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Through a typical solid-state reaction followed by planetary ball milling, ABO3 structured perovskite Bi0.5Na0.5ZrO3 (BNZ) was employed as an additive to create the lead-free piezoceramic composite having compositional formula K0.47Na0.47Li0.06NbO3+(x)Bi0.5Na0.5ZrO3 where x = 0.0 wt% to 0.5 wt%. The prepared composites were characterized with the help of XRD, SEM, and FTIR. The XRD results indicated manifestation of morphotropic phase boundary (MPB), i.e. orthorhombic-tetragonal (O-T) phase boundary, for 0.4 wt% and 0.5 wt%. The SEM pictures revealed the microstructural properties of grain-grain size distribution and the average grain size of the composites. The elemental composition examination using EDAX revealed no foreign element contamination. The FTIR examination verified the development of perovskite, indicating that the BNZ has correctly fused into the KNLN matrix. The DC resistivity (ρdc) behavior was determined from IV and IR curves measured at room temperature together with varied temperature line up from 30 °C to 150 °C and a high dc resistivity ρdc of order ≈ 109 Ω cm was obtained for all the ceramics. The results have been analyzed and the mechanism pertaining to the results has been discussed in the paper. Thus the main idea was to develop a lead-free piezoceramic composite by incorporating Bi0.5Na0.5ZrO3 as an additive and investigating its effect on the above mentioned properties of the composite material. [ABSTRACT FROM AUTHOR]

In this paper, we studied the magnetism of Fe2N, using the ab initio and Monte Carlo studies. The magnetic moment and the exchange couplings are deduced by ab initio calculations. The obtained density of states is not symmetrical with respect to the axis of energy proving the ferromagnetic character of this compound. Any gap energy, at the Fermi level, is found confirming the metallic character of this compound. The Hamiltonian of this system consists of several physical parameters. Both the magnetic entropy and the maximum magnetic entropy are obtained. The relative cooling power and the magnetic hysteresis cycle are illustrated. The transition temperature TC value has been deduced and found to be about 252.01 K. This value is in good agreement with the experimental results presented. Also, we found that the magnetizations decrease rapidly to zero with increasing temperature. This is due to the ferromagnetic-paramagnetic phase transition caused by thermal energy. [ABSTRACT FROM AUTHOR]

In this paper, the shaft parts of failed machine tools were treated by laser cladding, and the shaft surface of 45# steel matrix was repaired. The microstructure, hardness and corrosion resistance of the cladding layer and quenched phase transformation zone were analyzed by metallographic microscope, Vickers microhardness tester, and friction and wear tester. The laser cladding layer was tested by friction and wear tester. The results showed that the friction coefficient of laser cladding layer was only 0.58, and it fluctuated slightly. The corrosion resistance of laser cladding layer was obviously increased. [ABSTRACT FROM AUTHOR]

In this paper, thick film antiferroelectric ceramics (1-x)(Pb0.97La0.02)(Zr0.46Sn0.48Ti0.06)O3-xH3BO3 ((1-x)PLZST-xH3BO3, x = 0–0.025) were prepared by solid state sintering and tape-casting method. The effects of boron-doping on the microstructure, dielectric properties and energy storage properties of (1-x)PLZST-xH3BO3 ceramics were investigated. Appropriate boron-doping can improve the stability of antiferroelectric phase, delay phase transition and increase saturation polarization strength. Compared with the undoped PLZST thick films, the maximum polarization intensity increased by 1.9 times and the residual polarization decreased by 37%. When x = 0.020, the maximum recoverable energy storage density is 2.74 J/cm3, and the energy storage efficiency is 88.12%. [ABSTRACT FROM AUTHOR]

