Photoluminescence evolution and high thermal stability of orange red-emitting Ba3-xSrxZnNb2O9: Eu3+phosphors

A series of Ba3-xSrxZnNb2O9: 0.3Eu(3+) (x = 0, 0.5, 1, 1.5, 2, 2.5, 3) orange-red phosphors were synthesized by high-temperature solid-phase reaction. In order to identify and describe the crystal structure, luminescence characteristics and thermal stability of the samples, XRD and luminescence spectroscopy tests were carried out. The refined XRD results showed that Eu3+ ions have been successfully doped into Ba3-xSrxZnNb2O9 matrix and occupied partly the sites of Eu3+ ions. Under UV excitation of 396 nm, the emission spectra of the samples are composed of two emission peaks near 593 nm and 612 nm with a slight blue shift, attributed to the increase in splitting degree of 5d electron orbit of Eu3+ ions. At 523 K, the thermal stabilities of phosphors with Sr2+ ion doping concentration of 2 and 3 are 82.14% and 84.33%, respectively. With the increase of Sr2+ ion concentration, the activation energy increases from 0.198 eV to 0.230 eV, better than the other reports. In addition, the CCT (below 2000 K) and color purity (above 95%) of the samples are calculated. A WLED device can be obtained by combining the as-prepared orange red-emitting phosphor with commercial blue (BaMgAl10O17: Eu2+) and green ((Sr, Ba)(2)SiO4: Eu2+) phosphors. All these indicated that the self-made phosphors are promising to be used in UV/n-UV pumped WLEDs requiring low CCT.