Novel phosphor GdY2SbO7 co-dope with Eu3+ and Bi3+ for optical thermometer.

A series of GdY2SbO7:Bi3+, Eu3+ phosphors were prepared using the conventional solid-state reaction. In this study, the photoluminescence properties and temperature sensitivity of the samples were investigated. When Bi3+ and Eu3+ were codoped into GdY2SbO7, the intensity of Bi3+ decreased with increasing Eu3+ concentration, indicating a potential energy transfer from Bi3+ to Eu3+. To examine the temperature sensitivity of the sample, its emission spectrum was investigated in the range of 300-500 K. Based on different temperature dependences of Bi3+ and Eu3+, the relative sensitivity (Sr) and absolute sensitivity (Sa) of the samples were calculated using the fluorescence intensity ratio (FIR) and thermochromic methods. In FIR modes, Sr based on IEu3+/IBi3+ reached 1.26 % K-1 at 500 K, while Sr on double excitation method reached 1.36 % K-1 at 340 K. In addition, according to the thermochromic properties of GdY2SbO7:Bi3+, Eu3+ phosphor, the temperature-sensing ability of the sample was investigated, and Sr reached a maximum value of 0.5996 % K-1 at 300 K.

Enhancement of luminescence, thermal stability and quantum efficiency with Ce3+ co-doped SrMg1·06Al9·94O17:Tb3+ phosphor.

In this study, the photoluminescence properties of a series of SrMg1·06Al9·94O17 (SMAO):Ce3+, Tb3+, and SMAO:Tb3+ phosphors were investigated. At an excitation wavelength of 230 nm, the SMAO:Tb3+ phosphor emitted green light at 544 nm. When Ce3+ ions were co-doped into SMAO:Tb3+, the excitation band red-shifted from 230 to 269 nm, and the emission intensity was enhanced up to approximately 28 times compared with that of Ce3+-free SMAO:Tb3+ because of the efficient energy transfer from Ce3+ → Tb3+ in the SMAO host. Moreover, with the introduction of Ce3+, the thermal stability of the phosphors improved significantly. The luminescence intensity of the SMAO:3 mol%Tb3+ phosphor at 450 K was approximately 47% of that at room temperature. With the co-doping of Ce3+ ions, the emission intensity at 450 K was as high as 67%. The internal quantum efficiency (IQE) of SMAO:3 mol%Tb3+, 3 mol%Ce3+ increased to 55.14%. The SMAO:Tb3+,Ce3+ phosphors have potential applications in solid-state lighting.

Metallization and Electrical Transport Behaviors of GaSb under High-Pressure.

The high-pressure metallization and electrical transport behaviors of GaSb were systematically investigated using in situ temperature-dependent electrical resistivity measurements, Hall effect measurements, transmission electron microscopy analysis, and first-principles calculations. The temperature-dependent resistivity measurements revealed pressure-induced metallization of GaSb at approximately 7.0 GPa, which corresponds to a structural phase transition from F-43m to Imma. In addition, the activation energies for the conductivity and Hall effect measurements indicated that GaSb undergoes a carrier-type inversion (p-type to n-type) at approximately 4.5 GPa before metallization. The first-principles calculations also revealed that GaSb undergoes a phase transition from F-43m to Imma at 7.0 GPa and explained the carrier-type inversion at approximately 4.5 GPa. Finally, transmission electron microscopy analysis revealed the effect of the interface on the electrical transport behavior of a small-resistance GaSb sample and explained the discontinuous change of resistivity after metallization. Under high pressure, GaSb undergoes grain refinement, the number of interfaces increases, and carrier transport becomes more difficult, increasing the electrical resistivity.