Radiation-induced defects in montebrasite: an electron paramagnetic resonance study of O- hole and Ti3+ electron centers

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dc.creatorLorena N. Dias
dc.creatorMauricio Veloso Brant Pinheiro
dc.creatorJoachim Karfunkel
dc.creatorJosé Roberto de Toledo
dc.creatorRicardo Augusto Scholz Cipriano
dc.creatorMario Luiz de Sá Carneiro Chaves
dc.creatorKlaus Wilhelm Heinrich Krambrock
dc.creatorRaphaela de Oliveira Gonçalves
dc.date.accessioned2022-11-07T17:33:35Z
dc.date.accessioned2025-09-09T00:08:54Z
dc.date.available2022-11-07T17:33:35Z
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.sponsorshipFINEP - Financiadora de Estudos e Projetos, Financiadora de Estudos e Projetos
dc.identifier.doihttps://doi.org/10.2138/am-2020-7168
dc.identifier.issn19453027
dc.identifier.urihttps://hdl.handle.net/1843/46981
dc.languageeng
dc.publisherUniversidade Federal de Minas Gerais
dc.relation.ispartofAmerican Mineralogist
dc.rightsAcesso Restrito
dc.subjectRessonância paramagnética eletrônica
dc.subject.otherMontebrasite
dc.subject.otherEPR
dc.subject.otherIrradiation
dc.subject.otherElectron-hole center
dc.subject.otherO- hole center
dc.subject.otherTi3+
dc.subject.otherColor enhancement
dc.titleRadiation-induced defects in montebrasite: an electron paramagnetic resonance study of O- hole and Ti3+ electron centers
dc.typeArtigo de periódico
local.citation.epage1059
local.citation.issue7
local.citation.spage1051
local.citation.volume105
local.description.resumoMontebrasite is a lithium aluminum phosphate mineral with the chemical formula LiAlPO4(Fx,OH1–x) and considered a rare gemstone material when exhibiting good crystallinity. In general, montebrasite is colorless, sometimes pale yellow or pale blue. Many minerals that do not have colors contain hydroxyl ions in their crystal structures and can develop color centers after ionization or particle irradiation, examples of which are topaz, quartz, and tourmaline. The color centers in these minerals are often related to O- hole centers, where the color is produced by bound small polarons inducing absorption bands in the near UV to the visible spectral range. In this work, colorless montebrasite specimens from Minas Gerais state, Brazil, were investigated by electron paramagnetic resonance (EPR) for radiation-induced defects and color centers. Although γ irradiation (up to a total dose of 1 MGy) did not visibly modify color, a 10 MeV electron irradiation (80 MGy) induced a pale greenish-blue color. Using EPR, O– hole centers were identified in both γ- or electron-irradiated montebrasite samples showing superhyperfine interactions with two nearly equivalent 27Al nuclei. In addition, two different Ti3+ electron centers were also observed. From the γ irradiation dose dependency and thermal stability experiments, it is concluded that production of O– hole centers is limited by simultaneous creation of Ti3+ electron centers located between two equivalent hydroxyl groups. In contrast, the concentration of O- hole centers can be strongly increased by high-dose electron irradiation independent of the type of Ti3+ electron centers. From detailed analysis of the EPR angular rotation patterns, microscopic models for the O- hole and Ti3+ electron centers are presented, as well as their role in the formation of color centers discussed and compared to other minerals.
local.identifier.orcidhttps://orcid.org/0000-0001-5722-6260
local.identifier.orcidhttps://orcid.org/0000-0001-9785-0279
local.identifier.orcidhttps://orcid.org/0000-0002-7562-0285
local.identifier.orcidhttps://orcid.org/0000-0003-1391-6694
local.publisher.countryBrasil
local.publisher.departmentICX - DEPARTAMENTO DE FÍSICA
local.publisher.departmentIGC - INSTITUTO DE GEOCIENCIAS
local.publisher.initialsUFMG
local.url.externahttps://pubs.geoscienceworld.org/msa/ammin/article/105/7/1051/587508/Radiation-induced-defects-in-montebrasite-An

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