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Sol-gel method is used to synthesize the Bi0.90Dy0.10FeO3-BaTi0.95Hf0.05O3 (BDyFO-BTHfO composite) multiferroic composite material. The structural formation was examined utilizing an X-ray diffraction (XRD) pattern preceded by Rietveld refinement utilizing the FULLPROF programme to confirm the presence of tetragonal and partially rhombohedral structures having space group P4mm and R3c, respectively. The dielectric characteristics of the BDyFO-BTHfO composite have been measured with respect to frequency (100 Hz to 1 MHz) and temperature (RT to 663K). Dielectric permittivity (ε) shows low-frequency dispersion which can be addressed by Maxwell-Wanger-type interfacial polarization. The synthesized composite material exhibits a negative magneto-dielectric (MD) effect when a magnetic field is operated (0.0 T to 2.0 T) and the obtained values are −9.61% and −19.68% for the ε and tanδ, respectively, at 1 kHz. The contribution of the grains, grain boundaries and electrode effects on the resistive characteristics of the samples was evaluated using comprehensive impedance spectroscopy using a Nyquist plot. The band gap (Eg) absorption of the synthesized sample was determined using Tauc's formula and found to be 2.05 eV. The BDyFO-BTHfO composite has improved magneto-dielectric, magneto impedance, and optical properties that support their potential usage in microelectronics, energy storage devices, and optoelectronic devices. [ABSTRACT FROM AUTHOR]

A Mn and Cu co-doping BiFeO3 (BFO) thin film was fabricated on FTO/glass substrate by sol-gel method with a sequential layer deposition process. The raw materials using in the starting solution were bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), iron(III) nitrate nonahydrate (Fe(NO3)3·9H2O). Manganese (II) acetate tetrahydrate (C4H6MnO4·4H2O) and copper (II) acetate monohydrate ((Ch3COO)2Cu·H2O) were used as dopants. All of these previous reagents were mixed together using ethylene glycol (HOCH2CH2OH) as solvent. The atomic ratio used was BiFe0.94Mn0.04Cu0.02O3 (BFMCO) and 5 mol% of excess of bismuth was employed to compensate its volatility during high temperature annealing. The structural, morphological, optical properties and the charge transport mechanisms of the sample were studied using X-rays Diffraction (XRD), Scanning Electron Microscopy (SEM) and UV-visible spectroscopy, respectively. The chemical composition was studied by X-ray Photoelectron Spectroscopy (XPS). Simultaneously, a comparison was made between BFO and BFMCO thin films, prepared and characterized by the same experimental process, which allowed and knowing the effect of Cu and Mn co-doping on the structure and physical properties of BFO. [ABSTRACT FROM AUTHOR]

In the frequency range of 3.2–12 GHz, the microwave energy absorption spectra of a series of the (1-x)BiFeO3 – xLaMnO3 solid solutions with a concentration of x = 0.1 − 0.9 were studied. The spectra contain the absorption maxima of the resonant type, the magnitudes, resonant frequencies, and number of which depend on the x concentration and temperature. At different heights from the surface of the samples under study, located on the microstrip line, the emission spectra of the electric and magnetic components of the microwave field were obtained. The X-ray diffraction data and the obtained absorption and emission spectra are interconnected and complement each other. The features of the spectra are discussed from the point of view of the contribution to the emission and absorption of the energy of the dielectric walls of the twins resonating in the electromagnetic field. The features of the magnetic moments of multiferroics are also discussed. [ABSTRACT FROM AUTHOR]

Studies of the dielectric and ferroelectric properties of c-oriented Ba2NdFeNb4O15 films is carried out at T = −190...200 °C using dielectric spectroscopy methods and ferroelectric hysteresis loops analysis. The films were obtained by RF-cathode sputtering method in an oxygen atmosphere. The PA-FE phase transition region, the features of the dielectric response formation, and the mechanisms responsible for that formation are revealed in the material. It is shown that the studied materials are characterized by high values of energy efficiency parameters. The reasons of the revealed regularities and the prospects of the use of these materials are discussed. [ABSTRACT FROM AUTHOR]

A new compound with formulation 0.4[Pb(Fe0.5Nb0.5)O3] −0.6[(Ba0.8Sr0.2)TiO3] was prepared by solid state route. The structural properties were analyzed by X-ray diffraction in terms of POWD and Rietveld analyses. X-ray photoelectron spectroscopy study provides for electronic structure. Structural vibrations and chemical compositions were analyzed by FTIR and Raman spectroscopy. Morphological and elemental analyses were done by FESEM and EDS studies. UV–Visible analysis was done to study the narrow band gap, effect of oxygen vacancy and Urbach energy. Dielectric characteristics show the diffuse phase transition. The room temperature multiferroicity was confirmed by P-E and M-H loop studies. [ABSTRACT FROM AUTHOR]

