This work investigates the effect of hydrostatic pressure on the excitation, emission and lifetime of Ti 3+ - doped Al 2 O 3 in the 0-110 kbar range. The application of pressure induces band shifts that are correlated with the corresponding local structural changes undergone by the TiO 6 complex. The increase of the Stokes-shift and the reduction of the Jahn-Teller (JT) splittings under pressure are analysed in terms of a simple model based on linear electron-phonon couplings to the a_{1_{\rm g}} and the JT e g vibrational modes. 相似文献
The multiferroic Pb(Fe1/2V1/2)O3 (PFV) bulk ceramic was fabricated by a conventional ceramic sintering method. The strong visible‐light photovoltaic effect in Sn‐doped‐In2O3(ITO)/PFV/ITO structure capacitor was observed. The open‐circuit voltage was up to ～0.7 V, which was much higher than the value (～0.3 V) in BiFeO3 film. The photo‐excited electric current is almost proportional to the incident light illumination intensity. The good visible‐light photovoltaic makes PFV ceramic a potential candidate for practical application in solar cell devices.
The dielectric and piezoelectric properties of pyrochlore-free lead zirconate titanate-lead zinc niobate ceramics were investigated systematically as a function of Sr doping. The powders of Pb(1?x)Srx[0.7(Zr1/2Ti1/2)–0.3(Zn1/3Nb2/3)]O3, where x?=?0–0.06 were prepared using the columbite-(wolframite) precursor method. The ceramic materials were characterized using X-ray diffraction, dielectric spectra, hysteresis and electromechanical measurements. The phase-pure perovskite phase of Sr-doped PZN--PZT ceramics was obtained over a wide compositional range. The results showed that the optimized electrical properties were also achieved at composition x?=?0.0, which were KP?=?0.69, d33?=?670?pC?N?1, Pr?=?31.9?µC?cm?2 and εrmax?=?18600. Maximum dielectric constant values of the systems decreased rapidly with increasing Sr concentration. Moreover, with increasing Sr concentration dielectric constant versus temperature curves become gradually broader. The diffuseness parameter increased significantly with Sr doping. Furthermore, Sr doping has been shown to produce a linear reduction in the transition temperature (Tm)?=?294.1–12.7x°C with concentration (x). Sr shifts the transition temperature of this system at a rate of 12.7°C?mol?1%. 相似文献
A novel surfactant-modulated precipitation method is proposed to produce pure perovskite Pb(Sc1/2Nb1/2)O3 (PSN) nanopowders at a low temperature of 700 °C. The samples were characterized by XRD, SEM, TEM, and HRTEM, respectively.
The results indicate that the powders exhibit a granular shape of 80 nm in diameter. It is believed that the nanosize of as-prepared
PSN powders is dependent on the well-dispersed performance, which arouse from the combined effects of both precipitant TMAH
and surfactant CTAB. The mechanism of the formation of the pure perovskite PSN nanopowders is discussed in detail. Our method
is expected to create a new, low-cost route to produce the promising nanopowders of multi-component perovskite systems. 相似文献
Physics of the Solid State - A method of synchronous measurement of the piezoresponse signal and electrical impedance when studying the processes of polarization switching in an external electric... 相似文献
We report on the modification of ferroelectric hysteresis in Pb(Nb,Zr,Ti)O3 thin films under the adsorption of CO2 gas. The samples were exposed to the gas in ultra high vacuum while different voltages between the top (Ag) and bottom (Pt) electrodes were applied. After dosing, the samples were heated from room temperature at 1.8 K/s, and a mass spectrometer was used to detect the desorbed molecules. The effective molecular sticking was demonstrated by the appearance of the carbon Auger peak in the surface of the sample and by the presence of CO2 in the desorption curves. After +(−) 9.9 V were applied to the bottom electrode during dosing, we found a shift of −0.52 (+0.58) μC/cm2 in the remnant polarization. These evidences suggest the existence of a depolarizing field induced by molecular adsorption at the surface of the top electrode, and contribute to highlight the potential use of ferroelectric thin films as gas sensors. 相似文献
The simultaneous application of electric and magnetic fields on single crystals of Sr-, Ba-and Pb-dinitrate yields an additional term to the pure electrogyration and Faraday effect. The symmetric part of the fourth-rank tensor of this magneto-electrogyration has been completely determined with the aid of a high-resolution computer-aided polarimetric device. In Pb(NO3)2 a maximum magneto-electrogyration of about 10% of the magnitude of electrogyration is observed when a magnetic field of 1000 kA/m (1.2 Tesla) is applied along [111]. The effects in Sr(NO3)2 and Ba(NO3)2 are much smaller. Index of refraction, electrogyration, Faraday effect, and the new magneto-electrogyration obey the same sequence: Pb(NO3)2 > Ba(NO3)2 > Sr(NO3)2. 相似文献
Polycrystalline samples of Pb(Mg1/4Zn1/4Nb1/2)O11/4 have been synthesized by high temperature columbite precursor solid state reaction technique. Using X-ray diffraction (XRD)
technique, compound formation in single phase cubic structure was observed and XRD analysis provided preliminary structural
data. Detailed studies of dielectric properties of the compound reveal that this compound has high dielectric constant and
diffuse phase transition in a wide range of temperatures around the Curie temperature. The charge deficiency of the compound
presumably gets compensated in the high temperature columbite precursor process of sample preparation which is supported by
single phasic form of the material. 相似文献
The specific heat of typical relaxors, Pb(Mg(1/3)Nb(2/3))O3 (PMN) and Pb(Mg(1/3)Ta(2/3))O3 (PMT), was measured by adiabatic and relaxation methods between 2 and 420 K. A broad anomaly was found in the specific heat curve over the wide temperature range between 150 and 500 K for PMN, and between 50 and 400 K for PMT, which provides evidence for the formation of ferroelectric nanoregions (FNR) in the paraelectric matrix. The entropy of the anomaly was estimated as 3.3 J K(-1) mol(-1) and 2.9 J K(-1) mol(-1) for PMN and PMT, respectively, which implies an order-disorder-type mechanism for the formation of FNR. 相似文献
