Pb₅(GeO₄)(Ge₂O₇) and Pb_3.32Ca_1.68(GeO₄)(Ge₂O₇): Two Nonlinear Optical Germanates Induced by Diverse PbOx Polyhedra

Abstract

Oxide nonlinear optical (NLO) crystals have drawn wide interest for their comprehensive physical performances including wide infrared (IR) transparency ranges, large band gaps, and good stability in open air. Here, two isostructural germanate oxides, Pb 5 (GeO 4 )(Ge 2 O 7 ) (1) and Pb 3.32 Ca 1.68 (GeO 4 )(Ge 2 O 7 ) (2), adopting the noncentrosymmetric (NCS) space group P6̅ , were composed via a conventional solidstate reaction. The latter was designed by the partial cation substitution strategy based on parent 1. The whole structures of 1 and 2 are composed of isolated distorted GeO 4 tetrahedra, Ge 2 O 7 dimers, and diverse M (M = Pb, Ca, or Pb/Ca)-centered polyhedra. They exhibit second-harmonic generation (SHG) responses around 3.3 and 1.4 times that of KH 2 PO 4 (KDP) under 1.064 μm laser radiation, respectively. Theoretical calculation results reveal that the Pb 2+ cations with stereoactive long pair (SCALP) electrons of 1 favor the large SHG response, while Pb-based polyhedra showing inert SCALP electrons make predominant contributions to the moderate SHG effect of 2.

The First UV Nonlinear Optical Selenite Material: Fluorination Control in CaYF(SeO3)2 and Y3F(SeO3)4

“…The underestimate for CaYF(SeO 3 ) 2 can be ascribed to the disordered structural model, which were often found in literatures. [46][47][48] For the ordered Y 3 F(SeO 3 ) 4 , the theoretical value is close to the experimental result.…”

The first quaternary rare-earth oxythiogermanate with second-harmonic generation and ferromagnetic behavior

“…Many compounds containing RE and tetrel elements have been investigated, and most of them are silicates and germanates. 19 However, there have been few investigations on RE oxythiogermanates and only pentanary La 3 Ga 3 Ge 2 S 3 O 10 15 has been reported. By screening oxides in the ICSD database with ABO 5 chemical compositions (A = divalent metal Ca, Sr, Ba, Pb, Sn, Eu; B = Si, Ge, Sn), we found the crystal structure of Pb 3 GeO 5 20 to appear similar to that of Eu 3 GeOS 4 —with GeO 4 tetrahedra isolated from each other in Pb 3 GeO 5 (Fig.…”

Pentanary Oxythiogermanates Ba3MGe3O2S8 (M = Ca, Zn) Featuring [Ge3O2S8]8– Trimers and {[MGe3O2S8]6–}∞ Chains: Structural Chemistry and Physical Properties

“…The IR spectra (Figure S9) for the powder samples demonstrate that both 1 and 2 have very wide IR transparency. The ∼700 cm –1 absorption peaks correspond to the stretching vibration of the Ge–O bonds, and the peak around 410 cm –1 corresponds to the vibration of the Ge–S bond …”