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In this work, (90)KBiFe2O5−(10)CoFe2O4 [KBFO(90)-CFO(10)] composite is synthesized in polycrystalline form following the sol-gel technique. The magnetic, dielectric, and signature of the magnetodielectric (MD) effect in the prepared composite is verified over a wide temperature range. The phase purity of the prepared KBFO-CFO composite is confirmed by the room temperature (RT) X-Ray diffraction technique. The RT magnetization study reveals the weak ferromagnetic nature of the composite. The dielectric study reveals an anomaly near 500 °C, expected to be a structural phase transition. The magnetic anomaly near the dielectric transition suggests the signature of the MD coupling of the composite. The composite's indirect band-gap of 1.01 eV made it suitable for technological applications. Finally, the prepared composite shows the signature of the MD effect, and the low band gap suggests it is ideal for photovoltaic applications. [ABSTRACT FROM AUTHOR]

We investigate the dielectric relaxation and magnetodielectric (MD) properties of the (1-x)Bi5Ti3FeO15/(x)Bi2Fe4O9 (x=0.0 and 0.3) composites. The sample is prepared by the sol-gel method to study its physical properties. The existence of mixed phases in the composite is assured by the Rietveld refinement of the XRD pattern. The dielectric data at different frequencies reveals the dispersive behavior of the pure cum composite samples. The εʹ vs. temperature reveals the appearance of relaxation behavior around 170 K in the composite. The frequency variation of the εʹʹ study excludes the Maxwell-Wagner origin of the dielectric relaxation. Further, the modified Curie-Weiss law analyzes the relaxor nature of the composite. The magnetic field-dependent MD% shows the maximum strength in the highly dielectric dispersive region. The maximum strength of MD effect ∼0.2% is found in composite at 300 K. [ABSTRACT FROM AUTHOR]

Holmium (Ho) substituted KBi0.95Ho0.05Fe2O5 polycrystalline having P2/c space group is synthesized using solid-state reaction route. The phase purity is characterized by x-ray diffraction measurement. The temperature-dependent dielectric permittivity (ε΄) and loss (tan δ) is analyzed over a wide temperature range (10 K to 300 K) in the presence of 1.3 T and 0 T magnetic field. The temperature-dependent dielectric permittivity and loss plots are shifting with the magnetic field. It indicates the presence of Magnetodielectric (MD) signature in KBi0.95Ho0.05Fe2O5 polycrystalline. Variation of magnetodielectric with magnetic field shows a butterfly-like MD loop, indicating MD coupling. The extracted maximum room temperature magnetodielectric coupling is found to be 0.2% in KBi0.95Ho0.05Fe2O5 sample. The magnetic field-dependent impedance measurement is carried out to address the extrinsic effects behind the MD coupling. These results made it a prominent candidate for multifunctional device applications and provided space to investigate further the microscopic origin behind it. [ABSTRACT FROM AUTHOR]

(1-x)Bi5Ti3FeO15−(x)La0.67Sr0.33MnO3 for x = 0.2 multiferroic composite is synthesized via sol-gel modified method. The Rietveld refinement of X-ray diffraction confirms the presence of both orthorhombic (BTFO) and rhombohedral (LSMO) crystal phase with space group A21am and R-3c respectively. Scanning electron microscope (SEM) along with the EDX spectrum reveals the existence of LSMO small grains in a BTFO matrix of the composite. The preliminary signature of the MD effect in the composite is investigated from the temperature dependence of dielectric constant and loss plot at a fixed applied magnetic field (0T and 1.3 T). The maximum magnitude of MD and ML response is observed to be ∼0.31% and ∼0.03% at 300 k. This arises due to the possible coexistence of both capacitive and magnetostrictive effects. [ABSTRACT FROM AUTHOR]

We have investigated dielectric and magnetodielectric (MD) properties of polycrystalline Y-type hexaferrite Ba2Mg1.5Ni0.5Fe12O22 (BMNF). Rietveld refinement of the X-ray diffraction pattern and hexagonal plate-like Field Emission Scanning Electron Microscope (FESEM) micrograph confirms the phase purity with the rhombohedral crystal structure (R-3m space group). Both temperatures dependent dielectric permittivity (ε׳) and dielectric loss (tan δ) show an anomaly around 150°C and 290°C. The comparable value of activation energy extracted from impedance spectroscopy above 290°C between σg and σgb indicates that relaxation and conduction mechanism may be attributing to the same entities. Room temperature magnetodielectric (MD) measurement at 1MHz indicates the step like increase at ∼8 kOe in dielectric constant (ε) with applied field but a reverse trend is observed for magneto-loss (ML) with step like feature preserving it nature. [ABSTRACT FROM AUTHOR]

The polycrystalline Fe2Te0.95Ta0.05O6 possessing tetragonal trirutile structure with P42/mnm space group is synthesized via solid state reaction route. Phase confirmation and structural parameter calculation are done by the Rietveld refinement of XRD data. We demonstrate the temperature and magnetic field dependent magnetic property and room temperature magnetoelectric (ME) behavior of the material. The temperature dependent magnetic susceptibility confirms the antiferromagnetic transition at 210K along with a broad transition prior to it due to presence of short range magnetic ordering. The typical temperature response of magnetic susceptibility like Fe2TeO6 parent material differ at 18K as it shows a transitional anomaly due to Ta doping. MH hysteresis measured at 300K and 2K shows an apparent linear behavior. A hysteretic ferromagnetic induction in low field region at 300K is observed due to doping induced modification in exchange interaction mechanisms. Presence of linear ME effect is confirmed through ME voltage measurement wit ME coefficients α/d ≈ 0.23 mV cm-1 Oe-1, β/d ≈ -3.47 × 10-4 mV cm-1 Oe-2, obtained by linear fit to M. Ferroelectric hysteresis loop is obtained by PE loop measurement using remanent polarization measurement with value ≈2.5 nC/cm2. [ABSTRACT FROM AUTHOR]

The phase pure polycrystalline KBiFe2O5with space group P2/c is synthesized following solid state reaction route. The temperature dependentreal and imaginary part of dielectric constant is studied over wide temperature (280 K to 850 K) and frequency range (100 Hz ≤ f ≤ 1 MHz). Two distinct anomaliesat around 390 K and 750K is observedin both real (ε) an imaginary (tanδ) part of dielectric constant which can be attributed to Maxwell-Wagner effect. Our DC susceptibility measurement up to room temperature does not show any transition even upto room temperature, giving an indication that its transition temperature is above room temperature. This aspect is further confirmed from M-H hysteresis loop which shows a weak ferromagnetic hysteresis loop at room temperature. The evidence of magnetodielectric (MD) coupling at room temperature is confirmedfrom magnetic field dependent dielectric measurement in the form of inverted butterfly shaped ε-H loop. [ABSTRACT FROM AUTHOR]