A new member of “114” family Ca1−xEuxBaZn2+xGa2−xO7 (x≤0.24): Structure and luminescence

• Ca1−xEuxBaZn2+xGa2−xO7 (x≤0.24) solid solutions were synthesized in air.
• Rietveld refinements of high quality powder XRD show good convergences.
• Ca1−xEuxBaZn2+xGa2−xO7 all crystallize in the space group P63mc.
• Luminescent spectra of Eu3+ show no quenching effect up to x=0.24.
• Optical band gaps for CaBaZn2Ga2O7 are estimated to be 3.8 eV.

New “114” oxides Ca1−xEuxBaZn2+xGa2−xO7 (x≤0.24) were synthesized by solid state reaction. Rietveld refinements were performed on high quality powder XRD data in the space group P63mc. Zn2+ and Ga3+ co-occupy T1 and T2 positions, which are both in tetrahedral coordinated environment. Comparing the host compound, O3 moves towards T2 cation as much as 0.08 Å when x=0.24. It is the most observable structural change during the substitution. By comparing the structures of CaBaZn2Ga2O7 (P63mc) and CaBaCo4O7 (Pbn21), we find that smaller cations in tetrahedral sites would lead to a lower symmetry in “114” oxides. Luminescent spectra show the noncentrosymmetric coordination of Eu3+, and the f–f excitations are comparable to CT-excitation. No concentration quenching was observed up to x=0.24. The optical band gaps were estimated to be 3.8 eV for Ca1−xEuxBaZn2+xGa2−xO7 (x=0, 0.16).

Reitveld refinements show Ca1−xEuxBaZn2+xGa2−xO7 all crystallize in P63mc. By Eu3+-doping, O3 show the most obvious movement (~0.08 Å) along the c-axis. Figure optionsDownload as PowerPoint slide