Page 58 - PR 2014 2016 10 Materials and Nanotechnology

334 Materials and Nanotechnology | Progress Report

Figure 68. Structure
o CdSiO :Pr ,
3+
3
Emission spectra
and mechanism
of persistent
luminescence of
CdSiO :Pr excited
3+
3
by UV radiation.

of one and three traps for the combustion and between the band gap (Eg) value obtained from
solid state prepared materials, respectively, the the synchrotron radiation excitation spectra
method of preparation has a significant influ- and the DFT calculation was deduced to results
ence on the defect structure of the materials. from the covalent bonding in the BaAl O host.
2 4
3+
2+
BaAl O : Eu , TR and CdSiO : TR materials The XANES spectroscopy showed a predomi-
3+
2 4 3
were investigated by absorption spectroscopy nance of Eu which can be present as a result
3+
in the infrared, scanning electron microscopy , of the in situ conditions of persistent lumines-
absorption spectroscopy, X-ray structure were cence during the X-ray irradiation (Figure 68).
studied by absorption of X-rays near the edge-
XANES absorption fine structure and X-ray ex- Multiferroic properties in rare earth doped
tended - EXAFS other than electron excitation oxide thin films
and emission spectroscopy in the regions of UV
and vacuum - UV- vis and thermoluminescence. For the last few decades, the consumption of
It was also investigate the photoluminescence electronic devices and the high demand for
properties of their excitation and emission data storage have shown great opportunities
spectra, the lifetime of excited states and the to create modern technologies that assure the
positions of the ground states of the ions TR 2+/3+ worldwide needs in computing development.
in the Band Gap. Mechanisms were discussed Some multiferroic materials have been exten-
for the persistent luminescence phenomenon sively studied. The BiFeO is considered the
3
of Eu ion doped in BaAl O matrix and TR only one that has at least two ferroic at room
2+
3+
2 4
ions doped in CdSiO matrix. The mismatch temperature, so that it has received special
3

Instituto de Pesquisas Energéticas e Nucleares