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Sm-doped Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (Sm-PMN-PT) bulk materials have revealed outstanding ferroelectric and piezoelectric properties due to enhanced local structural heterogeneity. In this study, we further explore the potential of Sm-PMN-PT by fabricating epitaxial thin films by pulsed laser deposition, revealing that Sm doping significantly improves the capacitive energy-storage, piezoelectric, electrocaloric, and pyroelectric properties of PMN-PT thin films. These Sm-PMN-PT thin films exhibit fatigue-free performance up to 10 9 charge-discharge cycles and maintain thermal stability across a wide temperature range from -40 to 200 °C. Notably, the films demonstrate a colossal electrocaloric effect with a temperature change of 59.4 K and a remarkable pyroelectric energy density reaching 40 J cm -3 . By using scanning transmission electron microscopy and phase-field modeling, we revealed that these exceptional properties arise from the increased local structural heterogeneity and strong local electric fields along spontaneous polarization directions, facilitating the nucleation of polymorphic nanodomains characterized by a slush-like polar structure. These findings highlight the enormous potential of Sm-PMN-PT films in capacitive energy storage and solid-state electrothermal energy interconversion. Furthermore, this approach holds broad potential for other relaxor ferroelectrics by enabling the manipulation of nanodomain structures, paving the way for developing robust multifunctional materials.

Hypothesis: Contact-line motion upon drying of a sessile droplet strongly affects the solute transport and solvent evaporation profile. Hence, it should have a strong impact on the deposit formation and might be responsible for volcano-like, dome-like and flat deposit morphologies., Experiments: A method based on a thin-film interference was used to track the drop height profile and contact line motion during the drying. A diverse set of drying scenarios was obtained by using inks with different solvent compositions and by adjusting the substrate wetting properties. The experimental data was compared to the predictions of a phenomenological model., Findings: We highlight the essential role of contact-line mobility on the deposit morphology of solution-based inks. A pinned contact line produces exclusively ring-like deposits under normal conditions. On the contrary, drops with a mobile contact line can produce ring-, flat- or dome-like morphology. The developed phenomenological model shows that the deposit morphology depends on solvent evaporation profile, evolution of the drop radius relative to its contact angle, and the ratio between initial and maximal (gelling) solute concentration. These parameters can be adjusted by the ink solvent composition and substrate wetting behaviour, which provides a way for deposition of uniform and flat deposits via inkjet printing., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

We show how sintering in different atmospheres affects the structural, microstructural, and functional properties of ~30 μm thick films of K 0.5 Na 0.5 NbO 3 (KNN) modified with 0.38 mol% K 5.4 Cu 1.3 Ta 10 O 29 and 1 mol% CuO. The films were screen printed on platinized alumina substrates and sintered at 1100 °C in oxygen or in air with or without the packing powder (PP). The films have a preferential crystallographic orientation of the monoclinic perovskite phase in the [100] and [-101] directions. Sintering in the presence of PP contributes to obtaining phase-pure films, which is not the case for the films sintered without any PP notwithstanding the sintering atmosphere. The latter group is characterized by a slightly finer grain size, from 0.1 μm to ~2 μm, and lower porosity, ~6% compared with ~13%. Using piezoresponse force microscopy (PFM) and electron backscatter diffraction (EBSD) analysis of oxygen-sintered films, we found that the perovskite grains are composed of multiple domains which are preferentially oriented. Thick films sintered in oxygen exhibit a piezoelectric d coefficient of 64 pm/V and an effective thickness coupling coefficient 33 coefficient of 64 pm/V and an effective thickness coupling coefficient k t of 43%, as well as very low mechanical losses of less than 0.5%, making them promising candidates for lead-free piezoelectric energy harvesting applications.

Additive manufacturing has dramatically transformed the design and fabrication of advanced objects. Printed electronics-an additive thin-film processing technology-aims to realize low-cost, large-area electronics, and fabrication of devices with highly customized architectures. Recent advances in printing technology have led to several innovative applications; however, layer-on-layer deposition persists as a challenging issue. Here, the additive manufacturing of functional oxide devices by inkjet printing is presented. Two conditions appear critical for successful layer-on-layer printing: (i) preservation of stable surface properties and (ii) suppression of the material accumulation at the edges of a feature upon drying. The former condition was satisfied by introducing a surface modification layer of a polymer with nanotextured topography, and the latter was satisfied by designing the solvent composition of the ink. The developed process is highly efficient and enables conformal stacking of functional oxide layers according to the user-defined geometry, sequence arrangement, and layer thickness. To prove the effectiveness of this concept, we demonstrate an additive manufacture of all-oxide ferroelectric multilayer capacitors/transducers. Printed multilayer devices offer a significant increase in the capacitance density and the electromechanical voltage response in comparison to the single-layer devices. Further growth in the number of available functional oxide inks will enable arbitrary device architectures with novel functionalities.

