XueYing Zhang

p-type conduction in wide-gap Zn1−xMgxO films grown by ultrasonic spray pyrolysis

p-type Zn1−xMgxO films doped with N and Al have been deposited by means of introducing Mg into p-type N- and Al-doped ZnO films using ultrasonic spray pyrolysis (USP) method. The structure of the films is confirmed by x-ray diffraction. Hall-effect measurements indicate that the p-type Zn1−xMgxO film shows a low resistivity of 6.4×10−2Ωcm, high mobility of 11.7cm2∕Vs and high carrier concentration of 8.31×1018cm−3 at room temperature. Furthermore, the optical absorption edge and photoluminescence (PL) peak of p-type Zn1−xMgxO film shift to a shorter wavelength of 356nm while maintaining excellent electrical performances. The blueshift extent of the film based on p-type ZnO film was not as distinct as compared to that of Zn1−xMgxO film based on pure ZnO film, perhaps owing to the variations in the effectiveness of Mg incorporation in the p-type Zn1−xMgxO film and in the Zn1−xMgxO film.

Self-assembly of Ag∕SiOx spherules in triangular pattern on strained surface of primary particles

Spontaneous emergence of nanoscaled structures provides a potential alternative to the conventional bottom-up and top-down fabrication techniques. By a two-step thermal evaporation of mixed Ag2O and SiO2 powder onto sapphire substrate, concentric Ag∕SiOx spherules were assembled into a triangular pattern upon cooling on the spherical surface of large particles, which, of generally a few microns in dimension, were primarily grown with the substrate held at 1270K. The occasional presence of pentagon or heptagon defect, as required by the spherical geometry of the primary particle, was also recognized. Strain field in the oxide shell arising from expansion mismatch with the silver core seeds the subsequent nucleation events. The triangular pattern of the secondary nanoparticles can be accounted for with a minimized strain energy in the spherical surface. The self-assembled structure of striking uniformity is promising for the generation of a large family of building blocks for device production.

Blends of pre‐irradiated polypropylene powder and syndiotactic 1,2‐polybutadiene: isothermal and nonisothermal crystallisation kinetics

Purpose – The purpose of this paper is to study the isothermal and nonisothermal crystallisation kinetics of pure polypropylene (PP), 1 kGy pre‐irradiated PP and 1 kGy pre‐irradiated PP/syndiotactic 1,2‐polybutadiene (s‐1,2 PB) (90/10) blends by differential scanning calorimetry.Design/methodology/approach – The Avrami equation, modified Avrami equation, Ozawa equation and the treatment by combining the Avrami and Ozawa equation were used to analyse the isothermal and nonisothermal crystallisation of various samples.Findings – The s‐1,2 PB acted as a heterogeneous nucleation agent during the crystallisation of the PP/s‐1,2 PB blends and accelerated the crystallisation rate. The Avrami exponent n of the blends implied that the isothermal crystallisation kinetics of the blends followed a three‐dimensional growth via heterogeneous nucleation. The modified Avrami equation was limited to describe the nonisothermal crystallisation process of pure PP and 1 kGy pre‐irradiated PP, but it was successful for the ble...

Experimental Study of Two-alpha Emission from High-lying Excited States of 17,18 Ne

The experiments of two-alpha emission from Ne-17,Ne-18 excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of Ne-17 at the energy of 49.9 MeV/u and Ne-18 at 51.8 MeV/u bombarded a Au-197 target to populate excited states of Ne-17,Ne-18 via Coulomb excitation. Complete kinematics measurements were achieved by the detectors of a silicon strip and CsI+PIN array. The experimental results combined with simple MC simulations show the characteristic of sequential two-alpha emission via O-14 excited states for Ne-18. The results of two-alpha emission from Ne-17 are preliminary and need further analyses.