Frequency–temperature response of CaBi4Ti4O15 ceramic prepared by soft chemical route: Impedance and modulus spectroscopy characterization

S.K. Rout,S. Parida,E. Sinha,P.K. Barhai,I.W. Kim 한국물리학회 2010 Current Applied Physics Vol.10 No.3

Polycrystalline CaBi4Ti4O15 ceramic has been prepared through a modified chemical reaction technique. Room temperature X-ray diffraction (XRD) analysis shows the formation of a single phase orthorhombic perovskite structure. Simultaneous analysis of the complex impedance (Z*), and electric modulus (M*)spectroscopy was carried in the temperature range of 100–850 ℃. The dielectric relaxation is found to be of non-Debye type. The Nyquist plot shows the negative temperature coefficient of resistance type behavior. Two different conduction mechanisms are may be due to: (a) the dielectric relaxation processes due to localized conduction associated with oxygen vacancy; and (b) the non-localized conduction corresponding to long range conductivity associated with extrinsic mechanisms fundamentally associated due to the chemical inhomogeneity caused due to the difference in the ionic environment of Ca2+ and Bi3+ and their sharing in the A site of perovskite and [Bi2O2]2+ slabs. Different conductivity components are recognized inside the grain: long range dc conductivity at low frequency region, a capacitive behavior at higher frequencies, and a universal power law behavior in an intermediate-frequency region where grain boundary contributions are neglected.

Phase formation and dielectric study of Bi doped BaTi0.75Zr0.25O3 ceramic

T. Badapanda,S.K. Rout,S. Panigrahi,T.P. Sinha 한국물리학회 2009 Current Applied Physics Vol.9 No.4

Perovskite types Ba1-xBi2x/3Ti0.75Zr0.25O3 (with x = 0.0, 0.025, 0.05) ceramics have been prepared through solid state reaction route. The room temperature XRD study suggests that all the compositions have single phase cubic symmetry with space group Pm-3m. Temperature dependent dielectric studies of the ceramics have been investigated in the frequency range of 50 Hz–1 MHz. The densities of the samples are determined using Archimedes’ principle and found to be ~98% of X-ray density. The dielectric study revealed diffuse phase transition of second order. A broad dielectric anomaly coupled with the shift of dielectric maxima toward a higher temperature with increasing frequency indicates the relaxor-type behavior in the ceramics. The diffusivity increases with increase in Bi contents in the studied composition range. The transition temperature decreases with increase in Bi contents due to the decrease in grain size. Perovskite types Ba1-xBi2x/3Ti0.75Zr0.25O3 (with x = 0.0, 0.025, 0.05) ceramics have been prepared through solid state reaction route. The room temperature XRD study suggests that all the compositions have single phase cubic symmetry with space group Pm-3m. Temperature dependent dielectric studies of the ceramics have been investigated in the frequency range of 50 Hz–1 MHz. The densities of the samples are determined using Archimedes’ principle and found to be ~98% of X-ray density. The dielectric study revealed diffuse phase transition of second order. A broad dielectric anomaly coupled with the shift of dielectric maxima toward a higher temperature with increasing frequency indicates the relaxor-type behavior in the ceramics. The diffusivity increases with increase in Bi contents in the studied composition range. The transition temperature decreases with increase in Bi contents due to the decrease in grain size.

Composition dependent crossover from ferroelectric to relaxor-ferroelectric in NBT-ST-KNN ceramics

Singha A.,Praharaj S.,Rout S.K.,Rout D. 한국물리학회 2022 Current Applied Physics Vol.36 No.-

Composition driven crossover from ferroelectric (FE) to relaxor-ferroelectric (RFE) is systematically investigated in (0.8-x)(Na0.5Bi0.5)TiO3-0.2SrTiO3-x(K0.5Na0.5)NbO3 (NBT-ST-xKNN) ceramics in the light of ferroelectric and dielectric (ε) response. The appearance of constricted polarization-electric field loop and double current densityelectric field peaks in the proximity of x = 0.02 suggests a co-existence of FE and RFE phases. The system attains a maximumε ~4200 and tan δ < 0.1 at x = 0.02. Broad ε(T) peaks reveal a greater degree of disorder due to KNN substitution and their deconvolution demonstrates three different relaxation/polarization processes related to low and high-temperature nanodomains. The composition with x = 0.1 exhibits maximum broadness in ε(T) profiles resulting in a temperature-insensitive permittivity variation of ±15% (ε125 ◦C,100 kHz~2007) over a span of ~280 ◦ C. A remarkably low (TCε)100kHz of − 75 ppm/◦ C is also achieved for x = 0.1 from 100 to 300 ◦C proposing it to be a potential capacitor material.

