A series of solid solutions of polar aluminoborate materials, Al 5-x Ga x BO 9 (0.0 ≤ x ≤ 0.5) have been synthesized by standard solid-state reactions using Al 2 O 3 , Ga 2 O 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-x Ga x BO 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 5 BO 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-x Ga x BO 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