Carbonate coprecipitate precursors were prepared by mixed nitrate solutions containing M2+(M2+=Sr2+,Ba2+),Y3+ and Er3+ as the cation sources and(NH4)2CO3 as the precipitator.MY2S4:Er3+ phosphors were synthesized by calcining the carbonate precursors with CS2 as the sulfurization reagent at 1050 ℃ for 4 h.XRD patterns show that the synthesized SrY2S4 and BaY2S4 crystalline powders possess the orthorhombic [CaFe2O4]-type structure.Photoluminescent measurements indicate that there were mainly red emitting(4F9/2→4I15/2) and green emitting(2H11/2→4I15/2 and 4S3/2→4I15/2) of Er3+ in the SrY2S4 while there was only red emitting(4F9/2→4I15/2) in BaY2S4:Er3+.BaY2S4:Er3+ is considered as a novel red phosphor candidate with a high monochromaticity.
Nanophosphor with the nominal composition of Ca 0.8Zn 0.2TiO3∶Pr 3+, Na+ （CZTOPN） was synthesized at relatively low temperature by the sol-gel method. Metal ions were dispersed by citric acid in ethylene glycol solvent and then react with Ti（OC4H9）4 to form sol and gel. The decomposition process of the precursor, and crystallization and particle size of CZTOPN were examined by thermal analysis （TG-DSC）, powder X-ray diffraction （XRD）, and scan election microscopy （SEM）. Results of TG-DSC and XRD reveal that the composition of Ca 0.8Zn 0.2TiO3∶Pr 3+, Na+ changes with the sintering temperature. SEM data indicate that the diameter of particles is under 50 nm even if the sintering temperature increases to 1000 ℃. In contrast to a solid state reaction, the excitation spectra of samples synthesized by the sol-gel method shift blue about 10 nm and the emission intensity at 617 nm increases significantly.
Ca2-xSrxZn4Ti15O36∶Pr red long decay phosphor was synthesized by high temperature solid state reaction. Photoluminescence property and crystalline and unit cell parameters of the orthorhombic were investigated by fluorescence spectrophotometer and by powder X-ray diffraction, respectively. The emission intensity at 618 nm changes sharply when the concentration of Sr2+ （x） is less than 0.1 and the emission intensity reaches the maximum when x is equal to 0.007. There is an obviously broad excitation band at 270 nm when x is equal to 0.003 and it disappears gradually when x is over 0.01. The unit cell a parameter of Ca2-xSrxZn4Ti15O36∶Pr decreases while c parameter increases with the increases of the concentration of the doped Sr2+. When x is over 0.1 the value of the unit cell parameters a and c become stable. TL peaks of Ca2Zn4Ti15O36∶Pr, Ca1.993Sr0.007Zn4Ti15O36∶0.002Pr3+, 0.002Na+, are located at 62 ℃, 88 ℃, respectively, which indicates that there are deeper traps in Ca1.993Sr0.007Zn4 Ti15O36∶0.002Pr3+, 0.002Na+.
