Avci, Nursen

Poelman, Dirk

Smet, Philippe

English

Ghent University Academic Bibliography

Non-aqueous sol-gel synthesis of CaAl2O4: Eu  Nursen Avci*, Philippe Smet and Dirk Poelman  LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Gent/Belgium (*email: nursen.avci@ugent.be)  Alkaline earth aluminates MAl2O4 (M= Ca, Sr and Ba) are well-known materials due to their mechanical strength, high resistance to chemical attack, and excellent dielectric properties. In addition to these superior properties, alkaline earth aluminates doped with divalent europium show bright violet (CaAl2O4) to green (SrAl2O4) afterglow luminescence [1]. Rare earth co-doped alkaline earth aluminates combining long decay time with high initial brightness are amongst the best persistent luminescent materials [2]. To prepare them different kinds of techniques have been used such as solid state reaction, co-precipitation, microwave, Pechini, combustion and sol-gel. In these methods, sol-gel puts forwards some benefits namely relatively low preparation temperature, control of the stoichiometry with simple equipment and high homogeneity.  In this work we summarize the preparation and optical properties of CaAl2O4: Eu. CaAl2O4 with different Eu concentrations (from 0% to 3%) was prepared via non-aqueous sol-gel technique using calcium nitrate tetrahydrate (Ca(NO3)2.4H2O), aluminium sec-butoxide Al[O(CH3)CHC2H5]3), butanol (n-BuOH), acetylacetone (AcAcH) and hydrated europium nitrate. After the preparation, samples were annealed at different temperatures (from 800 to 1200oC) for 1 h in air to obtain monoclinic calcium aluminates. Subsequently to reduce Eu3+ to Eu2+ different methods were used like annealing under H2/N2 atmosphere.  In previous investigations it was suggested the strongest luminescence in this material is obtained for the monoclinic phase. The minimum reported temperature to obtain monoclinic CaAl2O4 is around 1200oC. The X–ray diffraction (XRD) spectra of undoped and doped samples reveal that the formation of monoclinic phase begins at 900oC and extra phases start to form at 1100oC (fig1).  Photoluminescence measurements show that the optimum temperature is 1000oC.  The influence of the doping concentration and the persistent luminescence properties of CaAl2O4: Eu will be reported.   Fig1. XRD spectra of undoped CaAl2O4 annealed at various temperatures. 1. J. Sanchez-Benıtez, A. de Andres, M. Marchal, E. Cordoncillo, M. Vallet Regi and P. Escribano, J. Solid State Chem. 171, 273 (2003). 2. K. Van den Eeckhout, P. F. Smet, D. Poelman, Materials  3, 2536 (2010)    T2  Oral presentation 

Non-aqueous sol-gel synthesis of CaAl2O4:Eu

https://biblio.ugent.be/publication/2141657/file/3146158.pdf

Non-aqueous sol-gel synthesis of CaAl2O4:Eu

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Ghent University Academic Bibliography