A new compound with formulation 0.4[Pb(Fe0.5Nb0.5)O3] −0.6[(Ba0.8Sr0.2)TiO3] was prepared by solid state route. The structural properties were analyzed by X-ray diffraction in terms of POWD and Rietveld analyses. X-ray photoelectron spectroscopy study provides for electronic structure. Structural vibrations and chemical compositions were analyzed by FTIR and Raman spectroscopy. Morphological and elemental analyses were done by FESEM and EDS studies. UV–Visible analysis was done to study the narrow band gap, effect of oxygen vacancy and Urbach energy. Dielectric characteristics show the diffuse phase transition. The room temperature multiferroicity was confirmed by P-E and M-H loop studies. [ABSTRACT FROM AUTHOR]

The phase composition, structure, and dielectric properties of the Ba2NdFeNb4O15 (BNFNO) multiferroic ceramics have been studied by X-ray diffraction analysis and dielectric spectroscopy. It has been shown that the material is single-phase and has a tetragonal structure with a = 12.477 Å, c = 3.923 Å, V = 611 Å3 unit cell parameters at room temperature. The presence of two relaxations processes has been revealed in the temperature range of 10 ÷ 325 K and frequency range of 20 ÷ 106 Hz. The reasons for the revealed regularities and the prospects for using this material in the form of nanosized thin films are discussed. [ABSTRACT FROM AUTHOR]

Methods for controlling (by magnetic field, changing temperature, and optical pumping) the properties of nanoregions forming due to self-organization during phase separation in Eu0.8Ce0.2Mn2O5 multiferroics are studied. Such nanoregions are superlattices (semiconductor heterostructures). The dynamically equilibrium states of superlattices (their long-lived ground states) are formed during cycling under magnetic field. Such states of superlattices are electrically neutral and consist of ferromagnetic layers. A set of ferromagnetic resonances from superlattices layers make it possible to distinguish the states of superlattices. The optical pumping of various powers allows controlling both the magnetic and electrical properties of superlattices. [ABSTRACT FROM AUTHOR]

The effect of rare-earth ions Er3+, which has a large orbital contribution to the magnetic moment, on the phase transitions and states of the phase separation nanoregions has been studied in multiferroic ErMn2O5. These nanoregions are semiconductor heterostructures formed due to self-organization processes in the ErMn2O5 matrix. A significant effect of Er3+ ions, the moments of which are rigidly oriented along the c axis of the crystal, on the magnetic dynamics, heat capacity, and multiferroic properties of superlattices layers in a wide temperature range of 5 ÷ 300 K has been revealed. [ABSTRACT FROM AUTHOR]

Binary A B O 3 and ternary AB′0.5B″0.5O3 oxides with a complex perovskite structure, possessing the consecutive ferroelectric or antiferroelectric phase transitions at TC and ferromagnetic, antiferromagnetic, or ferrimagnetic phase transitions at TN, are considered together with classical ferroelectrics and antiferroelectrics. The common correlations between these temperatures, their differences TС-TN and interatomic bond A-O (δAO) or B-O (δBO) strains are revealed. Some common correlations between their temperatures TС, TN, TС-TN differences, and δAO or δBO are revealed. It is established that these differences for multiferroics are in common dependences with classical ferroelectrics and antiferroelectrics. [ABSTRACT FROM AUTHOR]

The effect of rare-earth ions Er3+, which has a large orbital contribution to the magnetic moment, on the phase transitions and states of the phase separation nanoregions has been studied in multiferroic ErMn2O5. These nanoregions are semiconductor heterostructures formed due to self-organization processes in the ErMn2O5 matrix. A significant effect of Er3+ ions, the moments of which are rigidly oriented along the c axis of the crystal, on the magnetic dynamics, heat capacity, and multiferroic properties of superlattices layers in a wide temperature range of 5 ÷ 300 K has been revealed. [ABSTRACT FROM AUTHOR]

BiMnO3 (BMO) ceramics was synthesized and sintered by mechanochemical method. Effect of sintering on the structure and multiferroic was investigated by XRD, FESEM, HRTEM, ferroelectric and magnetic study. These studies synchronously exhibited the formation of distinct nanostructured monoclinic perovskite (C2 space group) phase with crystallite size range from 5 to 40 nm. The dielectric study revealed a significant dependence of εr and tanδ with the change in sintering temperature. P-E loop and magnetization studies revealed a trend of increase in Pr (0.396 μC/cm2 to 0.50 μC/cm2) and decrease in Ms (0.125 to 0.085) respectively with the rise in sintering temperature. [ABSTRACT FROM AUTHOR]

