Synthesis of a new phosphor based on rare earth oxycarbonate

Abstract

A new synthesis route to easily obtain the II-type lanthanum oxycarbonate in a single phase has been developed by using a simple flux method, and photoluminescence properties of Eu 3+- or Tb 3+-doped La 2O 2CO 3 were characterized. These new phosphors, the II-type La 2O 2CO 3:Eu 3+ and La 2O 2CO 3:Tb 3+, were synthesized by the calcination with a flux in a flow of 10%CO 2–90%N 2 gas, where lithium carbonate or a 0.476Li 2CO 3–0.270Na 2CO 3–0.254K 2CO 3 eutectic mixture was employed as the flux. The higher emission intensity was observed by employing the Li 2CO 3–Na 2CO 3–K 2CO 3 eutectic system, which has a considerably lower melting point (663 K) than that of Li 2CO 3 (999 K). The red and green emission intensities became maximum at the composition of La 2O 2CO 3:6at.%Eu 3+ and La 2O 2CO 3:17at.%Tb 3+, and the relative emission intensities compared with the commercial Y 2O 3:Eu 3+ and LaPO 4:Ce 3+,Tb 3+ phosphors were 22.5 and 60.0%, respectively.