Abstract A barium strontium titanate Ba0.65Sr0.35TiO3 and its lithium (Li) and copper (Cu) doped thin films have fabricated on quartz substrates based on sol-gel and spin-coating method. Chemical solution deposition with spin-coating technique deposited the thin films. The addition of Li and Cu dopants lead to the change of lattice constant and the change of grain size. From Scherrer’s equation, it found that BLST and BCST thin films have larger and smaller grain size than that of BST, respectively. It also revealed that the crystal structures formed in a phase between cubic and tetragonal structure. Scanning electron microscopy was confirmed homogenous surfaces of thin film and energy dispersive x-ray was showed chemical composition according to the considered stoichiometry.

Abstract Exothermic effect of entropy change by dipole orintation upon E in T-C second order phase transition ferroelectrics is modeled with statistic method. Formula of entropy change and temperature change were derived, showing sharp drop of entropy in higher temperature for higher E, exothermic peak shifts to high temperature with E, and 180° turning of dipole with a critical electric field prevails entropy change in ferroelectric phase, while 180° turning dominates entropy change in paraelectric phase. The results of numerical simulation can explain regulation of heating effect of the ferroelectrics. Morphotropic phase boundary will possess giant exothermic effect in principle.

Abstract Dielectric properties of nanostructured strontium titanate samples sintered from nanoparticles obtained by grinding of previously synthesized SrTiO3 and nanoparticles obtained by chemical deposition were studied in the temperature range 10–300 K. The first sample shows the characteristic features of a relaxor ferroelectric. The dispersion of the dielectric response observed in the vicinity of 40 K is characterized by two relaxation processes, with broad spectra of relaxation times. It is assumed that the “high-temperature” relaxation process is associated with the dynamics of the elastic domain. Possible mechanisms for the interaction of elastic deformation and polarization are discussed.

Abstract Micro-Raman spectroscopy and method of Raman data calibration are proposed for the quantitative study of the proton-exchanged LiNbO3 channel waveguides, which contain the different HxLi1–xNbO3 phases, depending on the fabrication conditions. The spectroscopic parameters, phase composition and electro-optic properties of these waveguides have been found to be depending on the small variation of stoichiometry in the near-congruent lithium niobate substrates used for waveguides fabrication.

Abstract A piezoelectric composite transducer was developed in this study to improve the bandwidth and beamwidth of the high-frequency transducer. The piezocomposite was designed as arc-shaped to expand the beamwidth, and the matching layer technique was adopted to increase the bandwidth. The directivity function was obtained by the acoustic field theory. The parameters of the matching layer were also calculated using the quarter-wavelength model. Then, a novel preparation process of arc 1–3 piezoelectric composite was given in detail. Finally, the arc 1–3 piezocomposite and transducer were prepared and tested. The bandwidth and beamwidth of the transducer reach 100 kHz and 123°, respectively. Experimental results show that the designed transducer realizes the aims of broadband and wide-beam.

Abstract The resonant frequency difference of piezoelectric transformers (PTs) with a classical parallel connection could worsen system performance, then the mechanical coupling of PTs was proposed to avoid the disadvantage. Experimental results showed that when the difference was relatively small, the performance of the classical parallel system and proposed mechanical coupling system was similar. However, when the difference increased, the maximum output power of a classical parallel system at a temperature rise of 20 °C reduced by 32.6% and that of mechanical coupling system reduced by 7.7%. This indicated mechanical coupling was better than classical parallel connection in improving the output power of PTs.

Abstract Antiferroelectric double loops and double dielectric peaks occurred at an electric field circle synchronously are confirmed theretically by solving the kittel’s function with the idea of different responses of dipoles to applied electric field (E) in E-direction and anti-E-direction in antiferroelectrics. By solving problem of inversion of dipoles to ferroelectric phase controlled by thermodynamic parameters and the antiferroelectric coupling coefficient in antiferroelectric phase, the numerically simulated results exhibit that antiferroelectric phase can transform to ferroelectric phase with two approaches: decrease in temperature to a critical temperature, and increase in parameter α0. The results are well coincident with experimental results.

Abstract The differences between demagnetization fields and depolarization fields were compared. The most fundamental reason is the existence of electric charges but the nonexistence of magnetic charges. For ferroics (ferromagnetics and ferroelectrics), the non-equilibrium thermodynamics of phase transitions was considered and the conclusion remains the same.