In the present paper, Nd, Nb co-doped La2Mo2O9 system is investigated to understand phase transition, ionic conductivity and dielectric relaxation phenomenon. X-ray diffraction study confirms order-disorder phase transition by disappearance of peak splitting of (231) in co-doped LMX system, which is associated with monoclinic phase and is observed for LMX-Pure at around 2θ = 47–48°. In co-doped system, two dielectric relaxation peaks are observed, which are associated with diffusion process between O(1)-O(2) and O(1)-O(3) oxygen ion ←→ vacancies sites, while diffusion process O(1)-O(3) is supposed to be occurred in parent system having single relaxation peak. Thus dielectric relaxation phenomenon indicates phase transition is proceeding with static-to-dynamic disorder transition. Electric modulus data are revealed to ascertain correlation of relaxation dynamics and oxy-ion conductivity in co-doped LMX system. The extracted data of activation energy of oxy-ion conductivity at intermediate temperature range (500–700 °C) of co-doped samples is found relatively lower than that of the parent sample. The study reveals that incorporation of Nd, Nb co-doped in LMX system successfully suppress the phase transition and enhanced ionic conductivity at intermediate temperature range and found suitable as electrolytes for intermediate temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

Temperature dependences of Brillouin light scattering spectra from Ba0.5Sr0.5 Nb2O6 (SBN 50) film were obtained. The deviations of the Brillouin shift dependence from linear near ferroelectric phase transition are due to electric fields in the local regions with symmetry breaking. A maximum of Brillouin line width is more than twice of the corresponding width in a bulk crystal of the same composition. This broadening is attributed to the confinement of the acoustic phonons. Optical second harmonic generation measurements (SHG) showed that the transition from the polar to the nonpolar phase occurred at a temperature characteristic of SBN-50. [ABSTRACT FROM AUTHOR]

In this study, we aim to investigate theoretically the critical characteristics of spin −1/2 four-leg nanotube for the nanotechnology applications. The Ising model simulated by Monte Carlo simulation is adopted with the first exchange coupling J , the second exchange coupling between the second nearest neighbor atomic spins J ′ and the transverse exchange coupling J z , and the external magnetic field h as parameters. Herein, we examine the local properties of spin −1/2 four-leg nanotube by analyzing the magnetization, susceptibility and hysteresis loop behavior as function of J ′ , J Z and h. The obtained results show that the isotropic ‐ 1 / 2 four-leg nanotube Ising model presents critical behavior at ferromagnetic to paramagnetic phase transition where the Curie temperature T C increases according to vertical and second nearest neighbor exchange coupling. Furthermore, under external magnetic field, the magnetization keeps the second order transition and the magnetic susceptibility declines with the increase of applied external magnetic field value. In addition to that, we have found single ferromagnetic hysteresis loops, for which the shape increases by increasing the second nearest neighbor exchange coupling when T = J. Finally, the critical temperature shows perfect mirror symmetry relative to the vertical and increases with the second nearest neighbor exchange coupling. [ABSTRACT FROM AUTHOR]

This study investigates the dielectric properties, including dielectric constant (ɛ′), dielectric loss (ɛ″), tangent delta (tan δ), and AC conductivity (σac), of PVA/Y2O3 polymer nanocomposites (PNCs). The dielectric behavior of the PNCs was examined as a function of frequency and temperature. The results revealed that the addition of Y2O3 nanoparticles to the PVA matrix influenced the dielectric properties of the composites. In contrast to pure PVA, the PVA/Y2O3 PNCs with a 15 wt% Y2O3 loading exhibited high values of ɛ′, ɛ″, tan δ and σac are 647.49, 1607.48, 9.70 and 1.024 × 10−5, respectively, at low frequency and at particular temperature. Furthermore, the electrical properties of PVA/Y2O3 PNCs were also investigated using the Cole-Cole plots. These plots provide valuable insights into the complex impedance behavior and allow for comprehensive understanding of the electrical response of the nanocomposites. [ABSTRACT FROM AUTHOR]

Crystal structure and Dielectric properties investigation of lead-free Bi0.35Na0.25Li0.1Sr0.3TiO3 (BNLST) composite is reported. The required solid solution was synthesized using oxides and carbonates via the solid-state reaction method. The stoichiometrically weighed and mixed powder was calcined at 800 °C for 12 h, and the pellets were sintered at 1250 °C for 2 h. XRD measurements confirm the formation of single-phase rhombohedral perovskite structure and the crystal structure was refined using the X'Pert High-score plus software. The full-width half maxima of the XRD peak was used to compute the average crystallite size employing the Debye-Scherrer, Williamson-Hall, and Halder-Wagner techniques. The BNLST's dielectric measurements were performed as a function of temperature at five distinct frequencies in the range of 100 Hz–1 MHz. The phase transition temperatures are shifted toward room temperature with the doping of Li and Sr. The diffuseness parameters of the phase transition, the a.c. electrical conductivity and the activation energy are estimated for the BNLST composite. [ABSTRACT FROM AUTHOR]

