Wydział Chemii

Małgorzata Puchalska

Adam Watras

2016

Journal of Solid State Chemistry

238

259-266

10.1016/j.jssc.2016.03.031

Naukowa

Angielski

Artykuł

We present a detailed analysis of luminescence behavior of singly Nd³⁺doped and Nd³⁺, Na⁺co-doped calcium aluminates powders: Ca_1−xNd_xAl₄O₇and Ca_1−2xNd_xNa_xAl₄O₇(x=0.001-0.1). Relatively intense Nd³⁺luminescence in IR region corresponding to typical⁴F_3/2→⁴I_J(J=9/2-13/2) transitions with maximum located at about 1079nm was obtained in all samples on direct excitation into f-f levels. The effect of dopant concentration and charge compensation by co-doping with Na⁺ions on morphology and optical properties were studied. The results show that both, the Nd³⁺concentration and the alkali metal co-doping affected the optical properties but had no influence on the powders morphology. The studies of luminescence spectra (298 and 77K) in a function of dopant concentration showed an increasing distortion of the local symmetry of Nd³⁺with raising activator content due to certain defects created in the crystal lattice. On the other hand Na⁺addition led to significant narrowing of absorption and luminescence bands and also a reduction of the number of their components, showing smaller disturbance of Nd³⁺ions local symmetries. Consequently, charge compensated by Na⁺co-doping materials showed significantly enhanced Nd³⁺luminescence. The decrease of emission intensity and luminescence lifetimes with increase of activator concentration was attributed mainly to phonon-assisted cross-relaxation processes between Nd³⁺ions. Analysis with Inokuti-Hirayama model indicated dipole-dipole mechanism of ion-ion interaction. Na⁺addition led to much smaller concentration quenching due to smaller clustering of dopant ions in CaAl₄O₇lattice.

Calcium aluminate, Enhanced Nd3+ luminescence, charge compensation, absorption spectra, decay kinetics

http://dx.doi.org/10.1016/j.jssc.2016.03.031

http://www.elsevier.com