A first-principles-derived scheme, that incorporates ferroelectric and antiferrodistortive degrees of freedom, is developed to study finite-temperature properties PbZr1-xTixO3 solid solutions near its morphotropic phase boundary. The use this numerical technique (i) resolves controversies about the monoclinic ground-state for some Ti compositions, (ii) leads discovery an overlooked phase, (iii) yields three multiphase points, are each associated with four phases. Additional neutron...

Ab initio simulations and experimental techniques are combined to reveal that, unlike what was commonly accepted for more than 30 years, perovskites related materials enhance their ferroelectricity as hydrostatic pressure increases above a critical value. This unexpected high-pressure is different in nature from conventional because it driven by an original electronic effect rather long-range interactions.

We report a room-temperature high-pressure x-ray and Raman scattering investigation of lead titanate (PbTiO3) up to 63 GPa. Three continuous phase transitions at 13, 20, 45 GPa between tetragonal-like phases occur. As result, no evidence is found for pressure-induced morphotropic boundary. Our study provides experimental that PbTiO3 presents complex sequence accommodating pressure through mechanisms involving oxygen octahedra tilting reentrance ferroelectricity.

Combining density-functional calculations and x-ray diffraction experiments, we show that ${\text{BiFeO}}_{3}$ epitaxially grown under compressive strain on cubic substrates evolves from the monoclinic $Cc$ phase (resulting strain-induced deformation of ground-state rhombohedral $R3c$ phase) to $Cm$ with increasing misfit, transition being at about $\ensuremath{-}4.5\mathrm{%}/\ensuremath{-}5.5\mathrm{%}$. Moreover, polarization only rotates (instead increasing) for misfit ranging 0%...

The recent discovery of giant electrostrictors has re-ignited the interest in electrostriction, an electromechanical coupling existing all dielectrics but overshadowed by its linear counterpart: piezoelectricity. In this review, after a reminder classical we propose definition electrostriction based on two empirical relations (Newnam relation and one propose). From definition, review previous reports electrostrictors, to assess their nature. Focusing ones satisfying our compare performances...

The restored strain energy in $\mathrm{Pb}{\mathrm{Zn}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_{3}$ (PZN) and $9%\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_{3}$-doped PZN (PZN-9%PT) relaxor crystals has been studied by means of acoustic emission (AE). Two types AE activity signals have recorded: (i) related to temperature- or electric-field-induced macroscopic phase transitions (ii) associated with formation/disappearance intrinsic polar nanoregions. Monitoring under varying [001] electric fields...

Strain engineering aims to take advantage of the stress field imposed by substrates on thin films. It requires an understanding consequences fields physical properties deposited materials. This is achieved in ferroelectric films through use misfit-strain phase diagrams that show stability regions for possible phases. These encompass bulk phases as well new ones exhibiting symmetries are not present bulk. For solid solution lead zirconate–lead titanate, Pb(Zr1−xTix)O3, monoclinic found...

The effect of biaxial strain on the oxygen octahedra rotations in a LaVO${}_{3}$ thin film is investigated using synchrotron radiation. First, we find that adopts distorted orthorhombic structure under compressive stress induced by SrTiO${}_{3}$ substrate. Second, separate contribution to superstructure peaks arising from cation displacement and VO${}_{6}$ order quantify rotation angles. Finally, an original ${a}^{\ensuremath{-}}{a}^{+}{c}^{\ensuremath{-}}$ tilt system, which imposed These...

An applied stress field ${\ensuremath{\sigma}}_{3}$ can reversibly change the temperature of an elastocaloric material under adiabatic conditions, and $\ensuremath{\Delta}{T}_{{\ensuremath{\sigma}}_{3}}$ is usually maximized near phase transitions. Using a thermodynamic approach, we demonstrate that strength $\ensuremath{\alpha}=|\ensuremath{\Delta}{T}_{{\ensuremath{\sigma}}_{3}}|/|{\ensuremath{\sigma}}_{3}|$ 0.016 K/MPa be achieved benefiting from full first-order transition in...

Barocaloric effect in BaTiO3 single crystal is studied by a thermodynamic phenomenological model. It demonstrated that giant barocaloric can be achieved near room temperature with an adiabatic change of more than 3 K and span about 50 K. As expected, the electrocaloric peak shifted towards pressure. However, slight reduction found contrast to relaxor ferroelectrics LiNbO3. We believe our findings could open potential route combining pressure-mediated for cooling devices.

Abstract “Giant” electrostrictors are materials that exhibit anomalously large quadratic electromechanical coupling. Few such have been discovered and the origin of their remarkable properties is still under debate. Here several new giant based on iso‐ alio‐valent substitutions in La 2 Mo O 9 reported. The dielectric, elastic, anelastic electrostrictive ‐based measured show no correlation with ionic radius substituent element, contrary to what has reported for doped ceria. site affect more...

