Lanthanide substitution in Y<sub>2</sub>O<sub>3</sub>:Eu<sup>3+</sup> red phosphors for blue LED excitation.

Y2O3:Eu 3+ phosphors are utilized as UV-excited red emitting phosphors.Blue LEDs emit light at a wavelength around 460 nm, and Y2O3:Eu 3+ shows a slight fluorescence emission due to blue excitation by direct excitation of Eu 3+ .In this study, RE2O3:Eu 3+ (RE= Y,La,Gd,Lu) was prepared based on Y2O3:Eu 3+ , and the intensity of red emission by blue excitation was investigated.The main phase of the prepared samples was identified as RE2O3 by X-ray diffraction measurement, and Y, Gd, and Lu had similar structures, but only La had a different structure.Excitation (Em 613 nm) and fluorescence (Ex 466 nm) spectra showed that Gd2O3:Eu 3+ exhibited higher emission intensity than Y2O3:Eu 3+ , while La2O3:Eu 3+ showed the strongest emission at the longer wavelength of 628 nm.Diffuse reflectance spectra showed that Lu2O3:Eu 3+ and Gd2O3:Eu 3+ showed stronger blue absorption than Y2O3:Eu 3+ , while La2O3:Eu 3+ changed to the by-product La(OH)3 with time, and both emission intensity and absorption decreased.These results indicate that Gd2O3:Eu 3+ is superior to Y2O3:Eu 3+ in blue light absorption and red emission.