KZn4SbO7 and KZn4Sb3O12: syntheses, structures and photophysics of Sb5+ control materials

Abstract

Two novel compounds KZn₄SbO₇ (1) and KZn₄Sb₃O₁₂ (2) having quasi-white light emission and second-harmonic generation are prepared, and their single-crystal structures are characterized as P6₃mc and R3 space groups, respectively. The crystal structure transition from high symmetry P6₃mc of 1 to low symmetry R3 of 2 arises from the large contents of Sb⁵⁺ diluter in wurtzite-type ZnO crystals (ionic ratio of Sb⁵⁺/Zn²⁺ = 1/4 and 3/4 for crystals 1 and 2). The lifetime and quantum efficiency of luminescence are measured, and the density of states and frequency doubling coefficients are calculated for the two compounds. The strong charge transfers from O²⁻ to Sb⁵⁺, and blue-shifts of absorption edge and emission bands originate from a large Sb⁵⁺ ion content for compound 2. Further, large charge transfer from O²⁻ to Sb⁵⁺ lead to high quantum efficiency and low lifetime, and weak second-harmonic generation intensity for compound 2.