Intrinsic defect related luminescence in ZrO2

The studies of ZrO 2 and yttrium stabilized ZrO 2 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 ZrO 2 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 ZrO 2 , deep traps for electrons and holes exist. The oxygen vacancies are proposed to be the traps for electrons.

Luminescence Properties and Energy Transfer Processes in Nanosized Cerium Doped YAG

Luminescence properties of cerium doped Y3Al5O12 (YAG) nanocrystals in form of nanopowders and nanoceramics have been studied. The comparative analysis of luminescence characteristics for nano- and single-crystals has been done. It was detected that an excitonic mechanism of the energy transfer from the host lattice to cerium ions does not work in nanopowders and nanoceramics. It was also shown that antisite-related and self-trapped exciton-related luminescence bands are suppressed strongly in nanopowders, and it can be excited only under certain circumstances. These bands practically disappeared in the nanoceramic samples. It was suggested that nanoparticle's surface, which is an efficient…

Luminescence Properties of ZnO Nanocrystals and Ceramics

The luminescence excitation spectra, luminescence spectra and the nanosecond-scale decay kinetics were studied. The ZnO and ZnO:Al nanopowders were prepared by vaporization-condensation in a solar furnace using different raw powders: commercial, hydrothermal and those obtained by plasma synthesis. Exciton-phonon as well as exciton-exciton interaction processes in nanopowders, a bulk crystal and ZnO ceramics were studied and compared. The fast decay and low afterglow intensity of ZnO nanopowders and ceramics support these materials for scintillators.

Microwave-Driven Hydrothermal Synthesis of Oxide Nanopowders for Applications in Optoelectronics

Comparison of ZrO2:Y nanocrystals and macroscopic single crystal luminescence

The luminescence spectra of a tetragonally structured ZrO2:Y single crystal and nanocrystals were compared. It was found that the number of luminescence centers contributed to the spectra. The excitation of luminescence within the band gap region led to different luminescence spectra for the single crystal and nanocrystal samples, whereas recombinative luminescence spectra were the same for both samples. The origin of this difference is that in the nanocrystals, even under excitation within the band gap, charge carriers were created. Zirconium- oxygen complexes distorted by intrinsic defects were proposed to be the luminescence centres responsible for the wide luminescence band observed.

Europium doped zirconia luminescence

Abstract 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 cm−3; 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.

The time-resolved luminescence characteristics of Ce and Ce/Pr doped YAG ceramics obtained by high pressure technique

Abstract 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.

Peculiarities of luminescent properties of cerium doped YAG transparent nanoceramics

Abstract Optical and luminescence properties of transparent nanosized cerium doped Y 3 Al 5 O 12 (YAG:Ce) ceramics have been studied. YAG:Ce nanoceramics were obtained by means of low temperature and high pressure (LTHP) sintering method. Nanoceramic samples were sintered in the 2–8 GPa pressure range, whereas Ce 3+ concentration was varied in the 0.5–5 at. % range. It is shown that, in contrast to the single crystal, a strong rise of absorption coefficient was detected already at wavelength shorter than 400 nm in all nanoceramic samples studied. Furthermore, in nanoceramic samples unusual UV emission band near 3.1 eV was observed, which is not observed in the YAG:Ce single crystal. High pr…