19 research outputs found
Neutron Diffraction, Mossbauer and Electron Paramagnetic Resonance Studies of Pb0.8Bi0.2Fe0.6Nb0.4O3 Multiferroic
No full textThe Pb0.8Bi0.2Fe0.6Nb0.4O3 (PFN-BFO) multiferroic solid solution was synthesized by single step solid state reaction method with low calcination (700 degrees C/2h) and sintering (800 degrees C/3h) temperatures. Single phase formation was confirmed through X Ray Diffraction (XRD) and Neutron Diffraction (ND) at room temperature (RT). The structural analysis was carried out by Rietveld refinement through the Fullprof program. Refined XRD and ND patterns confirms the monoclinic structure with Cm space group and obtained cell parameters from the ND data are a = 5.6449(8) angstrom, b = 5.6536(5) angstrom, c = 4.0017(6) beta = 30(4). ND data at RT exhibits G-type antiferromagnetic structure. The Mossbauer and Electron Paramagnetic Resonance (EPR) spectroscopy studies were carried out at RT. The isomer shift and the quadrupole splitting of the Mossbauer spectra confirm the Fe in +3 states. An EPR spectrum shows a single broad slight asymmetric line, is an evidence of Fe in +3 states. ND, Mssbauer and EPR studies are the clear evidence of existence of antiferromagnetic ordering near room temperature
Room temperature structural and dielectric studies of Pb(Fe0.585Nb0.25W0.165)O3 solid solution
No full textThe perovskite A(BBB)O3 structure Pb(Fe0.585Nb0.25W0.165)O3 (PFNW) multiferroic material was synthesized
by single step solid state reaction method. The single phase was achieved at low temperature with optimized synthesis
parameters as calcination (700°C/2hr) and sintering (800 °C /3hr). Single phase was confirmed by room temperature (RT)
X-ray diffraction (XRD).The scanning electron microscopy (SEM) shows the uniform distribution of grains throughout the
surface of PFNW and the energy dispersive X-ray spectroscopy (EDX) confirms the exact elemental composition as that
of the experimental. Fourier transform infrared spectroscopy (FTIR) exhibits two absorption bands at 602 cm-1
and 1385
cm-1
corresponds to the bending and stretching vibrations of metal oxides. RT dielectric studies (dielectric constant, tan,
AC conductivity) exhibits maximum values at lower frequency region and decreases as the frequency increases. Thesingle
semicircular arc in RT impedance spectra (Nyquist plot)indicatesthe contribution to the conductivity is from grains only.
Hence PFNW is a potential candidate for near room temperature applications
Structural, vibrational and magnetic studies of Pb(Fe0.585Nb0.25W0.165)O3 multiferroic solid solution
No full textStructural and low temperature dielectric studies on Pb0.8Bi0.2Fe0.6Nb0.4O3 multiferroic solid solution
No full textSingle Phase Synthesis; Neutron Diffraction and Dielectric Studies on 0.6PbFe0.5Nb0.5O3-0.4BiFeO3 Multiferroic
No full text0.6Pb(Fe0.5Nb0.5)O3-0.4BiFeO3 (0.6PFN-0.4BFO) multiferroic solid solution was synthesized by single step solid state reaction method. The optimized synthesis parameters for 0.6PFN-0.4BFO multiferroic was calcination at 700 °C /2 hr and sintering at 800 °C /3 hr. Single phase was confirmed though room temperature X-ray Diffraction (XRD) and room temperature Neutron Diffraction (ND). XRD and ND data were well fitted with monoclinic structure with Cm space group. The magnetic structure was refined using the propagation vector k = (0.5; 0.5; 0.5) and the structure was found to be G-type antiferromagnetic. The dielectric constant and loss tangent of 0.6PFN-0.4BFO shows the frequency and temperature dependent nature. Loss tangent exhibits the thermally dependent relaxation peaks. 0.6PFN-0.4BFO is a potential candidate for above room temperature applications
Synthesis and Characterization of Flexible Films of PVDF/Pb(Fe0.585Nb0.25W0.165) O3 Polymer Multiferroic Composites
