MgGa_(2)O_(4)∶Cr^(3+),Al^(3+)近红外发光长余辉纳米粒子的制备及发光性能研究

利用乙二醇辅助共沉淀法,制备了小尺寸近红外发光Al^(3+)共掺杂镓酸镁(MgGa_(2)O_(4))∶0.3%Cr^(3+)(MGO∶0.3%Cr^(3+),Al^(3+))长余辉发光纳米粒子(PLNP),考察了Al^(3+)掺杂对MGO∶0.3%Cr^(3+)晶体结构和光学性质的影响。研究结果表明,Al^(3+)掺杂对MGO∶0.3%Cr^(3+)的晶体结构无影响,但能提高MGO∶0.3%Cr^(3+)的发光强度。当Al^(3+)掺杂量为0.4%(摩尔分数)时,MGO∶0.3%Cr^(3+),0.4%Al^(3+)(Al^(3+)、Cr^(3+)相对于Ga^(3+)的物质的量比,摩尔分数)PLNP发光强度最强,余辉平均发光寿命从46.98s(MGO∶0.3%Cr^(3+))增大至78.75s(MGO∶0.3%Cr^(3+),0.4%Al^(3+)),平均粒径为(6.53±1.79)nm。本研究为制备小尺寸和高发光强度的PLNP提供了一种有效的方法。此外,高发光强度和长余辉寿命的MGO∶0.3%Cr^(3+),0.4%Al^(3+) PLNP为光学传感、成像和治疗等提供了材料支撑。

绿色长余辉发光材料MgGa_(2)O_(4):Mn^(2+)的制备及性能研究

采用高温固相法合成了MgGa_(2)O_(4):x Mn^(2+)(x=0.5%,1%,3%,5%)系列绿色长余辉发光材料。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、发光光谱、余辉光谱、热释光谱等表征手段对其长余辉发光性能进行了研究。样品的发射光谱的结果表明,Mn^(2+)在509 nm处的特征发射峰,对应Mn^(2+)离子的^(4)T_(1)(4G)→^(6)A_(1)(^(6)S)电子跃迁,随着Mn^(2+)掺杂浓度的增加,其发光强度先增强后减弱,掺杂浓度为3%时样品具有最好的发光性能;掺杂浓度为1%时其余辉强度最强,余辉时间可以持续1h以上;热释光谱在342 K附近出现一个宽峰,这表明样品存在大量的陷阱,这有利于捕获被激发的电子,形成长余辉发光。

Novel transparent MgGa_(2)O_(4) and Ni^(2+)-doped MgGa_(2)O_(4) ceramics

In this study we fabricated, for the first time, magnesium gallate (MgGa_(2)O_(4), a partially inverted spinel) transparent ceramics, both undoped and doped with 1 at% Ni. The specimens were derived from in-house prepared powder, with a crystallite size of ∼10 nm (by wet chemistry) and densified by pulsed electric current sintering (PECS;peak temperature 950 ℃ for 90 min). Densification levels of 99.84% and 99.52% of theoretical density were attained for doped and undoped materials, respectively. Doping with Ni was seen to marginally improve the densification level. Quite transparent specimens were produced: the best showing transmission of ∼89% of the theoretical level (thickness t = 0.85 mm). The absorption spectra revealed that the dopant was accumulated as Ni^(2+) in the octahedral sites of the lattice, as occurs in single-crystal specimens. After excitation at 980 nm, the doped disks exhibited a wide fluorescence band centered at 1264 nm.