~50 nm的LiNbO_3纳米晶。用透射电子显微镜验证了晶体的物相纯度和近球形。单纳米晶体二次谐波信号的功率和偏振关系表明，纳米晶体具有非中心对称点群3m，从块体材料中已知的二阶非线性光学系数在所研究的所有纳米晶体中都完全存在。晶体的体积仍然是频率转换的主要来源，它们是自发极化的。
Nanocrystals of lithium niobate (LiNbO3) with diameters of between 5 and 50 nm were produced by a combination of sol-gel synthesis and wet-chemical etching. The phase purity and nearly spherical shape of the crystals were verified by transmission electron microscopy. Power and polarization dependences of the second harmonic signal of single nanocrystals reveal that the nanocrystals have the noncentrosymmetric point group 3m and that the second-order nonlinear optical coefficients known from the bulk material are fully present in all nanocrystals studied. The volume of the crystals is still the main source of frequency conversion and they are spontaneously polarized.