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Objective: Although increasing the amount of inert hydrophobic material can improve the anti-caking performance of compound fertilizer, carrying inert hydrophobic material hinders the applicability of compound fertilizer in mechanized fertilization and the integrated technology of water and fertilizer. In order to reduce the amount of inert hydrophobic material applied to the outer surface of the compound fertilizer particles, in this article, the type and proportion of nitrogen salt, phosphorus salt, and potassium salt were limited so as to increase the anti-caking performance of the particles. Methods: The anti-caking performance of 17-17-17SOP nitro-compound fertilizer granules (AN-NPK) was modified by the following three measures: (1) APP (ammonium polyphosphate) was used to replace some inorganic phosphates; (2) reducing the mass fraction of AN (ammonium nitrate) and introducing KN (potassium nitrate) to supplement the nitrate nitrogen in the compound fertilizer, and maintain the same ratio of nitrate nitrogen and ammonium nitrogen in AN-NPK; (3) reduce the mass fraction of KS (potassium sulfate), and shift the molar ratio of NO3/SO4 away from 2.0. The AN modified by APP and KN was characterized by X-ray diffraction and differential scanning calorimetry. The mechanism of improving the anti-caking performance of AN-NPK was demonstrated. Results: The results showed that when the mass fraction of APP in the formula was 0%, 8%, 16%, and 21%, the anti-caking performance of AN-NPK is gradually increased, the transverse shear force of the agglomerates decreased from 135.65 N to 94.02, 67.45, and 60.32 N. When 10% KN and 12% APP were added to AN-NPK, the transverse shear force continued to decrease to 33.25 N. Conclusion: The mechanism of improving anti-caking performance of AN-NPK is as follows:(1) APP with oligomeric degree has higher solubility and mobility than monoammonium phosphate and diammonium phosphate, resulting in higher enrichment on the surface of AN-NPK; (2) at the granulation temperature of 80 °C, KN releases more potassium ions than KS, and more AN was modified in the granulation process of AN-NPK. In summary, APP combined with KN weakens the phase transition effect of AN and reduces the salt ion concentration on the surface of AN-NPK. [ABSTRACT FROM AUTHOR]

Temperature and field dependences of dielectric permittivity ε and unipolar electric field-induced strain S of the 0.675Pb(Mg1/3Nb2/3)O3−0.325PbTiO3 ceramics have been studied in the 25...200 °C range. Temperature dependences of both dielectric permittivity and converse piezoelectric modulus d*33 show anomalies corresponding to phase transitions between rhombohedral (monoclinic), tetragonal, and cubic phases. Based on the data of dielectric and field-induced strain studies, the E,T-phase diagram is plotted. The possible critical behavior of converse piezoelectric modulus d*33 and its correlation with the position of the known critical point in the E,T-phase diagram of PMN-xPT system are discussed. [ABSTRACT FROM AUTHOR]

Bi0.6Nd0.4Fe0.5M0.5O3 (M – Mn, Cr) compositions with perovskite structure were fabricated by a high-pressure synthesis. Mӧssbauer studies have shown that doping with Nd does not change substantially Neel temperature values of Bi0.6Nd0.4 Fe0.5M0.5O3 (M – Cr, Mn) compositions. However, the Fe3+ and Mn3+ ions seem to be inhomogeneously distributed in the crystal lattice and form Fe-poor and Fe-rich regions. Similar result was obtained by us earlier for Bi(Fe1-xCrx)O3 solid solution. Both compositions studied exhibit a giant dielectric response in a wide temperature range. The giant dielectric response seems to be due to the relaxation of electrons or polarons trapped by oxygen vacancies. [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]

Ceramic samples of new compositions (1−x)(0.9NaNbO3 − 0.1BaTiO3) − xBaZrO3 (x = 0 ÷ 0.05) modified by SiO2 oxide additive were prepared; their phase composition, structure parameters, microstructure, dielectric and ferroelectric properties were studied. Formation of a phase with a perovskite structure with a tetragonal unit cell was established, which volume increased due to partial replacement of A and B cations by Ba2+ and Zr4+ ones with large ionic radii. Decrease in the temperature of ferroelectric phase transitions and corresponding increase in polarization and electrocaloric effect indicates a positive effect of doping on the functional properties of sodium niobate-based ceramics. [ABSTRACT FROM AUTHOR]

