Ferroelastic Properties Research Articles

Influence of CuO, MnO2, NiO, Bi2O3, and Fe2O3 modifiers on the crystalline structure and electrophysical properties of (Na,Li)NbO3 solid solutions

Solid solutions were obtained on the basis of (Na,Li)NbO3 binary system, modified by addition of minor amount (not greater than 5 wt%) of various elements’ monoxides, including their combinations. This study focuses on the peculiar features of their crystalline structure, grain structure, and thermal-frequency behavior of relative permittivity. The modifications by simple Mn and Cu oxides demonstrate a retention of crystalline structure of initial solid solution. Addition of NiO leads to transformation of phase state, which is stipulated by high stereochemistry activity and emission ability of Ni(II). A noticeable variation of phase state occurs also due to the combined modification by the above-mentioned oxides and Bi2O3+Fe2O3 ones. It is established that high-temperature anomalies of dielectric properties are related to partial reduction of niobium. It was also shown that the given modified lead-free solid solutions are characterized with improved piezoelectric, ferroelastic, and mechanical properties, and they can be applied in the field of microwave engineering.

Control of mechanical response of freestanding PbZr0.52Ti0.48O3 films through texture

The texture of piezoelectric lead zirconate titanate (PZT) thin films plays a key role in their mechanical response and linearity in the stress vs. strain behavior. The open circuit mechanical properties of PZT films with controlled texture varying from 100% (001) to 100% (111) were quantified with the aid of direct strain measurements from freestanding thin film specimens. The texture was tuned using a highly {111}-textured Pt substrate and excess-Pb in the PbTiO3 seed layer. The mechanical and ferroelastic properties of 500 nm thick PZT (52/48) films were found to be strongly dependent on grain orientation: the lowest elastic modulus of 90 ± 2 GPa corresponded to pure (001) texture, and its value increased linearly with the percentage of (111) texture reaching 122 ± 3 GPa for pure (111) texture. These elastic modulus values were between those computed for transversely isotropic textured PZT films by using the soft and hard bulk PZT compliance coefficients. Pure (001) texture exhibited maximum non-linearity and ferroelastic domain switching, contrary to pure (111) texture that exhibited more linearity and the least amount of switching. A micromechanics model was employed to calculate the strain due to domain switching. The model fitted well the non-linearities in the experimental stress–strain curves of (001) and (111) textured PZT films, predicting 17% and 10% of switched 90° domains that initially were favorably aligned with the applied stress in (001) and (111) textured PZT films, respectively.

Electrically controlled non-volatile switching of magnetism in multiferroic heterostructures via engineered ferroelastic domain states

In this work we addressed a key challenge in realizing multiferroics-based reconfigurable magnetic devices, which is the ability to switch between distinct collective magnetic states in a reversible and stable manner with a control voltage. Three possible non-volatile switching mechanisms have been demonstrated, arising from the nature of the domain states in pervoskite PZN-PT crystal that the ferroelectric polarization reversal is partially coupled to the ferroelastic strain. Electric impulse non-volatile control of magnetic anisotropy in FeGaB/PZN-PT and domain distribution of FeGaB during the ferroelectric switching have been observed, which agrees very well with simulation results. These approaches provide a platform for realizing electric impulse non-volatile tuning of the order parameters that are coupled to the lattice strain in thin-film heterostructures, showing great potentials in achieving reconfigurable, compact, light-weight and ultra-low-power electronics. Thin films that switch magnetic states with electric impulses and strain effects have potential for ultra-low power spintronic devices. The coupled magnetic, ferroelectric, and ferroelastic properties of multiferroic materials make them attractive candidates for future non-volatile memory systems. Ming Liu from Xi’an Jiaotong University in China and an international team have now discovered three different ways to manipulate magnetic domains in a multiferroic, multilayered device through ferroelectrical partially-coupled ferroelastic domain switching. Depositing an iron–gallium–boron thin film on top of a piezoelectric substrate produced two stable and reversible lattice strain states accessible through a control voltage. Electric impulses could also trigger phase transitions in the piezoelectric that in turn, switched magnetic states in the mechanically coupled iron–gallium–boron layer. Computational modelling helped visualize the mechanisms behind the electrically-controlled tuning exhibited by this prototype. (a–c) Reciprocal space maps about (022) reflections of PZN-PT (011) under various poling states, exhibiting various ferroelastic strain states. (d) Electric impulse-induced non-volatile tuning of magnetic anisotropy between the distinct strain states A and B due to the ferroelectric partially coupled ferroelastic domain switching. (e) Hysteresis loops of magnetic resonance fields of FeGaB as a function of the electric field applied on PZN-PT (011), arising from the electric field-induced ferroelectric phase transition from rhombohedral to orthogonal (R–O).

