Jyoshna Rout - Academia.edu (original) (raw)

Papers by Jyoshna Rout

Indian Journal of Physics, 2018

The multiferroic BiFeO3 and Bi0.8A0.2Fe0.8Mn0.2O3 (A = Ca, Sr) have been synthesized using direct... more The multiferroic BiFeO3 and Bi0.8A0.2Fe0.8Mn0.2O3 (A = Ca, Sr) have been synthesized using direct mechanosynthesis. Detailed investigations were made on the influence of Ca–Mn and Sr–Mn co-substitutions on the structure change, electric and magnetic properties of the BFO. Rietveld refinement on the XRD pattern of the modified samples clarifies the structural transition from R3c:H (parent BiFeO3) to the biphasic structure (R3c: H + Pnma). Scanning electron micrographs confirmed the polycrystalline nature of the materials and each of the microstructure comprised of uniformly distributed grains with less porosity. The dielectric measurements reveal that enhancement in dielectric properties due to the reduction of oxygen vacancies by substitutional ions. Studies of frequency-dependence of impedance and related parameters exhibit that the electrical properties of the materials are strongly dependent on temperature, and bear a good correlation with its microstructure. The bulk resistance ...

Journal of Advanced Dielectrics, Sep 1, 2016

The Bi 2 Fe 2 WO 9 ceramic was prepared using a standard solid-state reaction technique. Prelimin... more The Bi 2 Fe 2 WO 9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM) exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200 C and 450 C: first one may be related to magnetic whereas second one may be related to ferroelectric phase transition. The field dependent magnetic study of the material shows the existence of small remnant magnetization (M r) of 0.052 em/g at room temperature. The existence of magneto-electric (ME) coupling coefficient along with above properties confirms multi-ferroic characteristics of the compound. Selected range temperature and frequency dependent electrical parameters (impedance, modulus, conductivity) of the compound shows that electric properties are correlated to its microstructure. Detailed studies of frequency dependence of ac conductivity suggest that the material obeys Jonscher's universal power law.

Ceramics International

Some lead-free compounds of a general formula (Bi 1-x Sr x)(Fe 1-x Mn x)O 3 (x = 0-0.15 with the ... more Some lead-free compounds of a general formula (Bi 1-x Sr x)(Fe 1-x Mn x)O 3 (x = 0-0.15 with the interval of 0.05) were prepared by a mechanical alloying followed by sintering process. Structural, electrical and magnetic characteristics of multi-doped elements (Sr-Mn) in bismuth ferrite have been examined at different field frequencies and temperatures. X-ray diffraction studies suggest the rhombohedral phase for x ≤ 0.1 and the orthorhombic phase for x = 0.15. Study of frequency-dependent dielectric properties showed the enhancing trend of dielectric constant with increasing co-doping concentration. Detailed analysis of impedance data at different frequencies and temperature estimated the contribution of grains and grain boundaries in the capacitive and resistive properties of the studied samples. The study of magnetic properties exhibits the weak ferromagnetism in co-substituted samples with maximum saturation magnetization (M s = 0.121 emu/gm) for higher concentration of doping (x = 0.15). The magneto-electric coefficient (α ME), measured with the varying DC magnetizing field under fixed AC magnetic field, is found to be 15.368 Oe.

Journal of Materials Science Materials in Electronics, Jul 23, 2013

ABSTRACT Bi2Fe2W3O15 was prepared in the polycrystalline form using a standard solid-state reacti... more ABSTRACT Bi2Fe2W3O15 was prepared in the polycrystalline form using a standard solid-state reaction technique in order to study its dielectric and electrical properties. The formation of a single-phase compound was confirmed by preliminary X-ray structural studies of the material. Studies of electrical properties (impedance, modulus and conductivity) of the compound over a wide range of temperature and frequency provide many interesting results. The impedance and modulus parameters were calculated using complex plane formalism, and suitable equivalent circuits have been proposed for different temperature and frequency regions. The nature of variation of ac conductivity with frequency at different temperatures obeys the Jonscher’s universal power law. The temperature-dependence of dc conductivity pattern follows the Arrhenius behavior.

We have synthesized (Pb 1-x Sm x)(Sn y Ti 1-y) 1-x/4 O 3 (PSmST) polycrystalline ferroelectric ce... more We have synthesized (Pb 1-x Sm x)(Sn y Ti 1-y) 1-x/4 O 3 (PSmST) polycrystalline ferroelectric ceramics with x = 0⋅ ⋅05, 0⋅ ⋅07, 0⋅ ⋅1 and y = 0⋅ ⋅45 by a solid-state reaction technique and performed preliminary X-ray diffraction (XRD) analysis, detailed temperature and frequency dependence dielectric measurements on them. The a.c. conductivity has been investigated over a wide range of temperature and the activation energy (E a.c.) has also been calculated. It is observed that (i) the dielectric permittivity (ε ε) and loss tangent (tan δ δ) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side with the increase of samarium ion (Sm +3) concentration at the Pb sites, and (iii) observed and calculated d-values of XRD patterns show that the compounds have been formed in orthorhombic single phase.

