Abstract
Calcium and barium zirconate powders based upon CaZrO3:Eu3 +,A and BaZrO3:Eu3 +,A (A=Li+ , Na+, K+) were prepared by combustion synthesis method and heating to ~1000 °C to improve crystallinity. The structure and morphology of materials were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results showed that CaZrO3:Eu3 +,A and BaZrO3:Eu3 +,A (A=Li+ , Na+ , K+ ) perovskites possessed orthorhombic and cubic structures, respectively. The morphologies of all powders were very similar consisting of small, coagulated, cubical particles with narrow size distributions and smooth and regular surfaces. The characteristic luminescences of Eu3+ ions in CaZrO3:Eu3+,A (A=Li+, Na+,
K+) lattices were present with strong emissions at 614 and 625 nm for 5D0→7F2 transitions with other weaker emissions observed at 575, 592, 655, and 701 nm corresponding to 5D0→7Fn transitions (where n=0, 1, 3, 4, respectively). In BaZrO3:Eu3 + both the 5D0→7F1 and 5D0→7F2 transitions at 595 and 613 nm were strong.
Photoluminescence intensities of CaZrO3:Eu3+ samples were higher than those of BaZrO3:Eu3+ lattices. This remarkable increase of photoluminescence intensity (corresponding to 5D0→7Fn transitions) was observed in CaZrO3:Eu3 + and BaZrO3:Eu3 + if co-doped with Li + ions. An additional broad band composed of many
peaks between 440 to 575 nm was observed in BaZrO3:Eu3 + ,A samples. The intensity of this band was greatest in Li+ co-doped samples and lowest for K+ doped samples.