One-Dimensional Ferroelectric Nanostructures: Synthesis, Properties, and Applications.

One‐dimensional (1D) ferroelectric nanostructures, such as nanowires, nanorods, nanotubes, nanobelts, and nanofibers, have been studied with increasing intensity in recent years. Because of their excellent ferroelectric, ferroelastic, pyroelectric, piezoelectric, inverse piezoelectric, ferroelectric‐photovoltaic (FE‐PV), and other unique physical properties, 1D ferroelectric nanostructures have been widely used in energy‐harvesting devices, nonvolatile random access memory applications, nanoelectromechanical systems, advanced sensors, FE‐PV devices, and photocatalysis mechanisms. This review summarizes the current state of 1D ferroelectric nanostructures and provides an overview of the synthesis methods, properties, and practical applications of 1D nanostructures. Finally, the prospects for future investigations are outlined.

In-situ structural investigations of ferroelasticity in soft and hard rhombohedral and tetragonal PZT

Despite the technological importance of hard and soft PZT, Pb(Zr,Ti)O3, ceramics, the mechanisms of ferroelectric hardening and softening remain widely discussed in the literature. The hardening and softening phenomena have traditionally been investigated in relation with dielectric manifestations such as aging of the dielectric susceptibility and constriction of the polarization-electric field hysteresis loop. Here, we present a systematic investigation of the ferroelectric and ferroelastic properties of soft and hard PZT in both the tetragonal and rhombohedral phases. A particular focus has been devoted to ferroelastic domain switching by characterizing the macroscopic mechanical constitutive behavior and in-situ synchrotron X-ray diffraction during compression. It is demonstrated that variation of the ordering state of point defects in PZT ceramics affects the switching behavior of both ferroelectric and ferroelastic domains under mechanical or electrical fields. Softening of the mechanical and electrical properties of originally hard PZT ceramics was conferred by quenching the materials from above the Curie temperature. The present findings are discussed with respect to the current understanding of hardening-softening transitions in ferroelectric materials.

Electrical conductivity and ferroelastic properties of Ti-substituted solid solutions (1 − x) BiFeO3 – x Bi0.5K0.5TiO3

The high crystallographic strain and polarization of BiFeO3 are attractive, but utilization of bulk BiFeO3 has been hindered by large leakage current and high coercive field. Here, we report on the electrical conductivity and ferroelasticity of BiFeO3 substituted with 10 and 20mol% Bi0.5K0.5TiO3. The electrical conductivity is reduced by several orders of magnitude with donor substitution of Fe with Ti, which also suppressed the strong dependence of the conductivity on partial pressure of oxygen. Hard ferroelastic properties of the as-sintered materials were demonstrated by stress–strain measurements. The coercive stress was strongly reduced by quenching from above the ferroelectric to paraelectric phase transition, and the remanent strain increased and coercive stress decreased with increasing temperature up to 400°C. Ferroelastic hardening was also observed with increasing Ti-donor substitution. The effect of donor substitution is discussed with respect to point defect chemistry and possible hardening mechanisms related to point defects.

