Harvey Amorín

• PhD
• Researcher at Spanish National Research Council

Materials with the capacity to transform mechanical stresses into electrical energy and vice versa include piezoelectric polymers and polymer composites. The chapter introduces the piezoelectric effect and discusses polymer composites, emphasizing the polymer matrix and fillers to enhance performance and tune specific materials characteristics. We...

Biobased and biodegradable poly-l-lactide (PLLA) stands out among piezoelectric polymers for its biocompatibility and environmental sustainability. Its piezoelectric response is closely related to the crystallinity and the alignment of polymer chains, which is conventionally obtained by drawing techniques. These are two-step processes with tight sh...

Simple and cost-effective procedures for the direct integration of ferroelectric perovskite oxides into Ni structures are necessary to realize related multifunctional metallic microelectromechanical systems, such as dual-source energy harvesters. This is especially difficult in the case of lead-containing morphotropic phase boundary materials for h...

Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT) stands out among lead‐free ferroelectric oxides under consideration to replace state‐of‐the‐art high‐sensitivity piezoelectric Pb(Zr,Ti)O 3 , for a range of energy conversion ceramic technologies. However, the best performances have been reported for very coarse‐grained materials, and attempts to refine micr...

Natural polymers such as cellulose have interesting tribo- and piezoelectric properties for paper-based energy harvesters, but their low performance in providing sufficient output power is still an impediment to a wider deployment for IoT and other low-power applications. In this study, different types of celluloses were combined with nanosized car...

Aurivillius layered oxides with general formula (Bi 2 O 2 )(A m−1 B m O 3m+1 ) stand out among room-temperature magnetoelectric multiferroics for their large magnetization. However, despite extensive research, there is an obvious lack of understanding of their magnetism. The chemical design strategy for obtaining multiferroism involves the incorpor...

Lead-free ferroelectric Ba0.85Ca0.15Zr0.1Ti0.9O3 stands out among environmentally friendly alternatives to commercial Pb(Zr,Ti)O3 piezoceramics for its large piezoelectric coefficients, and it is especially suitable for applications in which thermal depoling is not an issue like bio-implanted devices. However, ceramic processing by conventional mea...

Ceramic matrix composites (CMC) of 8 mol.% yttria-stabilized zirconia (8YSZ) mixed with natural fiber nanocellulose (0.75, 1, 2 wt.%) were prepared by spark plasma sintering (SPS). Nanocellulose markedly improved the densification of the 8YSZ ceramic matrix and induced significant grain size refinement. It was demonstrated that in situ graphitizati...

The perovskite (1-x)YMnO$_3$-xBiFeO$_3$ binary system is very promising because of its multiferroic end members. Nanocrystalline phases have been recently obtained by mechanosynthesis across the system, and the perovskite structural evolution has been described. Two continuous solid solutions with orthorhombic Pnma and rhombohedral R3c symmetries w...

Increasing energy autonomy and lowering dependence on lithium-based batteries are more and more appealing to meet our current and future needs of energy-demanding applications such as data acquisition, storage, and communication. In this respect, energy harvesting solutions from ambient sources represent a relevant solution by unravelling these cha...

The (1 – x)BiFeO3‐xPbTiO3 (BFO‐PTO) perovskite solid solution has great potential for being used in practical devices, as it exhibits significant ferroelectric response at its morphotropic phase boundary (MPB). However, the significant conduction, particularly high electrical leakage currents that BFO‐PTO films show at room temperature, deteriorate...

Magnetoelectric composites provide large enough room-temperature functional responses to enable a range of novel technologies, like uncooled high-sensitivity magnetic sensors. Magnetoelectricity in these composites appears as a product property of the piezoresponses of two elastically coupled ferroic phases. Coefficients then depend not only on the...

A promising approach for obtaining a large magnetoelectric response at room temperature in single-phase materials is to make use of phase-change phenomena at structural instabilities of a multiferroic state. This is the case of perovskites showing the morphotropic phase boundary (MPB) between ferroelectric polymorphs with differentiated magnetic or...