Temperature and field dependences of dielectric permittivity ε and unipolar electric field-induced strain S of the 0.675Pb(Mg1/3Nb2/3)O3−0.325PbTiO3 ceramics have been studied in the 25...200 °C range. Temperature dependences of both dielectric permittivity and converse piezoelectric modulus d*33 show anomalies corresponding to phase transitions between rhombohedral (monoclinic), tetragonal, and cubic phases. Based on the data of dielectric and field-induced strain studies, the E,T-phase diagram is plotted. The possible critical behavior of converse piezoelectric modulus d*33 and its correlation with the position of the known critical point in the E,T-phase diagram of PMN-xPT system are discussed. [ABSTRACT FROM AUTHOR]

We studied the formation of the domain structure as a result of the motion of a planar interphase boundary in the {001}-cut tetragonal PMN-PT crystals during cooling with oriented temperature gradient. The specialized heating/cooling stage was assembled for this purpose. Piezoresponse force microscopy was used to image the domain structure at the (001) and (010) surfaces of the samples with high spatial resolution, revealing a complex quasi-periodic domain pattern with a periodicity from 300 to 400 nm. [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]

The manuscript explores the electromagnetic and magnetocaloric characteristics of the intermetallic compound Gd 2 Cu 2 C d. One of the key findings is that Gd2Cu2Cd possesses a magnetic moment of approximately 7.13 μB. The simulated magnetic properties illustrate a second-order phase transition from ferromagnetic (FM) to paramagnetic (PM) occurring at approximately 130 K. This material exhibits a substantial magnetocaloric effect (MCE) across various external magnetic field strengths. To be more specific, this transition occurs at an external magnetic field of 4.0 T, in particular, at an external magnetic field of 4.0 T, the extreme magnetic entropy change ( Δ S mag ) is measured at 3.58 J/kg.K, and the relative cooling power (RCP) reaches 28 J/kg. Notably, with an increase in the external magnetic field, the maximum value of ( ΔS mag ) increases significantly, and the Curie temperature ( T C ) shifts toward lower temperatures. These results suggest that Gd 2 Cu 2 Cd has significant potential for applications in magnetic refrigeration that leverage the magnetocaloric effect. [ABSTRACT FROM AUTHOR]

(1-x)(Pb0.97La0.02)(Zr0.46Sn0.48Ti0.06)O3-xSiO2 ((1-x)PLZST-xSiO2, x = 0-0.025) thick film antiferroelectric ceramics were preapred by a traditional solid-state reaction method. The structure and dielectric properties related to the energy storage density in the (1-x)PLZST-xSiO2 system were investigated in detail. PLZST with 0.5%SiO2 content is superior to other SiO2 contents samples in terms of the structure, dielectric properties and phase transition modulation. The energy storage density reaches the maximum value of 1.66 J/cm3 accompanied by the energy efficiency of 86.92% in 0.995 PLZST-0.005SiO2. The results suggest that high energy storage density of PLZST system can be improved with phase transition modulation using SiO2. There is a large decrease in grain size after SiO2 doping. Modest phase transition modulation was achieved by introducing SiO2. The 0.995PLZST-0.005SiO2 sample has a good advantage over other SiO2 content samples in terms of the structure, dielectric properties and modest modulation of phase transition. [ABSTRACT FROM AUTHOR]

Bismuth layered compound with the composition SrBi1.5La0.5Nb2O9 has been prepared using conventional solid-state reaction method. Crystallographic planes have been identified using X-ray diffraction studies. The dielectric studies have been done as a function of frequency and temperature. Low temperature dielectric measurement shows phase transition in which peak dielectric constant shifts from 260K to 280K with the increase in frequency from 1 kHz to 1 MHz. Room temperature dielectric constant has been found to be nearly frequency independent for this composition making it a potential candidate for the capacitor applications. The prepared ceramic was modelled using the Vogel – Fulcher relationship. [ABSTRACT FROM AUTHOR]

