The nano-structural Al-doped ZnO thin films of different morphologies deposited on glass substrate were successfully fabricated at substrate temperature of 350 ℃ by an inexpensive spray pyrolysis method. The structur...The nano-structural Al-doped ZnO thin films of different morphologies deposited on glass substrate were successfully fabricated at substrate temperature of 350 ℃ by an inexpensive spray pyrolysis method. The structural, electrical, optical and photoluminescence properties were investigated. X-ray diffraction study revealed the crystalline wurtzite （hexagonal） structure of the films with nano-grains. Scanning electron microscopy （SEM） micrographs indicated the formation of a large variety of nano-structures during film growth. The spectral absorption of the films occurred at the absorption edge of -410 nm. In the present study, the optical band gap energy 3.28 eV of ZnO decreased gradually to 3.05 eV for 4 mol% of AI doping. The deep level activation energy decreased and carrier concentrations increased substantially with increasing doping. Exciting with the energy 3.543 eV （A=350 nm）, a narrow and a broad characteristic photoluminescence peaks that correspond to the near band edge （NBE） and deep level emissions （DLE）, respectively emerged.展开更多
A solid state reaction method was used to synthesize barium titanate （BT） and barium cerium titanate （BCT） ceramics at sintering temperature of 1473 K for 4 h. The effect of cerium （Ce） on the structure, microst...A solid state reaction method was used to synthesize barium titanate （BT） and barium cerium titanate （BCT） ceramics at sintering temperature of 1473 K for 4 h. The effect of cerium （Ce） on the structure, microstructure and dielectric properties of BCT was investigated. The scanning electron microscopy （SEM） investigations revealed that the grain size increases with increasing Ce content. The X-ray diffraction （XI^D） patterns showed mostly the BT phase, where the lattice parameter decreased with the addition of Ce. The temperature dependence of dielectric constant showed decrease in the phase transition temperature with higher Ce content. The dielectric constant decreased slightly with increasing frequency. The direct current （dc） density-voltage characteristics of the ceramics showed ohmic behavior for both the BT and BCT. As the temperature increased, the dc resistivity of the ceramics decreased. The activation energy increased with increasing Ce content.展开更多
The magnetic and structural properties of FINEMET alloy with a composition of Fe75.sCu1Nb1Si13.5B9 were investigated after primary and secondary crystallization of amorphous ribbon sample. The crystallization behavior...The magnetic and structural properties of FINEMET alloy with a composition of Fe75.sCu1Nb1Si13.5B9 were investigated after primary and secondary crystallization of amorphous ribbon sample. The crystallization behavior and the nanocrystal formation of the samples were performed by differential thermal analysis （DTA） which in turn was supported by X-ray diffraction （XRD） study. Temperature dependence of initial permeability of amorphous and devitrified toroid shaped samples has been measured. Enhancement of Curie temperature of the amorphous alloy has been observed due to the irreversible structural relaxation. With the appearance of nanocrystalline phase the Curie temperature of the residual amorphous phase gradually decrease with the increase of annealing temperature. Their temperature dependence reflects the characteristic annealing temperature evolution of the basic magnetic parameters in these nanocrystalline systems. Saturation magnetization, Ms, increases with annealing temperature Ta for the samples and finally decreases during annealing at a temperature much higher than peak crystallization temperature.展开更多
文摘The nano-structural Al-doped ZnO thin films of different morphologies deposited on glass substrate were successfully fabricated at substrate temperature of 350 ℃ by an inexpensive spray pyrolysis method. The structural, electrical, optical and photoluminescence properties were investigated. X-ray diffraction study revealed the crystalline wurtzite （hexagonal） structure of the films with nano-grains. Scanning electron microscopy （SEM） micrographs indicated the formation of a large variety of nano-structures during film growth. The spectral absorption of the films occurred at the absorption edge of -410 nm. In the present study, the optical band gap energy 3.28 eV of ZnO decreased gradually to 3.05 eV for 4 mol% of AI doping. The deep level activation energy decreased and carrier concentrations increased substantially with increasing doping. Exciting with the energy 3.543 eV （A=350 nm）, a narrow and a broad characteristic photoluminescence peaks that correspond to the near band edge （NBE） and deep level emissions （DLE）, respectively emerged.
文摘A solid state reaction method was used to synthesize barium titanate （BT） and barium cerium titanate （BCT） ceramics at sintering temperature of 1473 K for 4 h. The effect of cerium （Ce） on the structure, microstructure and dielectric properties of BCT was investigated. The scanning electron microscopy （SEM） investigations revealed that the grain size increases with increasing Ce content. The X-ray diffraction （XI^D） patterns showed mostly the BT phase, where the lattice parameter decreased with the addition of Ce. The temperature dependence of dielectric constant showed decrease in the phase transition temperature with higher Ce content. The dielectric constant decreased slightly with increasing frequency. The direct current （dc） density-voltage characteristics of the ceramics showed ohmic behavior for both the BT and BCT. As the temperature increased, the dc resistivity of the ceramics decreased. The activation energy increased with increasing Ce content.
文摘The magnetic and structural properties of FINEMET alloy with a composition of Fe75.sCu1Nb1Si13.5B9 were investigated after primary and secondary crystallization of amorphous ribbon sample. The crystallization behavior and the nanocrystal formation of the samples were performed by differential thermal analysis （DTA） which in turn was supported by X-ray diffraction （XRD） study. Temperature dependence of initial permeability of amorphous and devitrified toroid shaped samples has been measured. Enhancement of Curie temperature of the amorphous alloy has been observed due to the irreversible structural relaxation. With the appearance of nanocrystalline phase the Curie temperature of the residual amorphous phase gradually decrease with the increase of annealing temperature. Their temperature dependence reflects the characteristic annealing temperature evolution of the basic magnetic parameters in these nanocrystalline systems. Saturation magnetization, Ms, increases with annealing temperature Ta for the samples and finally decreases during annealing at a temperature much higher than peak crystallization temperature.
