Influence of the processing conditions and chemical environment on the crystal structures and phonon modes of lanthanide orthotantalates.

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MetadadosDescriçãoIdioma
Autor(es): dc.creatorSiqueira, Kisla Prislen Félix-
Autor(es): dc.creatorCarvalho, Géssica Borges de-
Autor(es): dc.creatorDias, Anderson-
Data de aceite: dc.date.accessioned2025-08-21T15:06:51Z-
Data de disponibilização: dc.date.available2025-08-21T15:06:51Z-
Data de envio: dc.date.issued2017-05-22-
Data de envio: dc.date.issued2017-05-22-
Data de envio: dc.date.issued2011-
Fonte completa do material: dc.identifierhttp://www.repositorio.ufop.br/handle/123456789/7771-
Fonte completa do material: dc.identifierhttp://pubs.rsc.org/en/content/articlepdf/2011/dt/c1dt10783f-
Fonte completa do material: dc.identifierhttps://doi.org/10.1039/c1dt10783f-
Fonte: dc.identifier.urihttp://educapes.capes.gov.br/handle/capes/1002684-
Descrição: dc.descriptionLanthanide orthotantalates RETaO4 (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) were synthesized by solid-state reaction in optimized conditions of temperature (1300 ◦C) and time (up to 14 h) to yield crystalline materials. The crystal structures of the obtained compounds were investigated by X-ray diffraction and Raman scattering. All the samples exhibited monoclinic structures, but with different arrangements as a function of the ionic radius of the rare-earth metal occupying the A-site. For compounds with the largest ionic radii (La–Pr), the ceramics crystallized in the monoclinic structure, P21/c (C52 h, #14, Z = 4), while the compounds with intermediate ionic radii (Nd–Tb) exhibited the fergusonite M-type structure, I2/a (C62 h, #15, Z = 4). Samples with the smallest ionic radii (Dy–Lu) presented the fergusonite M¢-type structure, P2/a (C42 h, #13, Z = 2). These last two groups of compounds exhibited phase transitions, which can be related to the processing temperature. The compounds belonging to the M-type structure are stable at high temperatures, whilst materials belonging to the M¢-type structure are stable at low temperatures. The results from XRD and Raman scattering allows us to understand the differences between these two structures in terms of the vibrational-active modes assigned to each space group. Also, the Raman patterns in addition to group-theory calculations for this complete lanthanide series were reported for the first time. The experimental results are in perfect agreement with theoretical calculations: samples with P21/c (#14) structure showed 36 Raman-active modes, while both I2/a (#15) and P2/a (#13) structures exhibited 18 Raman modes.-
Formato: dc.formatapplication/pdf-
Idioma: dc.languageen-
Direitos: dc.rightsrestrito-
Título: dc.titleInfluence of the processing conditions and chemical environment on the crystal structures and phonon modes of lanthanide orthotantalates.-
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