Mechanosynthesis and Multiferroic Properties of the BiFeO3-BiMnO3-PbTiO3 Ternary System along its Morphotropic Phase Boundary

International audienceA 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 systems is fostered by the presence of distinctive morphotropic phase boundaries (MPBs); multiferroic in the case of BiFeO3-PbTiO3, for which a high magnetoelectric response has been anticipated. Here, new compositions belonging to the ternary system BiFeO3-BiMnO3-PbTiO3, and specifically along the line that joins the former MPBs, have been prepared by mechanosynthesis to accomplish a thorough analysis of their multiferroic nature. Nanocrystalline powders with perovskite-type structure were obtained in the entire range of compositions, which all exhibited polymorphic phase coexistence allowing a line of MPBs to be established. The variation of the perovskite structural characteristics along this line has been defined, and correlated with those of the magnetic and electrical properties. A set of novel and promising multiferroic materials has been found for BiFeO3 rich compositions

Multiferroism and enhancement of material properties across the morphotropic phase boundary of BiFeO3-PbTiO3

Strong phase-change magnetoelectric responses have been anticipated by a first-principles investigation of phases in the perovskite BiFeO 3-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 promising approach for room temperature magnetoelectricity, which requires the identification of suitable material systems. We present here a comprehensive description of the electrical and electromechanical properties across one such system; the perovskite BiFeO3-PbTiO3 solid solution. All the temperature dependence of dielectric permittivity, ferroelectric hysteresis loops, and piezoelectric coefficients have been obtained, and are discussed in relation to the previously reported perovskite structural evolution. Results show ceramic materials to be very promising for ferroelectric random access memories (remnant polarization as high as 63 μC cm-2 with a comparatively low coercive field of 4.5 kV mm-1 for MPB compositions) and high temperature electromechanical transduction (crystal piezoelectric coefficient of 87 pC N-1 with a Curie temperature above 873 K). Moreover, the occurrence of phase changes between the monoclinic and tetragonal polymorphs under high electric fields is indicated, while the canted antiferromagnetic character of the phases involved is corroborated. © 2014 AIP Publishing LLC.Funded by MINECO (Spain) through the MAT2011-23709 project. Dr. H. Amorín thanks financial support by MICINN Ramón y Cajal Programme (RYC-2008-03247). Ms. C. Correas and Ms. C. M. Fernández-Posada also thank the specific financial support of FPI Programme (BES-2008-005409 and BES-2012-053017, respectively).Peer Reviewe

Effect of carbon nanotubes on calcium carbonate/calcium silicate phase and morphology

The composition and microstructure of different CaCO3-Ca2SiO4-carbon nanotube composites have been studied. Materials have been characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (SEM), thermogravimetric/differential thermal analysis (TG/DTA), and Fourier-transform infrared (FTIR) spectroscopy. The morphology and structure of the inorganic systems are affected by the presence of multiwall carbon nanotubes (MWCNT) during the hydration processes and the nature of the MWCNT/SDS interface plays a role in the curing stages of the composite enhancing the growth of calcium silicate

Nanostructured fusiform hydroxyapatite particles precipitated from aquaculture wastewater

The present work represents a new approach for the isolation of uniform nano particulate hydroxyapatite (HAp). The chemical characterization of a calcium phosphate product obtained from industrial trout farm aquaculture wastewater by two different routes, washing either with a basic aqueous medium (washNaOH) or followed by a further washing with ethanol (washEtOH), is explored. Characterization of the isolated materials includes morphology studies (SEM and TEM), structural (XRD, electron diffraction), compositional (EDX) and thermogravimetric analysis (TGA). The obtained products are a mixture of different compounds, with hydroxyapatite the predominant phase. The morphology is unusually nanometric size with fusiform shaped particles, such characteristics are ordinarily only obtained by synthetic routes. This process of phosphate precipitation represents a unique self-sufficient process to be compared to conventional chemical or biological practices for precipitating phosphate