Poly(methyl methacrylate-co-methacrylic acid) (PMMA-co-MAA) copolymer containing ionizable moieties is here investigated as a melt processing additive for PVDF to develop high-quality ferro/piezoelectric polymer films by extrusion-calendering. The PVDF/PMMA-co-MAA miscibility and the β-phase crystallization from the melt state at high cooling rates...

The perovskite (1−x)YMnO3−xBiFeO3 binary system is very promising because of its multiferroic end members. Nanocrystalline phases have been recently obtained by mechanosynthesis across the system, and the perovskite structural evolution has been described. Two continuous solid solutions with orthorhombic Pnma and rhombohedral R3c symmetries were fo...

Herein we report on novel multiferroic core–shell nanostructures of cobalt ferrite (CoFe2O4)–bismuth, sodium titanate doped with barium titanate (BNT–BT0.08), prepared by a two–step wet chemical procedure, using the sol–gel technique. The fraction of CoFe2O4 was varied from 1:0.5 to 1:1.5 = BNT–BT0.08/CoFe2O4 (molar ratio). X–ray diffraction confir...

Li- and Ta-modified K0.5Na0.5NbO3 compounds are among the most promising lead-free ferroelectrics for high-sensitivity piezoelectric ceramic materials, and are potentially capable of replacing Pb(Zr,Ti)O3. They are also being investigated as piezoelectric components in environmentally friendly magnetoelectric composites. However, most suitable modi...

Phase-change functional responses can be obtained in perovskite solid solutions at structural instabilities involving multiferroic states, a very promising approach for realizing magnetoelectric effects at room temperature. A line of multiferroic morphotropic phase boundaries (MPBs) has been described within the phase diagram of the BiFeO3-BiMnO3-P...

The magnetic, magnetostrictive, and electrical properties of Ga- and Mn-doped cobalt ferrite are reported as a function of composition. Materials with improved functionality for magnetoelectric composites are obtained. Magnetic characterizations reveal the effectiveness of the dopants to reduce the typically high magneto-crystalline anisotropy of c...

K 0.5 Na 0.5 NbO 3 -based materials are serious candidates to replace lead-based piezoceramics since they show excellent electrical and piezoelectric properties. The tape casting technique can be used to obtain highly textured KNN-based ceramics; however, despite industrial and environmental advantages of water-based processing, there are not repor...

Magnetoelectric composites are an enabling material technology for a range of novel devices like electrically-tunable magnetic microwave components or room-temperature-operation high-sensitivity magnetic sensors. Among the different approaches under development, cofired ceramic layered composites provide large effective magnetoelectric coefficients...

The ferromagnetic perovskite oxide BiMnO3 is a highly topical material, and the solid solutions it forms with antiferromagnetic/ferroelectric BiFeO3 and with ferroelectric PbTiO3 result in distinctive polar/nonpolar morphotropic phase boundaries (MPBs). The exploitation of such a type of MPBs could be a novel approach to engineer novel multiferroic...

The broadband dielectric properties of high sensitivity piezoelectric 0.36BiScO3-0.64PbTiO3 ceramics with average grain sizes from 1.6 μm down to 26 nm were investigated in the 100–500 K temperature range. The grain size dependence of the dielectric permittivity was analysed within the effective medium approximation. It was found that the generalis...

Low temperature processing of environmentally-friendly (K,Na)NbO3- and CoFe2O4-based layered composites has been accomplished by hot pressing, and their electrical, piezoelectric and magnetoelectric properties have been characterized. High quality composite three-layer CoFe2O4/K0.5Na0.5NbO3/CoFe2O4 structures with defect-free interfaces were obtain...

Finite element analysis is used to simulate the magnetoelectric response of magnetostrictive-piezoelectric NiFe2O4-Bi0.36Pb0.64Sc0.36Ti0.64O3 ceramic two-layer, three-layer, and multilayer structures considering finite geometry and introducing the conductivity of the magnetic component. Results are compared with those obtained with existing approxi...

Composite materials consisting of two dissimilar ferroic phases are an excellent alternative to single-phase multiferroics for a wide range of magnetoelectric technologies. In composites with strain-mediated magnetoelectric coupling the response is strongly dependent on the characteristics of the interface between the two mechanically coupled phase...