Hexagonal $\mathrm{ErFe}{\mathrm{O}}_{3}$ thin films fabricated by a pulsed laser deposition method were investigated x-ray diffraction (XRD) and transmission electron microscopy. No structural phase transition was observed between 20 900 K. Ferroelectric $D\ensuremath{-}E$ hysteresis loops obtained at room temperature using the double-wave method, magnitude of spontaneous polarization determined to be $200\phantom{\rule{0.16em}{0ex}}\mathrm{nC}/\mathrm{c}{\mathrm{m}}^{2}$. The existence...

The coexistence of ferroelectricity and magnetic order in epitaxial hexagonal YbFeO 3 (h-YbFeO ) thin films deposited on yttria stabilized zirconia substrates is examined using an impedance analyzer, a second harmonic generation (SHG) microscope, X-ray diffractometer, transmission electron microscope superconducting quantum interference device magnetometer. results show that h-YbFeO exhibit below 350 K with threefold translational periodicity along the [110] direction similar to rare earth...

Combining temperature-dependent x-ray diffraction, Raman spectroscopy and first-principles-based effective Hamiltonian calculations, we show that varying the thickness of (Ba0.8Sr0.2)TiO3 (BST) thin films deposited on same single substrate (namely, MgO) enables us to change not only magnitude but also sign misfit strain. Such previously overlooked control strain allows several properties these (e.g. Curie temperature, symmetry ferroelectric phases, dielectric response) be tuned even...

We present a study in which ferroelectric phase transition temperatures epitaxial KxNa1−xNbO3 films are altered systematically by choosing different (110)-oriented rare-earth scandate substrates and variation of the potassium to sodium ratio. Our results prove capability continuously shift ferroelectric-to-ferroelectric from monoclinic MC orthorhombic c-phase about 400 °C via application anisotropic compressive strain. The was investigated detail monitoring temperature dependence domain...

We report a high-pressure investigation of the relaxor ferroelectric lead zinc niobate ${\mathrm{PbZn}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_{3}$ (PZN) up to $46\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, which is highest pressure yet attained in study relaxors. The evolution both Raman and x-ray scattering with gives evidence for important instabilities, find its expression three successive phase transitions. observed pressure-induced suppression diffuse above...

Abstract Electrostrictive materials exhibit a strain that is proportional to the square of induced polarization. In linear dielectrics where permittivity constant, this electromechanical also electric field. However, under increasing amplitudes driving field, sometimes saturates; electrostrictive coefficients therefore appear depend on amplitude field used measure them. Here, methodology showing apparent dependence consequence neglecting higher‐order phenomena presented. When these are taken...

The structural evolution of epitaxial monodomain (only 180° domains) ferroelectric PbTiO3 thin film has been investigated, using high-resolution, temperature-dependent, x-ray diffraction. full set lattice parameters was obtained from room temperature up to 850K. It allowed the calculation different strains stored in at temperature, underlying difference between mechanical strain and misfit strain. as a function also calculated found be consistent with theoretical temperature-misfit phase...

A nonlinear thermodynamic theory is applied to strained ferroelectric superlattices and used determine the dependence of superlattice permittivity on composition. To that end, spontaneous polarizations field-induced polarization changes in layers $A$ $B$ with thicknesses ${t}_{A}$ ${t}_{B}$ are calculated as a function volume fraction ${\ensuremath{\phi}}_{A}={t}_{A}/({t}_{A}+{t}_{B})$. The existence dielectric anomaly at specific composition ${\ensuremath{\phi}}_{A}^{\ensuremath{\ast}}$...

The interplay between charge, spin, orbital and lattice degrees of freedom in transition metal oxides has motivated extensive research aiming to understand the coupling phenomena these multifunctional materials. Among them, rare earth vanadates are Mott insulators characterized by spin orderings strongly influenced distortions. Using epitaxial strain as a means tailor unit cell deformation, we report here on first thin films PrVO3 grown (001)-oriented SrTiO3 substrate pulsed laser...

We report the observation of electric spontaneous polarization in YbFe2O4, one candidate “electronic ferroelectric,” where ferroelectricity originates from polar charge order. Though we have proposed that LuFe2O4 ordering iron ions having different valence states give rise to ferroelectricity, some reports questioned not only electronic origin but also existence itself this system. In response this, show a direct macroscopic evidence by clear P-E hysteresis loop YbFe2O4 belonging same system...

The direct magnetoelectric (ME) effect mediated by lattice strains induced in a ferroelectric film ferromagnetic substrate is evaluated using first-principles-based calculations. To that end, the strain sensitivity of polarization and permittivity are calculated as function in-plane biaxial for Pb(Zr0.52Ti0.48)O3 films under various depolarizing fields. It found ME voltage coefficient varies nonmonotonically with this may reach giant values exceeding 100 Vcm-1 Oe-1 over range can be...