L. Grigorjeva , D. Millers , K. Smits , A. Sarakovskis , W. Lojkowski , A. Swiderska-Sroda , W. Strek ,
Transparent Ce and Ce/Pr doped YAG ceramics were prepared under high pressures (up to 8 GPa) and relative
low temperature (450 C). Grain size of the ceramics is less than 50 nm. However unknown defects
or disorders strains on grain boundaries caused the additional absorption in these ceramics. The luminescence
intensity, spectra and the decay time dependence on pressure applied during ceramic preparation
were studied. Concentration of some intrinsic point defect was reduced under the high pressure applied
for sintering process.
It is shown that formation time of the excited state of Ce luminescence depends on the pressure applied
during ceramic sintering.
Optical Materials 34 (2012) 986–989
A.N. Trukhin, K. Smits , A. Sharakosky , G. Chikvaidze , T.I. Dyuzheva , L.M. Lityagina
It is obtained that, as grown, non-irradiated stishovite single crystals possess a luminescence center.
Three excimer pulsed lasers (KrF, 248 nm; ArF, 193 nm; F2, 157 nm) were used for photoluminescence
(PL) excitation. Two PL bands were observed. One, in UV range with the maximum at 4.770.1 eV with
FWHM equal to 0.9570.1 eV, mainly is seen under ArF laser. Another, in blue range with the maximum
at 370.2 eV with FWHM equal to 0.870.2 eV, is seen under all three lasers. The UV band main fast
component of decay is with time constant t¼1.270.1 ns for the range of temperatures 16–150 K.
The blue band decay possesses fast and slow components. The fast component of the blue band decay is
about 1.2 ns. The slow component of the blue band well corresponds to exponent with time constant
equal to 1771 ms within the temperature range 16–200 K. deviations from exponential decay were
observed as well and explained by influence of nearest interstitial OH groups on the luminescence
center. The UV band was not detected for F2 laser excitation. For the case of KrF laser only a structure
less tail up to 4.6 eV was detected. Both the UV and the blue bands were also found in recombination
process with two components having characteristic time about 1 and 60 ms. For blue band recombination
luminescence decay is lasting to ms range of time with power law decay t1.
For the case of X-ray excitation the luminescence intensity exhibits strong drop down above 100 K.
such an effect does not take place in the case of photoexcitation with lasers. The activation energies for
both cases are different as well. Average value of that is 0.0370.01 eV for the case of X-ray
luminescence and it is 0.1570.05 eV for the case of PL. So, the processes of thermal quenching are
different for these kinds of excitation and, probably, are related to interaction of the luminescence
center with OH groups.
Stishovite crystal irradiated with pulses of electron beam (270 kV, 200 A, 10 ns) demonstrates a
decrease of luminescence intensity excited with X-ray. So, irradiation with electron beam shows on
destruction of luminescent defects.
The nature of luminescence excited in the transparency range of stishovite is ascribed to a defect
existing in the crystal after growth. Similarity of the stishovite luminescence with that of oxygen
deficient silica glass and induced by radiation luminescence of a-quartz crystal presumes similar nature
of centers in those materials.
Journal of Luminescence 131 (2011) 2273–2278
L. Grigorjeva , D. Millers , K. Smits , V. Pankratov , W. Łojkowski, J. Fidelus , T. Chudoba , K. Bienkowski , C. Monty
Fast photoluminescence spectra in the spectral region of 3.1–3.45 eV in ZnO and ZnO:Al ceramics were
studied at 14 and 300 K. Ceramics with grains smaller than 100 nm were sintered from nanopowders
by high pressure (8 GPa) and low temperature (350 C). Ceramics with grain sizes 1–5 lm were sintered
at 1400 C. It is shown that excitonic luminescence spectra depend on the ceramics grain size, post preparing
annealing and doping. The excitonic luminescence decay time was faster than 2 ns and the afterglow
at 30 ns was 0.05%.
Optical Materials 2009
Krisjanis Smits, Larisa Grigorjeva, Donats Millers, Janusz D. Fidelus, and Witold Lojkowski
Abstract—The time-resolved luminescence was studied for
ZrO:Y single crystal and nanocrystals. The similar recombination
centres were found in both—single crystal and nanocrystals.
Luminescence decay is within 200 ns in nanocrystals, whereas it
extends to the microseconds in single crystal. It was shown that
the defects responsible for transient absorption were not involved
directly in radiative recombination process.
IEEE Transactions on Nuclear Science, VOL. 55, NO. 3, JUNE 2008
Digital Object Identifier 10.1109/TNS.2008.924077