Synthesis and Er3+ upconversion emission characteristics of calcined Er2O3-MgO-Nb2O5 phosphors for temperature sensing

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Original languageEnglish
Pages (from-to)674-683
Journal / PublicationScience of Advanced Materials
Issue number4
Publication statusPublished - Apr 2014


A number of Er2O3+MgO+Nb2O5 phosphors with different molar ratios were calcined. The crystalline phases contained in these phosphors are determined by X-ray diffraction. The results show that two solid-state reactions, namely Er2O3+Nb2O5 =2ErNbO4 and 4MgO+Nb2O5 =Mg4Nb2O9, take place, with the former tending to occur faster than the latter. The phases in the phosphors may contain two or three phases among ErNbO4, MgO, Er2O3 and Mg4Nb2O9, depending on the Nb2O5 content. The Er3+ spectroscopic features of these phosphors were investigated, providing evidence for the Er3+-related phases determined from the X-ray diffraction data. The upconversion mechanism study shows that either cooperative energy-transfer or excited-state absorption, or both, play a role in the upconversion emission, and that each fluorescence band is dominated by the emission of the ErNbO4 phase. Further study of thermal effects shows that the upconversion intensity decreases with increasing temperature, with the 560 nm emission revealing stronger temperature sensitivity than the 530 and 670 nm emissions. Mg doping adjusts the ErNbO4 phase content and hence determines the fluorescent intensity. On the other hand, the Mg presence increases the multi-phonon relaxation probability and, hence, the temperature sensitivity of upconversion intensity. Without the Mg doping, the 560 nm upconversion emission intensity reduces by 40% with the temperature increase of only 57 °C. The Mg presence leads to further reduction by as much as 65%, showing that the phosphors are promising candidates for temperature sensing. © 2014 by American Scientific Publishers.

Research Area(s)

  • Crystalline phase, Er2O3 +MgO+Nb2O5 phosphor, Er3+ upconversion emission, Temperature sensitivity

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