The photoluminescence, dielectric relaxation, ferroelectric hysteresis, and field-induced strain properties of Pr3+-doped 0.24Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 (PIN-PMN-PT:Pr3+) multifunctional ceramics have been investigated. It was found that Pr3+ doping enhanced the dielectric diffuseness and relaxation behavior of PIN-PMN-PT ceramics. Slim P-E loops and S-E curves appear in PIN-PMN-PT:Pr3+ ceramics when the Pr3+ doping concentration reaches 1.4 mol%. Local domain configurations associated with phase transitions were investigated by piezoresponse force microscopy (PFM). Large electrostrictive coefficient Q33 (?0.03 m4/C2) and high energy-storage efficiency η (92%) were obtained in 2 mol% Pr3+-doped PIN-PMN-PT ceramic in the ergodic relaxor (ER) phase at room temperature. The giant electrostrictive effect and excellent energy-storage performance are related to the field-induced dynamic behavior of polar nanoregions (PNRs). The results show that the PIN-PMN-PT:Pr3+ system is an excellent multifunctional material for making electromechanical and energy storage devices. 相似文献
It is of great significance to study the soil pore structure for soil reinforcement and ground treatment because it can be used to evaluate the solidification effect and explain the curing mechanism. The pore and compression characteristics of clay from Wuhan in China before and after solidification by ionic soil stabilizer (ISS) in different soil initial states were studied by the use of standard consolidation test, environmental scanning electron microscope analysis, specific surface area (SSA) test, and analysis by PCAS software. Results show that the influence sequence of soil initial states on the change of pore characteristics and ISS-solidification effectiveness was as follows: reducing initial water content + remolding soil > reducing initial water content > remolding soil > natural soil with high initial water content. Besides, loading can also increase the solidification effect. Compared to random and chaotic pore directions of natural clay, remolded solidified clay had a more certain direction after curing and compression. In addition, the total pore number and SSA decreased from 1190 to 756 by 36.47% and 109.690 m2/g to 87.837 m2/g by 19.92% respectively. Results indicate that ISS-clay solidification effect in practical engineering is closely related to the soil initial pre-curing state and can lead to the change of pore direction, decrease of pore number, reduction of pore size and porosity, and formation of larger aggregates.
Nd3+ doped strontium fluorophosphate (S-FAP), with chemical formula Sr5(PO4)3F, nanopowders were prepared using the co-precipitation method. The prepared powders had no impurity phase with a grain size of about 30 nm and the doping limit of Nd3+ ions in strontium fluorophosphate is about 9 at.%. The morphology and particle size were determined by the doping concentration of Nd3+. Anisotropic Nd: S-FAP transparent ceramics with different Nd3+ doping concentrations were fabricated successfully by the simple hot-pressing method. The grain size of prepared S-FAP transparent ceramics decreased first and then increased with the increase of Nd3+ concentration. The 2 at.% Nd: S-FAP ceramic presented the highest optical transmittance at all wavelengths range. The characteristic transitions from the ground state to the excited states of Nd3+ ions were observed from the absorption spectra, and the absorption cross-section was calculated at 3.71 × 10–20 cm2. The influence of Nd3+ ion concentration on luminescence intensity and fluorescence lifetime was studied under 796 nm excitation. The strong emission of 4F3/2→4I9/2 transition in Nd: S-FAP was calculated by Judd–Ofelt (J-O) theory. 相似文献