عنوان

Spectroscopic studies of zinc tungstate and doped zinc tungstate single crystals

Number

TLpq304065093

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Spectroscopic studies of zinc tungstate and doped zinc tungstate single crystals

General Material Designation

[Thesis]

First Statement of Responsibility

H. Wang

Subsequent Statement of Responsibility

F. D. Medina

Name of Publisher, Distributor, etc.

Florida Atlantic University

Date of Publication, Distribution, etc.

1993

Specific Material Designation and Extent of Item

241

Dissertation or thesis details and type of degree

Ph.D.

Body granting the degree

Florida Atlantic University

Text preceding or following the note

1993

Text of Note

Zinc tungstate (ZnWO4) is promising as a scintillator and laser host material. However, the presence of color centers limit its applications. It has been found that special annealing techniques or doping with metallic elements such as Nb or Sb can bleach the samples (Zhou et al. 1986a, 1986b, 1989). A group-theoretical analysis of the characteristic lattice vibrational modes for ZnWO4 single crystals is given. The mode assignments have been made. The temperature dependence of the Raman spectra has been obtained experimentally in various polarization geometries. Anharmonic contributions and interactions between phonons are discussed. Photoluminescence studies of ZnWO4 (colored, color-free), ZnWO4:Nb and ZnWO4:Sb have been carried out in the temperature range from 11 to 430 K. All samples show the blue emission band. An IR emission band with a zero-phonon line (ZPL) has been found in ZnWO4 colored samples only. The lineshape function of the emission bands has been theoretically studied and compared with the experimental results. Radiative, non-radiative and multiphonon transitions have been investigated in the thermal quenching model. The temperature dependences of the intensity, the frequency and the linewidth of the ZPL have been studied. Using the Single Configurational Coordinate model, the linear coupling between electrons and phonons has been analyzed. The quadratic coupling of electrons and phonons has been studied in the Debye approximation. The coupling of electronic transitions to normal vibrational modes, pseudo-localized vibrational modes and localized modes is also discussed.

Applied sciences

Condensation

Optics

photoluminescence

Pure sciences

zinc tungstate

F. D. Medina

H. Wang

Electronic name

p

[Thesis]

276903

a

Y