Photoluminescence, Non-Reduction and Thermal Stability Characteristics of Red Phosphors Ca3La3(1-x)Eu3x(BO3)5 Prepared in Reducing Atmosphere

A series of Ca3La3(1-x)Eu3x(BO3)(5) phosphors were prepared via a solid-state reaction under reducing atmosphere. Rietveld refinements were performed by adopting the powder X-ray diffraction data, which indicates the occupations of Eu3+ on both La3+ and Ca2+ sites with a preferred location on the La3+ site over the Ca2+ site. This kind of phosphors could be excited by UV and blue LED in solid-state lighting technology and the CIE chromaticity coordinates for phosphors CLBO: 0.06Eu(3+) (lambda(ex) = 254 nm) and CLBO: 0.12Eu(3+) (lambda(ex) = 393 nm) are (0.6712, 0.3328) and (0.6685, 0.3287), respectively, which are compliant with the national television system committee (NTSC) standard for red chromaticity. The energy transfer rate between the Eu3+-Eu3+ pairs is weak that proved by the results of the decay process and the efficiency of the Eu3+5D0 -> F-7(2) emission. The mechanism responsible for the non-reduction of Eu3+ was analyzed, which was determined by two factors: 1) no element of the host matrix can be oxidized and 2), cationic vacancies which can be regarded as the electron donor cannot exist. The temperature dependence study shows thermal quenching behavior is attributed to crossover from the D-5(0) excited state of the Eu3+ to the charge transfer state band and these phosphors have good thermal stability. (C) 2014 The Electrochemical Society. All rights reserved.