Structural and Luminescent Properties of Eu~(2+)-doped Aluminates Prepared by the Sol-gel Method

摘要

Alkaline earth aluminates with the overall nominal compositions Mg_(0.5)Sr_(0.5)Al2O4 (MSA), Ca_(0.5)Sr_(0.5)Al2O4 (CSA) and Ca_(0.5)Mg_(0.5)Al2O4 (CMA) doped with 0.5 or 1 mol% of Eu~(2+) ions were obtained by a modified aqueous sol-gel method and annealed in a reductive atmosphere at 900, 1000, 1100 and 1300 °C. The sample compositions and their structures were studied by XRD employing the Rietveld method. Solid solubility was confirmed in CSA only, due to the similar ionic radii of Ca~(2+) and Sr~(2+). UV excited luminescence was observed in the blue region (k = 440 nm) in samples of CSA and CMA containing the monoclinic phase of CaAl2O4 and in the green region (k = 512 nm) in samples of MSA containing hexagonal or monoclinic phases of SrAl2O4.