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In this work, MgGeO 3 :Pr3+ system is prepared by high-temperature solid phase method under the condition of different temperature and Pr content. MgGeO 3 :Pr3+ could emit 622 nm (red), 716 nm (red), 903 nm (NIR) and 1081 nm (NIR) lights under the external excitation of 251 nm and 425–500 nm. Due to the different excitation wavelengths, MgGeO 3 :Pr3+ has completely different electronic transition paths, resulting in a much larger emission intensity under 251 nm excitation than that excited by 425∼500 nm. When the incident light wavelength is 251 nm, the excitation process is VB→1D 2 level of Pr3+, and the emission is due to transition of 1D 2 →3H 4 , 1D 2 →3H 5 , 1D 2 →3H 6 (3F 2) and 1D 2 →3F 3,4. When the wavelength of incident light is 425∼500 nm, the excitation process is 3H 4 →CB, the emission is CB→1D 2 , and then 1D 2 →3H 4 , 1D 2 →3H 5 , 1D 2 →3H 6 (3F 2) and 1D 2 →3F 3,4. At the same time, the emission spectrum and X-ray diffraction measurements show that the most fundamental factor determining the emission intensity of the sample is the concentration of the luminescent center (Pr3+ that can emit light) in the MgGeO 3 grain. Increasing the sintering temperature and Pr element content in raw materials can increase the of Pr3+ concentration in the grain (increase the concentration of the luminescent center). However, if the concentration of Pr3+ in the grain is too high, Pr3+ would lose the function of the luminescence center, resulting in a decrease in the concentration of the luminescence center, thereby reducing the luminescence intensity. [ABSTRACT FROM AUTHOR]

The iron-coordinated polyaniline (PANI-Fe) integrated nanomaterials was prepared by chemical oxidative and in-situ electrochemical polymerization, which was applied to supercapacitor electrodes. The N–Fe coordination bond is formed between FeCl 3 and the N of quinone diimine to enhance the interaction of the polyaniline molecular chain. The PANI-Fe electrode material forms a crosslinked porous fiber framework through two-step oxidation, which greatly improves the energy storage capacity of PANI-Fe. PANI-Fe achieves higher capacitance of 642 F g−1 at 1 A g−1 than PANI of 310 F g−1, and maintains high capacitance retention of 82.4 % when the current density increases from 1 to 10 A g−1. According to first-principles calculations, the Fermi energy (N(E)) of PANI-Fe drop down to 0.265 eV from 0.901 eV of PANI, which proves that its conductivity is improved. The change of the electrostatic potential of PANI-Fe indicates that the formation of the N–Fe coordination bond can improve the carrier transport behavior. PANI-Fe has a smaller HOMO-LUMO energy gap than PANI, indicating that the formation of N–Fe coordination bonds can increase the electrical activity of PANI. [ABSTRACT FROM AUTHOR]