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To develop new phosphor materials for optical temperature sensing application, a series of Yb3+-Tb3+ and Eu3+ doped Ca2Gd8(SiO4)6O2 (CGS) phosphors were designed by solid-state reaction method. Upon 980 nm excitation, the green emission of Tb3+ was observed in the CGS:0.8Yb3+, xTb3+ (0.08 ≤ x ≤ 1.2) phosphors, which could be mainly owing to the cooperative energy transfer from Yb3+ to Tb3+. The corresponding upconversion (UC) luminescence mechanism was studied by using the dependence of UC emission intensity on excitation powder. The temperature-dependence indicates that the ratio of the Tb3+ emission intensities of I5D4 and I5D3 changes with temperature, which shows a linear relationship. The high absolute sensitivity was achieved to be about 0.431 K−1. Upon 463 nm excitation, the Eu3+ 5D0,1-7FJ transitions were found in the Eu3+-activated CGS. The investigation on temperature-dependence reveals that with increasing temperature the intensities of 5D0-7FJ transitions decrease but those of 5D1-7FJ transitions increase gradually, owing to the thermally coupled 5D0 and 5D1 levels. The fluorescence lifetime based temperature sensing properties was studied in this sample. [ABSTRACT FROM AUTHOR]

Utilization of naturally occurring limonene from renewable biomass as a key starting material for the synthesis of valuable chemicals is a promising avenue to reduce both the dependence on nonrenewable fossil fuels and global CO 2 emission. Herein, we report a highly active tremella-like ZnCo 2 O 4 catalyst for the selective oxidation of limonene with molecular oxygen under mild reaction conditions. The developed ZnCo 2 O 4 catalyst exhibits an appealing reaction performance with a limonene conversion of 93.5% (reaction rate of 0.0823 mmol g cat -1 h -1 ) and selectivity of 75.8% for 1,2-limonene oxide (LO), far outperforming the monometallic oxides of ZnO and Co 3 O 4 . Detained experimental characterizations and analyses manifest that the substitution of Zn into the Co 3 O 4 framework can facilitate the formation of more unsaturated coordination sites and oxygen vacancies due to the modified chemical environment of Co atoms, inducing a beneficial synergistic intermetallic effect for the limonene oxidation catalysis.