作者机构:
[Ding, XX; Huang, ZX; Gan, ZW; Tang, C; Huang, XT; Cheng, C; Qi, SR] Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
通讯机构:
[Gan, ZW] C;Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
关键词:
Oxide;Silicon;Thin Film;SiO2;Boron
摘要:
A novel method was demonstrated to fabricate boron nitride nanotube films on silicon substrate in a location-controlled fashion. The pre-deposited SiO2 layer on the substrate controls the growth space of BN nanotubes synthesized by an ammonothermal reaction of boron and its oxide.
作者机构:
[Lu, HF] Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.;Tsing Hua Univ, Dept Phys, Beijing 100084, Peoples R China.
通讯机构:
[Lu, HF] C;Cent China Normal Univ, Dept Phys, Wuhan 430079, Peoples R China.
关键词:
noise;Fokker–Planck equation;SQUID;shunted
摘要:
An analytical expression for the stationary probability distribution of the DC superconducting quantum interference device (SQUID) with a resistively shunted inductance driven by thermal noise is derived from the two-dimensional Fokker–Planck equation. The effects on the SQUID characteristics subject to a large thermal fluctuation with a noise parameter Γ>0.20 are discussed by taking into account the thermal noise in the accuracy of numerical simulation. This theory is valid for a reduced inductance β≤1. The analytical formulae for the SQUID characteristics, e.g. the circulating current, the average voltage and the voltage modulation, are obtained and discussed. The theory shows that the voltage modulation increases with the shunted inductance more efficiently for a large inductance parameter β and small fluctuation parameter Γ.
作者机构:
[Duan, JX; Tu, PH; Huang, XT; Liu, JP; Ai, HH] Cent China Normal Univ, Dept Phys, Ctr Nanosci & Technol, Wuhan 430079, Peoples R China.
通讯机构:
[Huang, XT] C;Cent China Normal Univ, Dept Phys, Ctr Nanosci & Technol, Wuhan 430079, Peoples R China.
关键词:
Crystal morphology;Growth from solutions;Semiconducting II-VI materials;ZnO
摘要:
A convenient wet chemical method has been developed to synthesize flower-like ZnO micron-size structures composed of whiskers in large quantities at 60 °C for 24 h, employing Zn(NO3)2·6H2O, NH3·H2O as the starting materials in the presence of polyethylene glycol (PEG) and CS2. XRD result proves the formation of ZnO with wurtzite structure. Selected area electron diffraction (SAED) patterns confirm that the product is single crystal nature. The observations from SEM and TEM reveal that two kinds of products with diameter of micron size, having spheral symmetry and circumferential symmetry, are produced. The possible growth mechanism of the assembled architecture is proposed. It is found that PEG and CS2 play important roles in the morphological and structural control of ZnO microncrystallites.
作者机构:
[Gu J.; Huang X.-T.] Department of Physics, Central China Normal University, Wuhan 430079, China;Department of Physics, Tsinghua University, Beijing 100084, China;[Lu H.-F.] Department of Physics, Central China Normal University, Wuhan 430079, China, Department of Physics, Tsinghua University, Beijing 100084, China
通讯机构:
[Lu, H.-F.] D;Department of Physics, , Wuhan 430079, China
摘要:
An analysis expression for the stationary probability distribution of asymmetric superconducting quantum interference device with two Josephson junctions (dc SQUID) driven by thermal noise is derived from two-dimensional Fokker-Planck equation, where the potential condition is satisfied. Two of the three asymmetric parameters, inductance asymmetric parameter η and critical current asymmetric parameter a, can be changed in this condition, but resistance asymmetric parameter ρ cannot be changed. The "ripple" phenomenon of circulating current can disappear with the change of coefficient α. The effects of asymmetric parameters on current-voltage relationship and transfer function of dc SQUID system are also represented.
摘要:
Comparative study on the diameter distribution of MgO nanowires has been carried out. MgO nanowires could be synthesized by the direct reaction between metallic magnesium and silica, and the obtained nanowires have diameters ranging from 50 to 200 nm and lengths of several hundreds nanometers, exhibiting a straight wire. The diameter can be downscaled to smaller than 50 nm, and the nanowire exhibits a curved and twisted one-dimensional structure with lengths up to several micrometers, when a fine support catalyst was used as the reactant. The diameter-controlled growth mechanism was also explained in this work.