Polarization rotation and occurrence of monoclinic and triclinic states were investigated in Pb0.1Sr0.9TiO3. For this composition, the rhombohedral ground state may coexist with a tetragonal state close in free energy and become sensitive to electric and mechanical stimuli. The polarization path under an electric field and biaxial strain involves a monoclinic state, while for uniaxial strain the transition involves both monoclinic and triclinic states. Longitudinal and shear piezoelectric constants are enhanced in the induced monoclinic and tetragonal states, respectively. Low-temperature secondary peaks in the literature-reported dielectric spectra can be explained as polycrystalline average of dielectric tensor components of the low-symmetry structures. [ABSTRACT FROM AUTHOR]

The dielectric constant measurements of Fe implanted TlInS2 and TlGaSe2 crystals without and under application of constant magnetic field have been performed. It has been observed that the implantation of the crystals with Fe ions caused the formation of ferromagnetic layer in the irradiated region, which leads to considerable shifts of the successive incommensurate and commensurate phase transitions to high temperatures in the heating regime. Remarkable shifts of the phase transition temperatures back to the low temperature region on heating of the samples were observed on applying the magnetic field perpendicularly to the implanted surface. None changes of the phase transition temperature points on measurements of the samples have been observed in cooling regime. The obtained results are interpreted as magnetodielectric effects that resulted from magnetoelectric coupling between ferromagnetic and ferroelectric constituents of the composite structure. [ABSTRACT FROM AUTHOR]

The results of studying the differential thermal analysis signal and X-ray diffraction patterns of nanocomposites, obtained by embedding cesium nitrate into carbon nanotubes, are presented. For comparison, similar results are presented for bulk CsNO3. A decrease in the Curie temperature of nanocomposite cesium nitrate was found. Possible causes of the detected changes are discussed. [ABSTRACT FROM AUTHOR]

Experimental studies of elastic, anelastic, dielectric, polarization and thermal properties of sodium trihydrogen selenite NaN3(SeO3)2 crystal in the temperature range of 5–210 K. Above the ferroelectric Curie temperature, an intermediate ferroelastic β′-phase was detected between the paraelectric α-phase and the ferroelectric β-phase. The phase transition from α- to β′–phase at 195 K is classified as a first-order transition, accompanied by the occurrence of spontaneous deformation x6s. When the temperature decreases, in addition to the previously known transition from the β-phase to the γ-phase, a new phase transition from the γ-phase to the nonpolar η-phase at a temperature of 112.4 K was detected. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectrics play an important role for technological applications, mainly for using in the fabrication of actuators, transducers and sensors. Therefore, there has been an increasing interest of the scientific community in the investigation of the physical properties of such system in order to better elucidate the observed intriguing and unsolved phenomena. In this work, relaxor Pb(Mg1/3Nb2/3)O3 (PMN) ceramic system was prepared and the dielectric properties have been studied in details as a function of frequency, temperature and magnitude of the DC-bias electric field. Results reveal that the temperature dependence of the dielectric permittivity can be successfully described in the whole analyzed temperature range (100–400 K) by using a macroscopic statistical model, which describe the dielectric response in relaxor systems with diffuse phase transition (DPT). By using this phenomenological model, the temperature and DC-bias electric field dependences of the dielectric permittivity have been also revisited, from the analysis of the DPT behavior, promoting a careful discussion on the nature of the phase transition in relaxors materials. The calculated sizes of the polar nanoregions (PNRs) suggest the development of a structural disorder in the studied system, which promote the high diffuse ferroelectric transition as the amplitude of the DC-bias electric field increases. [ABSTRACT FROM AUTHOR]