The microstructure, dielectric and magnetic characteristics, and magnetodielectric effect in multiferroic 0.5BiFeO3-0.5PbFe0.5Nb0.5O3 ceramics are studied. It is determined that 0.5BiFeO3-5PbFe0.5Nb0.5O3 belongs to the relaxor ferroelectrics group by the nature of changes in the real and imaginary parts of the complex permittivity at T = 30–300 °C. It is discovered that the material is in magnetic phase at room temperature. The magnetodielectric effect (positive and negative) is detected at T < 200°С. The maximum value of magnetodielectric coefficient is 1.64%. The reasons for the identified regularities are discussed. [ABSTRACT FROM AUTHOR]

0.5BiFeO3-0.5Pb1-xSrxTiO3 (0 ≤ x ≤ 1) solid solution compositions were synthesized using solid phase reactions route from high-purity oxides. Mössbauer studies showed that for 0.5BiFeO3-0.5PbTiO3 (x = 0) the magnetic phase transition temperature TM value was about 130 K. Substitution of Sr for Pb led to a dramatic decrease in TM, though the Fe content did not change with x and for 0.5BiFeO3-0.5SrTiO3 (x = 1) TM was only ≈20 K. This dramatic difference in TM values seems to be due to additional contribution of the magnetic superexchange between Fe3+ ions via the empty 6p states of Bi3+ and Pb2+ ions to the overall superexchange. [ABSTRACT FROM AUTHOR]

In the present article, a brief introduction about multiferroic composites is provided. Recent advancement in the field of multiferroic composites is discussed by classifying these in bulk composites, thick & thin films and other heterostructures. Research findings of some renowned work are summarized, considering new emerging materials, new methods of synthesis and latest characterization techniques. Further recent applications are discussed along with future challenges of the field. [ABSTRACT FROM AUTHOR]

Multiferroic Pb(Fe0.5Nb0.5)1-xCexO3 (x = 0.025, 0.05, 0.075, 0.10) ceramic compositions were prepared by solid state synthesis and usual sintering. XRD studies have shown a formation of the perovskite structure in all the compositions studied. However a small amount of pyrochlore phase was detected in Ce-doped compositions with x ≥ 0.075. Scanning electron microscopy studies and elemental analysis have shown that at the boundaries of the large grains of nearly pure PbFe0.5Nb0.5O3 there exist a lot of small submicron grains enriched by Ce. Concentration dependencies of the unit-cell parameter and temperatures of ferroelectric and magnetic phase transitions also imply that solubility of Ce in PFN does not exceed ≈ 2 at.%. [ABSTRACT FROM AUTHOR]

Bi0.75La0.25FeO3 sample has been fabricated by a novel hydrothermal-assisted co-precipitation method. The X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) studies confirmed that the sample was crystallized in orthorhombic (Pbnm) and rhombohedral (R3c) phases. Using differential thermal analysis (DTA), it is observed that the sample exhibits a Neel temperature (TN= 581 K) and Curie temperature (TC=1017K). UV-visible absorption spectrum of the sample exhibits two doubly degenerate d-d transitions and three charge transfer transitions. The temperature dependence of dielectric constant of the sample at different frequencies (0.12 to 100 kHz) exhibits two anomaly peaks at 497 and 707 K. An asymmetric shift in the coercive field of the hysteresis loop (M-H) indicates the presence of exchange bias effect in the sample. [ABSTRACT FROM AUTHOR]

Ba4SmFe0.5Nb9.5O30 ceramics were prepared by solid-state reaction method and the sample crystallized into single phase tungsten bronze (TB) structure with space group P4bm. The absence of dielectric peak suggests that there is no long-range ferroelectric order exists above room temperature (RT). Therefore, the observed ferroelectric property should be related to the polar nanoregions that survived to Burns temperature TB. Obvious RT ferromagnetism is observed for the first time in Ba4SmFe0.5Nb9.5O30 ceramics and it could be interpreted as the effective exchange coupling interaction between oxygen vacancies and Fe ions 3d spins, while the isolated Fe ions create the paramagnetic characteristic. In addition, the RT ferromagnetism and ferroelectricity also confirms that introduce of Fe ions could help to change TB structural ferroelectric to RT multiferroic material effectively. [ABSTRACT FROM AUTHOR]

