resumo
It was proved quite recently that luminescence thermometry may benefit from utilizing the 5d -> 4f/4f -> 4f intensity ratio of Pr(3+)transitions. This paper presents a comprehensive study of Lu-2(Ge-x,Si1-x)O-5:Pr phosphors in the full range of Ge concentrations (x= 0-1) for luminescence thermometry. Silicon substitution by germanium allows effective management of their thermometric properties through bandgap engineering. The Ge/Si ratio controls the range of temperatures within which the 5d -> 4f Pr(3+)luminescence can be detected. This, in turn, defines the range of temperatures within which the 5d -> 4f/4f -> 4f emission intensity ratio can be utilized for thermometry. Altogether, the bandgap engineering allows widening the operating range of thermometers (17-700 K), fine-tunes the range of temperatures with the highest relative sensitivity, and reduces the inaccuracy of the measurements. The kinetics of the 5d -> 4f luminescence is also controlled by bandgap engineering and can be also used for luminescence thermometry. The Lu-2(Ge-x,Si1-x)O-5:Pr phosphors were, thus, designed as dual-mode luminescence thermometers exploiting either the inter- and intra-configurational intensity ratios or the 5d -> 4f decay time. The highest relative thermal sensitivity, 3.54% K-1, was found at 17 K for Lu-2(Ge-0.75,Si-0.25)O-5:Pr and at 350 K for Lu2SiO5:Pr and it was combined with a very low (<0.03 K) temperature uncertainty. Herein, we proved that bandgap engineering is a promising and effective approach to developing high-performance luminescence thermometers.
palavras-chave
FLUORESCENCE INTENSITY RATIO; TEMPERATURE-DEPENDENCE; PR3+ LUMINESCENCE; CRYSTAL-STRUCTURE; PHOSPHORS; EMISSION; LIFETIME; ENERGY; LEVEL; CE3+
categoria
Materials Science; Physics
autores
Sojka, M; Brites, CDS; Carlos, LD; Zych, E
nossos autores
Carlos Brites
Professor associado
Luís Carlos
Professor CatedráticoProjectos
agradecimentos
This work was developed within the scope of the project financed by the National Science Centre (NCN), Poland, under grant UMO-2017/25/B/ST5/00824 and the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by Portuguese funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Financial support from FCT (PTDC/CTM-NAN/4647/2014, NANOHEATCONTROL - POCI-01-0145-FEDER-031469) is also acknowledged. E. Z. and L. D. C. are grateful to the Polish National Agency for Academic Exchange (NAWA) for support under the NAWA-Bekker PPN/BEK/2018/1/00333/DEC/1 and NAWA-Ulam PPN/ULM/2019/1/00077/U/00001 projects, respectively.