Journal of Computational and Theoretical Nanoscience

The (BiBa)0.5(FeMn)0.5O3 ceramic was synthesized by a solid-state reaction (mixed oxide) techniqu... more The (BiBa)0.5(FeMn)0.5O3 ceramic was synthesized by a solid-state reaction (mixed oxide) technique. The formation of single-phase compound was confirmed by preliminary x-ray structural studies of the material. Room temperature surface morphology and textures of the sample was recorded by a scanning electron microscope, which reveals the uniform distribution of grains in the sample. The ferroelectric properties of the material have been confirmed from dielectric and polarization studies. The impedance, electrical modulus and electric conductivity of the material have been studied using a complex impedance spectroscopy technique. A strong correlation between these electrical parameters and microstructure (bulk, grain boundary, nature of charge carrier etc) of the materials was established. The frequency dependence of ac conductivity suggests that the sample obeys Jonscher's universal power law.

Journal of Electronic Materials, 2015

Ceramics International, 2015

ABSTRACT The polycrystalline samples of (Bi1-xCax)(Fe1-xMnx)O3 with x=0, 0.05, 0.10, 0.15 mol fra... more ABSTRACT The polycrystalline samples of (Bi1-xCax)(Fe1-xMnx)O3 with x=0, 0.05, 0.10, 0.15 mol fraction were prepared by synthesized by initial mixing of precursors by high-energy ball milling, and subsequent thermal treatment of the milled powders. Study of basic crystal parameters using x-ray diffraction technique of the calcined samples suggests that all the materials are crystallized in the distorted-perovskite (rhombohedral) structure which was supplemented and supported by their FTIR studies. The dielectric properties of the materials were investigated as a function of temperature and frequency and the temperature dependent dielectric constant and loss tangent of the modified system vary with substitution concentration (x) and frequency. Detailed studies of impedance exhibit that the electrical properties of the prepared systems are strongly dependent on temperature and frequency, and thus show a good correlation with their microstructures (i.e., bulk, grain boundary, etc.). Further, it is interesting to see the contributions of bulk, grain boundary and electrode in the impedance plots. The decrease in value of bulk resistance on increasing temperature suggests the existence of negative temperature co-efficient of resistance (NTCR) behavior in the materials. Room temperature M-H hysteresis measurements reveal that magnetization increases due to the structural distortion, and partial destruction of spin cycloid is caused by co-doping in BiFeO3 ceramics. Unlike magnetic response, the ferroelectric properties of the samples were found be enhanced on increasing mole fraction of x in BiFeO3.

Materials Research Bulletin, 2015

ABSTRACT The polycrystalline sample of (Bi0.5Ba0.5) (Fe0.5Ti0.5) O3 (BF-BT) was prepared by a sta... more ABSTRACT The polycrystalline sample of (Bi0.5Ba0.5) (Fe0.5Ti0.5) O3 (BF-BT) was prepared by a standard mixed oxide method. Analysis of room temperature XRD pattern and Raman/FTIR spectra of the compound does not exhibit any change in its crystal structure of BaTiO3 on addition of BiFeO3 in equal ratio. The surface morphology of the gold-plated sintered pellet sample recorded by SEM (scanning electron microscope) exhibits a uniform distribution of grains with less porosity. Detailed studies of nature and quantity of variation of dielectric constant, tangent loss and polarization with temperature and frequency indicate the existence of ferroelectric phase transition at high-temperature. There is a low-temperature anti-ferromagnetic phase transition below 375 °C in the material. Detailed studies of electrical properties (impedance, modulus, etc) of the material confirmed a strong correlation between micro-structure and properties.

Journal of Materials Science: Materials in Electronics, 2015

ABSTRACT In this study we report the synthesis of (Bi0.85Sr0.15)(Fe0.85Mn0.15)O3 ceramic using th... more ABSTRACT In this study we report the synthesis of (Bi0.85Sr0.15)(Fe0.85Mn0.15)O3 ceramic using the thermo-mechanical (high-energy ball-milling and heat treatment) technique. Study of basic structural parameters of the material using X-ray diffraction technique confirms the formation of a single-phase compound with rhombohedral symmetry. The high-magnification scanning electron micrograph shows the distribution and size of grains on the surface of the sample. Detailed studies of dielectric and electrical properties of the material in a wide range of temperature (25-350 °C) and frequency (1 kHz-1 MHz) using dielectric and complex impedance spectroscopic methods have provided many interesting results. The temperature-frequency Nyquist plots of the material exhibit the existence and magnitude of grain and grain boundary contributions to the electrical parameters at high temperatures. Study of ac conductivity suggests that the material obeys Jonscher’s universal power law. The material shows weak ferromagnetism at room temperature with saturation magnetization (2Ms) of 0.24 emu/gm.