Impulse excitation is a suitable tool to determine the temperature dependence of Young's modulus and to monitor the ferroelectric phase transition of unpoled barium titanate ceramics (tetragonal-to-cubic and vice versa). By measurement from room temperature to 200–300 °C and back, it is found that there is an elastic anomaly with a sharp minimum (at 120 °C during heating and 110 °C during cooling, with a completely reproducible hysteresis), below and above which Young's modulus exhibits values of 40–50 GPa and up to 90 GPa, respectively, and damping changes abruptly from values of order 0.01 to less than 0.001. [ABSTRACT FROM AUTHOR]

The results of studying the dielectric permittivity, the third harmonic coefficient, and the DTA signal for Al2O3 nanoporous matrices filled with rubidium nitrate are presented. A shift of the phase transition Tc ≈ 437 K by 3 K to the low-temperature region and an increase in the temperature hysteresis of the phase transition from 14 K for polycrystalline RbNO3 to 33 K for RbNO3 in the pores of the Al2O3 oxide film were found. [ABSTRACT FROM AUTHOR]

The formation of charged domain walls (CDWs) in the bulk was studied in lithium tantalate LiTaO3 (LT) and lithium niobate LiNbO3 (LT) crystals with various composition gradients along the polar axis produced by partial vapor transport equilibration (VTE). Under the action of the pyroelectric field upon cooling after the phase transition, the shape of a CDW in LT changed significantly, in contrast to LN: the ledges appeared at CDW and grew toward the polar surfaces. The creation of tail-to-tail and head-to-head CDWs with controlled shape is important for various applications. [ABSTRACT FROM AUTHOR]

Structural transition, tetragonality, and dielectric properties are investigated along with thermal and compositional expansion of lead strontium titanate in order to reveal composition dependence and structure-property relation of the ferroelectric structure. Based on the available structural and dielectric data, dielectric stiffness and temperature-dependent paraelectric cubic lattice parameters are analyzed. Non-zero sixth-order free energy coefficients are derived for strontium titanate. Spontaneous polarization, spontaneous strain, volumetric change, and dielectric permittivity are modeled as a function of composition, and the theoretical results are in agreement with experimental data reported in the literature and reveal solid solution effect. [ABSTRACT FROM AUTHOR]

Stabilization of monoclinic distortion in [111]-oriented strained and strain-relaxed PbTiO3 epitaxial films are investigated using a phenomenological model. Under the effect of biaxial strain due to SrTiO3, temperature stability of monoclinic structure induced by vertical compressive stress is investigated. Due to relaxation of substrate constraint in-plane misfit of the epitaxial system changes from isotropic to anisotropic. Strain relaxation mediated formation of monoclinic structure, polarization, volume and shear strain, and dielectric and piezoelectric constants are investigated and compared with experimental data in the literature. For anisotropically strained [111] epitaxial films mechanical boundary conditions that facilitate enhancement of physical constants are explored. [ABSTRACT FROM AUTHOR]

The displacive phase transition in BaxSr1-xTiO3 (BST) ceramic due to the mole fraction differences was investigated using x-ray diffraction assisted by Rietveld analysis. Detailed Rietveld analysis showed that BST undergoes a structural phase transformation from cubic to tetragonal phase. Average crystallite size and microstrain present in the powders were studied using the Wilson and Debye–Scherrer equation. The crystal structure of samples was refined by the Rietveld method, and an expansion on the unit cell parameters was determined. These analyses revealed an increment in the unit cell strain and an increase in the crystallite size when the mole fraction was increased. [ABSTRACT FROM AUTHOR]

The SrxBa1 –xNb2O6 crystals with x = 0.33, 0.5, 0.61, 0.75 were studied by Raman and Brillouin light scattering in a wide temperature range. The experimental temperature dependences of the central peak's integral intensity and the position and width of the longitudinal acoustic mode were plotted using derivative analysis. It is shown that the temperature at which the abnormal behavior begins (the so-called Burns temperature) is only slightly different for all the crystals under study, while the phase transition temperatures differ significantly. It allows asserting the identical microscopic nature of the Burns temperature in SrxBa1 –xNb2O6 crystals. [ABSTRACT FROM AUTHOR]

