VIBRATIONAL-SPECTRA AND LUMINESCENCE PROPERTIES OF LA4VBO10-EU3+

The luminescence properties of the solid solutions (La-1-x Eu-x)(4)VBO10 were investigated and compared with those of LaBO3:Eu3+. It was found that in La4VBO10 the EU(3+) ion occupies two different crystallografic sites. In the luminescence spectra both the narrow lines connected with D-5(1), D-5(0) --> F-7(j) transitions and the weak, broad band with lambda(max)=580 nm interpreted as the emission of VO4 groups are observed. Vibronic spectra associated with F-7(0) --> D-5(2) transition, which probe vibrations about rare earth element site, were also measured and compared with Raman- and IR-spectroscopy data. The results show that relatively low rate multiphonon relaxation for D-5(1) state is due to the small contribution of the berate anions to the density of phonon states near rare-earth ion.