Study on the observation of Eu2+ and Eu3+ valence states in low silica calcium aluminosilicate glasses

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The optical, magnetic and structural properties of Eu doped low silica calcium aluminosilicate glasses were investigated. The optical absorption coefficient presented two bands at 39 246 and 29 416 cm(-1), which were assigned respectively to the 4f(7) (S-8(7/2)) -> 4f(6) (4F(J)) 5d (T-2g), and 4f(7) (S-8(7/2)) -> 4f(6) (4F(J)) 5d (E-g) transitions of Eu2+. The fluorescence measured at 300 K on a sample doped with 0.5 wt% of Eu2O3 exhibited a broad band centered at 17 350 cm(-1), which is attributed to the 4f(6)5d -> 4f(7) transition of Eu2+, whereas the additional peaks are due to the D-5(0) -> F-7(J) (J = 1, 2, 4) transitions of Eu3+. From magnetization and XANES data it was possible to evaluate the fractions of Eu2+ and Eu3+ for the sample doped with 0.5 and 5.0 wt% of Eu2O3, the values of which were approximately 30 and 70%, respectively.225Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP