Na0.5Bi4.5-xEuxTi4O15 （NBT-xEu^3＋） ceramics with x= 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu^3＋ ceramics show the strongest red and orange emissi...Na0.5Bi4.5-xEuxTi4O15 （NBT-xEu^3＋） ceramics with x= 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu^3＋ ceramics show the strongest red and orange emissions corresponding to the 5D0 → 7F2 （617 nm） and 5D0→ 7F1 （596 nm） transitions, respectively. The strongest excitation band around 465 nm matches well with the emission wavelength of commercial InGaN-based blue LED chip, indicating that Eu^3＋-doped NBT ceramics may be used as potential environmental friendly red-orange phosphor for W-LEDs application. As an inherent ferroelectric and piezoelectric material, the electrical properties of this potentially multifunctional electro-optical material have been also studied. The introduction of Eu^3＋ distinctly increased the Curie temperature （Tc） of NBT-xEu^3＋ ceramics from 640℃ to 711℃ as x ranges from 0 to 0.40. For higher temperature applications, the electrical conductivity was also investigated. The conduction of charge carriers in hightemperature range originates from the conducting electrons from the ionization of oxygen vacancies. High Tc and low tanδ makes Eu^3＋-doped NBT ceramic also suitable for high temperature piezoelectric sensor applications and electro-optical integration.展开更多
The SiO2-Fe3O4 core-shell nanostructures were synthesized by sol-gel chemistry. The morphological features of the nanostructures were examined by field emission scanning electron microscopy which revealed the core-she...The SiO2-Fe3O4 core-shell nanostructures were synthesized by sol-gel chemistry. The morphological features of the nanostructures were examined by field emission scanning electron microscopy which revealed the core-shell nature of the nanoparticles. X-ray diffraction studies evidenced the formation of SiO2-Fe3O4 core-shell nanostructures with high degree of homogeneity. The elemental composition of the SiO2-Fe3O4 core-shell nanostructures was determined by energy-dispersive X-ray spectroscopy analysis. Fourier transform infrared spectroscopy showed the Si-O-Fe stretching vibrations. On analysis of the optical properties with UV-Vis spectra and Tauc＇s plot, it was found that the band gap of SiO2-Fe3O4 core-shell nanostructures diminished to 1.5 eV. Investigation of the electrical properties of the core-shell nanostructures using field-dependent conductivity measurements presented a significant increase in photoconductivity as compared to those of its single components, thereby rendering them as promising candidates for application as photo- electrodes in dye-sensitized solar cells.展开更多
Bilayered FTO/AZO （fluorine doped tin oxide/aluminium doped zinc oxide） films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction （XRD） profiles of bilayered films showed th...Bilayered FTO/AZO （fluorine doped tin oxide/aluminium doped zinc oxide） films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction （XRD） profiles of bilayered films showed that in the case of lower thickness FTO over layers, （002） plane of ZnO phase had the highest intensity, whereas the predominance was changed in favour of （200） plane of SnO2 phase for higher thickness FTO over layer. UV studies showed that bilayered FTO/AZO films exhibited a sharp absorption edge as that of AZO film. The decrease in the photoluminescence （PL） peak at 420 nm with increasing FTO over layer thickness indicated a reduction in the zinc vacancies which caused a reduction in the sheet resistance （Rsh）. Electrical studies revealed that, eventhough the Rsh value （916Ω/□） of bilayered FTO （313 nm）/AZO （314 nm） film was found to be higher than that of FTO single layer film （72Ω/□）, it was much lower than that of AZO single layer film （5661Ω/□））. The atomic force microscopy （AFM） images reflect the characteristic features of both zinc oxide and tin oxide films.展开更多
The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) an...The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) and decrease the resistance temperature coefficient (α) of Pd. and (ρ.α) Pd-RE ls equal to (ρ· α)Pd.The RE elements before Gd reduce the thermo-emf of Pd on Cu. other heavy RE enhance the thermo-emf.The experimental data of normalized Pd-0.1 at.-%RE alloys indicate that the effect of light RE additives on the specific resistivity of Pd is larger than that of heavy RE and Ce. Eu and Yb show anomalous strong effect. The valence and atomic size are main factors influencing the electrical properties.展开更多
The a-Si∶H films with different thickness smaller than 1 μm were deposited by plasma enhanced chemical vapor deposition (PECVD) under the optimum deposition conditions. The effect of different thickness on film prop...The a-Si∶H films with different thickness smaller than 1 μm were deposited by plasma enhanced chemical vapor deposition (PECVD) under the optimum deposition conditions. The effect of different thickness on film properties is analyzed.The results show that,with the increase of the film thickness,the dark conductivity, photoconductivity and threshold voltage increase, the optical gap and peak ratio of TA to TO in the Raman spectra decrease, the refractive index keeps almost constant, and the optical absorption coefficient and current ratio of on/off state first maximize and then reduce.展开更多
基金Acknowledgements This work was financially supported by the National Natural Science Foundation of China （Grant Nos. 51562014 and 51262009）and the Natural Science Foundation of Jiangxi, China （Grant Nos. 20133ACB20002 and 20142BAB216009）, and partially sponsored by Colleges and Universities ＂Advanced Ceramics＂ Scientific and Technological Innovation Team of Jiangxi Province.