A high temperature MD effect has been observed in Pr3Fe5O12 (PrIG) which is a new member of rare earth iron garnets (RIG) family. Research indicates that this material has two dielectric relaxations in the temperature range from 370 K to 565 K and a dielectric anomaly around 580 K. The first dielectric relaxation is attributed to the conduction for the similar activation energy with conduction. The other dielectric relaxation in the higher temperature range originated from the inhomogeneous structure. And, the coupling between the ferrimagnetic phase transition and the dielectric response was observed at 1 kHz 0.35 T 580K. [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]

Ferroelectric liquid crystals(FLCs), an exciting class of liquid crystals(LCs), found potential applications in the display as well as non-display regimes due to their fast response, low driving voltage and nonvolatile memory. The amalgamation of nanoparticles into FLCs has opened up new avenues in the LCs research field by alterations/modification of the existing properties of LCs. In this work, porous carbon nanoparticles (PCNPs) were dispersed into FLC mixture (W206E) and investigated their doping effect on FLC's textural, phase transition temperatures and dielectric studies in planar-aligned cells. Dielectric spectroscopy was carried out in the frequency range of 20 Hz to 10 MHz to explore the frequency as well as the temperature dependent of FLC in the entire SmC* region. The transition temperature of FLC mixture is increased by 4 °C in PCNPs doped FLC sample then undoped FLC sample. Nearly 8.42% increase in permittivity is observed. A Gold stone relaxation mode at ∼627 Hz was observed at lower frequency. [ABSTRACT FROM AUTHOR]

Liquid crystals are self-organized anisotropic fluids which exhibit ordered states ranging from nematics to smectics/hexatics. Hybridized liquid crystals with nanoparticles broaden the research area in finding the novel functional devices. Reported herein, the study of highly stable room temperature nematic liquid crystal E7 and carbon-coated cobalt (Co) nanoparticles. Dispersion of 0.50 wt.% Co into E7 has been introduced to tailor the physical parameters of host E7. Dielectric studies have been performed in planar as well as homeotropic cells in the frequency range of 20 Hz–10MHz while photoluminescence spectra have been recorded at excitation wavelength of 325 nm in planar cells. Dielectric studies reveal the change in phase transition temperature and molecular dynamics associated with magnetic nanoparticles doped liquid crystals. Quenching in photoluminescence intensity has been observed with the inclusion of Co nanoparticles due to the formation of non-radiative channels in the composite system. The intercalation of Co nanoparticles into E7 studies manifests the strong correlation between liquid crystals and nanoparticles. Allocation of magnetic attributes onto liquid crystal molecules finds potential applications in advanced magnetic materials, information devices and optical devices. [ABSTRACT FROM AUTHOR]

BaBi4Sn4O15, a Sn-modified ceramic sample of layered ferroelectric oxide family, is developed using a high-temperature mixed oxide route after firing for calcination at 810 °C for 6 h in steps of 50 °C starting from 600 °C. An introductory XRD study of the compound displays the development of the new orthorhombic structured single-phase compound at atmospheric conditions. The electrical behaviors of the compound are investigated in a wide temperature span (30–500 °C) and frequencies ranging from 0.1 kHz to 1 MHz using an impedance analyzer. Dielectric behavior informs that the compound has a phase transition from Ferro to Paraelectric at 370 °C, which is well above room temperature. The impact of temperature and frequency on complex immittance parameters (impedance and modulus) is analyzed using an LCR meter in a broad temperature & frequency span. The electrical properties confirm; (a) the existence of semiconductor-like NTCR (negative temperature coefficients of resistance) behavior, (b) the evidence of the electric relaxation process as a function of temperature, (c) the existence of electric relaxation ascribed to the simultaneous contribution of bulk & bulk interfaces to the electrical behavior, and (d) presence of the non-Debye type relaxation phenomena. The frequency-dependent conductivity follows Jonscher's universal power law. [ABSTRACT FROM AUTHOR]

Triglycine fluoberyllate (TGFB) is an important member of hydrogen bonded order disorder type ferroelectrics, resembling other ferroelectrics which belongs to its group it experiences phase transition at certain temperature. In current theoretical work by utilizing Green's function (double time thermal dependent) and modified pseudospin two-sublattice mode model we are analyzing ferroelectric behavior of TGFB crystal. For this purpose we are evaluating expressions for shift (Δ) , width (Γ) , soft mode frequency ( Ω ̂ ) , dielectric constant (ε) and loss tangent (tan δ) , after that by utilizing model values for TGFB crystal thermal dependence of Ω ̂ , ε and tan δ have been calculated. Comparison illustrates that theoretical results obtained by us are in good harmony with experimental results. [ABSTRACT FROM AUTHOR]