Lead nickel tungsten titanate Pb(Ni1/3 Ti1/3 W1/3) O3 single perovskite ceramics were prepared by using a high temperature solid-state reaction technique. The structural analysis of the sample confirms tetragonal crystal structure with space group P4mm having average crystallite size 73 nm, which is well supported from FTIR observations. The dielectric spectra with function of frequency and temperature suggest that sample is semiconducting in nature following NTCR behavior. The complex impedance results showed the contribution of grain and grain boundaries in the conduction mechanism. The activation energies were determined from the ac conductivity data in the temperature range of 200–350 °C and 360–500 °C. It has been observed that with the rise of frequency and temperature, the activation energy increases in the sample. The greater value of activation energy always supports the conduction mechanism due to hopping of the charge carriers. The semicircular arcs of Cole-Cole plots confirm that the sample is semiconducting in nature which supports our dielectric results. [ABSTRACT FROM AUTHOR]

In the present work the acoustic band structure of a two-dimensional phononic crystal containing an organic ferroelectric (PVDF- polyvinylidene fluoride) and muliferroic material (LiVCuO4) were investigated by the plane-wave-expansion method. A two-dimensional PC with square lattices composed of LiVCuO4 cylindrical rods embedded in the PVDF matrix are studied to find the existence of stop bands for the waves of certain energy. This phononic bandgap – forbidden frequency range – allows sound to be controlled in many useful ways in structures that can act as sonic filters, waveguides or resonant cavities. Phononic band diagram ω = ω(k) for a 2D PC, in which non-dimensional frequencies ωa/2πc (c-velocity of wave) were plotted versus the wavevector k along the Γ-X-M-Γ path in the square Brillouin zone show four stop bands in the frequency range 0.01–8.0 kHz. The ferroelectric properties of PVDF and unusual properties of multiferroic LiVCuO4 give us the ability to control the wave propagation through the PC in over a wide frequency range. [ABSTRACT FROM AUTHOR]

Multilayer (14 layers, 115–122 nm thick each) BiFeO3/CoFe2O4/substrate (BFO/CFO) and CoFe2O4/BiFeO3/substrate (CFO/BFO) nanocomposites were obtained by the method of sol-gel synthesis. It is shown that all samples of the obtained nanocomposites have multiferroic properties at room temperature. At the same time, there is a clearly demonstrated effect of the layering order on the values of remnant polarization and magnetization of these samples. This influence originates from the much smaller size of the crystallites in the BiFeO3 layers for the samples deposited in order (BFO/CFO) at various annealing temperatures (700, 725, and 750 °C). [ABSTRACT FROM AUTHOR]

Concentration dependences of magnetic phase transitions temperatures TM for several solid solutions of perovskite multiferroics BiFeO3, PbFe1/2Nb1/2O3 (PFN), and PbFe0.5Sb0.5O3 (PFS) have been studied using Mössbauer spectroscopy. In all the solid solutions studied, the values of TM were found to depend not only on the concentration of the Fe3+ ions in the lattice, but also on the short-range and/or long-range ordering of Fe3+ and B5+ ions, as well as on the mean lattice parameter values and on the nontrivial magnetic superexchange involving the empty p-orbitals of Pb2+ and Bi3+ cations. [ABSTRACT FROM AUTHOR]

In the present work, the acoustic band structure of a two-dimensional (2D) phononic crystal containing a multiferroic and liquid were investigated by the plane-wave-expansion method. 2D PnC with triangular and honeycomb lattices composed of LiCu2O4 cylindrical rods embedded in the seawater matrix are studied to find the existence of stop bands for the waves of certain energy. Phononic band diagram ω=ω(k) for a 2D PC, in which nondimensional frequencies ωa/2πc (c-velocity of wave) were plotted versus the wavevector k along the г-X-M-г path in the Brillouin zone show few stop bands in the frequency range between 10 and 110 kHz. [ABSTRACT FROM AUTHOR]

In this report, we present an investigation of the optical properties and band structure calculations for the photonic structures based on the multiferroic materials- BaMnF4. We calculate the photonic bands and optical properties of BaMnF4/LiNbO3 based photonic crystal. We study the photonic band gap and optical properties of the photonic structures, numerically analyzed in the IR frequency region by using the FDTD method for various incidence angles, number of periods in the PC and the nature/geometry of the materials. [ABSTRACT FROM AUTHOR]

Magnetoelectric coupling in xNiFe2O4 (NFO) – (1-x) ErMnO3 (EMO) (x = 0.1, 0.3 and 0.5) lead free multiferroic nanocomposites prepared through pyrophoric reaction method has been investigated at room temperature. The value of magnetoelectric coefficient is found to ∼1.48 mV/cmOe at a frequency of 1 kHz in longitudinal configuration for 0.5NFO – 0.5EMO nanocomposites. The observed magnetoelectric coefficient for all those nanocomposites may be due to the presence of magnetostriction and magnetodielectric properties of piezomagnetic component of the composites. Also, the value of magnetoelectric coefficient is found to depend on ErMnO3 volume fraction. Moreover, magnetic field tuning of ac electrical properties have been observed. Nyquist plots at different applied dc magnetic field show the significant contributions of grain boundaries and grain of the samples. The magnetodielectric constant is found to be ∼47% at a frequency of 1 kHz for 0.5NFO – 0.5EMO nanocomposites. [ABSTRACT FROM AUTHOR]