1H and 2H Magic Angle Spinning Nuclear Magnetic Resonance Study of Phase Transition in KH3(SeO3)2 and Deuterated KD3(SeO3)2

The chemical shifts and spin–lattice relaxation times T 1ρ in KH3(SeO3)2 and deuterated KD3(SeO3)2 were measured in the rotating frame as functions of temperature by 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) and 2H MAS NMR, respectively. There were no significant changes in T 1ρ for 1H and 2H nuclei near T C, except for a change in the number of proton signals. The transition is driven by the number of resonance lines resulting from the crystal’s ferroelastic properties. Near T m, the chemical shifts and T 1ρ values for 1H and 2H in the two materials changed abruptly, which implies variation of the structural geometry.

Temperature-dependent R-curve behavior of the lead-free ferroelectric 0.615Ba(Zr0.2Ti0.8)O3–0.385(Ba0.7Ca0.3)TiO3 ceramic

The temperature-dependent crack growth resistance behavior of the lead-free (1−x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 (x=0.385) ceramic was characterized using compact-tension specimens from 25°C to 60°C. The observed plateau fracture toughness at 25°C was found to be approximately 37% lower than commercial Pb(Zr,Ti)O3. At elevated temperature, the maximum fracture toughness displayed a decrease, which was found to be related to the temperature-dependent elastic and ferroelastic properties. Mechanical measurements are presented that demonstrate decreasing effective switching strain, coercive stress and Young’s modulus with increasing temperature.

Structural characteristics for phase transitions of [N(CH3)4]2CuCl4 by 13C CP/MAS NMR and 14N NMR

Structure geometry changes in [N(CH3)4]2CuCl4 near the phase transition temperature were studied by 13C CP/MAS NMR and 14N NMR spectrum. We distinguished the two chemically inequivalent N(1)(CH3)4 and N(2)(CH3)4 groups by 13C CP/MAS NMR and 14N NMR spectrum. The abrupt changes in chemical shifts and the split of the NMR signals near the phase transition temperatures for 13C and 14N are explained by a structural phase transition, implying that the structural geometry depends on the temperature. The mechanism behind this phase transition is based on ferroelasticity, and is also mainly related to the 14N ions in N(CH3)4 ions. Furthermore, both phases III and IV exhibit ferroelastic properties with identical orientational domains.

Monoclinic–Orthorhombic Phase Transition in ZSM-5 Zeolite: Spontaneous Strain Variation and Thermodynamic Properties

Modeling the ferroelastic properties of the monoclinic–orthorhombic phase transition of ZSM-5 zeolites is very relevant to the understanding of the effects of lattice strain on adsorption and diffusion properties of these microporous materials widely used in catalysis and water treatment. Using very accurate synchrotron X-ray diffraction data, we report here the analysis of spontaneous strain variation across the transition. According to the Landau theory, the behavior of the order parameter reveals the tricritical character of this transition from ferroelastic to paraelastic phase in ZSM-5. Combination of results from Landau analysis with calorimetric data allows the calculation of thermodynamic quantities which are in good agreement with the experimentally derived ones.

Piezodielectric properties of PMN-PZT-PT solid solutions under the action of high temperatures

The piezodielectric and ferroelastic properties of solid solutions of the multi-component system 0.98(xPbTiO3−yPbZrO3−zPbNb2/3Mg1/3O3)-0.02PbGeO3 are studied in the temperature range of 30–400°C. Abnormalities of the above dependences are revealed, and it is suggested that the observed phenomena are of a physical nature.

