Pohkok Ooi
材料科学技术（英文）
Polarized far infrared (FIR) reflectance technique was applied to study the optical properties of a bulk wurtzite zinc oxide (ZnO) single crystal. Room temperature polarized FIR reflectance spectra were taken at various angles of incidence, from 20° to 70°. The theoretical polarized FIR reflectance spectra were simulated based on the anisotropic dielectric function model. Good agreement was achieved between the experimental and the theoretical FIR reflectance spectra. Through this work, a complete set of reststrahlen parameters of a bulk wurtzite ZnO at the Brillouin zone centre was obtained. Additionally, other FIR optical properties such as the real and the imaginary parts of the complex dielectric function, real and imaginary parts of the refractive index, the absorption coefficient and the reciprocal of the absorption coefficient were also obtained by using numerical calculation.
关键词:
Zinc oxide
Hu Wang Juan Xie Kangping Yan Ming Duan
材料科学技术（英文）
Different morphologies of zinc oxide (ZnO), including microrods, hexagonal pyramid-like rods and flower-like rod aggregates, had been synthesized, respectively, on glass substrates by controlling the reaction conditions (such as precursor concentration, reaction time and pH value) of hydrothermal method. The morphologies of the as-obtained ZnO were observed with scanning electron microscopy and transmission electron microscopy.
Also, the crystalline natures of di®erent ZnO crystals were analyzed with X-ray diffraction. The possible growth mechanism of ZnO crystals with di®erent morphologies was discussed.
关键词:
Zinc oxide
Xianwu Xiu
材料科学技术（英文）
Transparent conducting molybdenum-doped zinc oxide (MZO) films were successfully prepared by radio frequency (RF) magnetron sputtering method on glass substrates under different substrate temperatures. The nature of MZO film is polycrystalline with hexagonal structure and a preferred orientation along c-axis. With increasing substrate temperature from room temperature to 400°C, the crystallinity of the films is deteriorated and the resistivity increases sharply due to both the decrease of carrier concentration and Hall mobility. The lowest resistivity achieved is 9.2×10-4 Ω· cm with a high Hall mobility of 30 cm2·V-1·s-1 for the film deposited at room temperature. The average transmittance in the visible range exceeds 85% for all the samples. The optical band gap decreases from 3.30 to 3.25 eV with substrate temperature from room temperature to 400°C.
关键词:
Zinc oxide
,
钼
,
衬底温度
,
磁控溅射
Vinod Kumar
,
R.G. Singh
材料科学技术（英文）
The paper has reported the structural, transport and optical properties of boron doped zinc oxide (ZnO:B) thin films grown on glass substrate by sol-gel spin coating process. It is observed from the analysis of the X-ray diffraction (XRD) results that the crystalline quality of the films is improved with increasing B concentration. A crystallite size of ~17 nm is obtained for B doped films. A minimum resistivity of 7.9×10-4 Ωcm is obtained at 0.6 at.% of B concentration in the ZnO:B films. Ionized and intragrain cluster scattering are found to dominate the scattering mechanism in ZnO:B films. Optical interference pattern in transmittance spectra shows good homogeneity with a transparency of ~88% in the visible region. The band gap of the films is increased from 3.24 to 3.35 eV with increasing B concentration. Band gap widening is analyzed in terms of Burstein-Moss shift. The origin of the broad band photoluminescence (PL) spectra is explained in terms of the intragrain cluster scattering.
关键词:
Zinc oxide
Vinod Kumar
,
R.G. Singh
材料科学技术（英文）
The paper has reported the structural, transport and optical properties of boron doped zinc oxide (ZnO:B) thin films grown on glass substrate by sol-gel spin coating process. It is observed from the analysis of the X-ray diffraction (XRD) results that the crystalline quality of the films is improved with increasing B concentration. A crystallite size of ~17 nm is obtained for B doped films. A minimum resistivity of 7.9×10-4 Ωcm is obtained at 0.6 at.% of B concentration in the ZnO:B films. Ionized and intragrain cluster scattering are found to dominate the scattering mechanism in ZnO:B films. Optical interference pattern in transmittance spectra shows good homogeneity with a transparency of ~88% in the visible region. The band gap of the films is increased from 3.24 to 3.35 eV with increasing B concentration. Band gap widening is analyzed in terms of Burstein-Moss shift. The origin of the broad band photoluminescence (PL) spectra is explained in terms of the intragrain cluster scattering.
关键词:
Zinc oxide
Jin MA
,
Xiaotao HAO
,
Shiyong ZHANG
,
Honglei MA
材料科学技术（英文）
Transparent conducting Al-doped zinc oxide (ZnO:Al) films with good adhesion have been deposited on polyimide thin film substrates by r.f. magnetron sputtering technique at low substrate temperature (25~180℃). The structural, optical and electrical properties of the deposited films were investigated. High quality films with electrical resistivity as low as 8.5×10-4 w\c·cm and the average transmittance over 74% in the wavelength range of the visible spectrum have been obtained. The electron carrier concentrations are in the range from 2.9×1020 to 7.1×1020 cm-3 with mobilities from 4 to 8.8 cm2V－1s－1 The densities of the films are in the range from 4.58 to 5.16 g/cm－3.
关键词:
Zinc oxide
,
null
,
null
王帅
,
刘海超
催化学报
doi:10.1016/S1872-2067(14)60094-2
分别采用均匀共沉淀法、沉积-沉淀法和传统的共沉淀法制备了3种具有相似组成的Cu-ZnO-Al2O3催化剂(CZA-HP, CAZ-DP和CZA-CP)；同时还采用均匀共沉淀法制备了Cu-ZnO催化剂(CZ-HP)以用于比较. X射线衍射表征结果表明,以上方法制备的Cu-Zn-Al碱式碳酸盐前体中Cu2+, Zn2+和Al3+的混合均匀程度的顺序为CZA-DP90%). Cu-ZnO-Al2O3催化剂表面单位Cu原子的本征活性顺序为CZA-DP < CZA-CP < CZ-HP < CZA-HP,与它们的氧化还原能力相一致.此外, Al2O3的添加还显著地抑制了Cu粒子在反应过程中的聚集,提高了催化剂的稳定性.经6次循环使用后, CZ-HP中Cu粒子的粒径从13.2增至45.2 nm,活性相应下降了45%；而CZA-HP中Cu粒子的粒径从8.3增至19.0 nm,活性仅下降了10%.
关键词:
甘油
,
选择性氢解
,
丙二醇
,
铜
,
氧化锌
,
氧化铝
,
碱式碳酸盐前体
,
构效关系
,
催化剂稳定性
Ali Saidi
,
Kamran Azari
材料科学技术（英文）
Industrial application of microwave, as a heating source for material processing, was reviewed. The feasibility of carbothermic reduction of zinc oxide concentrate, as well as the effect of operating parameters was investigated, using a home style microwave oven at 2.45 GHz. Zinc oxide concentrate does not effectively absorb microwave energy, while any source of carbon, which is used as the reduction agent, absorbs microwave energy very well. In this respect coke breeze was found to be the best, and thus, coke was used both as the reducing agent and the absorbent of microwave energy. It was also found that any increase in the carbon content and size, increases the reduction rate. Increasing the microwave power and the size of the sample could also increase the reduction rate. Further investigation shows that when zinc oxide is exposed to the microwave for some time, the rate of the reduction by conventional method increases.
关键词:
Microwave
,
null
,
null