The temperature dependence of the dielectric properties, along with the field and frequency dependences of the magnetoelectric properties of a CoFe2O4/Pb(ZrxTi1-x)O3/CoFe2O4 laminate structure has been investigated. The longitudinal magnetoelectric experiments were performed using an AC magnetic field of 3 Oe, with DC magnetic field biases from 0 to 1000 Oe and frequencies of 100 to 92 kHz. The dielectric measurements were taken from 100 Hz to 1 MHz at three temperature conditions: 295 K, the temperature decreasing at 2°K/min to 150 K, and then increasing the temperature up to 295 K again. [ABSTRACT FROM AUTHOR]

In this work, we reported investigations on the structural, magnetic and dielectric properties of Mn doped 0.9BiFeO3-0.1BaTiO3 multiferroic compounds. X-ray diffraction studies revealed that the materials crystallized in a pure distorted rhombohedral perovskite structure. A significant magnetization increase (reaching 0.50 emu/g) was observed for Mn - doped samples. The dielectric characterization revealed that for the un-doped sample two conductivity mechanisms are present, one starting around 177 K and other around 325 K. In the doped samples, however, one of these mechanisms was suppressed increasing the resistivity and decreasing the dielectric losses of the samples. [ABSTRACT FROM AUTHOR]

Multiferroic GdMnO3was synthesized by the modified sol-gel route. The GdMnO3precursor were sintered for 2 hours at different temperatures ranging from 300 (GMO300) to 800°C (GMO800). X-ray diffraction pattern shows that the crystallinity improves with sintering temperatures. The Raman data and Fourier transform infrared analysis also support the X-ray diffraction data. UV-Visible spectrum of the sample GMO300 shows absorption peak at 2.39 eV whereas the completely crystallized sample sintered at 800°C (GMO800) shows two absorption bands at 2.25 and 2.56 eV. These bands are attributed to the Mn (d-d) transitions. Higher energy bands at (3.27 and 4.94 eV) of GMO700 and (3.26, 4.40, 4.74 and 5.08 eV) of GMO800 are attributed to the charge transfer transitions from O(2p) to Mn(3d) state. Moreover, the completely crystallized sample (GMO800) exhibits the signature of magneto-dielectric coupling. [ABSTRACT FROM PUBLISHER]

Bismuth ferrite (BiFeO3or BFO) and manganese doped bismuth ferrite (BiFe1-xMnxO3, × = 0.1, × = 0.2) ceramic samples were fabricated using sol-gel processing technique. Pure phase BFO powder and its composites were obtained after annealing the as-prepared powder at 500°C. Ceramic samples were then fabricated by pressing in the form of circular discs followed by sintering at 550°C for 2 hours. The influence of Mn doping on structural, morphological and dielectric properties of BiFeO3were studied and analysed. The frequency responses of dielectric constant (κ) and loss tangent (tanδ) have been investigated over a wide range of frequencies at room temperature. [ABSTRACT FROM PUBLISHER]

We present the structural investigation on multiferroic Ba1-xSrxMnO3perovskite manganites with x = 0.50, 0.60, 0.70 and 0.75 synthesized by combustion method. Rietveld refinement of powder X-ray diffraction data reveals the hexagonal structure with space group P63/mmc for all compositions. The unit cell lattice parameters for Ba1-xSrxMnO3decrease monotonically with Sr-substitution on Ba-site. The value of structural tolerance factor decreases from 1.047 for x = 0.50 to 1.018 for x = 0.75. [ABSTRACT FROM PUBLISHER]

Phase-pure ferroelectric ceramics of (BFO)1-x(KBT)x(x = 0.0, 0.05, 0.10, 0.15 and 0.2) have been prepared through conventional solid state reaction method. The perovskite structure and existence of structural transition have been confirmed through X-Ray diffraction analysis. Dielectric measurements of (BFO)1-x(KBT)xsamples have been carried out in a wide range of frequency (100 −1 MHz) and temperature between 30 and 500°C. Polarization Vs electric field measurements on (BFO)1-x(KBT)x(x = 0.05 and 0.1) compositions showed better PE response than (BFO)1-x(KBT)x(x = 0). While, compositions corresponding to (BFO)1-x(KBT)x(x = 0.15 and 0.2) showed poor and leaky loop due to existence of structural transition from rhombohedral (polar) to orthorhombic (non-polar) phase. Further, Leakage current characteristics of all compositions have been studied. [ABSTRACT FROM PUBLISHER]

