Shuaiqi Zhao,Yujie Chen,Yumeng Ge,Hongbin Zhang,Kai Yang,Shiqing Xu,Xiaolei Yang,Gongxun Bai
Multicolor phosphors are crucial components in various applications such as screen displays, lighting fixtures, and color imaging technologies. Despite their widespread use, they still encounter some obstacles in multicolored luminescence. Here, we synthesized a series of Gd 2 ZnTiO 6 phosphors doped with Tb 3+ and Eu 3+ using a high-temperature solid-state reaction method. By employing Reisfeld's approximation theory and Dexter's multipolar interaction theory, we analyzed the energy transfer mechanism from Tb 3+ to Eu 3+ . Our findings indicate that the Tb 3+ to Eu 3+ energy transfer is facilitated by quadrupole-quadrupole interactions. Additionally, we assessed the thermal stability of Gd 2 ZnTiO 6 :Tb 3+ , Eu 3+ using temperature-variable emission spectroscopy across a temperature range of 303–463 K. The Gd 2 ZnTiO 6 phosphors exhibited polychromatic luminescence ranging from green (0.3632, 0.61033) to red (0.6521, 0.3481) under 381 nm excitation by adjusting the content of Eu 3+ and Tb 3+ . Consequently, the Gd 2 ZnTiO 6 :Tb 3+ , Eu 3+ phosphors exhibit excellent luminescence performance coupled with remarkable thermal stability, offering a valuable reference for the advancement of novel and robust luminescent materials.
Teng Zheng,Laihui Luo,Peng Du,Stefan Lis,Ulises R. Rodríguez-Mendoza,Víctor Lavín,Marcin Runowski
Remote temperature and pressure monitoring provides new and exciting chances to explore the variation of luminescence properties of compounds under extreme conditions. Herein, series of Mn 4+ -activated, double perovskite Gd 2 ZnTiO 6 phosphors were prepared to develop novel, bifunctional sensors of temperature and pressure. Upon 345 nm excitation, bright red emission originating from Mn 4+ is generated, and its intensity is affected by doping content, where the optimal intensity is achieved at 0.3 mol% of Mn 4+ doping. The determined concentration quenching mechanism is mainly governed by a dipole–dipole interaction. The internal and external quantum efficiencies of the synthesized phosphors are as high as 95.6% and 83.2%, respectively. Besides, the crystal-field strength and nephelauxetic effect are theoretically discussed to identify their impacts on the emission characteristics of Mn 4+ . Furthermore, via analysing the temperature-dependent emission bandwidth and lifetime, the thermometric properties of the resultant phosphors are explored, and the maximum relative thermal sensitivities for the Gd 2 ZnTiO 6 :Mn 4+ phosphor with optimal doping are 0.34% and 2.43% K −1 at 423 K, respectively. Additionally, the influence of pressure on the luminescence performance of the studied phosphors is investigated. When pressure increases, a significant red-shift of the emission band is observed, showing the pressure sensitivity is as high as 1.11 nm/GPa. Notably, during the compression and decompression processes, the prepared phosphors possess stable phase structure, which is confirmed by the pressure-dependent Raman spectra. These results suggest that the highly-efficient double perovskite Mn 4+ -activated Gd 2 ZnTiO 6 phosphors are promising bifunctional luminescent platforms, for both luminescence thermometry and manometry applications.
Herein, we report on the magnetic and magnetocaloric properties of a distorted double-perovskite, Gd2ZnTiO6, through static magnetization and heat capacity measurements, and mean-field analysis. The most pronounced isothermal magnetic entropy change −ΔSM, and relative cooling power RCP are found to be 53.5 J K−1 kg−1 and 620.6 J kg−1, respectively, under a field change of 9 T at 3.1 K with a large adiabatic temperature change Tad of 23.7 K, far exceeding the commercial cryo-coolant Gd3Ga5O12 (GGG). The results suggest that Gd2ZnTiO6 is a potential working refrigerant material for the targeted liquefaction of helium.
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