Improved Photoluminescence of Ce~(3+) Activated LaAl(Si_(6-Z)Al_z)(N_(10-z)O_z) (z~1) Blue Oxynitride Phosphors by Calcium Co-Doping

摘要

(La,Ce)Al(Si_(6_Z)Al_z)(N_(10-Z)O-z) (z~1) (termed JEM crystal phase) co-doped with calcium was investigated in this work, aiming to control its photoluminescence spectrum. The JEM phase can be obtained as a dominant phase in a wide range of Ca and Ce concentrations by the gas-pressure sintering method. The excitation and emission spectra of JEM phosphor were shifted to longer wavelength by increasing Ca, which is ascribed to the enhanced ligand field around Ce ions as a result of decreases in lattice constants. The peak excitation wavelength can approach 405 nm for the samples with high Ca concentrations, which enables the JEM blue phosphors to be applied in solid state lighting using violet LED chips.