KZn(4)SbO(7) and KZn(4)Sb(3)O(12): syntheses, structures and photophysics of Sb(5+) control materials.

ABSTRACT

Two novel compounds KZn(4)SbO(7) (1) and KZn(4)Sb(3)O(12) (2) having quasi-white light emission and second-harmonic generation are prepared, and their single-crystal structures are characterized as P6(3)mc and R3 space groups, respectively. The crystal structure transition from high symmetry P6(3)mc of 1 to low symmetry R3 of 2 arises from the large contents of Sb(5+) diluter in wurtzite-type ZnO crystals (ionic ratio of Sb(5+)/Zn(2+) = 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 O(2-) to Sb(5+), and blue-shifts of absorption edge and emission bands originate from a large Sb(5+) ion content for compound 2. Further, large charge transfer from O(2-) to Sb(5+) lead to high quantum efficiency and low lifetime, and weak second-harmonic generation intensity for compound 2.