Blue emission and color-tunable behavior in Tm 3+singly- and Dy 3+/Tm 3 co-doped CaLaGa 3 O 7 phosphors

Tm 3+ singly- and Dy 3+ /Tm 3+ co -doped CaLaGa 3 O 7 phosphors were prepared successfully by a high -temperature solid-state reaction method and their structure, spectroscopic properties, as well as energy transfer processes between Dy 3+ and Tm 3+ were studied. The XRD measurements show that all the prepared phosphors have a tetragonal structure. The emission proved that under excitation by 355 nm, 455 nm blue light was obtained in Tm 3+ : CaLaGa 3 O 7 phosphor with a high color purity (99%). For Dy 3+ /Tm 3+ : CaLaGa 3 O 7 , the emission spectra exhibited the typical yellow emissions of Dy 3+ and blue light of Tm 3+ . More importantly, the relative emission intensity of Dy 3+ and Tm 3+ can be varied by modifying the concentration of Tm 3+ and the exciting wavelength, indicating that the luminescence color is tunable. Further, optimal white -light emission was achieved when codoped 0.01 Tm 3+ and 0.02 Dy 3+ under 355 nm excitation. Meanwhile, the CIE chromaticity coordinates, color temperature value and color purity of the 0.02 Dy 3+ /0.01 Tm 3+ : CaLaGa 3 O 7 phosphor were calculated to be ( x = 0.3321, y = 0.3231), 5515 K and 7.18%, respectively, which are close to the standard white -light illumination. Moreover, the study on the decay curves indicates that mutual energy transfers between Dy 3+ and Tm 3+ take place in the Dy 3+ /Tm 3+ : CaLaGa 3 O 7 phosphor. The above findings suggest that the prepared phosphors have potential applications in light emission devices.