In order to obtain a wide-range magnetoelectric (ME) response on a ME nanocomposite that matches industry requirements, Tb0.3Dy0.7Fe1.92 (Terfenol-D)/CoFe2O4/P(VDF-TrFE) flexible films were produced by the solvent casting technique and their morphologic, piezoelectric, magnetic and magnetoelectric properties were investigated. The obtained composit...

Microwave processing is an attractive approach for the production of materials with improved properties, using fast heating curves. In this work, SrBi2Ta2O9 samples were obtained by the mixture of oxides (Bi2O3, Ta2O5 and SrCO3). The microstructural evolution during microwave sintering was investigated by scanning electron microscopy in association...

There is a growing activity in the search of novel single-phase multiferroics that could finally provide distinctive magnetoelectric responses at room temperature, for they would enable a range of potentially disruptive technologies, making use of the ability of controlling polarization with a magnetic field or magnetism with an electric one (for e...

Mechanosynthesis is demonstrated as an effective means of introducing A-site non-stoichiometry in BiMO 3-PbTiO 3 systems. • A-site non-stoichiometry is demonstrated as an effective means of engineering BiMO 3-PbTiO 3 systems for specific applications. • A point defect engineered BiScO 3-PbTiO 3 is presented with a largely enhanced voltage response...

BiScO3–PbTiO3 is used as a model system of BiMO3–PbTiO3 perovskite solid solutions with enhanced electromechanical response at ferroelectric morphotropic phase boundaries, and high Curie temperature to demonstrate specific point defect engineering for high power operation. The objective is to obtain a range of piezoelectric ceramics comparable to h...

In this work, Li3xLa2/3−xTiO3 powder with nominal lithium content (x = 0.08) was synthesized by mechano synthesis method. Spark plasma sintering (SPS) was employed to prepare lithium lanthanum titanium oxide solid-state ceramic. The techniques of X-ray diffraction, high resolution scanning electron microscopy, and Raman spectroscopy were used to ch...

Recently, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of phases in the BiFeO3–BiCoO3 perovskite binary system, associated with the existence of a discontinuous morphotropic phase boundary (MPB) between multiferroic polymorphs of rhombohedral and tetragonal symmetries. This might be a general...

Ceramic nanostructuring is a topical area of research in ferroelectric materials that is driven by current technological trends in consumer electronics like mobile phones; namely, that of enhancing performance while reducing size. In spite of the large potential impact of the miniaturized piezoelectric technologies, their feasibility, either they a...

The dielectric properties of high-temperature piezoelectric 0.36BiScO3–0.64PbTiO3 ceramics located at the morphotropic phase boundary with decreasing average grain sizes from 1.6 μm down to 26 nm were investigated in the 100–500 K temperature range and 100 Hz–40 GHz frequency region. Analysis of the current data and comparison with results of Porok...

The interest in multiferroics is growing rapidly and focuses in the search of novel single phase materials with room temperature magnetoelectric coupling. A highly topical set of materials are ABO 3 perovskite oxides, in which multiferroicity is chemically engineered by making use of the stereochemical activity of an A-site cation with lone pair (i...

The role of Pr6O11 addition on the structure, microstructure, electrical, and electromechanical properties of lead-free (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 piezoelectric ceramics has been systemically investigated. Addition of praseodymium (Pr) results in improved ferroelectric and piezoelectric properties. XRD analysis revealed the co-existence of rhom...

The role of BiFeO3 addition on the crystal structure, microstructure, and the electrical and electromechanical properties of high-sensitivity Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3 ferroelectric ceramics for compositions at the morphotropic phase boundary (MPB) is investigated. A perovskite solid solution from nano-sized BiFeO3 and Bi0.5Na0.5TiO3–Bi0.5K0.5Ti...

A highly topical set of materials are those ABO3 perovskite oxides, in which multiferroicity is chemically engineered by placing ferroelectrically and magnetically active cations in A- and B-site, respectively. This is the case of the BiFeO3 and BiMnO3 perovskites, and also of the solid solutions they form with PbTiO3. Interest in these binary syst...