OS1605 固体酸化物形燃料電池用空気極材料の強弾性的性質

Temperature and frequency dependence of Young's modulus and internal friction of La_<0.6>Sr_<0.4>Co_<0.2>Fe_<0.8>O_<3-δ> were evaluated by dynamic mechanical analysis. A relaxation peak in the internal friction which follows a significant decrease in the Young's modulus was observed. It was suggested that the peak was derived from domain reorientations. An introduction of oxygen vacancies into the sample significantly changed the temperature dependence of the Young's modulus and the internal friction. The Young's modulus became larger especially below 400 K. A small peak which depended on the oxygen vacancy concentration was observed when the oxygen vacancies were introduced. This peak was considered to be due to oxygen vacancy diffusion. Such significant changes in the temperature dependence of the Young's modulus and the internal friction may be caused by crystal structure change and pinning of domain walls by the oxygen vacancies.

Temperature-dependent R-curve behavior of Pb(Zr1−xTix)O3

The crack growth resistance behavior of polycrystalline Pb(Zr1−xTix)O3 has been characterized in a novel experimental arrangement between 24 and 140°C. Experimental measurements were carried out on compact tension specimens submerged in a temperature-controlled silicone oil bath. The results show a decrease in the observed shielding toughness, leading to an overall reduction in the maximum toughness. The temperature-dependent stress–strain behavior and elastic properties were characterized, providing an insight into the effect of the changing ferroelastic properties on the temperature-dependent fracture behavior.

Characteristic features of the structural properties, phase transitions, and ferroelastic properties in LiK1−xRbxSO4 (x=0, 0.2, and 1) crystals

We report a systematic nuclear magnetic resonance (NMR) study of alkaline ions in LiK1−x RbxSO4 (x=0, 0.2, and 1) crystals, which was performed to investigate the effects of the random distribution of the Rb substitutional cation on the sequence of phase transitions. When a fraction of potassium ions in the pure LiKSO4 crystal is partially replaced by rubidium ions, we compare the structural properties of LiKSO4, LiK0.8Rb0.2SO4, and LiRbSO4 single crystals. The presence of the Rb ions stabilizes the trigonal structure and prevents the breaking of trigonal symmetry at low temperature. The partial substitution of Rb for K changes the transition temperature, and the ferroelastic property of pure LiKSO4 at low temperatures does not appear in the LiK0.8Rb0.2SO4 crystal down to 100K.

Structural properties in mixed LiK1−x(NH4)xSO4 (x = 0, 0.06, and 1) crystals by nuclear magnetic resonance

LiK1−x(NH4)xSO4 (x=0, 0.06, and 1) mixed crystals were grown using the slow evaporation method, and their lattice constants were determined by X-ray diffraction. In order to determine the effects of the NH4 concentration on the phase transitions and the physical properties of mixed LiK1−x(NH4)xSO4 crystals (x=0.06), we compared its NMR spectra and relaxation times with those of pure LiKSO4 and LiNH4SO4 crystals. After the partial replacement of potassium ions by ammonium ions, the ammonium ions occupy the same locations in the lattice as the potassium ions. The presence of the NH4 ions stabilizes the trigonal structure and prevents the breaking of trigonal symmetry at low temperatures. The main effects produced by the substitution of potassium ions with ammonium ions are the variations of the phase transition temperatures and the absence of ferroelastic properties.

Elastic and anelastic anomalies associated with the antiferromagnetic ordering transition in wüstite, FexO

The elastic and anelastic properties of three different samples of FexO have been determined in the frequency range 0.1–2 MHz by resonant ultrasound spectroscopy and in the range 0.1–50 Hz by dynamic mechanical analysis in order to characterize ferroelastic aspects of the magnetic ordering transition at TN ∼ 195 K. No evidence was found of separate structural and magnetic transitions but softening of the shear modulus was consistent with the involvement of bilinear coupling, λe4q, between a symmetry-breaking strain, e4, and a structural order parameter, q. Unlike a purely ferroelastic transition, however, C44 does not go to zero at the critical temperature, , due to the intervention of the magnetic ordering at a higher temperature. The overall pattern of behaviour is nevertheless consistent with what would be expected for a system with separate structural and magnetic instabilities, linear–quadratic coupling between the structural (q) and magnetic (m) driving order parameters, λqm2, and . Comparison with data from the literature appears to confirm the same pattern in MnO and NiO, with a smaller difference between TN and in the former and a larger difference in the latter. Strong attenuation of acoustic resonances at high frequencies and a familiar pattern of attenuation at low frequencies suggest that twin walls in the rhombohedral phase have typical ferroelastic properties. Acoustic dissipation in the stability field of the cubic phase is tentatively attributed to anelastic relaxations of the defect ordered structure of non-stoichiometric wüstite or of the interface between local regions of wüstite and magnetite, with a rate controlling step determined by the diffusion of iron.

