A series of solid solutions of polar aluminoborate materials, Al 5-xGa xBO 9 (0.0 ≤ x ≤ 0.5) have been synthesized by standard solid-state reactions using Al 2O 3, Ga 2O 5, and B(OH) 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 5-xGa xBO 9 crystallize in the polar noncentrosymmetric space group, Cmc2 1, with a three-dimensional structure consisting of distorted MO 4, MO 5, MO 6, and BO 3 polyhedra (M = Al or Ga). Powder second-harmonic generating (SHG) measurements on the Al 5BO 9 using 1064 nm radiation, indicate the material has a SHG efficiency of approximately 2 times that of α-SiO 2 and is not phase-matchable (type 1). Further nonlinear optical (NLO) measurements on the Al 5-xGa xBO 9 solid solutions indicate a sharp increase in SHG efficiency up to 10 times that of α-SiO 2 for x ≥ 0.4. Close structural examination suggests that the alignment of the asymmetric π-delocalization of BO 3 groups is responsible for the abrupt increase of SHG efficiency.
ASJC Scopus subject areas
- Inorganic Chemistry