A highly topical set of perovskite oxides are high-sensitivity piezoelectric ones, among which Pb(Zr,Ti)O3 at the morphotropic phase boundary (MPB) between ferroelectric rhombohedral and tetragonal polymorphic phases is reckoned a case study. Piezoelectric ceramics are used in a wide range of mature, electromechanical transduction technologies like...

Piezoresponse force microscopy has been used for the local characterization of high sensitivity piezoelectric BiScO3-PbTiO3 ceramics with compositions close to the morphotropic phase boundary, with decreasing grain sizes down to 28 nm. The use of this high resolution technique has allowed not only the analysis of the evolution of the ferroelectric...

Perovskite BiMO 3-PbTiO 3 (M: cation in octahedral coordination) solid solutions with ferroelectric morphotropic phase boundaries (MPBs) and high Curie temperatures like BiScO 3-PbTiO 3 are under extensive research for extending the operation range of high sensitivity piezoelectric ceramics beyond 200ºC. This is fostered by current industrial requi...

The apparent contradiction between the persistence of the polar state in morphotropic phase boundary BiScO3–PbTiO3 at the nanoscale, and the vanishing of the macroscopic ferroelectric switching and of the dielectric anomaly associated with the ferroelectric phase transition in nanostructured ceramics is solved. Raman spectroscopy results unambiguou...

Strong phase-change magnetoelectric responses have been anticipated by a first-principles investigation of phases in the perovskite BiFeO3-BiCoO3 solid solution, specifically at the morphotropic phase boundary (MPB) between the multiferroic rhombohedral and tetragonal polymorphs. This might be a general property of multiferroic MPBs and a novel pro...

Thin film multiferroic nanocomposites might enable a range of potentially disruptive integrated magnetoelectric devices for information storage, spintronics, microwave telecommunications and magnetic sensing. With this aim, we have investigated ion implantation of magnetic species into ferroelectric single crystal targets as a radically novel appro...

Lead-free (1 - x)Bi0.5Na0.5TiO3-xBi0.5K0.5TiO3 [(BNKTx); x = 0.18, 0.20, 0.22, 0.24] piezoelectric ceramics were prepared via conventional solid-state reactions. Phase characterization using x-ray diffraction showed coexistence of perovskite rhombohedral and tetragonal polymorphs as anticipated for compositions across the morphotropic phase boundar...

Pb(Mg1/3Nb2/3)O3–PbTiO3 is used as a model system of perovskite solid solutions with very high piezoelectric response at tailored morphotropic phase boundaries to demonstrate the processing of textured ceramics by ceramic-only technology. A novel homogeneous templated grain growth approach that uses conventional ceramic procedures and a single-sour...

Polycrystalline samples of lead-free Ca and Ta co-substituted potassium sodium niobate (K0.5Na0.5NbO3, KNN) ceramics have been prepared by solid state reaction technique. X-ray diffraction showed formation of a single-phase perovskite structure with orthorhombic symmetry. Substitution inhibits the grain growth, improves densification and decreases...

Aurivillius phase oxide ferroelectrics have attracted great interest as a lead-free replacement of PZT, especially for high-temperature applications. In this work, we report the growth of high-quality SrBi2Ta2O9 (SBT) single crystals by self-flux solution method. According to X-ray topography, the crystals with sizes up to 7 × 5 × 0.05 mm3 show per...

Multiferroic magnetoelectric materials have become the focus of intensive research activity, driven by applications in novel multifunctional devices, e.g., memories, spintronics. A highly topical set of materials are ABO 3 perovskite oxides, in which multiferroicity is chemically engineered by introducing ferroelectrically and magnetically active c...

Conductivity is a main issue in research on multiferroic perovskite oxides, which makes the characterization of their ferroelectric properties difficult, and for several compounds even to unambiguously state their ferroelectric nature. In this report, we use ferroelectric BiMnO3-PbTiO3 as a model system to study the relationships among synthesis, p...

Polycrystalline sample of lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 ceramic has been synthesized by solid state reaction method. Single-phase perovskite structure with rhombohedral symmetry was confirmed by x-ray diffraction. Temperature dependent dielectric permittivity studies demonstrated frequency independent behavior, indicating that t...

