Full-color tuning by controlling the substitution of cations in europium doped Sr8-xLa2+x(PO4)6-x(SiO4) xO2 phosphors

• Published in: Dyes and pigments 2019-01, Vol.160, p.145-150
• Main Authors: Dorim, Kim, Byung Chun, Choi, Sung Heum, Park, Jung Hwan, Kim, Kiwan, Jang, Jung Hyun, Jeong
• Format: Article
• Language: English
• ISSN: 0143-7208; 1873-3743
• DOI: 10.1016/j.dyepig.2018.08.011

A full-color tunable phosphor by co-substituting Sr2+ and P5+ for La3+ and Si4+ in the single phased oxy-apatite Sr8-xLa2+x (PO4)6-x (SiO4)xO2: Eu2+ (SLPSiO; x = 0, 2, 4, 6) phosphor were prepared via solid state reaction method from powder based precursors. The crystal structure information of cell parameters and average bond lengths from luminescence centers to its ligands was analyzed using Rietveld refinement. All the crystal structure of series of phosphors include two different sites of Eu2+, the 7-coordinated Sr1 sites and the 9-coordinated Sr2 sites. The different behaviors of luminescence evolution were due to the Eu2+ ions prefer higher energy sites in the Sr8La2(PO4)6O2 (for x = 0) host, but lower energy sites in the Sr2La8(SiO4)6O2 host (for x = 6). Also, the red PL originating from the trivalent europium ions appeared due to the increase in the La3+/Sr2+ ratio with increasing x. The blue point (0.2016, 0.1144), bluish white (5000–8300 K CCT), and yellowish white point (2600–3700 K CCT) in the CIE coordination through red colors are included in the ‘Fabricated LED’ curve, which are suitable for the application of these blends in white-light near UV LEDs. Moreover, the internal quantum efficiency of the x = 0 phosphor approached up to 90%. •The wide range of the emission spectra of Sr8-xLa2+x (PO4)6-x (SiO4)xO2: Eu2+ (x = 0, 2, 4, 6) were clarified by Van Uitert equation and the crystal field strength equation.•The thermal stability and the IQE (internal quantum efficiency) of the Sr8La2(PO4)6O2: Eu2+ (for x = 0) phosphor was found to be up to 79% and 90%, respectively.•By adjusting x with a fixed excitation wavelength, the emission of this phosphor series can be tuned from blue to red. Moreover, by adjusting the excitation wavelength with a fixed x, a tunable phosphor with full color coverage can be achieved.•Fabricated pc-LEDs using Sr8-xLa2+x (PO4)6-x (SiO4)xO2: Eu2+ (x = 0, 2, 4, 6) phosphor pumped by a near-UV chip achieved from cold white to warm white.