K. Smits , L. Grigorjeva , D. Millers, A. Sarakovskis, J. Grabis, W. Lojkowski
The studies of ZrO2 and yttrium stabilized ZrO2 nanocrystals luminescence as well as yttrium stabilized
single crystal luminescence and induced absorption showed that the intrinsic defects are responsible
for luminescence at room temperature. These defects form a quasi-continuum of states in ZrO2 band
gap and are the origin of the luminescence spectrum dependence on the excitation energy.
Luminescence centers are oxygen vacancies related but not the vacancies themselves. At room
temperature, in ZrO2, deep traps for electrons and holes exist. The oxygen vacancies are proposed to
be the traps for electrons.
Journal of Luminescence 131 (2011) 2058–2062
Krisjanis Smits , Larisa Grigorjeva a, Donats Millers , Anatolijs Sarakovskis , Agnieszka Opalinska ,
Janusz D. Fidelus , Witold Lojkowski
The luminescence properties and crystalline structure of ZrO2:Eu nanocrystals doped with different concentrations
of Eu were studied. Luminescence from the Eu2+ state was not observed even if the electrons
and holes were created up to 1019 cm3; thus it was suggested the Eu3+ was not an efficient trap for
electrons possibly due to Eu3+ negative charge relative to the crystalline lattice. The mutual interaction
between Eu3+ ions was not strong up to 5 at.% concentration. The stabilization of ZrO2 tetragonal as well
as cubic structure by Eu3+ is possible.
Optical Materials 32 (2010) 827–831
L. Grigorjeva, D. Millers, A. Kalinko, V. Pankratov, K. Smits
The nanostructured oxide materials such as ZnO, ZrO2, and Y3Al5O12 (YAG) are perspective materials for transparent scintillating and/or
laser ceramics. The luminescence properties of single crystals, nanopowders and ceramic were compared. Nominally pure and rare-earth doped
nanopowders and ceramics have been studied by means of time-resolved luminescence spectroscopy.
The fast blue luminescence band was studied in ZnO ceramics sintering from different raw materials.
The luminescence centres of ZrO2:Y were compared in a single crystal, ceramic and nanopowder.
It is shown that ceramic sintering parameters have a strong influence on time-resolved luminescence characteristics in cerium-doped YAG.
Journal of The European Ceramic Society
Janusz D. Fidelus and Witold Łojkowski, Donats Millers, Krisjanis Smits and Larisa Grigorjeva
Abstract It was shown that ZrO2 nanopowders and
nanoceramics can be used as an optical oxygen sensor,
where the luminescence signal is proportional to the
partial oxygen pressure in gases. The nanopowders were
obtained in a hydrothermal microwave driven process
followed by annealing at 750oC. Nanoceramics were
obtained by sintering at pressures up to 6 GPa and at
250oC so that grain growth did not occur. Luminescence
of both materials depends linearly on the oxygen content
in nitrogen-oxygen mixtures for 2.1% – 25 vol% oxygen
content. For luminescence excitation using a laser beam,
the luminescence intensity decreases as oxygen pressure
increases. For excitation with an electron beam, the
opposite effect is observed – the lower the oxygen
pressure, the lower the luminescence signal. The
experimental results are explained in terms of
luminescence centers being distorted lattice sites close to
Proceedings of IEEE Sensors 2009