A new non-centrosymmetric Gd-based borate crystal Rb7SrGd2(B5O10)3: growth, structure, and nonlinear optical and magnetic properties

Abstract

A new non-centrosymmetric borate crystal, Rb₇SrGd₂(B₅O₁₀)₃, was successfully grown via the spontaneous nucleation technique from the Rb₂O–B₂O₃–SrO self-flux system. It crystallizes in the trigonal system space group R32 with lattice parameters a = b = 13.4975(5) Å, c = 15.3223(8) Å, α = β = 90°, γ = 120°, and Z = 3. Its three-dimensional framework is composed of isolated GdO₆ and SrO₆ octahedra, RbO_n (n = 6 and 8) polyhedra, and [B₅O₁₀]⁵⁻ clusters. Rb₇SrGd₂(B₅O₁₀)₃ exhibits multifunctional properties, and has both moderate second harmonic generation (SHG) responses (0.5 × KDP) and paramagnetic characteristics with μ_eff = 8.18μ_B. Thermal stability, Fourier transform infrared spectroscopy, and UV-Vis-NIR diffuse reflectance spectroscopy were performed to characterize the title compound. Its electronic band structures and density of states were also investigated via first-principles calculations.