Noncentrosymmetric YVSe₂O₈ and Centrosymmetric YVTe₂O₈: Macroscopic Centricities Influenced by the Size of Lone Pair Cation Linkers

Abstract

Two new quaternary vanadium selenite and tellurite, i.e., YVSe2O8 and YVTe2O8, have been synthesized through hydrothermal and solid-state reactions. Both of the reported materials exhibit three-dimensional framework structures that are composed of layers of corner-shared VO6 octahedra, layers of edge-shared YO8 groups, and SeO3 or TeO3 linkers. While YVSe2O8 crystallizes in the orthorhombic noncentrosymmetric (NCS) space group, Abm2, YVTe2O8 reveals the monoclinic centrosymmetric (CS) space group, C2/m. The band gaps for YVSe2O8 and YVTe2O8 are calculated to be 2.7 and 2.2 eV, respectively, from the UV-vis diffuse reflectance spectra. Powder second harmonic generation (SHG) measurements using 1064 nm radiation reveals that NCS YVSe2O8 has a similar SHG efficiency to that of NH4H2PO4 (ADP). Detailed explanations of the structure-property relationships, effect of lone pair cation size on the macroscopic centricities, and full characterizations including infrared spectroscopy, thermal analyses, and elemental analyses are also presented.

Structural characterization of quaternary selenites of tungsten(VI), A 2W3SeO12 (A = NH4, Cs, Rb, K or Tl)

“…Both SOJT distortions lead to acentric coordination environments that are conducive for NCS structures (Halasyamani 2004). For example, Cs 2 Mo 3 TeO 12 (Vidyavathy Balraj & Vidyasagar, 1998) and YVSe 2 O 8 (Kim et al, 2014) have non-centrosymmetric layered structures with these SOJT distortions and exhibit SHG activity. It needs to be mentioned that quaternary selenites and tellurites containing d 0 transition-metal ions, such as YVTe 2 O 8 (Kim et al, 2014), are also known to have centrosymmetric structures and exhibit no SHG activity.…”

Mixed-Metal Carbonate Fluorides as Deep-Ultraviolet Nonlinear Optical Materials

“…A number of other design strategies toward the creation of new NLO materials have been reported. These involve using distorted chalcogenide polyhedra, − cations susceptible to second-order Jahn–Teller distortions, − and cations with a stereoactive lone-pair of electrons. − An issue with these design approaches is that either the birefringence is not appropriate or the absorption edge is not deep enough for DUV NLO applications.…”

Macroscopic polarity control with alkali metal cation size and coordination environment in a series of tin iodates

“…[28][29][30] Other reported elements controlling the macroscopic polarity include framework flexibility and the hydrogen bonding effect. [31][32][33][34][35][36] Here we report hydrothermal syntheses and thorough characterization of six new stoichiometrically similar molecular tin iodates, A 2 Sn(IO 3 ) 6 (A = Li, Na, K, Rb, Cs) and Sn 2+ Sn 4+ (IO 3 ) 6 . We will demonstrate how the cation size and coordination environment influence the polarity of the materials.…”