Crystal structure and characterization of a novel ferroelastic ionic crystal: 1-Aminopyridinium iodide (C5H7N2)+I−

1-Aminopyridinium iodide (API) undergoes a reversible first-order phase transition (PT) II→I at 384K. The single-crystal X-ray diffraction studies have been carried out at 110, 280 and 401K. The compound crystallizes in the monoclinic space group P21/c (phase II) and exhibits ferroelastic properties. High temperature paraelastic phase (I) is described by the trigonal symmetry (space group R3¯m) with the 6-site cations disorder. The mechanism of PT is governed by both cationic dynamics and shifts of the I− anions. The conductivity that emerges when approaching the PT temperature is believed to be associated with the charge transfer from I− anion to the 1-aminopyridinium cation.

Reconstructive phase transitions and physical properties of mixed LiK0.9Na0.1SO4 crystals

LiK0.9Na0.1SO4 mixed crystals were grown using the slow evaporation method, and their properties were compared with those of pure LiKSO4 crystals. The physical properties and phase transition temperatures of the LiK0.9Na0.1SO4 mixed crystals were obtained by performing 7Li, 39K, and 23Na nuclear magnetic resonance relaxation and differential scanning calorimetry. Based on the changes in the splitting of the NMR lines and the dependence of the relaxation time on temperature, the molecular motions for each ion in pure LiKSO4 and mixed LiK0.9Na0.1SO4 crystals were different by partial replacing of K ions with Na ions. And, the partial substitution of Na for K changes the phase behavior, and disappears the ferroelastic properties.

A nuclear magnetic resonance study of the structural properties and molecular motions of Li 2KH(SO 4) 2 and LiKSO 4 single crystals

The structural properties and relaxation mechanisms of Li 2KH(SO 4) 2 crystals were determined using the temperature dependences of NMR spectra and the spin–lattice relaxation times ( T 1) of their 1H, 7Li, and 39K nuclei. The results obtained were compared with the previously reported physical properties of LiKSO 4 crystals. The substitution of the potassium ions with protons in the LiKSO 4 crystals were variations in the phase transition temperatures, and the non-appearance of ferroelastic properties. The 7Li T 1 for the Li 2KH(SO 4) 2 crystals was much shorter than the 7Li T 1 for the LiKSO 4 crystals, and these findings indicate that the presence of the protons in Li 2KH(SO 4) 2 causes the Li ions to move with greater freedom.

Study of the structural properties and phase transitions of LiCs 1−x(NH 4) xSO 4 ( x = 0.1 and 0.4) mixed crystals by 1H, 7Li, and 133Cs nuclear magnetic resonance

LiCs 1− x (NH 4) x SO 4 ( x = 0.1 and 0.4) mixed crystals were grown using the slow evaporation method, and their lattice constants were determined with X-ray diffraction. The structural properties and phase transitions of the LiCs 1− x (NH 4) x SO 4 mixed crystals were studied by 1H, 7Li, and 133Cs nuclear magnetic resonance relaxation analyses and differential scanning calorimetry. On the basis of the results, along with previous reports on the structural properties of pure LiCsSO 4 and LiNH 4SO 4 single crystals, the effects of partially replacing cesium ions with ammonium ions were examined. The results showed that the introduction of a small quantity of ammonium ions into LiCsSO 4 crystals induces a change in the phase transition temperatures and causes the ferroelastic properties to almost completely disappear.