Papers by Author: Shuai Qin Yu

Abstract: Theoretical study on the electronic structure of small FemAln(m+n=6) clusters has been carried out at the BPW91 level, and the electronic structures, binding energy and vertical ionization potential of clusters were evaluated. For the stable clusters, the iron atoms gather together and form a maximum of Fe-Fe bonds, and the aluminum atoms locate around Fe core with a maximum of Fe-Al bonds. The binding energy and vertical ionization potential show that the Fe5Al, Fe4Al2 and Fe3Al3 clusters have higher stability, which results provide insight into the properties of iron-aluminides can be obtained from a finite size cluster model.

Abstract: Theoretical study on the geometric structures and magnetic properties of small (FeAl)n (n=1-4) clusters has been carried out at the BPW91 level. In all the (FeAl)n clusters, the iron atoms are brought together, yielding a maximum of Fe-Fe bonds, and the aluminum atoms are located around a Fe core with a maximum of Fe-Al bonds which is different the bulk ordered FeAl alloy dominated by the Fe-Al bonds. As opposed to the bulk FeAl with non-magnetic, the small nano-clusters are highly magnetic moment dominated by Fe-Fe clustering.

Abstract: Ba0.7Sr0.3TiO3 (BST) thin films have been prepared on copper foils via sol-gel method in almost inert atmosphere containing different level of oxygen which was achieved by flowing high purified argon with the varied rate from 0.3 L/min to 2.0 L/min. X-ray diffraction pattern of the BST thin film exhibits dominant perovskite phase. SEM images reveal good crystallization and much dense structure of the thin film. The BST thin film annealed at almost inert atmosphere by flowing the high purified argon at the rate of 0.5 L/min, exhibits highest dielectric constants which are 1549.65 and 1350.86 at the frequency of 10 kHz and 1 MHz, respectively. Additionally, the film also shows optimized ferroelectric behavior and low leakage current density. The mechanism of the annealing atmosphere on properties of BST thin films was investigated.