Second-harmonic generating properties of polar noncentrosymmetric aluminoborate solid solutions, Al sub(5-x)Ga sub(x)BO sub(9) (0.0 less than or equal to x less than or equal to 0.5)

• Published in: Dalton transactions : an international journal of inorganic chemistry 2012-02, Vol.41 (11), p.3233-3238
• Main Authors: Shin, Yiseul, Lee, Dong Woo, Hong, Jongin, Kwak, Kyungwon, Ok, Kang Min
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Asymmetry; Diffraction; Distortion; Gallium; Polyhedrons; Solid solutions; Three dimensional
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt11971d

A series of solid solutions of polar aluminoborate materials, Al sub(5-x)Ga sub(x)BO sub(9) (0.0 less than or equal to x less than or equal to 0.5) have been synthesized by standard solid-state reactions using Al sub(2)O sub(3), Ga sub(2)O sub(5), and B(OH) sub(3) as reagents. The phase purities, crystal structures, and solid solution behavior of the reported materials have been investigated by powder X-ray diffraction. Solid solutions of Al sub(5-x)Ga sub(x)BO sub(9) crystallize in the polar noncentrosymmetric space group, Cmc2 sub(1), with a three-dimensional structure consisting of distorted MO sub(4), MO sub(5), MO sub(6), and BO sub(3) polyhedra (M = Al or Ga). Powder second-harmonic generating (SHG) measurements on the Al sub(5)BO sub(9) using 1064 nm radiation, indicate the material has a SHG efficiency of approximately 2 times that of alpha -SiO sub(2) and is not phase-matchable (type 1). Further nonlinear optical (NLO) measurements on the Al sub(5-x)Ga sub(x)BO sub(9) solid solutions indicate a sharp increase in SHG efficiency up to 10 times that of alpha -SiO sub(2) for x greater than or equal to 0.4. Close structural examination suggests that the alignment of the asymmetric pi -delocalization of BO sub(3) groups is responsible for the abrupt increase of SHG efficiency.