We have investigated the occurrence of phase-change functional responses in the BiFeO3-PbTiO3 perovskite solid solution, analogous to those anticipated by a recent first-principles study of BiFeO3-BiCoO3. Like the former system, BiFeO3-PbTiO3 shows a morphotropic phase boundary (MPB) between multiferroic polymorphs of rhombohedral and tetragonal sy...

The combination of the quantitative texture analysis and Rietveld methods is used to study the preferential orientation of morphotropic phase boundary (MPB) Pb(Mg1/3Nb2/3)O3‐PbTiO3 ceramics obtained by homogeneous Templated Grain Growth. Their complex structure, with the coexistence of several polymorphs, and the presence of texture that is require...

by Hana Uršič "The spatial distribution of the out-of-plane and in-plane components of ferroelectric polarization in (1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 thick films with x = 0.35 on Al2O3 substrates has been studied by piezoresponse force microscopy. Complex non-180◦ domain configurations with strong variations in characteristic length (from micrometr...

The BiMnO3+δ phase has been prepared by mechanosynthesis, at ambient pressure and room temperature, as nanocrystalline powders. This oxide exhibits a metastable character, similar to those prepared by high-pressure and high-temperature methods, remaining stable up to 673 K. Nanostructured ceramic materials (92% densification), maintaining the BiMnO...

Mechanochemical methods have been demonstrated to be an effective means of synthesizing nanocrystalline high sensitivity piezoelectric low tolerance factor perovskites capable of providing enough material to carry out systematic studies on the processing of ceramics and on their properties. Here BiScO3-PbTiO3 is used as a model system of general Bi...

Two-phase magnetostrictive–piezoelectric thin film composites are key materials to the development of a range of potentially disruptive magnetoelectric technologies, such as electrical-writing magnetic-reading random access memories. However, multiferroic thin film composites prepared so far show neither magnetoelectric switching nor magnetoelectri...

Piezoelectric oxides are currently being considered in combination with magnetic materials for the development of magnetoelectric composites, in which stress transfer across the interface is a key issue. In this context, we report here a detailed study of the mechanochemical activation processes of the ferroelectric perovskite BiScO3–PbTiO3 and of...

Low temperature, reversible mechanical effects in BiMnO3–PbTiO3 are shown to be analogous to those reported in multiferroic BiFeO3. The same stiffening (on cooling) has been found in ferroelectric BiScO3–PbTiO3 that shows negligible conduction. This has allowed permittivity and polarization studies, not possible in BiMnO3–PbTiO3, to be accomplished...

The combination of non-conventional methods of synthesis (mechanosynthesis) and sintering (SPS) has been used for the preparation of nanostructured BiScO3–PbTiO3 ceramics with tailored grain size. The key to control grain growth in the nanoscale is to achieve a significant densification during initial stages of the SPS, mainly by particle rearrange...

The Thermally Stimulated Depolarization Current (TSDC) and pyroelectric properties of the modified SBN ferroelectric ceramic system were studied for different lanthanum and titanium doping concentrations. The TSDC measurements show the pyroelectric peak for all compositions while a second smaller peak at higher temperature, possibly associated to i...

The influence of the ferroelectric to paraelectric transition on the relaxation parameters of conductive processes in ferroelectric materials is studied in the time domain. Three well-known ferroelectric systems were chosen with transition temperatures in different regions, these are, high-temperature PbNb ₂ O ₆ -based ceramic...

In this paper, we review and update current research at ICMM on the processing of submicron-and nanostructured ceramics of high sensitivity piezoelectric materials, and on the study of the grain size effects on the macroscopic properties. Nanocrystalline powders synthesised by mechanochemical activation are being used for the processing. Firstly, c...

Nanostructured ceramics of high-temperature piezoelectric 0.375BiScO3-0.625PbTiO3 were prepared by spark plasma sintering of nanocrystalline powders obtained by mechanosynthesis. The macroscopic electrical properties were characterized on dense ceramics with decreasing average grain size down to 28 nm. Results indicate that the electric field is sc...