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]

The material Ba(Ti0.5Mn0.5)O3 synthesized through the conventional solid-state reaction method has hexagonal structure free from any impurity phase. The complex dielectric dispersion, temperature and frequency-dependent dielectric, impedance, AC conductivity, and leakage behavior of the sample are studied. The impedance study of the material encloses non-Debye type relaxation, negative temperature coefficient of resistance nature and the grain and grain boundary effects. The ferroelectric to paraelectric phase transition occurs at TC ∼ 270 °C. The dielectric constant and loss-tangent values are found to be less as compared to that of the parent barium titanate sample. Rg < Rgb, that is, grain boundary has greater opposition than the grain region. The material follows correlated barrier hopping model. The carrier transport process through AC conductivity study obeys the Jonscher's power law and the Arrhenius relation while varying with the frequency and temperature. [ABSTRACT FROM AUTHOR]

Antiferroelectric properties of copper formate tetrahydrate (CFT) crystal having phase transition temperature at were investigated theoretically. CFT have a layer-type structure in which layers of are sandwiched between the layers of copper formate in the lattice plane. By considering modified two sublattice pseudospin lattice coupled mode model Hamiltonian and double-time temperature-dependent Green function method for antiferroelectric copper formate tetrahydrate (CFT) crystal, the phase transition properties of crystal have been studied. Expressions are derived for soft mode frequency, dielectric constant and loss tangent for considered crystal. Model values are fitted in the derived expressions and the dependence of the above properties on temperature have been calculated. Theoretically obtained results are compared with experimental data and show similarities between them. Dielectric constant as a function of temperature shows a behaviour of the first-order transition with a large discontinuity at the transition point. These properties can be employed in a wide range of applications including memory devices, solar cells, biosensors and photovoltaic devices. [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]

The chiral smectic-C to smectic-C (SmC *-SmC) phase transition has been studied using dynamic renormalization group (DRG) analysis. Langevin equations are derived from the nonlinear elastic model of the SmC *-SmC phase transition. The DRG equations are derived. The DRG analysis predicts the Kosterlitz-Thouless transition at low frequency limit and Kardar-Parisi-Zhang (KPZ) fixed point. The DRG calculation confirms that the SmC*-SmC phase transition belong to the KPZ universality class. [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]

Chemical, optical, and thermal characterization are carried out for seven hydrogen bond thermotropic liquid crystalline complexes formed between pentyloxy benzoic acid (5BAO) and p-n-alkyl benzoic acids (nBA, where n refers alkyl carbon chain length which varies from ethyl to octyl. FTIR, ¹H, and 13C Nuclear Magnetic Resonance (NMR) establishes the chemical investigations. Nematic and smectic F are the mesophases observed. Polarizing Optical Microscopic (POM) studies ensures the mesophases identified. Thermal investigation using Differential Scanning Calorimeter (DSC), provides the phase transition temperatures, enthalpy values, thermal stability factor, specific heat capacity values, and thermal equilibrium of the mesogenic complexes. [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 effect of graphene nanoparticles on the smectic-C* to smectic-C*A (SmC* to SmC*A) phase transition in antiferroelectric liquid crystal is studied theoretically. Model free energy is based on Flory-Huggins free energy of isotropic mixing and Landau theory of phase transition. The effect of graphene nanoparticles concentration on tilt angle, spontaneous polarization and dielectric susceptibility in the smectic-C*A phase of the SmC* to SmC*A phase transition has been studied extensively. The qualitative agreement between theoretical and experimental results is found. [ABSTRACT FROM AUTHOR]

The physical nature of the phenomenon of negative thermal expansion coefficient seen in the polar crystals and ferroelectrics is considered. Usually it is observed at low temperatures but especially evident in vicinity of ferroelectric phase transitions. This phenomenon is associated with fundamental nature of non-centrosymmetric crystals, caused by electronegativity difference of adjoined ions forming polar crystal. Negative thermal expansion coefficient indicates a change in the nature of forces of the attraction at close proximity of ions forming polar bond. The thermal expansion minimum is specified by the configurational entropy, conditioned by polar bonds self-ordering in pyroelectrics and ferroelectrics. [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]

