Callaghan Innovation Research Papers

Back to Research Papers

TitleRare-earth-size effects on the thermoluminescence and second-harmonic generation
Publication TypeJournal Article
Year of Publication2001
AuthorsTownsend, P.D., Jazmati A.K., Karali T., Maghrabi M., Raymond S.G., and Yang B.
JournalJournal of Physics Condensed Matter
Pagination2211 - 2224
Date Published2001
ISSN09538984 (ISSN)
KeywordsCrystal defects, Crystal lattices, High temperature effects, Ions, Lattice strain, Rare earth elements, Rare earth size effect, Second harmonic generation, Strain, Substitution reactions, Thermoluminescence
AbstractThe substitution of rare-earth ions into insulating host crystals introduces lattice strains and, for non-trivalent sites, a need for charge compensation. Such effects alter the site symmetry and this is reflected in properties such as the wavelength, linewidth, lifetime and relative intensity of the rare-earth transitions. Equally clear, but less well documented, is the influence on second-harmonic generation (even from cubic crystal lattices). For example, in bismuth germanate, second-harmonic generation efficiency varies by factors of more than 100 as a result of different rare-earth dopant ions. The ions are variously incorporated as substitutional ions, pairs, clusters, or even as precipitates of new phases, but the detailed modelling is often speculative. This article summarizes some recent studies which explore the role of rare-earth ions in thermoluminescence and second-harmonic generation. There are numerous differences in glow peak temperature, for nominally the same defect sites, which are thought to indicate charge trapping and recombination within coupled defect sites, or within a large complex. Size and cluster effects can be modified by heat treatments. This review considers the similarity and trends seen between numerous host lattices which are doped with rare-earth ions. For thermoluminescence there are trends in the variation in glow peak temperature with ion size, with movements of 20 to 50 K. Examples are seen in many hosts with extreme effects being suggested for zircon, with peak shifts of 200 K (probably from precipitate phases).

Back to top