Junhua Xi

Enhanced performance of nano-Bi2WO6-graphene as pseudocapacitor electrodes by charge transfer channel.

The nano-Bi2WO6/reduced graphene oxide composite obtained by a simple hydrothermal reaction demonstrates a larger specific capacitance of 922 F/g at a charge and discharge currents of 3 A/g with longer cycle life. The As comparison, pristine Bi2WO6 nanoparticles have poor specific capacitance of 574 F/g at a charge and discharge currents of 2 A/g with weak cycle life. Though analyzing the Cyclic voltammetry curves, it is found that there are two oxidation reaction occurring in the materials: oxidation of Bi (III) to Bi (IV) and Bi (III) to Bi (V). The oxidation of Bi (III) to Bi (IV) is reversible while Bi (III) to Bi (V) will cause nonreversible destroy on structure. In this nano-Bi2WO6/reduced graphene oxide composite, graphene with well conductivity will enhance the electrically conducting as charge transfer channel, so that electrons will be transfer much faster in oxidation and most Bi (III) is oxidized to be Bi (IV) which ensure larger specific capacitance and long cycle life. This nano-Bi2WO6/reduced graphene oxide composite has application prospect in high-performance pseudo-capacitors.

STUDIES ON STRUCTURAL AND RESISTIVE SWITCHING PROPERTIES OF Al/ZnO/Al STRUCTURED RESISTIVE RANDOM ACCESS MEMORY

Recently, resistive random access memory has been continuously investigated in order to replace the flash memory. In this paper, Al/ZnO/Al structured device was fabricated by magnetron sputtering and vacuum thermal evaporation. Systematic study has been conducted to explore the structural, morphological, and the resistive switching properties of ZnO films with Al metal as both bottom and top electrodes. The resistive switching mechanism of Al/ZnO/Al device was analyzed based on the above study.

UV-assisted mechanoluminescence properties of SrAl2O4:(Eu,Dy) for impact sensing

SrAl2O4:(Eu,Dy) is one of the most promising mechanoluminescence materials that have potential applications in stress sensing, lighting, imaging and energy conversion. However, the ML intensity decays with the afterglow time of SrAl2O4:(Eu,Dy), which hampers its application in the real world. Here, the mechanoluminescence property of SrAl2O4:(Eu,Dy) was investigated by impact of a load. A method was proposed to overcome the drawback of the mechanoluminescence decay behavior associated with the afterglow time. During the measurement of mechanoluminescence, continuous UV irradiation on SrAl2O4:(Eu,Dy) can effectively realize steady-state mechanoluminescence that is independent of the afterglow time. The underlying mechanism is discussed in this paper.

EFFECTS OF TiOx INTERLAYER ON RESISTANCE SWITCHING OF Pt/TiOx/ZnO/n+-Si STRUCTURES

In this paper, we fabricated Pt/TiOx/ZnO/n+-Si structures by inserting TiOx interlayer between Pt top electrode (TE) and ZnO thin film for non-volatile resistive random access memory (ReRAM) applications. Effects of TiOx interlayer with different thickness on the resistance switching of Pt/TiOx/ZnO/n+-Si structures were investigated. Conduction behaviors in high and low resistance state (HRS and LRS) fit well with the trap-controlled space-charge-limited conduction (SCLC) and Ohmic behavior, respectively. Variations of set and reset voltages and HRS and LRS resistances of Pt/TiOx/ZnO/n+-Si structures were investigated as a function of TiOx thickness. Switching cycling tests were attempted to evaluate the endurance reliability of Pt/TiOx/ZnO/n+-Si structures. Additionally, the switching mechanism was analyzed by the filament model.

Effects of boric acid on structural and luminescent properties of BaAl2O4:(Eu2+, Dy3+) phosphors

Eu2+/Dy3+-codoped BaAl2O4 phosphors were prepared by conventional solid-state reaction with boric acid flux. The effects of boric acid on structural and luminescent properties of BaAl2O4:(Eu2+, Dy3+) were investigated. The crystallinity of BaAl2O4 improved with increasing amount of H3BO3. Incorporation of Eu2+ and Dy3+ ions into effective lattice sites was promoted by H3BO3 addition. As a result, Eu2+ emission in BaAl2O4 was greatly enhanced by H3BO3, and the duration of persistent luminescence increased with the amount of H3BO3. However, the decay lifetime of persistent luminescence was not strongly influenced by the amount of H3BO3.