[Synthesis of CaLaAl3O7:Eu3+ by gel-combustion method and its luminescence properties].

ABSTRACT

Using the gel-combustion method the precursors of GaLa(1-x)Al3O7 xEu3+ (0.05 < or = x < or = 0.8) were prepared. When annealing temperature was below 700 degrees C, the materials were in amorphous state, while as annealing temperature was above 800 degrees C, the high purity CaLa(1-x)Al3O7 xEu3+ crystalline materials were obtained. The luminescence properties of GaLa(1-x)Al3O7 xEu3+ both in amorphous and crystalline phases were investigated, and the results of excitation spectrum show a similar charge transition band of Eu3+--O2- between 230 nm and 320 nm and a series of f--f transition of Eu3+ ion. However, the strongest band of amorphous material was at 465 nm corresponding to (7)F0--(5)D2 transition, and those of the crystalline materials were at 394 nm corresponding to (7)F0--(5)L6 transition of Eu3+ ion. In amorphous state materials the emission intensity of excitation wavelength 465 nm was stronger than that of 394 nm, and composition of (5)D0--(7)F0 transition at 578 rim, (5)D0--(7)F1 transition at 587 rim and (5)D0--(7)F2 transition at 615 rim. In crystalline material, the emission intensity of excitation wavelength of 394 run was stronger than that of 465 rim, the (5)D0--(7)F0 transition disappeared, and the (5)D0--(7)F1 transition split into 587 rim and 596 rim. With the increase in temperature, the strongest band at 615 rim increased, and what is more, the (5)D0--(7)F1 transition increased remarkably. In CaLa(1-x)Al3O7 xEu3+, when x=0.2 for the co-doping Eu3+ ion and the mol proportion of citric acid and metal ion (C/M) was 1.2, the luminescence intensity was the highest.