Raman and IR spectra of Nb-doped PTC Ba1-xPbxTiO3 semiconducting ceramics (x = 0,0. 28,0. 296,0. 313,0. 330,0. 370) have been measured, and mode assignments of Raman scattering frequencies and infrared absorption peak...Raman and IR spectra of Nb-doped PTC Ba1-xPbxTiO3 semiconducting ceramics (x = 0,0. 28,0. 296,0. 313,0. 330,0. 370) have been measured, and mode assignments of Raman scattering frequencies and infrared absorption peaks have been made at room temperature. The influence of Pb2+ ions content on resistivity temperature characteristics and vibration spectra for the Ea1-xPbxTiO3, ceramics have been discussed,and the temperature dependence of the Raman spectra in tetragonal and cubic phases have been investigated from 25 to 340℃. The results indicated that the Raman spectra of the paraelectric phase above Curie point are obviously different from that of ferroelectric phase below Curie point are obviously different from that of ferroelectric phase below Curie point for all the samples. Curie point of each sample,which is determined by resistivity-temperature characteristic measurment, is in good agreement with the results of Raman analysis. The ferroelectric phase transition in the PTCR Bai-xPbxTiO3 ceramics belongs to a distortion or displacement transition.展开更多
Stoichiometric Ba（MnxTi（1-x）O3） （BMT） thin films with various values of x were deposited on Si（111） substrates by the sol-gel technique. The influence of Mn content on the optical properties was studied by spe...Stoichiometric Ba（MnxTi（1-x）O3） （BMT） thin films with various values of x were deposited on Si（111） substrates by the sol-gel technique. The influence of Mn content on the optical properties was studied by spectroscopic ellipsometry （SE） in the UV–Vis–NIR region. By fitting the measured ellipsometric parameter （Ψ and Δ） with a four-phase model （air/BMT＋voids/BMT/Si（111））, the key optical constants of the thin films have been obtained. It was found that the refractive index n and the extinction coefficient k increase with increasing Mn content due to the increase in the packing density. Furthermore, a strong dependence of the optical band gap Eg on Mn/Ti ratios in the deposited films was observed, and it was inferred that the energy level of conduction bands decreases with increasing Mn content.展开更多
文摘Raman and IR spectra of Nb-doped PTC Ba1-xPbxTiO3 semiconducting ceramics (x = 0,0. 28,0. 296,0. 313,0. 330,0. 370) have been measured, and mode assignments of Raman scattering frequencies and infrared absorption peaks have been made at room temperature. The influence of Pb2+ ions content on resistivity temperature characteristics and vibration spectra for the Ea1-xPbxTiO3, ceramics have been discussed,and the temperature dependence of the Raman spectra in tetragonal and cubic phases have been investigated from 25 to 340℃. The results indicated that the Raman spectra of the paraelectric phase above Curie point are obviously different from that of ferroelectric phase below Curie point are obviously different from that of ferroelectric phase below Curie point for all the samples. Curie point of each sample,which is determined by resistivity-temperature characteristic measurment, is in good agreement with the results of Raman analysis. The ferroelectric phase transition in the PTCR Bai-xPbxTiO3 ceramics belongs to a distortion or displacement transition.
基金Project supported by the National Natural Science Foundation of China(Grant No.60976016)the Postdoctoral Science Foundation of China(Grant No.2012M511250)the Foundation Co-established by Henan Province and the Ministry of Henan University,China(Grant No.SBGJ090503)
文摘Stoichiometric Ba（MnxTi（1-x）O3） （BMT） thin films with various values of x were deposited on Si（111） substrates by the sol-gel technique. The influence of Mn content on the optical properties was studied by spectroscopic ellipsometry （SE） in the UV–Vis–NIR region. By fitting the measured ellipsometric parameter （Ψ and Δ） with a four-phase model （air/BMT＋voids/BMT/Si（111））, the key optical constants of the thin films have been obtained. It was found that the refractive index n and the extinction coefficient k increase with increasing Mn content due to the increase in the packing density. Furthermore, a strong dependence of the optical band gap Eg on Mn/Ti ratios in the deposited films was observed, and it was inferred that the energy level of conduction bands decreases with increasing Mn content.
