In situ Raman and time-resolved luminescence investigation of the local structure of ZrO 2 in the amorphous to crystalline phase transition
2012 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 31, 16776-16783 p.Article in journal (Refereed) Published
The local structure of europium doped and impregnated ZrO 2 in the amorphous state and during crystallization is investigated by in situ X-ray diffraction and in situ Raman, high-resolution transmission electron microscopy (HRTEM) and time-resolved photoluminescence spectroscopy. From Raman spectra excited at three different wavelengths (Î» ex= 488, 514, and 633 nm), both phonon modes of ZrO 2 and photoluminescence (PL) corresponding to europium electronic transitions were investigated. In the as-synthetized state, samples were X-ray and Raman amorphous with few tetragonal (also monoclinic) crystallites being observed under HRTEM microscopy. In situ XRD patterns show that all samples crystallize in the tetragonal phase around 450 Â°C. The time-resolved PL spectra of europium doped and impregnated ZrO 2 show spectral dynamics with time delay after lamp/laser pulse which is assigned to the coexistence of the different amorphous and crystalline components or unreacted europium precursor. From in situ Raman spectra, crystallization was detected at 300-350 Â°C, monitoring for the characteristic tetragonal-like 5D 0- 7F 2 emission of europium at 606 nm. The ratio of tetragonal to amorphous emission increased abruptly from ca. 2-4% at 300-400 Â°C to almost 25% at 400-450 Â°C, whereas at 500 Â°C the emission is mostly tetragonal. A similar trend was found with the ex situ calcined samples, but relative strong tetragonal emission was observed at lower temperature in the range of 350 to 400 Â°C.
Place, publisher, year, edition, pages
2012. Vol. 116, no 31, 16776-16783 p.
Europium-Doped Zirconia, X-Ray-Absorption, Stabilized Zirconia, Room-Temperature, Oxygen Diffusion, Nanocrystals, Spectroscopy, Nanoparticles, Composites, Polymorphs
IdentifiersURN: urn:nbn:se:kth:diva-101521DOI: 10.1021/jp3040538ISI: 000307264500052ScopusID: 2-s2.0-84864977120OAI: oai:DiVA.org:kth-101521DiVA: diva2:549356
QC 201209042012-09-042012-08-302012-11-01Bibliographically approved