Wydział Chemii

Małgorzata Puchalska

Eugeniusz Zych

Paulina Bolek

2019

Journal of Alloys and Compounds

806

798-805

10.1016/j.jallcom.2019.07.307

Naukowa

Angielski

Artykuł

In the present work, bismuth-doped CaAl₄O₇ phosphor powders were obtained via modified Pechini citrate process and their photoluminescence, radioluminescence and thermally stimulated luminescence properties were studied down to 20 K. At room temperature excitation in UV led to broad-band ³P_0,1 → ¹S₀ Bi³⁺ luminescence with three maxima located in blue-green part of spectrum as well as Bi²⁺ emission around 760 nm assigned to the ²P_3/2 → ²P_1/2 transition. At 150 K an additional Bi³⁺emission band peaking at 370 nm appeared and its intensity increased significantly upon further cooling. The presence of a few luminescent centers of Bi³⁺ in CaAl₄O₇was assigned to the presence of defects disturbing the local symmetry of activator ions. The radioluminescence spectra showed only two bands, an intense one at 760 nm clearly related to Bi²⁺ and a very weak component at 555 nm associated with one of the Bi³⁺ sites. These two emissions were also observed in the thermoluminescence of the material following its exposure to X-rays. The Bi³⁺luminescence is suitably positioned to contribute the cyan color to white-LEDs. Its quantum yield is satisfactory, close to 40%. The Bi²⁺ 720–850 nm emission is attractive for bioimaging as it appears in the I^st biological window.

CaAl4O7, Bi3+, Bi2+, Luminescence, Thermoluminescence, Decay kinetics

http://dx.doi.org/10.1016/j.jallcom.2019.07.307

http://www.elsevier.com