纳米晶ZrO_2∶Er^(3+)的制备及发光性质

Preparation and Luminescent Properties of Nanocrystalline ZrO_2∶Er^(3+)

制备了纳米晶ZrO2∶Er3+发光粉体,所制备的粉体室温下具有Er3+离子特征荧光发射,主发射有蓝光和绿光两部分,其中位于406,474nm的蓝光较强。对不同煅烧温度下所制备的样品研究表明:因不同温度下所制得样品的晶相不同,绿光区的发光中心也不同。当四方相和单斜相达到一定的比例时,发光最强。同时观测到Er3+离子的上转换发射(包括绿光和红光两部分)。讨论了上转换发射的跃迁机制,976nm激发下的上转换过程是双光子过程。荧光强度与Er3+的掺杂浓度关系研究表明,Er3+在ZrO2中有浓度猝灭现象,最适宜掺杂浓度的原子数分数为0.9%(Er3+/Zr4+)。

Rare earth doped nanocrystalline ZrO2 have attracted great interest. For zirconium oxide has a low phonon energy of about 470 cm^-1 and a high refractive index of about 2.1 and is chemically and thermally stable. And rare earth ions, especially erbium, have played an important role in the development of optical communication technology during the past few decades. Recently, erbium doped luminescent materials have received considerable attention for its luminescence and frequency upconversion of infrared radiation into the visible region. The nanocrystalline ZrO2： Er^3＋ powders with room temperature sharp characteristic emissions were prepared by co-precipitation method. The main work concerns the structures, the luminescence emissions and upconversion emissions change of nanoparticles with the sintering temperature. For ZrO2 sintered at 600 ℃ the spectra is dominated by the peaks centered at 30.28° （ 101 ） t characteristic of the tetragonal structure. For ZrO2 sintered at 800 ℃ the spectra is dominated by the peaks centered at 28.35 °（-1,1,1 ）m and 31.65° （ 1,1,1 ） m characteristic of the monoclinic structure, but there also exist the tetragonal structure. The tetragonal structure almost totally converts to the monoclinic structure for ZrO2 sintered at 950 ℃. The luminescence emissions contain the blue emission and the green than that of the green emission. There exist two emission emission. The intensity of the blue emission is greater centers of Er^3 ＋ in different crystalline phases. One is monoclinic phase, and the other is tetragonal phase. We also find that the emission intensity reaches the maximum value when the ratio of the tetragonal phase to the monoclinic phase comes to a certain value. The room temperature upconversion emission of these samples is also observed and the upconversion emission mechanism is given. We find that the quadratic dependence of the green emissions on excitation power indicates that a two-photon absorption process occurs under 976 nm excitation, The effect of the doped concentration of Er^3 ＋ on the fluorescence emission intensity has been discussed, and the concentration quenching will occur when the concentration of Er^3 ＋ is more than 0.9% （ atomic fraction） Er^3 ＋.