Two Noncentrosymmetric Bismuth Phosphates: Rational Design Synthesis and Optical Properties

Developing strategies to rational design noncentrosymmetric structure still attract much interest for their applications in nonlinear optical and piezoelectric materials. Two noncentrosymmetric (NCS) alkaline earth metal bismuth phosphates have been successfully achieved via partial replacement of Bi3+ with Ca2+ or Sr2+ ions. BiCa(H0.5PO4)(2) (designated as CaBiPO) and BiSr(H0.5PO4)(2) (designated as SrBiPO), together with their solid solution Bi(Sr1-xCax)(H0.5PO4)(2) (0 < x <= 0.5), crystallize in the NCS space group C2. Both CaBiPO and SrBiPO exhibit ultraviolet nonlinear optical (NLO) properties, and their second-harmonic generation effects belong to type-II phase matching. Meanwhile, they could also act as photoluminescence hosts in which the Eu3+-doping samples SrBiPO:xEu(3+) (x = 0.02-0.2) emit orange light. The effect of different radius ions on the derivative structures and the structure-NLO property relationship has also been discussed in detail.