Boosted UV emission on the optically and thermally stimulated luminescence of CaB6O10:Gd,Ag phosphors excited by X-rays

Autor(es)

Franca, Leonardo V. S. ^[1] ; Baffa, Oswaldo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, FFCLRP, Dept Fis, BR-14040900 Ribeirao Preto - Brazil

• Tipo de documento: Artigo Científico
• Fonte: APPLIED MATERIALS TODAY; v. 21, DEC 2020.
• Citações Web of Science: 0

Resumo

The luminescent properties of X-ray phosphors based on optically stimulated luminescence (OSL) are quite fortuitous, since it demands the existence of both trapping and recombination (luminescent) centers. Nevertheless, lanthanide-doped materials have changed this paradigm by two main reasons: lanthanide doping provides the development of high efficient phosphors and allows for a relatively easy prediction of the energy-levels of the trapping centers involved in OSL phenomena. In view of that, this work reveals some luminescent and dosimetric properties of a phosphor never reported before, i.e., gadolinium and silver doped CaB6O10 polycrystalline samples. The phosphor synthesis followed a solid state reaction method and was optimized regarding the concentration of dopants for a better OSL response. Comparing to non-doped samples, the OSL showed an enhancement of similar to 140x when doped with gadolinium and silver. The phosphor exhibited a high UV emission under blue stimulation (475 nm), with a linear dose response for the range analyzed (1 mGy up to 2 Gy) and a minimum detectable dose of similar to 40 mu Gy. The material exhibited a fading of similar to 30% within the first 24 h after irradiation, which is attributed to shallow traps created by Ag+ incorporation. Wavelength-resolved thermoluminescence (TL) and OSL spectra revealed a sharp 317 nm emission, which is ascribed to P-6(J) -> S-8(7/2) transition of Gd3+ centers, indicating that the Gd3+ has a crucial role in the luminescence mechanisms. In addition, the OSL spectrum exhibited also a broad emission at 350 nm attributed to D-3(J), D-1(2) -> S-1(0) transitions of Ag+ centers. Insights on the luminescent processes are given, including the role of Gd3+ and Ag+ centers in the trapping and recombination processes responsible for the TL and OSL. New mechanisms of luminescent enhancement by silver incorporation are suggested. (C) 2020 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 13/07699-0 - Centro de Pesquisa, Inovação e Difusão em Neuromatemática - NeuroMat
• Beneficiário: Oswaldo Baffa Filho
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs