New insights on the structural and optical-vibration properties of noncentrosymmetric lanthanides pyrogermanates

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dc.creatorGuilherme Mendes Martins
dc.creatorCristiano Fantini Leite
dc.creatorLeandro Malard Moreira
dc.creatorPâmela de Oliveira Coelho
dc.creatorRoberto Luiz Moreira
dc.creatorAnderson Dias
dc.date.accessioned2023-11-30T18:06:18Z
dc.date.accessioned2025-09-09T00:41:24Z
dc.date.available2023-11-30T18:06:18Z
dc.date.issued2020
dc.description.sponsorshipCNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
dc.description.sponsorshipFAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
dc.description.sponsorshipCAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
dc.description.sponsorshipOutra Agência
dc.identifier.doihttps://doi.org/10.1016/j.ceramint.2020.02.133
dc.identifier.issn0272-8842
dc.identifier.urihttps://hdl.handle.net/1843/61575
dc.languageeng
dc.publisherUniversidade Federal de Minas Gerais
dc.relation.ispartofVibrational Spectroscopy
dc.rightsAcesso Restrito
dc.subjectMaterial cerâmico
dc.subjectRaman, Espectroscopia de
dc.subjectCompostos de lantânio
dc.subjectPropriedades magnéticas
dc.subject.otherCeramics
dc.subject.otherRaman spectroscopy
dc.subject.otherPyrogermanates
dc.subject.otherLanthanides
dc.subject.otherPhonon modes
dc.subject.otherSpin ice
dc.titleNew insights on the structural and optical-vibration properties of noncentrosymmetric lanthanides pyrogermanates
dc.typeArtigo de periódico
local.citation.epage13501
local.citation.issue9
local.citation.spage13491
local.citation.volume46
local.description.resumoA complete series of noncentrosymmetric Ln2Ge2O7 materials (Ln = lanthanides) were obtained by the molten-salts processing route. Triclinic (P1 space group) as well as tetragonal (P41212 space group) structures were observed, respectively, for the La–Eu compounds (larger ions) and for the Gd–Lu ones (smaller ions). The optical-vibration properties of both groups of samples were well investigated by Raman spectroscopy besides group-theory calculations. All the predicted phonon modes were discerned for the triclinic polar phase, while the most significant phonon modes of the tetragonal phase were determined. Beside the well-known classical dependence of the phonon wavenumbers with the ionic radii of the lanthanide (hardening of the higher-frequency modes from La to Lu), it was observed an opposite softening of the low-frequency modes within the triclinic phase (La–Eu samples). This result could be related to the contribution of the increasing lanthanide masses, added to the high lattice anharmonicity near the phase boundary between the triclinic and tetragonal phases, which can be a consequence of the strong changes in the coordination numbers of the Ln-polyhedra. Once the polar triclinic phase and the noncentrosymmetric tetragonal structure are thermally stable, and owing to the low-temperature magnetic features already shown by of non-cubic Ln2Ge2O7 compounds, we believe that some of these materials could present magnetoelectric or related properties.
local.identifier.orcidhttps://orcid.org/0000-0001-7620-6708
local.identifier.orcidhttps://orcid.org/0000-0003-0436-7857
local.identifier.orcidhttps://orcid.org/0000-0003-4207-9653
local.identifier.orcidhttps://orcid.org/0000-0001-6820-0269
local.identifier.orcidhttps://orcid.org/0000-0001-7413-1087
local.publisher.countryBrasil
local.publisher.departmentICX - DEPARTAMENTO DE FÍSICA
local.publisher.departmentICX - DEPARTAMENTO DE QUÍMICA
local.publisher.initialsUFMG
local.url.externahttps://www.sciencedirect.com/science/article/pii/S0272884220304569

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