Abstract Based on the Devonshire theory, the E-induced effects of polarization, dielectrics, hysteresis loop, and energy storage are investigated. Numerical simulations confirm that the ferroelectrics with soft ferroelectricity with properties of small and E-sensitive polarization, abrupt decrease of dielectric peak with increasing E, sloped and slender hysteresis loop with central narrow when approaching Tc, and symmetry energy storage peak, much less than Tc, towards high temperature with increasing E, can be the candidate of high energy storage materials. HIGHLIGHTS E-induced polarization effect is related with thermodynamic parameters of ferroelectrics. Peak of energy storage shifts to high temperature under high-E. Larger induced polarization is corresponding to higher energy storage.

AbstractA series of combustion assisted low-temperature neodymium substituted Ni–Zn–Fe (NZF) nanoparticles were synthesized to unravel the impact on functional behavior of NZF due to the presence of larger Nd ions. The nanopowders were structurally evaluated with X-ray diffraction and infrared spectroscopy measurements without further heat treatment. X-ray diffraction clearly evident the monophasic nature of all the samples and solubility of Nd ions in the spinel unit cell. The average crystallite size from Scherrer and Williamson–Hall method are found below 30 and 20 nm for all the samples, respectively. A distinct shift was observed in most intense peak (3 1 1) suggesting the adjustment among interionic distances to accommodate larger ions. The microstructure, morphology was evaluated from SEM measurements. Magnetic measurements at room temperature show a dramatic change in magnetization, improvement in soft-magnetic nature with low coercivity behavior with Nd substitution. The variation of resistance with respect to humidity conditions suggested that these materials are potentially suitable for resistive humidity sensor applications.

AbstractMicrowave sintering has been known as the effective method to prepare ceramics. In this study, the microwave sintering method was used to synthesize 0.96(K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3-0.04CaZrO3 ceramics. The effect of holding time on the properties of ceramics was investigated. With the holding time of 30 min, the excellent piezoelectric properties (d33 = 286 pC/N) can be achieved.

Abstract The equilibrium thermodynamic approach to ferroic hysteresis was recalled firstly, especially according to the ferroelectric case. Then based on the uniqueness of equilibrium state, it was showed that a ferroic hysteresis loop is composed of stationary states but not equilibrium ones, especially according to the ferromagnetic case. So, it was concluded that the equilibrium thermodynamic approach to ferroic hysteresis is not reliable. Life-force should be bestowed on the domain structure dynamic approach and the non-equilibrium thermodynamic approach.

AbstractThe service life of piezoelectric devices is significantly affected by the electric fatigue load. The randomness of loads and nonuniformity of material properties caused by random distribution of internal defects in piezoelectric body will lead to the dispersion of the failure life of piezoelectric devices. Predicting failure probability of piezoelectric materials under electric fatigue load is essential for the reliability and life prediction of piezoelectric structures and devices. In this paper, the initial damage of piezoelectric materials is modeled as a random variable. Based on the methods of probability theory and statistics, the failure probability assessment model of piezoelectric materials under electric fatigue load is proposed. The probability density function of initial damage is obtained by observation and statistics of initial defect area. The failure probability assessment model of piezoelectric materials under electric fatigue load can be obtained by probability theory and integral method. Meanwhile, the failure probability evolution of piezoelectric materials under various electric fatigue loads is considered. The results show that the failure life and dispersion of piezoelectric materials is significantly affected by electric fatigue load, and the variation of failure probability under various electric loads is similar. Based on the proposed failure probability assessment models, the randomness of the electric load and randomly distributed initial defects of materials are considered in the damage evolution and performance prediction of piezoelectric structures, which is an important supplement to the reliability prediction and application of piezoelectric devices.

AbstractThe polycrystalline ternary ferroelectric ceramic of PMN-PYN-PT (PMN = PbMg1/3Nb2/3O3, PYN = PbYbl/3Nb2/3O3, PT = PbTiO3) were synthesized by conventional solid state reaction technique. The structural, electrical and energy-storage properties of the ceramic were investigated. X-ray diffraction studies reveal that the ceramic has a coexistence of both tetragonal and rhombohedral phases. Dielectric studies of the sintered samples were studied as a function of temperature ranging from room temperature to 400 °C and in the wide frequency range of 1–50 kHz which shows good relaxor behavior. P-E hysteresis loops for the ceramic confirm good ferroelectric properties, exhibiting at (Pr ∼ 17.5 µC cm−2, Ec ∼ 36.5 and Pm ∼ 20.3) were obtained for PMN-PYN-PT. Energy storage density (W) of 0.13 Jcm−3 was achieved at 50 kV/cm1. The optimum piezoelectric coefficient and piezoelectric voltage coefficient (d33 ∼ 412 pC/N, g33 ∼1.6) measured on the poled sample for PMN-PYN-PT, respectively. From these analyses, the reported ceramic is a promising candidate for energy-storage capacitor applications.

