Fabrication And Property Of Chlorosilicate Phosphor Used For White LEDs

Rear earth ions doped chlorosilicate and molybdate phosphors have been synthesized by solid state methods and their luminescent properties were studied. The results indicated that they are better luminescent materials for white LED. The main research content was as follow:Ca₇(SiO₄)2Cl₆:Eu²⁺phosphor was prepared using high temperature solid state method. The excitation and emission spectra were measured by fluorescence spectrometer. The l excitation spectrum is a a broad band from 400nm to 300nm, which can be effective excited by nearly ultraviolet. Excited by 350nm UV light, the phosphor will emit green light in the visible light centered at 500nm. The Eu²⁺concentration had intense influence on the luminescent properties. The emission spectra of samples with different dopping concentration of Eu²⁺ ions were measured, which indicated that the emission intensity reached the maximum when the Eu²⁺ concentration was 0.75mol% and concentration quenching would occur if more Eu²⁺ ions was added.A green phosphor Sr₇Si2O7Cl3:Eu²⁺ was prepared at 850℃and its luminescent properties were investigated. Monitoring 440 and 502nm wavelength, two different excitation spectra were obtained, which illuminated that Eu²⁺ may be located at two different crystal lattice sites. The emission peaks located at 502nm, which blonged to green light. The emission intensity of Sr₇Si2O7Cl3:Eu²⁺ increased with Eu²⁺ ions concentration and reached maximum when the Eu²⁺ concentration was 0.4mol%. The intensity decreased if Eu²⁺ ions concentration unceasingly increased.The Ba₇Si₂O₇C_l3:Eu²⁺ phosphor was prepared at 760℃. Monitoring 503nm wavelength, the excitation spectra indicated that it was a broad excitation spectrum in the UV region, which matched well with UV chip. The emission spectrum took on a single peak broad band centered at 503nm excited by 365nm, which belonged to green region. The optimal doped concentration of Eu²⁺ ions was 1.0mol%. The results indicated that this phosphor had better luminescent properties.A series of Sr1-mCamMoO4:0.04Dy³⁺phosphors with different Sr/Ca ratio had been prepared by high-temperature solid state method. The luminescent properties of samples were investigated in detail. The excitation spectra is composed of a broadband spectrum and a series of narrowband composition and the strongest excitation peak located 350nm in the region of 325-475nm. Material color parameters constantly varied with Sr/Ca and the luminescent material with different colour temperature could be obtained by adjusting Sr/Ca.