Lead free ferroelectric ceramics of K0.5Na0.5NbO3(KNN) and K0.5Na0.5Nb0.975Co0.025O3(KNN-Co) have been synthesized by solid state reaction method. X-ray diffraction studies reveals that both pure and cobalt doped KNN ceramics exhibits orthorhombic structure belonging to the space groupAmm2. Temperature dependent dielectric measurements shows an increase in Curie temperature (TC) for KNN-Co compared to KNN. Well saturated hysteresis loops have been obtained for both compositions from the P-E loop measurements. Further, magnetic behaviour of KNN and KNN-Co ceramics have been studied. [ABSTRACT FROM PUBLISHER]

We present the results of studies on the dielectric properties of polycrystalline Bi1-xCaxFeO3(x = 0.05, 0.10, 0.20) (BCFO) multiferroics. Rietveld refined XRD patterns confirm the single phasic nature of 5% & 10% Ca – doped samples crystallizing in superimposed R3c (Rhombohedral) + Pm 3m (Cubic) space group symmetry while 20% Ca – doped sample crystallize in Pm 3m symmetry. Frequency and temperature dependent dielectric constant (ϵ) studies show the contribution of grain and grain boundaries in the system. Complex impedance graph exhibits a single semicircular arc for all the samples, indicating the contribution of grain interior (bulk) property of the material. [ABSTRACT FROM AUTHOR]

Presently, the effect of divalent Ca ions on the structural and transport properties of YMnO3is studied. A series of (Y1-xCaxMnO3x = 0.00, 0.03, 0.05, 0.1, 0.25) samples were synthesized by solid state reaction method. X-ray diffraction shows that pure YMnO3have hexagonal while Ca doped compounds possess mixed (hexagonal and orthorhombic) phase for all concentrations of Ca. Ferroelectric behavior of all samples was also investigated by PE loop. Furthermore, dielectric constant is found to improve after Ca doping which is understood in terms of electronic phase separation that generally occurs in charge ordered manganites. [ABSTRACT FROM AUTHOR]

In this study we made an attempt to fabricate magnetoelectric composite of magnetostrictive NZFO layer on piezoelectric PSLZT multilayer by co-sintering them directly. Microstructural analyses of the layered composite were made to study their interface which is crucial for elastic coupling. Initially (Ni0.7Zn0.3)Fe2O4and (Sr, La) modified PZT were synthesized by solid oxide route, thick films of them were fabricated by tape casting technique with layer thickness of 100 μm and these layers were laminated together. Here Ag-Pd electrodes were screen printed on individual piezoceramic layers. These NZFO-PSLZT laminated composites were co-sintered between 950 to 1050°C for 2 h. Individual layers of NZFO and six layers of PSLZT with Ag-Pd electrode were also sintered in the same condition for comparison. Scanning electron microscopy was employed to analyze the interface of the co-sintered multilayer. Microstructures of the composite cross section revealed dense thick film with less inter diffusion. Magnetic force microscopy (MFM) was utilized to study the magnetic domains on top surface of individual NZFO layer and NZFO-PSLZT composite. Dielectric behavior of six layered PSLZT was compared with laminated NZFO-PSLZT composite. The properties of co-sintered NZFO-PSLZT composite were correlated with its microstructure. [ABSTRACT FROM AUTHOR]

Size effect and lattice strain effect for charge ordered structure and magnetic properties were investigated on the nano particles of geometrically spin and charge frustrated system YbFe2O4. The lattice strain of the nano particle was controlled with the ratio of Yb and Fe (2.00 ≤ Fe/Yb ≤ 2.04) in liquid synthesizing method. It was found that the lattice strain is not affected by the magnetic transition temperature, however the anomalous behavior at a lower magnetic transition (TLT) with an increment of the Fe / Yb ratio was detected. The development of charge ordering was two-dimensional and magnetic ordering goes down for all samples in spite of the variation of the local lattice strain. This is the first report of the coupling of charge and spin ordering to the size effect in this material. These results suggest that the discussion on the electric polarization induced from the charge ordering in this material need to care the long-range interaction like surface effect. [ABSTRACT FROM AUTHOR]

The paper first introduces the basic physics behind perovskite multiferroics. Then the recent progress on simple, complex perovskites, and manganites are briefly reviewed. The review discloses two important directions on achievement multiferrocity in perovskite: pay with strain engineering and adjust octahedral deformation. The authors also suggest that specific issues like leakage current and characterization platforms are also very important for the study of multiferroics. [ABSTRACT FROM PUBLISHER]