Direct electrocaloric effect of BaTiO3-based ceramic materials was measured during poling and partial reverse poling using a square-wave electric field. A strong influence of the amplitude of the reverse bias field on the electrocaloric response was found. With increasing amplitude of the reverse bias field, the electrocaloric response was suppressed depending on the coercive field of the material and nature of the ferroelectric-to-paraelectric phase transition. [ABSTRACT FROM AUTHOR]

In this work, we studied the nature of repolarization processes in KNN-0.05Ta ceramics in the temperature range of structural phase transition. We have found the anomalous behavior of reverse dependences ε'(Ε=), while measuring the response in weak ac-fields in the sample exposed to the constant bias field. Behavior of ε'(Ε=) was compared with the polarization loops measured in sinusoidal fields of various amplitudes. [ABSTRACT FROM AUTHOR]

The effect of rare-earth ions Er3+, which has a large orbital contribution to the magnetic moment, on the phase transitions and states of the phase separation nanoregions has been studied in multiferroic ErMn2O5. These nanoregions are semiconductor heterostructures formed due to self-organization processes in the ErMn2O5 matrix. A significant effect of Er3+ ions, the moments of which are rigidly oriented along the c axis of the crystal, on the magnetic dynamics, heat capacity, and multiferroic properties of superlattices layers in a wide temperature range of 5 ÷ 300 K has been revealed. [ABSTRACT FROM AUTHOR]

It is established that during the domain structure relaxation process after its removal from the equilibrium state by an alternating electric field, the sign of the coefficient c of the electric energy density decomposition in powers of a single polarization component changes from "+" to "–". The signs of the coefficient c, obtained experimentally and assumed from the Landau-Ginzburg-Devonshire theory, coincide at the initial moment after "electric field annealing". [ABSTRACT FROM AUTHOR]

0.9Bi1-xNdxFeO3 − 0.1PbTiO3 solid solution with x = 0.05, 0.10, 0.15 and 0.20 were success fully synthesized by the standard solid-state reaction method. The effect of Nd3+ion substitution on structural, micro structural, ferroelectric, magnetic and dielectric properties of 0.9BiFeO3-0.1PbTiO3 have been investigated. The XRD analysis for the samples under study revealed distorted rhombohedral structure with R3C space group. 0.9Bi1-xNdxFeO3 − 0.1PbTiO3 i.e. (BNFPT)x with x = 0.05, 0.10, 0.15 and 0.20 compounds crystallized as single-phase materials with the same structure as the parent BiFeO3 compound. The SEM study revealed the uniform grain scattering for all prepared samples. Raman spectroscopy showed disappearance of some Raman modes indicated a structural phase transition with substitution of Nd dopants at Bi site and also confirmed the distorted rhombohedral perovskite structure of (BNFPT)x compounds with R3c symmetry. Dielectric measurements reveals that, around Neel temperature, all the samples exhibit magneto-electric coupling and also improved dielectric properties with addition of dopants in BiFeO3(BFO) compound. All the prepared samples exhibit weak ferro-magnetic character at room temperature. However, the variation in linear behavior and enhancement in magnetization is found at 5 K which shows gradual increase in remnant magnetization from 0.00785 emu/g to 0.37513 emu/g with increase in Nd doping for all (BNFPT)x samples. Nd doping reduces leakage current by three orders of magnitude, from 10−4 to 10−7. Ferroelectric study revealed the pinning effect in hysteresis loops with low remnant polarization and coercive field which can be related to the energy storage performance of the samples. [ABSTRACT FROM AUTHOR]

Optical and dielectric studies of lead zirconate and lead hafnate single crystals have been carried out under an extended hydrostatic pressure (up to 1.2 GPa) and high electric field action (up to 6 ⋅ 10 7 V / m ). Using the obtained results, new-type phase diagrams have been constructed on the electric field E – hydrostatic pressure p plane. A particular approximate equation of the Clausius – Clapeyron type which refers to the E, p-phase diagrams has been derived and verified. [ABSTRACT FROM AUTHOR]