From Pb<sub>6</sub>(HPO<sub>3</sub>)(H<sub>2</sub>PO<sub>3</sub>)Cl<sub>9</sub> to Pb<sub>6</sub>(HPO<sub>3</sub>)<sub>2</sub>Br<sub>8</sub>(H<sub>2</sub>O)·H<sub>2</sub>O: Halogen Regulation to Achieve Inorganic Metal Phosphite Halide Nonlinear Optical Material with Unprecedented Pb-Centered Polyhedral Units
Ru‐Ling Tang, Liang Ma, Yi‐Lei Lv, Wenlong Liu, Sheng‐Ping Guo
Abstract
Nonlinear optical (NLO) crystals are widely used in various fields. The introduction of lone-pair cations is regarded as an effective strategy to explore NLO crystals. In this work, two novel lead phosphite halides, centrosymmetric Pb 6 (HPO 3 )(H 2 PO 3 )Cl 9 and noncentrosymmetric Pb 6 (HPO 3 ) 2 Br 8 (H 2 O)·H 2 O, were obtained via a hydrothermal method. Pb 6 (HPO 3 )(H 2 PO 3 )Cl 9 is the first reported lone-pair metal phosphite with two kinds of phosphite groups (HPO 3 2– and H 2 PO 3 – ) and Pb 6 (HPO 3 ) 2 Br 8 (H 2 O)·H 2 O is the first inorganic NLO phosphite halide with a phase-matchable SHG effect of 1.02 × KDP. In addition, the Pb-centered polyhedral units of PbOCl 4, PbOCl 6, PbO 2 Cl 5, PbO 2 Br 5, PbOBr 6, and PbO 3 (H 2 O)Br 3 in these two structures have never been reported before. An in-depth study on the structure–property relationship of the two compounds with halogen substitution is also performed.