Growth, structure and optical properties of PbBi3PO8 crystals

Nonlinear optical (NLO) materials with strong second-harmonic effect have important applications in the field of lasers. In this work, NLO crystal PbBi₃PO₈ was designed by introducing Pb²⁺ and Bi³⁺ ions with lone pair electrons and stereochemical activity into phosphate system, and was grown using high-temperature melting method. Yellow transparent crystal with the dimensions of 5 × 5 × 2 mm³ was obtained, and the structure, thermal and optical properties were studied. The results indicate that PbBi₃PO₈ crystal has highly disorder three-dimensional structure, formed by connecting Pb–O, Bi–O polyhedra and [PO₄] tetrahedra through common points or edges. The phosphate crystal shows wide transmission range of 381–5185 nm with the bandgap of 3.14 eV. Powder frequency doubling test shows that PbBi₃PO₈ crystal has large nonlinear optical response (2.3 × KDP), which can be credited to the synergistic effect of multiple Pb–O and Bi–O polyhedral polarizations and the consistent orientation of [PO₄] functional groups in the structure. This study provides a design method to improve the nonlinear performance of materials.