BiFe1-xCoxO3(x = 0, 0.05, 0.10, 0.15, 0.20, and 0.25) nanoparticles were prepared by a sol–gel method. A single-phase perovskite structure was formed in the pure BiFeO3particles. The secondary phase of Bi25FeO40was observed in Co doped samples and the phases of CoFe2O4were observed in BiFe0.8Co0.2O3and BiFe0.75Co0.25O3. The average crystal size of pure BiFeO3is about 84 nm and that was reduced from 84 nm to 49.7 nm with increasing Co content. Optical band gaps of BFCO nanoparticles decrease with the increase of Co concentration. The enhancement of room-temperature ferromagnetism was obtained in the Co doped BiFeO3particles. [ABSTRACT FROM PUBLISHER]

Ceramic samples of a new perovskite multiferroic PbFe0.5Sb0.5O3(PFS) with a differing degree S of long-range compositional ordering of the Fe3+and Sb5+cations were fabricated by a variation of the high-pressure-synthesis conditions. The S values estimated from the XRD data varied from 0.93 down to 0.17. The unit cell parameter was found to decrease with increasing S. In line with these results the fraction of the singlet component in the Mössbauer spectra was found to decrease with decreasing S. However, the temperatures and diffusion of dielectric permittivity maxima as well as the temperature of magnetic phase transition determined from Mössbauer data do not change substantially with S. These results imply that PFS remains highly ordered at the nanoscale. [ABSTRACT FROM PUBLISHER]

Temperature dependences of electric field-induced and magnetic field-induced optical second harmonic generation (SHG) were used to study La0.7Ca0.25MnO3/BaTiO3(LCMO/BTO) superlattice. Ferroic properties of the superlattice are reveal by magnetic field-induced and electric field-induced SHG hysteresis loops (“magnetic” and “electric” SHG loops). However, direct modifications of the SHG hysteresis loops by the other field (electric field for the “magnetic loop” and vice versa) were not found. Strong modifications of the “electric” SHG hysteresis loops occur at temperatures close to the paramagnetic-ferromagnetic and the insulator-metal phase transitions in LCMO. In this way, the magnetoelectric interaction in an LCMO/BTO superlattice was established indirectly. [ABSTRACT FROM AUTHOR]

YMnO3thin films were prepared based on a chemical solution deposition route. Their structure was studied as a function of the annealing temperature using X-ray diffraction, Raman spectroscopy, and electron backscatter diffraction. For annealing temperatures above 850°C the films, though crystallizing predominantly in aP63cmhexagonal structure, exhibit a thin Pnma orthorhombic phase close to the film-substrate interface. It is shown that the residual orthorhombic structure is associated with a substrate induced strain state, characterized by an expansion in the in-planeadirection, and a compression in the out of plaincdirection. [ABSTRACT FROM PUBLISHER]

Multiferroic Pb(Fe0.5Nb0.5)1-xSnxO3(x = 0.025, 0.05, 0.075, 0.10) ceramic compositions were prepared by solid state synthesis and usual sintering. XRD studies have shown a formation of the perovskite structure in all the compositions studied. However, a small amount of pyrochlore phase was detected in Sn-doped compositions with x ≥ 0.05. Scanning electron microscopy studies have shown that at the boundaries of the large grains there exist a lot of small submicron grains enriched by Sn. Concentration dependencies of the unit-cell parameter and ferroelectric phase transition temperatures also imply that solubility of Sn in PFN is limited to ≈ 5 at.%. [ABSTRACT FROM AUTHOR]

The local structure around Mn atoms in multiferroic CaMn7O12were studied by x-ray absorption fine structure with temperature across magnetic/ferroelectric polarization transition temperature (TC= TP). There is no variation of electronic configuration near TC, but a change of the disorder distribution of Mn-O bond. The first shell peak was best fitted by multi-FEFF codes with three Mn occupations of CaMn(1)3+3[Mn(2)3+Mn(3)4+]4O12. The larger Dybe-Waller σ2of Mn(1) manifests the larger distortion of Mn(1)-O distribution, which rises mainly from the variation of the bond length and/or coordination number (N). The fitted N of Mn(1) changes from 1.1 to 4.5 with the temperature decreasing. This indicates that the oxygen site shift towards the Mn(1) atom, making the average Mn(1)-O length short. Otherwise, the change of σ2and Δr are tiny at Mn(2) and Mn(3) sites near TC. The local structural variation of Mn(1) site is thus may considered as related to the magnetic/ferroelectric polarization transition. [ABSTRACT FROM AUTHOR]

Optical second harmonic generation (SHG), which is sensitive to the symmetry breaking, provides a powerful experimental technique for investigation of ferroic materials, i.e. ferroelectrics, magnetics, and multiferroics. A far-field confocal microscopy provides three-dimensional imaging of an order parameter of ferroics with a spatial resolution up to diffraction limit of a probing wavelength. In this paper, we discuss general important consideration regarding SHG microscopy and show new imaging techniques for ferroelectric and magnetic domains and switching, bio-inspired ferroelectrics, as well as femtosecond laser annealed ferroelectric microstructures. [ABSTRACT FROM PUBLISHER]

