Nanocomposites and nanomaterials

Structural investigations of the BaGa2O4 ceramics 
doped with Eu3+ ions 
A. Luchechko1, Yu. Kostiv2, H. Klym2, A. Ingram3, 
I. Karbovnyk1, O. Kravets4, O. Zaremba1

1Ivan Franko National University of Lviv, 
Tarnavskogo str., 107, Lviv-79017, Ukraine
2Lviv Polytechnic National University, Bandery str., 12, Lviv-79013, Ukraine 
E-mail: yura.kostiv@gmail.com
3Opole University of Technology, Ozimska str., 75, Opole- 45370, Poland
4 Lviv Polytechnic National University, Bandery str., 12, Lviv-79013, Ukraine 
E-mail: halyna.i.klym@lpnu.ua; klymha@yahoo.com 

The BaGa2O4 ceramics are perspective materials for different applications, for example, in optoelectronic devices, as a potential candidate for secondary electron emission coatings in plasma display panels, for proton ceramic fuel cells, etc. Doping of BaGa2O4 ceramics by rare-earth ions results in modification of their structural properties. In this work we analyzed phase composition, microstructure and free volumes in the BaGa2O4 ceramics with different amount of Eu3+ ions.
Samples of BaGa2O4 ceramics were obtained by solid-state reaction method from BaCO3 and Ga2O3 components with purity of 99.99%. Powders with 0, 1, 3 and 4 mol.% of Eu2O3 (99.99%) were mixed in an agate mortar for 6 h with further pressing in a steel mold. Prepared pellets were annealed at 1200 ºC for 12 h in air. After that, the annealing of ceramic samples was carried out at 1300 ºC for 4h. 
It is shown that BaGa2O4 ceramics are characterized by branched structure of grains, grain boundaries and pores. Base un-doped BaGa2O4 ceramics contain three phase, samples with 3 and 4 mol.% of Eu2O3 are two-phases (BaGa2O4 and Eu3GaO6 phases), while BaGa2O4 ceramics with 1 mol.% of Eu2O3 contain only one (Ba,Eu)Ga2O4 phase on own structural type. Free volume and nanopores were investigated by positron annihilation lifetime spectroscopy method using three- and four component fitting procedures. It is shown, that radius of nanopores calculated within Tao-Eldrup model from lifetime of the third component are near 0,3 nm.

1.	Kodu M., et al. Pulsed laser deposition of BaGa2O4 // Applied Physics A, 2008, 93(3), 801-805.