A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films
A protected annealing strategy to enhanced light emission and photostability of YAG:Ce nanoparticle-based films
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DOI：
10.1039/c0nr01000f
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发表时间：
2011-01-01
期刊：
影响因子：
6.7
通讯作者：
Boilot, Jean-Pierre
中科院分区：
文献类型：
--
作者：
Revaux, Amelie;Dantelle, Geraldine;Boilot, Jean-Pierre
开发YAG:Ce纳米粒子作为白光led的光转换器和生物标签的一个重大障碍是，很难找到能够同时控制结构、粒径和粒径分布，同时保持大块样品光学特性的制备条件。制备条件通常涉及前驱体的高温处理（高达1400摄氏度），这导致颗粒大小和聚集增加，并导致Ce（III）氧化为Ce（IV）。我们在这里报告了一种我们称之为保护退火的过程，该过程允许在高达1000摄氏度的温度下对预制前驱体颗粒进行热处理，同时保持其小尺寸和分散状态。在第一步中，通过糖热反应制备原始纳米颗粒，导致钇铝石榴石和薄水铝石晶体相的混合物。然后将预制的纳米颗粒分散在多孔二氧化硅中。复合材料在1000℃下退火，然后用氢氟酸溶解无定形二氧化硅，以恢复退火后的颗粒作为胶体分散体。这个简单的过程可以完成YAG结晶，同时保持其小尺寸。通过退火气氛可以控制Ce离子的氧化还原状态。得到的YAG:Ce （60 +/- 10 nm）颗粒可以分散成接近透明的水悬浮液，发光量子产率为60%。利用气溶胶喷涂技术可以在玻璃基板上沉积微米厚度的透明YAG:Ce纳米颗粒薄膜。由受保护退火策略制备的颗粒形成的薄膜比未经过这种退火的颗粒显着改善了光稳定性。
A significant obstacle in the development of YAG:Ce nanoparticles as light converters in white LEDs and as biological labels is associated with the difficulty of finding preparative conditions that allow simultaneous control of structure, particle size and size distribution, while maintaining the optical properties of bulk samples. Preparation conditions frequently involve high-temperature treatments of precursors (up to 1400 degrees C), which result in increased particle size and aggregation, and lead to oxidation of Ce(III) to Ce(IV). We report here a process that we term protected annealing, that allows the thermal treatment of preformed precursor particles at temperatures up to 1000 degrees C while preserving their small size and state of dispersion. In a first step, pristine nanoparticles are prepared by a glycothermal reaction, leading to a mixture of YAG and boehmite crystalline phases. The preformed nanoparticles are then dispersed in a porous silica. Annealing of the composite material at 1000 degrees C is followed by dissolution of the amorphous silica by hydrofluoric acid to recover the annealed particles as a colloidal dispersion. This simple process allows completion of YAG crystallization while preserving their small size. The redox state of Ce ions can be controlled through the annealing atmosphere. The obtained particles of YAG:Ce (60 +/- 10 nm in size) can be dispersed as nearly transparent aqueous suspensions, with a luminescence quantum yield of 60%. Transparent YAG:Ce nanoparticle-based films of micron thickness can be deposited on glass substrates using aerosol spraying. Films formed from particles prepared by the protected annealing strategy display significantly improved photostability over particles that have not been subject to such annealing.