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Luminescence of ZrO2 and ZnO nanocrystals

Donats Millers 2Larisa Grigorjeva 2Witold Łojkowski 1Agnieszka Opalińska 1Tomasz Strachowski 

1. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
2. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia


The luminescence of ZrO2 undoped and Pr doped different size nanocrystals has been studied within temperature range 300-800K. Luminescence of ZnO nanocrystals was studied in the range 85-500K.
Two main luminescence bands at ~1.9 eV and ~2.75 eV were observed in all undoped ZrO2 nanocrystals at RT. The intensity of luminescence at 2.75 eV strongly depends on temperature due to two reasons - temperature quenching of luminescence and reduction of the number of luminescence centers. Annealing of nanocrystals at 800K in the vacuum changes the luminescence spectrum. Band at ~2.75 eV diminish completely whereas band at ~ 1.9 eV survived.
It is suggested that the Zr-oxygen complex is responsible for luminescence band at ~2.75 eV and the high stability defect can account for the luminescence band at ~1.9 eV. The weak luminescence is observed at 1.9 eV even at 800K. The decay of luminescence is fast for both bands at RT. Close to 90% from the luminescence total intensity decays within 60ns, however a weak slow decaying component at 2.75 eV is observed also.
The luminescence band at ~2.75 eV is strongly suppressed in ZrO2:Pr due to effective energy transfer from intrinsic excitations to Pr and the luminescence band at ~1.9 eV became dominant in doped nanocrystals. The decay of this luminescence band after excitation pulse reveals a fast stage (70% from initial intensity decays during 50ns) followed by slower one extending to the microsecond range.
ZnO nanocrystals at 85K shows the known luminescence bands peaking at ~3.4 eV (excitons, bound excitons) and at ~2.0 eV (recombination at defect states). The luminescence intensity dependence on temperature is different for 3.4 eV and 2.0 eV band, however both bands were observable at RT. It is pointed out that the ZnO nanocrystals produced by different methods shows differences in luminescent properties.


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Presentation: oral at E-MRS Fall Meeting 2003, Symposium F, by Donats Millers
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-27 18:26
Revised:   2009-06-08 12:55