Adjustable valence states of europium in CaAlBO4 phosphor by means of enlarging the activator site and its luminescent properties

作者：Dai, W. B.; Song, E. H.; Wang, J. L.; Zhang, Q. Y.^*

来源：CrystEngComm, 2016, 18(15): 2679-2689.

DOI：10.1039/c6ce00125d

• LIGHT-EMITTING-DIODES
• ENERGY-TRANSFER
• PHOTOLUMINESCENCE PROPERTIES
• ABNORMAL REDUCTION
• EU2+ LUMINESCENCE
• IONS
• EU3+
• EMISSION
• AIR
• SUBSTITUTION

Eu-activated aluminoborates CaAlBO4 and its derivatives LixCa1-xAl1-xSixBO4 were synthesized by a conventional solid state reaction. The phosphors were characterized by powder X-ray diffraction (XRD). Rietveld refinement analysis was performed to reveal phase formation and changes in lattice parameters. Generation of direct white light emission was realized via incorporation of Si4+-Li+ to replace Al3+-Ca2+ for expanding the activator site in CaAlBO4. The average bond lengths of (Al, Si)-O and Ca-O were systematically shortened and elongated simultaneously, indicating that enlargement of the activator site corresponds to the doping amounts of Si4+-Li+, which play a critical role in the reduction process of Eu3+ to Eu2+. The different valence states of Europium were further confirmed by X-ray absorption near edge structure (XANES), time-resolved spectra, and photoluminescence. This work opens new vistas for designing phosphors in phosphor-converted light-emitting-diodes (pc-LEDs) by using a valence tunable activator via controlling the size of activator site.

• 出版日期2016
• 单位华南理工大学