Phase transition in ABi4Ti4O15 (A=Ca,Sr,Ba) Aurivillius oxides prepared through a soft chemical route

Rout, S. K.,Sinha, E.,Hussian, A.,Lee, J. S.,Ahn, C. W.,Kim, I. W.,Woo, S. I. American Institute of Physics 2009 JOURNAL OF APPLIED PHYSICS - Vol.105 No.2

Induced instability in local structure and ferroelectric polarization of rare earth modified BZT relaxor ceramics

S.K. Ghosh,S.K. Rout 한국물리학회 2016 Current Applied Physics Vol.16 No.9

Chemically induced instability in local symmetry of rare earth modified barium zirconate titanate relaxor ceramics Ba1-xLn2x/3Zr0.3Ti0.7O3 (Ln ¼ Sc, La, Sm, Nd, Eu and Gd), where x ¼ 0.02e0.10 and its effect on structural, microstructural, interband transition along with ferroelectric switching polarization are studied experimentally. Rare earth substitution induced A-site vacancies and distortion in three dimensional cation-oxygen networks leads to random local strain with short range ordering. In addition, these cations control the formation of grain, grain boundaries and band gap values. Substitution of rare earth ions induced intermediate energy levels in between conduction and valence band and guided the emission spectra towards blue-green region. At room temperature polarization hysteresis loop and normalized capacitance versus electric field loop indicated the existence of relaxation and polarization switching mechanism in these materials. However, at room temperature feeble polarization switching is observed in case of scandium, europium and gadolinium based BZT compositions indicated a weak relaxor phase whereas in lanthanum, samarium, neodymium substituted BZT materials shows a dominating relaxor phases induced by static and dynamic of nano size polar regions separated by non-polar region.

Dielectric and Frequency Dependent Transport Properties of Gadolinium Doped Bismuth Ferrite

A. K. Sahu,S. K. Satpathy,S.K. Rout,Banarji Behera 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.2

Ceramics of (Bi 1−x Gd x FeO 3 ) [x = 0.5, 0.6 and 0.7] were synthesized through mixed oxide method. Structural studies of the ceramics were done using X-ray diff raction technique. At high frequency, nearly flat response in the dielectric constant and dielectric loss with temperature up to 200 °C were observed. Dielectric constant found to increase with decrease in Gadolinium concentration. Frequency dependent electrical data analysis at diff erent temperatures suggested a temperature dependent non-Debye type relaxation process in the ceramics. Frequency dependence AC conductivity at different temperatures obeyed Jonscher’s universal power law. The temperature dependence of DC and AC conductivity was fitted with Arrhenius equation. The activation energies at different temperature ranges were calculated to understand the conduction process.

Lemanea manipurensis sp. nov. (Batrachospermales), a freshwater red algal species from North-East India

Ganesan, E.K.,West, J.A.,Zuccarello, G.C.,de Goer, S. Loiseaux,Rout, J. The Korean Society of Phycology 2015 ALGAE Vol.30 No.1

A new macroscopic riverine red algal species, Lemanea manipurensis sp. nov. (Batrachospermales) is described from Manipur in northeast India. It has a sparsely branched, pseudoparenchymatous thallus with a single, central axial filament that lacks cortical filaments. Spermatangia occur generally in isolated, low and indistinct patches or form an almost continuous ring around the axis. Carposporophytes project into the hollow thallus cavity without an ostiole. The most striking morphological feature is the carposporophyte with very short gonimoblast filaments having cylindrical, narrow and sparsely branched sterile filaments, the terminal cell of each branch with a single, large, elongate carpospore. The widely distributed L. fluviatilis has spherical carpospores in long branched chains. Phylogenetic analysis of rbcL sequence data and comparison with other Batrachospermales clearly show that our specimens do not align with other species of Lemanea and Paralemanea investigated thus far. Five specific names attributed in previous literature (1973-2014) to Lemanea from Manipur, L. australis, L. catenata, L. fluviatilis, L. mamillosa, and L. torulosa are rejected until critical anatomical and molecular evidence is available for specimens from the Manipur river systems. Taxa referable to Paralemanea were not confirmed for India in this study. In view of the high demand for food and medical uses of L. manipurensis in northeast India, conservation measures are needed for its long term survival. The present paper constitutes the first combined morphological / molecular study on a freshwater red alga from India.

Synthesis and Characterization of Homo Binuclear Complexes of UO₂(VI), Th(IV), ZrO(IV) and VO(IV) with Polyaza Macrocyclic Schiff-Bases

Mohapatra, R. K.,Rout, S. R.,Dash, D. C. Korean Chemical Society 2011 대한화학회지 Vol.55 No.2

Magnetotransport Studies on LCMO/STO Nanocomposites

L. Joshi,S. Keshri,S. K. Rout 한국자기학회 2008 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Dielectric Behavior of Yttrium doped Barium-zirconium-titanate Ceramics

T. Badapanda,S. Panigrahi,T. P. Sinha,우성일,S. K. Rout 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2

The ferroelectric behavior of the yttrium-doped barium-zirconium-titanate perovskite ceramics Ba1−xY2x/3Ti.75Zr0.25O3 (with x = 0.0, 0.01, 0. 025, 0.05) has been studied. The room temperature X-ray diffraition study suggests that all the compositions have a single-phase cubic symmetry with space group Pm-3m The temperature dependent dielectric constant of the ceramics was investigated in the frequency range from 50 Hz to 1 MHz. The density of the samples was determined using Archimedes’ principle and was found to be ~98% of the X-ray density. A broad dielectric anomaly coupled with a shift of the dielectric maximum towards a higher temperature with increasing frequency indicates relaxor-type behavior in the ceramics With increasing in yttrium content, the Curie temperature decreased, except for x = 0.01 where the Curie temperature increased. The relative permittivity decreased and broadened with increasing yttrium content.