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]

[011]-oriented unpoled relaxor ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals are studied by means of acoustic emission and dielectric methods in dependence on both temperature and dc bias electric field. The rhombohedral-cubic ferroelectric phase transition and the dielectric maximum as well as the intermediate temperature are successfully detected. Both rhombohedral-cubic ferroelectric phase transition and the dielectric maximum are studied in dependence on dc bias electric field, too. No the critical end point, but the tricritical one is detected. Existence of the supercritical behavior is discussed in these crystals. [ABSTRACT FROM AUTHOR]

A regression analysis of the temperature dependences of the elasticity coefficients in the cubic phase of BaTiO3 has been carried out. Two functions are proposed that include one or two critical temperatures (T1 and T2) located in the region of the phase transition to the tetragonal phase (T 1) and above the melting point of the single crystal (T 2). It is shown that the effective elasticity coefficient C e f (t) has three minima, one in the region of phase transition to the tetragonal phase, the second near the crystal melting temperature, and the third at a temperature t = 3502 o C , where the bulk modulus of elasticity B 0 (t) → 0. [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]

A regression analysis of the temperature dependences of the elasticity coefficients in the cubic phase of BaTiO3 has been carried out. Two functions are proposed that include one or two critical temperatures (T1 and T2) located in the region of the phase transition to the tetragonal phase (T 1) and above the melting point of the single crystal (T 2). It is shown that the effective elasticity coefficient C e f (t) has three minima, one in the region of phase transition to the tetragonal phase, the second near the crystal melting temperature, and the third at a temperature t = 3502 o C , where the bulk modulus of elasticity B 0 (t) → 0. [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]

Multicomponent ceramics based on PbMg1/3Nb2/3O3–PbTiO3 system were studied using X-ray diffraction at high electric fields. It was shown that electric field induced phase transition from initial pseudocubic phase to tetragonal one occurs at E > 5 kV/cm. Analysis of the intensities of the 200 X-ray peak components reveals the parameters of the tetragonal unit cell (с = 4.036 Å and а = 4.021 Å) and the degree of preferential domain orientation (≈ 35%) at E = 12 kV/cm. The results of X-ray diffraction studies are in a good agreement with the field-induced behavior of the macroscopic responses: strain, polarization, and dielectric permittivity. [ABSTRACT FROM AUTHOR]

Within the temperature range of −50–200 °C the dielectric properties of nanocrystalline samples of BaTiO3 and BaTiO3-SiO2 (1 wt % SiO2) were studied at frequencies of 25 Hz–1 MHz. The addition of 1 wt % SiO2 to the BaTiO3 leads to a noticeable decrease in the dielectric permittivity of the material and a slight decrease in the temperatures of the ferroelectric phase transition and the transition from the orthorhombic toward tetragonal phase. It is shown that the BaTiO3-SiO2 sample exhibits some features of a relaxor ferroelectric. It is revealed that a significant contribution to the ac conductivity in the ferroelectric phase of BaTiO3 - SiO2 comes from the domain and interphase boundaries dynamics. Above TC, the hopping mechanism of conduction dominates. [ABSTRACT FROM AUTHOR]

The temperature dependences of the complex permittivity components ε′ and ε″ for Ba1−xSrxTiO3 (0.1 ≤ x ≤ 0.7) solid solution obtained by two-stage ceramic technology were investigated. Both components ε′ and ε″ pass through the pronounced maxima near the Curie point. A growth of the ε′ maximum with an increase in the concentration of Sr atoms is associated with a reduction in the average grain size and an increase in the volume fraction of the intergranular layer having a lower ε′ compared to a grain. The increase in the diffusion of the phase transition with the concentration of Sr atoms is due to the greater heterogeneity of the solid solution. Based on the dielectric data, temperature dependences of the local order parameter were plotted. [ABSTRACT FROM AUTHOR]

