Pb@Pb Basket-like-Cluster-Based Lead Tellurate-Nitrate Kleinman-Forbidden Nonlinear-Optical Crystal: PbTeO(OH)(NO).

The first lead tellurate-nitrate nonlinear-optical (NLO) crystal, PbTeO(OH)(NO), featuring a 3D anionic diamondlike toplogical structural motif formulated as [PbO] constructed by unique nonanuclear basket-shaped Pb@PbO clusters has been hydrothermally achieved, in which the Pb@PbO cluster shows a core-shell structure with one PbO polyhedron enclosed by eight PbO (x = 3 and 4) polyhedera via edge and face sharing. The hexavalent Te in TeO(OH) octahedra is linked to a [PbO] cluster to form a rare [PbTeO(OH)] cationic framework. The compound demonstrates a powder second-harmonic-generation (SHG) response of about 1.2 times that of KHPO (KDP) as well as a wide transparency range. Calculations on the local dipole moment and SHG coefficient reveal that the net polarization is zero because of a Kleinman-forbidden point group. Further analysis shows that the SHG response results from structure-induced variations by thermal vibrations of the lattice rather than the intrinsic dipole moment, which offers another insight on the design of new NLO materials.