AbstractHigh-Curie temperature (TC) piezoelectric ceramics 0.15Pb(Mg1/3Nb2/3)O3-0.38PbHfO3-0.47PbTiO3 (0.15PMN-0.38PH-0.47PT) were fabricated via the citrate method, which shows pure perovskite structure. The ceramics have composition locating at the rhombohedral side around the morphotropic phase boundary (MPB), and present enhanced electrical properties as compared with those prepared by the solid-state reaction method via the columbite precursor technique. Temperature-dependent Raman spectroscopy not only proves the occurrence of the ferroelectric to paraelectric phase transition around TC, but also detects the successive phase symmetry transitions, which correlate with the polar nanoregions (PNRs) or the coexistence of multiple ferroelectric phases. Large quantities of fine stripe nanoscale ferroelectric domains are observed by piezoresponse force microscopy (PFM) in the 0.15PMN-0.38PH-0.47PT ceramics, which form the larger micron island domains. Temperature-dependent Raman spectra and PFM results indicate that the excellent dielectric, ferroelectric and piezoelectric properties of the 0.15PMN-0.38PH-0.47PT ceramics can be attributed to either the existence of the PNRs with low symmetry or the multiple-ferroelectric-phases coexistence around room temperature and the fine stripe ferroelectric domains.

AbstractWe study the capacitance of piezoelectric metal–insulator–semiconductor junctions. The linearized macroscopic theories of piezoelectric dielectrics and semiconductors are used. An analytical solution is obtained with an explicit expression for the junction capacitance. The contribution from the semiconductor part is characterized by the Debye length. When the semiconductor part is long compared to the Debye length, the junction capacitance can be written as a serial connection of two capacitors of the insulator and semiconductor parts. Because of piezoelectric coupling, a charge-stress coefficient is introduced to describe the junction behavior completely.

Abstract In this article, we report the results of the Rietveld and impedance analysis of Eu doped La1–xEuxMnO3 (LEMO; x = 0.10, 0.30, and 0.50) perovskite manganites synthesized by solid-state reaction method. Structural studies through Rietveld analysis confirm that a mixed-phase nature of all LEM samples having a hexagonal unit cell structure with a less detectable impurity (Eu2O3) ceramics. The patterns are zanalyzed in detail with structural distortion and strain in LEM manganites ceramics. Dielectric constant and modulus are found to increase with increasing Eu concentration. The samples LEM-0.10 shows the negative capacitance at low frequency and temperature, respectively.

Abstract BiFeO3 (BFO) and ZrO2 have been deposited on p-type (100) silicon substrate by sol-gel process and rf sputtering method, respectively. Metal-ferroelectric-insulator-semiconductor capacitor has been fabricated with 100 nm BFO and 10 nm ZrO2 shows maximum memory window of 1.54 V as compared to other fabricated capacitors with 5 and 15 nm insulating layer thickness. Improvement in current density has been also observed in different thickness of buffer layer of MFIS capacitors. The improved current density of order of 10-7 A/cm2 has been observed in MF(100nm)I(10nm)S structure. It has been also observed in MF(100nm)I(10nm)S structure that no charge value degrades up to 1011 iteration cycles.

Abstract From the view-point of non-equilibrium (or irreversible) statistical thermodynamics, the similarities and differences between the processes of (first-order) ferroelectric phase transition and those of ferroic hysteresis were compared. They are all irreversible. The former are local and rate-dependent, at the meanwhile, the latter are non-local and rate-independent.

AbstractThe CdSe thin film was deposited on glass substrate by homemade spray pyrolysis technique at substrate temperature 3000C. Further the film was characterized through X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), UV-Visible optical spectroscopy and Electrical. The XRD pattern of CdSe film shows polycrystalline hexagonal crystal structure with average crystalline size of the film was 16.3 nm. The SEM micrograph shows the film was uniform, adherent, without pin-hole and crack free. From EDAX analysis conform that the presence of Cd and Se in prepared film with elemental stoichiometry of Cd and Se was 49.30% and 50.70%, respectively. The optical band gap was direct band gap and it was found 1.78 eV. The electrical resistivity of the film at room temperature was 6.9 × 106 Ωcm.