Y(HSeO3)(SeO3)(H2O)·(H2O) and Y2(SeO3)2(SeO4)(H2O)2·(H2O)0.75: Two yttrium selenites with a short UV cut-off edge explored from pure selenite compounds

Two UV inorganic yttrium selenite optical materials, namely, Y(HSeO 3 )(SeO 3 )(H 2 O)·(H 2 O) (1) and Y 2 (SeO 3 ) 2 (SeO 4 )(H 2 O) 2 ·(H 2 O) 0.75 (2), have been synthesized successfully by hydrothermal reactions . Of these, Y 2 (SeO 3 ) 2 (SeO 4 )(H 2 O) 2 ·(H 2 O) 0.75 (2) is a new mixed valent selenium oxide containing Se(IV) and Se(VI) cations simultaneously. Y(HSeO 3 )(SeO 3 )(H 2 O)·(H 2 O) (1) shows a 3D structure composed of 2D yttrium selenite layers linked by O−H···O bonds. Y 2 (SeO 3 ) 2 (SeO 4 )(H 2 O) 2 ·(H 2 O) 0.75 (2) exhibits a 3D structure composed of 2D yttrium selenite layers connected by SeO 4 tetrahedron. Y(HSeO 3 )(SeO 3 )(H 2 O)·(H 2 O) (1) crystallized in a chiral space group P 2 1 2 1 2 1 and could display a moderate SHG intensity about 0.7 times of the commercial KH 2 PO 4 (KDP). Its powder laser damage threshold quantity was estimated to be 120.2 MW/cm 2 , which is about 46.2 times that of AGS (2.6 MW/cm 2 ). UV–vis–NIR spectra reflectance spectra showed that these solids are wide band gap compounds with Eg of 5.5 and 5.1 eV respectively. Theoretical calculations disclosed that Y(HSeO 3 )(SeO 3 )(H 2 O)·(H 2 O) (1) is an indirect band gap structures and its bandgaps is determined by O and Se atoms.