Nanoparticles of Fe-Co alloys and their oxides with the particle size below 20 nm were prepared by chemical vapor condensation process. The pure Ar, Ar+1%O2, Ar+3%O2 and Ar+6%O2 were used as carrier gases, with iron c...Nanoparticles of Fe-Co alloys and their oxides with the particle size below 20 nm were prepared by chemical vapor condensation process. The pure Ar, Ar+1%O2, Ar+3%O2 and Ar+6%O2 were used as carrier gases, with iron carbonyl and cobalt carbonyl as the precursors. XRD patterns showed that Fe-Co metallic nanoparticles were synthesized by using pure Ar as carrier gas, and only metal oxides were obtained using Ar+(>3)%O2 as carrier gas. The HRTEM images and TG-DTA curves were used to study the core-shell structure of the different nanoparticles. The nanoparticles obtained in pure Ar consist of black core and light shell with thickness of 2~4 nm. However, in the particles obtained in Ar+6%02, the oxides core with visible lattice fringes are surrounded by thin shell.展开更多
Diagnosability of a multiprocessor system is an important study topic. S. L. Peng, C. K. Lin, J. J. M. Tan, and L. H. Hsu [Appl. Math. Comput., 2012, 218（21）： 10406-10412] proposed a new measure for fault diagnosis...Diagnosability of a multiprocessor system is an important study topic. S. L. Peng, C. K. Lin, J. J. M. Tan, and L. H. Hsu [Appl. Math. Comput., 2012, 218（21）： 10406-10412] proposed a new measure for fault diagnosis of the system, which is called the 9-good-neighbor conditional diagnosability that restrains every fault-free node containing at least 9 fault-free neighbors. As a famous topological structure of intereonnection networks, the n-dimensional star graph Sn has many good properties. In this paper, we establish the 9_good-neighbor conditional diagnosability of Sn under the PMC model and MM＊ model.展开更多
In chalcogenide topological insulator materials, two types of magnetoresistance （MR） effects are widely discussed： a sharp MR dip around zero magnetic field, associated with the weak antilocalization （WAL） effect...In chalcogenide topological insulator materials, two types of magnetoresistance （MR） effects are widely discussed： a sharp MR dip around zero magnetic field, associated with the weak antilocalization （WAL） effect, and a linear MR （LMR） effect that generally persists to high fields and high temperatures. We have studied the MR of thin films of the topological insulator Bi2Te3 from the metallic to semiconducting transport regime. In the metallic samples, the WAL is difficult to identify owing to the low magnitude of the WAL compared to the samples＇ conductivity. Furthermore, the sharp WAL dip in the MR is dearly present in samples with a higher resistivity. To correctly account for the low-field MR with the quantitative theory of the WAL according to the Hikami-Larkin-Nagaoka （HLN） model, we find that the classical （linear） MR effect should be taken into account in combination with the WAL quantum correction. Otherwise, the WAL fitting alone yields an unrealistically large coefficient in the HLN analysis. This work clarifies the WAL and LMR as two distinct effects and offers an explanation for the overly large a in the WAL analysis of topological insulators in some studies.展开更多
基金the National Natural Science Foundatlon of China under projects 59725103 ,50171070.
文摘Nanoparticles of Fe-Co alloys and their oxides with the particle size below 20 nm were prepared by chemical vapor condensation process. The pure Ar, Ar+1%O2, Ar+3%O2 and Ar+6%O2 were used as carrier gases, with iron carbonyl and cobalt carbonyl as the precursors. XRD patterns showed that Fe-Co metallic nanoparticles were synthesized by using pure Ar as carrier gas, and only metal oxides were obtained using Ar+(>3)%O2 as carrier gas. The HRTEM images and TG-DTA curves were used to study the core-shell structure of the different nanoparticles. The nanoparticles obtained in pure Ar consist of black core and light shell with thickness of 2~4 nm. However, in the particles obtained in Ar+6%02, the oxides core with visible lattice fringes are surrounded by thin shell.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 61370001）.
文摘Diagnosability of a multiprocessor system is an important study topic. S. L. Peng, C. K. Lin, J. J. M. Tan, and L. H. Hsu [Appl. Math. Comput., 2012, 218（21）： 10406-10412] proposed a new measure for fault diagnosis of the system, which is called the 9-good-neighbor conditional diagnosability that restrains every fault-free node containing at least 9 fault-free neighbors. As a famous topological structure of intereonnection networks, the n-dimensional star graph Sn has many good properties. In this paper, we establish the 9_good-neighbor conditional diagnosability of Sn under the PMC model and MM＊ model.
文摘In chalcogenide topological insulator materials, two types of magnetoresistance （MR） effects are widely discussed： a sharp MR dip around zero magnetic field, associated with the weak antilocalization （WAL） effect, and a linear MR （LMR） effect that generally persists to high fields and high temperatures. We have studied the MR of thin films of the topological insulator Bi2Te3 from the metallic to semiconducting transport regime. In the metallic samples, the WAL is difficult to identify owing to the low magnitude of the WAL compared to the samples＇ conductivity. Furthermore, the sharp WAL dip in the MR is dearly present in samples with a higher resistivity. To correctly account for the low-field MR with the quantitative theory of the WAL according to the Hikami-Larkin-Nagaoka （HLN） model, we find that the classical （linear） MR effect should be taken into account in combination with the WAL quantum correction. Otherwise, the WAL fitting alone yields an unrealistically large coefficient in the HLN analysis. This work clarifies the WAL and LMR as two distinct effects and offers an explanation for the overly large a in the WAL analysis of topological insulators in some studies.