IntroductionExperimentalResults and Discussion Study of the (1 x) BiFe03 x PbTi03 System:Study of the x BiMn03 (1 x) PbTiOj SystemConclusion Acknowledgements

There is controversy about the persistence or not of the relaxor state in the nanoscale. We report here the dielectric properties of nanostructured ceramics of the Pb ( Zn _1/3 Nb _2/3) O ₃– Pb ( Fe _1/2 Nb _1/2) O ₃– PbTiO ₃ ternary system with an average grain size of 20 nm,...

The rheological behavior and tape-casting performance of ethanol-based Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) slurries is studied. A nanocrystalline powder obtained by mechanochemical activation was used. Suspensions were prepared up to solid contents of 32 vol%, significantly higher than those usually reported for nonaqueous systems. The feasibility of...

This paper deals with the transmission of acoustic waves through multilayered piezoelectric materials. It is modeled in an octet formalism via the hybrid matrix of the structure. The theoretical evolution with the angle and frequency of the transmission coefficients of ultrasonic plane waves propagating through a partially depoled PZT plate is comp...

The dielectric response of PbMg1/3Nb2/3O3-35%PbTiO3 ceramics (close to the morphotropic phase boundary) from 100 Hz up to 100 THz was determined in a broad temperature range of 5-900 K. Two ceramics were studied and compared: coarse grain ceramics (CGC) (grain size ˜4mum ) and fine grain ceramics (FGC) (grain size ˜150nm ). Both ceramics showed sim...

Samples were prepared by conventional powder mixing procedure. The starting powder MgCO 3 , BaCO 3 , TiO 2 and ZrO 2 (ALFA AESAR 99.9% pure) was weighed according to the formula (1-x) BaCO 3 + x MgCO 3 + 0.95TiO 2 + 0.05ZrO 2. x was varied from 0.025, 0.050 and 0.075. The XRD study at room temperature suggests that ceramics have pseudo cubic symmet...

Dielectric response e*(f,T) and polar phonon spectra of coarse grain (grain size ~ 4 mkm) and fine grain (grain size ~ 150 nm) ceramics of PbMg_(1/3)Nb_(2/3)O3-35%PbTiO3 were investigated at temperatures 10 - 900 K. e*(f,T) in coarse-grain ceramics exhibits relaxor behavior at high temperatures and a sharp anomaly at the ferroelectric phase transit...

We have studied the macroscopic electrical properties of highly dense, nanostructured ceramics of BiScO3–PbTiO3 with high Curie temperature and piezoelectric activity. Materials were processed by spark plasma sintering of nanocrystalline powder obtained by mechanosynthesis. Results indicate that the nanostructured material still presents the ferroe...

We investigated the grain size effect on the high temperature behaviour of PMN-35PT ceramics around the tetragonal–cubic phase transition using second harmonic generation (SHG) and dielectric spectroscopy. Our data revealed coexistence of the first-order ferroelectric phase transition and relaxor behaviour in the coarse grain (grain size ∼4 µm) µ_P...

The feasibility of a novel homogeneous templated grain growth approach for the processing of 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 ceramics is studied. Novelty rests on the use of a nanocrystalline powder synthesized by mechanochemical activation for the matrix, and also for obtaining the templates via conventional sintering. Templates are (1 0 0) facete...

The phase transition between the ferroelectric and relaxor states in 0.8Pb(Mg1/3Nb2/3)O3-0.2PbTiO3 ceramics with decreasing grain sizes in the submicron range, down to the nanoscale, has been studied with measurements of the temperature dependence of the dielectric and elastic properties across the transition. Results indicate that main size effect...

Textured SrBi2Ta2O9 (SBT) ceramics were fabricated via templated grain growth (TGG) technique using platelet-like SBT single crystal templates. The templates (5wt%) were embedded in a fine-grain SBT powder matrix containing 3wt% of Bi2O3 excess that were subjected to uniaxial pressing and sintering at 1000–1250°C for up to 24h. Microstructural char...

Nanocrystalline powders synthesized by mechanochemical activation were successfully used to process high-density submicron- and nanostructured 0.8Pb(Mg1/3Nb2/3)O3–0.2PbTiO3 perovskite phase ceramics by hot pressing, with average grain size ranging from 0.36 μm down to 88 nm. These materials are very suitable for studying the size dependence of the...