InNb 1−x P x O 4 :Eu 3+ red phosphors were synthesized by solid-state reaction and their luminescence properties were also studied through photoluminescence spectra. The excitation and emission spectra make it clear that the as-prepared phosphors can be effectively excited by near-ultraviolet (UV) 394 nm light and blue 466 nm light to emit strong red light located at 612 nm, due to the Eu 3+ transition of 5 D 0 → 7 F 2 . The luminescence intensity is dependent on phosphorus content, and it achieves the maximum at x = 0.4. Excessive phosphorus in the phosphors can result in reduction of luminescence intensity owing to concentration quenching. With the increasing content of phosphorus, the phosphors are prone to emit pure red light. This shows that the InNb 1.6 P 0.4 O 4 :0.04Eu 3+ phosphor may be a potential candidate as a red component for white light emitting-diodes.

A series of red-emitting phosphors InNbO 4 :Eu 3+ ,Bi 3+ was prepared by a high temperature solid-state reaction. The structure, size distribution and luminescence properties of the phosphors were respectively characterized by X-ray diffraction (XRD), laser particle size and molecular fluorescence spectrometer. The XRD results indicate that the phase-pure samples have been obtained and the crystal structure of the host has not changed under the Eu 3+ and Bi 3+ co-doping. The test of size distribution shows that the phosphor has a normal size distribution. The excitation spectra illustrate that the dominant sharp peaks are located at 394 nm ( 7 F 0 → 5 L 6 ) and 466 nm ( 7 F 0 → 5 D 2 ). Meanwhile, the emission spectra reveal that the phosphors excited by the wavelength of 394 nm or 466 nm have an intense red-emission line at 612 nm owing to the 5 D 0 → 7 F 2 transition of Eu 3+ . Bi 3+ doping has not changed the peak positions except the photoluminescence intensity. The emission intensity is related to Bi 3+ concentration, and it is up to the maximum when the Bi 3+ -doping concentration is 4 mol%. Due to good photoluminescence properties of the phosphor, the InNbO 4 :0.04Eu 3+ ,0.04Bi 3+ may be used as a red component for white light-emitting diodes.

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In this study, a novel negative stiffness spring is developed. The developed spring possesses the characteristics of the controllable stiffness and can be employed in vibration isolation system with a low resonance frequency. The controllable electromagnetic negative stiffness spring (CENSS) is obtained by the coaxial permanent magnets (PMs) and the circular current-carrying coils. The stiffness control is accomplished by changing the current in the coils. Furthermore, the mathematical model of CENSS is established, based on the filament method. According to the model, the relationship between the exciting current and the axial stiffness is obtained. Moreover, the influence of the structural parameters of CENSS on the magnetic force and the stiffness is analyzed. The results demonstrate that the thickness of PMs and the coils have the ability to adjust the range of the negative stiffness. Finally, performance experimental study of CENSS in the stiffness domain is carried out under different exciting currents and thicknesses. The experimental results have shown a good agreement with the model. It demonstrates that the performance of negative stiffness in CENSS can be controlled efficiently by the exciting current and optimized by the thickness.

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