Na2Mg1-xZnxSiO4 (0 ≤ x ≤ 1): Noncentrosymmetric Sodium Metal Silicate Solid Solutions with Ultraviolet Nonlinear Optical Properties

Stoichiometrically equivalent noncentrosymmetric (NCS) sodium metal silicates, Na2MgSiO4 and Na2ZnSiO4, and their solid solutions have been synthesized via solid-state reactions. The structures of the reported materials were determined by powder X-ray diffraction using the Rietveld method. A careful structural analysis indicates that the unit cell volumes of Na2Mg1-xZnxSiO4 solid solutions decrease as more Zn2+ cations are doped into the site of Mg2+. Also, the synthesized silicate solid solutions revealed three-dimensional frameworks consisting of highly distorted yet well-aligned MgO4 (or ZnO4) and SiO4 tetrahedra. The title compounds exhibit very large band gaps ranging from 5.57 to 6.05 eV. Second-harmonic generation (SHG) measurements indicate that the solid solutions are phase-matchable and the SHG efficiencies increase as more d(10) cation, Zn2+, is added to the backbone. A complete characterization is presented along with the explanation of the structure-SHG property relationship.