Estudos de materiais dopados com íons lantanídeos para aplicações em nanotermometria
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2023-10-31
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Universidade Federal de Goiás
Resumo
Optical phenomena such as luminescence of materials depend on several
characteristics such as temperature, dopants, crystalline structure, etc.
Electromagnetic emissions from materials doped with rare-earth ions can provide
thermal information regarding the environment where these materials are inserted.
Materials with good thermal sensitivity are considered promising for the development
of technologies for nanoscale temperature measurements. In this work, nine samples
previously prepared through different synthesis routes such as sol-gel process and
modified Pechini were analyzed. The samples studied have matrices of several
compounds such as aluminum borates (Al4B2O9) monophasic and embedded in silica,
aluminum germanates (Al6Ge2O13) monophasic and embedded in silica, yttrium
borates (YBO3) and yttrium aluminum silicates (YAS). Altogether, five trivalent
lanthanide ions were used as dopants of the samples: Nd, Eu, Er, Tb and Yb. The
emission spectra of the samples were analyzed at seven different temperatures from
25 °C to 55 °C with a variation of 5 °C. Diffuse reflectance spectra were studied to
confirm the presence of ions in the matrix and enable the calculation of the energy gap
for each sample. From the emission spectrum, photoluminescent intensity ratios (RIFs)
were calculated for the calculation of relative thermal sensitivities. The sample that
showed the highest value for relative thermal sensitivity (Sr) was the one with the
composition YBO3 : Nd3+, Eu3+, Er3+, Yb3+, Tb3+ synthesized at 900°C, presenting a
value of Sr = (1,52 ± 0,20) %.K-1
in the temperature range of 35°C and 55°C.
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SILVA, D. L. Estudos de materiais dopados com íons lantanídeos para aplicações em nanotermometria. 2023. 133 f. Dissertação (Mestrado em Física) - Instituto de Física, Universidade Federal de Goiás, Goiânia, 2023.