희토류 이온이 첨가된 NaM(PO3)3 (M=Mg, Zn, Sr, Ca) 형광체의 분광 특성 연구

Abstract

Luminescence properties of NaM(PO3)3(M=Mg,Zn,Ca,Sr) doped with Eu3+ and Tb3+ions and NaSr(PO3)3 doped with Eu2+ are investigated by optical and laser excitation spectroscopy. The phosphors were prepared by solid state reaction method and Eu2+ are reduced by carbothermal reduction method. The X-ray diffraction (XRD) was used to analyze the crystal structure and the crystallinity of the samples. The excitation and emission spectra and decay curve of NaM(PO3)3(M=Mg,Zn,Ca,Sr):Eu3+and Tb3+ (0.01 - 30 mol%) were measured at room temperature. Spectral features and excitation and emission spectra of NaMg(PO3)3:Eu3+ are found to be nearly the same as those to NaZn(PO3)3:Eu3+. The charge transfer band of O2- - Eu3+ shifts to lower energy with increasing Eu3+ concentration in NaM(PO3)3(M=Mg,Zn,Ca,Sr):Eu3+. The emission intensity of the 5D0 → 7F1transition is unusually strong compared with that of the5D0 → 7F2 transition. The intensity ratio 7F2/7F1 decreases with increasing Eu3+concentration indicating that the crystal field symmetry becomes higher with increasing Eu3+ concentration. No concentration quenching occurs up to 30 mol% Eu3+in NaCa(PO3)3:Eu3+ and NaSr(PO3)3:Eu3+. The f - d band of Tb3+ is observed in the excitation spectra of NaM(PO3)3(M=Mg,Zn,Ca,Sr):Tb3+ in the wavelength region 210 - 240 nm. Strong emission lines due to the 5D4→7FJ transition and weak emission lines due to the 5D3→7FJ transition are observed in the emission spectra of NaCa(PO3)3:Tb3+and NaSr(PO3)3:Tb3+. The energy transfer and cross relaxation between Tb3+ ions are discussed inNaM(PO3)3(M=Ca,Sr):Tb3