水热法制备YVO_4:Eu~(3+)的热处理及其发光性能

用水热法制备的YVO4:Eu3+分别在400～800℃下进行热处理,研究了所得样品的结构及其发光性能。实验结果表明:所得样品都为单相结构,随着热处理温度的升高,样品的结晶度变好,颗粒变大。在紫外光谱范围,YVO4:Eu3+的激发光谱由VO43-的吸收带和Eu3+的电荷迁移带组成。在真空紫外(VUV),激发光谱由基质吸收,Y3+、O2-的电荷迁移带组成。发射光谱均为Eu3+的5D0→7FJ(J=1,2,4)跃迁。紫外和真空紫外激发下,样品的发光强度比未经过热处理的样品有显著增强,归因于样品的结晶度的提高和OH-、VO43-等发光猝灭离子的去除。

Photoluminescence Properties of YVO4 : Eu3+ Phosphor after Thermal Treatment

YVO_4:Eu~(3+) was successfully synthesized by hydrothermal method, and was further thermally treated at 400~800 ℃, respectively. Their crystal structure, SEM(scanning electron microscope)images and luminescence properties were obtained in room temperature. XRD showed that YVO_4:Eu~(3+) was formed with good single phase, and when the temperature changes in 400～800 ℃, the crystallinity is higher and higher, and the crystal grain become bigger and bigger than untreated sample. SEM images also indicated the grain of the sample after treatment is bigger than that of YVO_4:Eu~(3+) before treatment. In the UV range, the excitation band is composed of a broad band with the maximum at about 260 nm and a sharp band with the maximum at about 395 nm. The peak of 260 nm is assigned to the overlap of VO~(3-)_4 ion and O~(2-)→Eu~(3+) charge transfer band absorption;the peak at 395 nm is due to ~7F_0→~5L_6 transition of Eu~(3+). In the VUV range, the excitation band was composed of a strong broad band at about 156 nm and a broad band at about 200 nm. The peak of 156 nm could be assigned to the absorption band of host, and the peak of 200 nm is assigned to the charge transfer band of O~(2-)→Y~(3+). After 200 nm, the shape of absorption spetrum is similar to the UV excitation spectra. under 254 nm excitation, the YVO_4:Eu~(3+) phosphor exhibits the well-known Eu~(3+) emission, which makes up of several sharp lines of Eu~(3+), namely the ~5D_0→~7F_1, ~5D_0→~7F_2, ~5D_0→~7F_4 transitions, respectively,the dominated emission peak is ~5D_0→~7F_2 at 619 nm under 147 nm excitation, their emission spectra are consistent with that under 254 nm excitation. With the temperature increasing in 400~800 ℃, the emission intensity of samples is improved because of the higher crystallinity, bigger grain, and removing of OH~- and VO~(3-)_4 which can quench the luminescence. Under 254 nm and 147 nm excitation, the emission intensity of the sample thermally treated at 800 ℃ is improved 90% and 95% comparing with the untreated sample, respectively. It was indicated that 800 ℃ is the best thermal treatment temperature.