The surface properties of a substrate are among the most important parameters in the printing technology of functional materials, determining not only the printing resolution but also the stability of the printed features. This paper addresses the wetting difficulties encountered during inkjet printing on homogeneous substrates as a result of improper surface properties. We show that the wetting of a substrate and, consequently, the quality of the printed pattern, can be mediated through the deposition of polymeric layers that are a few nanometers thick. The chemical nature of the polymers determines the surface energy and polarity of the thin layer. Some applications, however, require a rigorous adjustment of the surface properties. We propose a simple and precise method of surface-energy tailoring based on the thermal decomposition of poly(methyl methacrylate) (PMMA) layers. A smooth transition in the wetting occurs when the thickness of the PMMA layer approaches zero, probably due to percolation of the underlying surface of the substrate, which enables the inkjet printing of complex structures with a high resolution. In particular, the wetting of three substrate-ink systems was successfully adjusted using the thin polymeric layer: (i) a tantalum-oxide-based ink on indium-tin-oxide-coated glass, (ii) a ferroelectric lead zirconate titanate ink on a platinized silicon substrate, and (iii) a silver nanoparticle ink on an alumina substrate.

The existence and feasibility of the multicaloric, polycrystalline material 0.8Pb(Fe1/2Nb1/2)O3-0.2Pb(Mg1/2W1/2)O3, exhibiting magnetocaloric and electrocaloric properties, are demonstrated. Both the electrocaloric and magnetocaloric effects are observed over a broad temperature range below room temperature. The maximum magnetocaloric temperature change of ~0.26 K is obtained with a magnetic-field amplitude of 70 kOe at a temperature of 5 K, while the maximum electrocaloric temperature change of ~0.25 K is obtained with an electric-field amplitude of 60 kV/cm at a temperature of 180 K. The material allows a multicaloric cooling mode or a separate caloric-modes operation depending on the origin of the external field and the temperature at which the field is applied.

It has long been considered that polar nanoregions in relaxors form at Burns temperature T(d) ≈ 600K. High-temperature dielectric investigations of Pb(Mg(1/3)Nb(2/3)) O(3) (PMN) single crystal, PMN-PbTiO(3) ceramics, and (Pb,La) (Zr,Ti)O(3) ceramics reveal, however, that dielectric dispersion, detected around 600K, is due to the Maxwell-Wagner-type contributions of surface layers. The intrinsic response was analyzed in terms of the universal scaling, taking into account the asymptotic and the correction-to-scaling behavior, and the results imply much higher T(d) or formation of polar nanoregions in a broad temperature range. High values of the dielectric constant indicate, however, that polar order already exists at the highest measured temperatures of 800K. The obtained critical exponents indicate critical behavior associated with universality classes typically found in spin glasses.

The study of the smectic-A to chiral smectic-C(*) phase transition of the liquid crystal S-(+)-[4-(2(')-methyl butyl) phenyl 4(')-n-octylbiphenyl-4-carboxylate] (CE8) containing dispersed hydrophilic aerosils reveals novel properties, important to understanding quenched disorder and confinement in ferroelectric liquid crystals. Smectic layer compression leads to a distribution of transition temperatures inducing smearing of the macroscopic data across the transition. A pronounced confinement-induced pretransitional tilted order is observed.

The dielectric response of copper-phthalocyanine (CuPc) oligomers embedded in a poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) terpolymer matrix was studied. Although admixture of CuPc strongly increases the dielectric constant of the terpolymer at all temperatures, each of the two constituents determines the dielectric dynamics in a different temperature region-the relaxorlike matrix above and CuPc below the terpolymer's freezing temperature. Two relaxations, reflecting the charge carriers' response in CuPc, were detected. Results on ac conductivity reveal that the tunneling of polarons is the dominating charge transport mechanism.

The temperature dependence of the dielectric nonlinearities in a PMN single crystal and in 9/65/35 PLZT ceramics has been determined by measuring the first and third harmonic response as well as the dielectric behavior as a function of the dc electric field. In zero field a paraelectric-to-glass, and, in a high enough dc field, a glass-to-ferroelectriclike crossover in the temperature dependence of the nonlinear response have been observed. Both crossovers agree with the predictions of the spherical random-bond-random-field model. Relaxors thus undergo in zero field a transition to a spherical glass, while above the critical field a transition into a ferroelectric state occurs.