Multicomponent ceramics based on PbMg1/3Nb2/3O3–PbTiO3 system were studied using X-ray diffraction at high electric fields. It was shown that electric field induced phase transition from initial pseudocubic phase to tetragonal one occurs at E > 5 kV/cm. Analysis of the intensities of the 200 X-ray peak components reveals the parameters of the tetragonal unit cell (с = 4.036 Å and а = 4.021 Å) and the degree of preferential domain orientation (≈ 35%) at E = 12 kV/cm. The results of X-ray diffraction studies are in a good agreement with the field-induced behavior of the macroscopic responses: strain, polarization, and dielectric permittivity. [ABSTRACT FROM AUTHOR]

Within the temperature range of −50–200 °C the dielectric properties of nanocrystalline samples of BaTiO3 and BaTiO3-SiO2 (1 wt % SiO2) were studied at frequencies of 25 Hz–1 MHz. The addition of 1 wt % SiO2 to the BaTiO3 leads to a noticeable decrease in the dielectric permittivity of the material and a slight decrease in the temperatures of the ferroelectric phase transition and the transition from the orthorhombic toward tetragonal phase. It is shown that the BaTiO3-SiO2 sample exhibits some features of a relaxor ferroelectric. It is revealed that a significant contribution to the ac conductivity in the ferroelectric phase of BaTiO3 - SiO2 comes from the domain and interphase boundaries dynamics. Above TC, the hopping mechanism of conduction dominates. [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]

The demand to produce clean energy has been increasing over the last years due to the various climate changes, which are strongly afflicting the world. Therefore, it is necessary to implement new and alternative energy sources that contribute for the environment preservation. That is the case, for instance, of novel energy-storage devices, which could contribute for the current demand of clean energies. In fact, most of the system used nowadays are those lead-based materials, which are strongly pollutant and contribute for the environment contamination. In this way, the interest in the development and study of lead-free materials has become a real priority in the scientific community. The objective of the present work is to synthesize and investigate the physical properties of lead-free ferroelectric systems based on BaTiO3 (BT) with technological interest. In particular, the structural and dielectric properties have been investigated as a function of the Sn4+ content, used as a doping element in the BT hosting crystalline structure. The phase transition characteristics have been also analyzed in a wide temperature and frequency range. [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]

BaTiO3 ceramic powders are prepared by the solid phase reaction method. BaTiO3 ceramic powders are sintered at different temperatures for 3 h. The tetragonal phase of BaTiO3 powder is confirmed by XRD. It was found that as the sintering temperature increased, the grain size, density, and dielectric constant of BaTiO3 ceramics increased. All the BaTiO3 ceramic samples sintered at various temperatures for 3 h show the diffuse phase transition and the diffuseness parameter and curie-Weiss constant are also calculated. BaTiO3 ceramic samples sintered at 1200 °C show well-grown grain boundaries. The ferroelectric nature of sintered BaTiO3 ceramic samples studied using P-E hysteresis measurements. [ABSTRACT FROM AUTHOR]

Studies of the dielectric and ferroelectric properties of c-oriented Ba2NdFeNb4O15 films is carried out at T = −190...200 °C using dielectric spectroscopy methods and ferroelectric hysteresis loops analysis. The films were obtained by RF-cathode sputtering method in an oxygen atmosphere. The PA-FE phase transition region, the features of the dielectric response formation, and the mechanisms responsible for that formation are revealed in the material. It is shown that the studied materials are characterized by high values of energy efficiency parameters. The reasons of the revealed regularities and the prospects of the use of these materials are discussed. [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]

Using the RF cathode sputtering method, ferroelectric films of barium-strontium niobate Sr0.5Ba0.5Nb2O6 were synthesized on a semiconductor substrate. Their phase composition, crystal structure, nanostructure, dielectric, and ferroelectric characteristics were studied. The temperature ranges of phase transformations, the characteristic values of spontaneous polarization and coercive fields, the magnitude and nature of the change in the imaginary and real parts of the complex permittivity in the temperature range −190 ÷ 250 °C were established in the films. The reasons for the revealed regularities are discussed. [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]

For the first time, the dielectric relaxation and domain-wall freezing are reported for the single crystal of (CH3NH3)5Bi2Cl11 ferroelectric, which was tested in wide ranges of frequency (1 Hz–1 GHz) and temperature (50–350 K). The results demonstrated two relaxation regions obeying the Arrhenius and Vogel-Fulcher-Tammann laws. The freezing temperature was estimated at 86,3 K using extrapolation method. [ABSTRACT FROM AUTHOR]