Gao Guojun, Da Ning, Reibstein Sindy, Wondraczek Lothar
Department of Materials Science, University of Erlangen-Nuremberg, 91058 Erlangen, Germany.
Opt Express. 2010 Nov 8;18 Suppl 4:A575-83. doi: 10.1364/OE.18.00A575.
Intense photoluminescence was observed from mixed-valence Eu-doped nanocrystalline BaAl₂Si₂O₈/LaBO₃ glass ceramics. For preparation in air, the ratio between Eu3+ and Eu2+ luminescence depends on synthesis temperature. XRD, TEM and IR absorption spectra were employed to characterize the crystallization process and structural properties of the precursor glass and corresponding glass ceramics. When annealed at 950 °C, the material exhibited photoluminescence more than ten times stronger than was found in its glassy state. Spectroscopic data indicate that during such a heat treatment, even in air, a significant part of the Eu3+ ions is reduced to Eu2+. Lifetime of the ⁵D₀ state of Eu3+ increases with increasing heat treatment temperature. Eu3+ species are largely incorporated on La3+ sites in LaBO₃ crystallites whereas Eu2+ locates on Ba2+ sites in the hexacelsian phase. A mechanism for the internal reduction of Eu3+ to Eu2+ is proposed. Spectroscopic properties of the material suggest application in additive luminescent light generation.
在混合价态铕掺杂的纳米晶BaAl₂Si₂O₈/LaBO₃玻璃陶瓷中观察到强烈的光致发光现象。对于在空气中制备的样品，Eu³⁺和Eu²⁺发光之间的比例取决于合成温度。采用X射线衍射（XRD）、透射电子显微镜（TEM）和红外吸收光谱来表征前驱体玻璃及其相应玻璃陶瓷的结晶过程和结构性质。当在950℃退火时，该材料表现出的光致发光比其玻璃态时强十多倍。光谱数据表明，在这样的热处理过程中，即使在空气中，相当一部分Eu³⁺离子也会被还原为Eu²⁺。Eu³⁺的⁵D₀态寿命随着热处理温度的升高而增加。Eu³⁺主要掺入LaBO₃微晶中的La³⁺位点，而Eu²⁺位于六方钡长石相中的Ba²⁺位点。提出了Eu³⁺内部还原为Eu²⁺的机制。该材料的光谱性质表明其可应用于加性发光照明。
