A highly thermostable carbonatoperoxovanadate, Cs ₃ VO(O ₂ ) ₂ CO ₃ , exhibits a remarkably strong SHG response of approximately 23.0 times that of KDP, which is the largest among those of the reported NLO carbonate materials.

Fast cation transport in solids underpins energy storage. Materials design has focused on structures that can define transport pathways with minimal cation coordination change, restricting attention to a small part of chemical space. Motivated by the greater structural diversity of binary intermetallics than that of the metallic elements, we used two anions to build a pathway for three-dimensional superionic lithium ion conductivity that exploits multiple cation coordination environments. Li₇Si₂S₇I is a pure lithium ion conductor created by an ordering of sulphide and iodide that combines elements of hexagonal and cubic close-packing analogously to the structure of NiZr. The resulting diverse network of lithium positions with distinct geometries and anion coordination chemistries affords low barriers to transport, opening a large structural space for high cation conductivity.

Crystals of congruently melting noncentrosymmetric (NCS) mixed alkali metal nitrate, Rb₂Na(NO₃)₃, have been grown through solid state reactions. The material possesses layers with NaO₈ hexagonal bipyramids and NO₃ triangular units. Rb⁺ cations are residing in the interlayer space. Each NaO₈ hexagonal bipyramid shares its corners and edges with two and three NO₃ units, respectively, in order to fulfill a highly dense stacking in the unit cell. The NaO₈ groups share their six oxygen atoms in equatorial positions with three different NO₃ groups to generate a NaO₆-NO₃ layer with a parallel alignment. The optimized arrangement of the NO₃ groups and their high density in the structure together produce a strong second-harmonic generation (SHG) response. Powder SHG measurements indicate that Rb₂Na(NO₃)₃ has a strong SHG efficiency of five times that of KH₂PO₄ (KDP) and is type I phase-matchable. The calculated average nonlinear optical (NLO) susceptibility of Rb₂Na(NO₃)₃ turns out to be the largest value among the NLO materials composed of only [NO₃]⁻ anion. In addition, Rb₂Na(NO₃)₃ exhibits a wide transparency region ranging from UV to near IR, which suggests that the compound is a promising NLO material.