文摘Na0.5Bi4.5-xEuxTi4O15 （NBT-xEu^3＋） ceramics with x= 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu^3＋ ceramics show the strongest red and orange emissions corresponding to the 5D0 → 7F2 （617 nm） and 5D0→ 7F1 （596 nm） transitions, respectively. The strongest excitation band around 465 nm matches well with the emission wavelength of commercial InGaN-based blue LED chip, indicating that Eu^3＋-doped NBT ceramics may be used as potential environmental friendly red-orange phosphor for W-LEDs application. As an inherent ferroelectric and piezoelectric material, the electrical properties of this potentially multifunctional electro-optical material have been also studied. The introduction of Eu^3＋ distinctly increased the Curie temperature （Tc） of NBT-xEu^3＋ ceramics from 640℃ to 711℃ as x ranges from 0 to 0.40. For higher temperature applications, the electrical conductivity was also investigated. The conduction of charge carriers in hightemperature range originates from the conducting electrons from the ionization of oxygen vacancies. High Tc and low tanδ makes Eu^3＋-doped NBT ceramic also suitable for high temperature piezoelectric sensor applications and electro-optical integration.
文摘The SiO2-Fe3O4 core-shell nanostructures were synthesized by sol-gel chemistry. The morphological features of the nanostructures were examined by field emission scanning electron microscopy which revealed the core-shell nature of the nanoparticles. X-ray diffraction studies evidenced the formation of SiO2-Fe3O4 core-shell nanostructures with high degree of homogeneity. The elemental composition of the SiO2-Fe3O4 core-shell nanostructures was determined by energy-dispersive X-ray spectroscopy analysis. Fourier transform infrared spectroscopy showed the Si-O-Fe stretching vibrations. On analysis of the optical properties with UV-Vis spectra and Tauc＇s plot, it was found that the band gap of SiO2-Fe3O4 core-shell nanostructures diminished to 1.5 eV. Investigation of the electrical properties of the core-shell nanostructures using field-dependent conductivity measurements presented a significant increase in photoconductivity as compared to those of its single components, thereby rendering them as promising candidates for application as photo- electrodes in dye-sensitized solar cells.
基金The financial support from the University Grants Commission,New Delhi through the Major Research Project(F.No.40-28/2011(SR))
文摘Bilayered FTO/AZO （fluorine doped tin oxide/aluminium doped zinc oxide） films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction （XRD） profiles of bilayered films showed that in the case of lower thickness FTO over layers, （002） plane of ZnO phase had the highest intensity, whereas the predominance was changed in favour of （200） plane of SnO2 phase for higher thickness FTO over layer. UV studies showed that bilayered FTO/AZO films exhibited a sharp absorption edge as that of AZO film. The decrease in the photoluminescence （PL） peak at 420 nm with increasing FTO over layer thickness indicated a reduction in the zinc vacancies which caused a reduction in the sheet resistance （Rsh）. Electrical studies revealed that, eventhough the Rsh value （916Ω/□） of bilayered FTO （313 nm）/AZO （314 nm） film was found to be higher than that of FTO single layer film （72Ω/□）, it was much lower than that of AZO single layer film （5661Ω/□））. The atomic force microscopy （AFM） images reflect the characteristic features of both zinc oxide and tin oxide films.
文摘The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) and decrease the resistance temperature coefficient (α) of Pd. and (ρ.α) Pd-RE ls equal to (ρ· α)Pd.The RE elements before Gd reduce the thermo-emf of Pd on Cu. other heavy RE enhance the thermo-emf.The experimental data of normalized Pd-0.1 at.-%RE alloys indicate that the effect of light RE additives on the specific resistivity of Pd is larger than that of heavy RE and Ce. Eu and Yb show anomalous strong effect. The valence and atomic size are main factors influencing the electrical properties.
文摘The a-Si∶H films with different thickness smaller than 1 μm were deposited by plasma enhanced chemical vapor deposition (PECVD) under the optimum deposition conditions. The effect of different thickness on film properties is analyzed.The results show that,with the increase of the film thickness,the dark conductivity, photoconductivity and threshold voltage increase, the optical gap and peak ratio of TA to TO in the Raman spectra decrease, the refractive index keeps almost constant, and the optical absorption coefficient and current ratio of on/off state first maximize and then reduce.
