Hongyu Chen,Yunfei Wang,Jianing Wang,Yajuan Wang,Wenyan Liu
In recent years, CuInS 2 quantum dots have shown great potential for various applications due to their wide excitation wavelength range, symmetric emission wavelength range, long fluorescence lifetime and optical stability. However, the high cost of indium (In) limits its commercialization. In this study, we partially substituted the expensive In element with more affordable and abundant aluminum (Al) to reduce the cost of CuInS 2 quantum dots. CuInS 2 , CuAlInS, CuInS 2 /ZnS and CuAlInS/ZnS core/shell quantum dots were synthesized using one-pot method. Due to the incorporation of Al, their photoluminescence (PL) spectra exhibit a blue shift of about 5 nm. A time-resolved PL measurement indicated that the PL lifetime of the quantum dots was a characteristic feature of three dominating transitions from the conduction band to surface defect level, from the conduction band to an acceptor level, and from the donor level to an acceptor level. The temperature-dependent PL proves that after the introduction of Al, the FWHM of quantum dots does not show significant broadening with increasing temperature. Finally, CuInS 2 /ZnS and CuAlInS/ZnS quantum dot phosphor LEDs are produced. The brightness of the CuAlInS/ZnS quantum dot phosphor LED is slightly higher than that of CuInS 2 /ZnS quantum dot phosphor LEDs. The red-emitting CuAlInS/ZnS quantum dot phosphor LED with easy fabrication and no need for encapsulation can compensate for the lack of red light in warm white LED applications in future research.
Jiang L.,Zou Z. W.,Pei Q. M.,Zheng D. S.,Li F. S.,Tian Y. H.
Re 2 Mg(Ni 0.7 − x Co 0.2 Mn 0.1 Al x ) 9 ( x = 0‒0.04) alloys are prepared by induction melting, and the influence of the partial substitution of Ni by Al on the structure, hydrogen storage, and electrochemical properties of the alloys are investigated systematically. These alloys mainly consist of two main phases with LaNi 5 phase and (La,Mg) 2 Ni 7 phase, and minor LaNi 2 phase. The pressure-composition isotherms shows that, with Al content increasing in the alloys, the maximum hydrogen storage capacity decreased from 1.16 wt% ( x = 0) to 0.99 wt% ( x = 0.04). The changes of enthalpy and entropy reveal that the thermodynamic stability and the disordered degree of the hydride alloys increase with the Al addition. Results of electrochemical studies indicate that the substitution of Al for Ni can noticeably improve the cycle stability of the alloy electrode. The capacity retention after 80 cycles is enhanced from 63.6% ( x = 0) to 76.5% ( x = 0.04). However, the maximum discharge capacity of the alloys decreases. The Re 2 Mg(Ni 0.7 − x Co 0.2 Mn 0.1 Al x ) 9 ( x = 0‒0.04) alloys exhibit excellent dischargeability.
A high remanence ratio of hexagonal barium ferrite film is urgently needed for self-biased microwave devices. In this work, the aluminum-substituted hexagonal barium ferrite films (BaFe (12−x) Al x O 19 ) with different substituting concentrations (x = 0, 1.5, 2, 2.5, 3) were deposited on the Al 2 O 3 substrate by pulsed laser deposition method using self-sintered BaFe (12−x) Al x O 19 target. Firstly, the targets with different Al concentrations were sintered by the solid phase method and exhibited high dense, uniform microstructure, and high purity. Then, the influence of the Al ions concentration on the crystal structure, morphology, and magnetic and microwave properties of BaFe (12−x) Al x O 19 films was studied in detail. Structural characterizations confirm that the Al prefers to substitute for 2a, 4f2 and 2b sites and promotes the grain (formed as single-domain) orientation growth, which results in a decrease in the saturation magnetization, an increase of remanence ratio and anisotropy field. Consequently, a high remanence ratio of 95 % was obtained for BaFe (12−x) Al x O 19 film at x = 3, and also displays a high anisotropy field (27.7 kOe), a low saturation magnetization (1758 G) and an appropriate ferromagnetic resonance linewidth (～436 Oe), which can be applied in self-biased devices.
危险品化学品经营许可证（带存储）