Materiales multiferroicos con fórmula general Bix+yPb1-x-yFexMnyTi1-x-yO3. Desde su síntesis y su nanoestructuración, hasta sus propiedades ferroicas

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada. Fecha de lectura: 17-02-201

Study of Nanocrystalline BiMnO3--PbTiO3: Synthesis, Structural Elucidation, and Magnetic Characterization of the Whole Solid Solution

International audienceIn the last ten years, the study and the search for new multiferroic materials have been a major challenge due to their potential applications in electronic technology. In this way, bismuth-containing perovskites (BiMO3), and particularly those in which the metal M position is occupied by a magnetically active cation, have been extensively investigated as possible multiferroic materials. From the point of view of synthesis, only a few of the possible bismuth-containing perovskites can be prepared by conventional methods but at high pressures. Herein, the preparation of one of these potential multiferroic systems, the solid solution xBiMnO3-(1−x)PbTiO3 by mechanosynthesis is reported. Note that this synthetic method allows the oxides with high x values, and more particularly the BiMnO3 phase, to be obtained as nanocrystalline phases, in a single step and at room temperature without the application of external pressure. These results confirm that, in the case of Bi perovskites, mechanosynthesis is a good alternative to high-pressure synthesis. These materials have been studied from the point of view of their structural characteristics by precession electron diffraction and magnetic property measurements

Mechanosynthesis and characterization of the multiferroic BiMnO3-BiFeO3-PbTiO3 ternary system at morphotropic phase boundaries

Paper presented at European Congress and Exhibition on Advanced Materials and Processes (EUROMAT 2013), which took place in Seville (Spain) during 8-13th September 2013

Mechanosynthesis and multiferroic properties of the BiFeO3-BiMnO3-PbTiO3 ternary system along its morphotropic phase boundary

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 systems is fostered by the presence of distinctive morphotropic phase boundaries (MPBs), multiferroic in the case of BiFeO3-PbTiO3, for which a high magnetoelectric response has been anticipated. Here, new compositions belonging to the ternary system BiFeO3-BiMnO3-PbTiO3, and specifically along the line that joins the former MPBs, have been prepared by mechanosynthesis to accomplish a thorough analysis of their multiferroic nature. Nanocrystalline powders with a perovskite-type structure were obtained in the entire range of compositions, which all exhibited polymorphic phase coexistence allowing a line of MPBs to be established. The variation of the perovskite structural characteristics along this line has been defined, and correlated with those of the magnetic and electrical properties. A set of novel and promising multiferroic materials have been found for BiFeO3 rich compositions.This work has been founded by the Spanish MINECO (MAT2011-23709). C.M.F-P and H.A. thanks financial support by MINECO (BES 2012-053017) and Ramón y Cajal Programme, respectively. Collaboration between ICMM and ISCR was framed within the COST Action MP0904 SIMUFER

Preparación y caracterización de cerámicas del sistema ternario multiferroico BiMnO3¿BiFeO3¿PbTiO3 en la frontera de fase morfotrópica

Comunicación presentada en la XI Reunión Nacional de Electrocerámica que lugar en el Instituto de Ciencia de Materiales de Aragón (España) los días 19-21 de junio de 2013. Fue presentada en la sesión 3: materiales magnéticos y multiferroicos

Nanostructured BiMnO3+δ obtained at ambient pressure: analysis of its multiferroicity

International audienceThe BiMnO3+delta 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 BiMnO3+delta composition, have been successfully processed by the spark plasma sintering technique, at the very low temperature of 673 K, in a time as short as 6 minutes. Conditions of synthesis and sintering are the key factors that determine the actual delta value, or Mn oxidation state. This parameter plays an important role in their magnetic properties, which vary from ferromagnetic for lower delta values (the case of the mechanosynthesized and SPS processed samples) to spin-glass behavior for higher delta values (thermally annealed samples). Electrical measurements, carried out on the dense BiMnO3+delta ceramic material, show no evidence of ferroelectricity down to 77 K, in good accordance with previous structural studies that indicated their centrosymmetric structures