X-ray, magnetic, and Mossbauer studies of a PbFe0.5Ta0.5O3powder have been carried out. For the first time temperature dependence of the unit cell parameters was obtained. Antiferromagnetic Neel temperature TN≈180 K was determined using the results of Mossbauer studies. In the vicinity of TNan anomaly in the temperature dependence of the monoclinic angle β was revealed in PFT. This anomaly seems to be due to the magnetoelectric coupling. [ABSTRACT FROM PUBLISHER]

Some peculiar features of magnetic x,T-phase diagram of (1-x)PbFe1/2Nb1/2O3-xPbTiO3system at x ≈ 0.1 have been ascribed previously to the change of the lattice symmetry from rhombohedral to tetragonal or to the decrease of the lattice parameter with x. We carried out structural, dielectric, magnetization, and Mossbauer studies of (1-x)PbFe1/2Nb1/2O3-xPbZrO3system, where the symmetry remains rhombohedral, while the lattice parameter increases with x. However, the magnetic x,T-phase diagram of (1-x)PbFe1/2Nb1/2O3-xPbZrO3appeared to be very similar to that of (1-x)PbFe1/2Nb1/2O3-xPbTiO3. Anomalies of composition dependence of magnetic phase transition temperatures at x ≈ 0.1 are supposed to be due to the percolation phase transition. [ABSTRACT FROM PUBLISHER]

CuFe2O4/Pt/Pb(Zr0.52Ti0.48)O3(PZT) multilayer thin films were grown on (111)-oriented Pt/TiO2/SiO2/Si<100> substrate. PZT layer was fabricated by the sol-gel method. Afterwards, Pt layer was deposited by ion beam sputtering method. Finally, CuFe2O4layer were deposited using pulsed laser deposition method (PLD). The film structure is tri-layered type, where the bottom PZT layer covered the whole substrate, while Pt and CuFe2O4layers were deposited through circular shadow masks to measure ferroelectric and magnetoelectric properties. Film microstructure was observed using XRD and FE-SEM. Magnetoelectric coefficients were calculated by measured magnetoelectric voltages using magnetoelectric measurement system. [ABSTRACT FROM PUBLISHER]

Precise measurements of specific heat were performed on high quality single crystals of multiferroic LuFe2O4by using anaccalorimeter. The thermal anomalies corresponding to four known phase transitions were observed at 220 K(Tg), 260 K (TN), 380 K (T3CO) and 590 K (T2CO). In addition to them, a new clear anomaly was detected at 305 K. No other distinct anomaly could be observed below 220 K down to 100 K. It is clarified that the temperature dependence of the order parameter associated with this new phase transition at 305 K is quite similar to those of spontaneous polarization reported previously by Ikedaet al. [ABSTRACT FROM PUBLISHER]

Bismuth ferrite (BiFeO3, short for BFO) powders were prepared at low temperature using sol-gel process. Single-phase BiFeO3powders with distorted perovskite structure were obtained after calcining at 600°C. According to the Scherrer formula the calculated crystallite size (DXRD) is about 39 nm. The value of the average particle size (DBET) is larger than that ofDXRD. A typical magnetic hysteresis loop was observed at room temperature, indicating that the BiFeO3nanoparticles show a weak ferromagnetic order. The remnant magnetization (2Mr) and coercive field (2HC) are 0.033 emu/g and 395 Oe, respectively. [ABSTRACT FROM AUTHOR]

0.8BiFeO3-0.2BaTiO3thin films on (111) oriented Pt/TiO2/SiO2/Si<100> substrates were prepared by pulsed laser deposition. Various deposition parameters, such as deposition temperature and oxygen pressure, have been studied and optimized to get better quality films. Based on the X-ray diffraction analysis, single phase perovskite films were obtained at the deposition temperature of 700°C and an oxygen partial pressure of 10 mTorr and 330 mTorr. The BFO-BTO film deposited under higher oxygen pressure, i.e. 330 mTorr, showed smaller leakage current in electrical property, (010) preferred orientation in crystal structure, and enhanced ferromagnetic property compared to the film deposited at 10 mTorr. From our results, we suggest 0.8BiFeO3-0.2BaTiO3solid solution thin film for one of candidates to resolving the current poor dielectric property of single BFO multiferroic thin film by a partial substitution of Ba and Ti ions for Bi and Fe sites of BiFeO3structure, respectively. [ABSTRACT FROM AUTHOR]