No full textThe films of Poly(Vinylidene Fluoride)/Pb(Fe0.585Nb0.25W0.165)O3(PVDF/PFNW) polymermultiferroic composites were prepared using standard solution casting method. The room temperature XRD confirms the presence of different phases of PVDF matrix and the PFNW filler perovskite phase of the incorporated ceramics. The morphology studies show the surface appearance of the films with agglomerative nature. The dielectric constant and loss tangent of PVDF/PFNWshow the frequency dependent nature. The dielectric constant and loss tangent was increasedwith increasing the weight percent of PFNW particles in the PVDF matrixshowing the evidence of strong dependence on PFNW substitution into the PVDF matrix. Real part of the impedance and modulus decreased with increasing PFNW concentration indicates the increase of conductivity in the composite
Low temperature impedance, modulus and conductivity studies of Pb0.8Bi0.2Fe0.6Nb0.4O3 multiferroic
No full textElectric field induced structural, magnetic and ferroelectric properties of 0.6PbFe0.5Nb0.5O3-0.4BiFeO3 multiferroic solid solution
No full textIn this paper, 0.6PbFe0.5Nb0.5O3-0.4BiFeO3 (PBFN) multiferroic was electrically poled at room temperature. The influence of electric poling on structure was studied in detail by XRD and Raman measurements. The poling impacts on magnetic and ferroelectric properties were studied through susceptibility and ferroelectric measurements. XRD analysis of the poled sample exhibits the strengthening of Fe/Nb/Bi–O bonds. Raman measurements were carried out at different temperatures (300 K–650 K). Raman spectra of the unpoled sample exhibited seven active modes at 254, 470, 566, 684, 804, 979 and 1111.1 cm−1 at room temperature. The poled sample showed change in intensity around Bi–O and Fe–O modes due to spin-phonon coupling. Temperature dependent magnetization measurements revealed the presence of converse magnetoelectric effect. Ferroelectric measurements showed the influence of electric poling with increase in coercive field. Hence, controlling the magnetization with electrical poling finds more potential applications in multiferroics
Single phase Pb0.7Bi0.3Fe0.65Nb0.35O3 multiferroic: Neutron diffraction, impedance and modulus studies
No full textThe Pb0.7Bi0.3Fe0.65Nb0.35O3 (PBFNO) multiferroic solid solution was synthesized by using single step solid state reaction method. Single phase formation was confirmed through room temperature (RT) X Ray Diffraction (XRD) and Neutron Diffraction (ND). Rietveld refinement was used to perform the structural analysis using FullProf Suite program. RT XRD and ND patterns well fitted with monoclinic structure (Cm space group) and cell parameters from the ND data are found to be a = 5.6474(4) Å, b = 5.6415(3) Å, c = 3.9992(3) Å and β = 89.95(2)°. ND data at RT exhibits G-type antiferromagnetic structure. The electrical properties (impedance and modulus) of PBFNO were studied as a function of frequency (100 Hz – 5 MHz) and temperature (133 K – 293 K) by Impedance spectroscopy technique. Impedance and modulus spectroscopy studies confirm the contribution to the conductivity is from grains only and the relaxation is of non-Debye type. The PBFNO sample exhibits negative temperature coefficient of resistance (NTCR) behaviour. PBFNO is found be a potential candidate for RT applications
Synthesis, structural and electron paramagnetic resonance studies on Pb0.9Bi0.1Fe0.7W0.3O3 ceramic
No full textA single phase Pb0.9Bi0.1Fe0.7W0.3O3 (0.9Pb(Fe2/3W1/3)O3 - 0.1BiFeO3 or PBFW) polycrystalline ceramic was synthesized by the two step solid state reaction method, with low-temperature sintering at 800°C for 30 mins and slow cooling to room temperature (RT). Detailed studies of RT X-ray diffraction (XRD) and Raman spectroscopy measurements confirm the formation of high symmetry cubic structure with Pm-3m space group. The Rietveld refinement was carried out on RT XRD data and the obtained structural parameters are a = b = c = 3.97563(6) Å and unit cell volume = 62.837 (2) Å3. Scanning Electron Microscopy (SEM) images show the uniform distribution of grains with some agglomerated nature. RT Raman spectroscopy reveals the main broad peak at 770 cm-1, related to the A1g mode, which confirms the formation of cubic (ABO3 perovskite) structure. The single symmetric electron paramagnetic resonance (EPR) line shape with g = 2.13985 observed in PBFW was identified to be due to Fe3+ ions
