11 research outputs found

    Colossal dielectric response of Mott insulating, nanocrystalline, T '-type Sm2CuO4 ceramics

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    In this paper, for the first time, we present the detailed temperature (-100 10(4)), in these SCO ceramics

    Exceptionally High Dielectric Constant in Ceramic Pr2CuO4

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    The pristine layered cuprate Pr2CuO4 samples of >95% density were fabricated as thin disks. The samples, analyzed by X-ray diffraction and Scanning electron microscopy, showed clean T-type phase with Rietveld refined lattice parameters a=b=3.95805(+/- 5)angstrom and c=12.2262(+/- 5)angstrom. The measured dielectric properties of the Pr2CuO4 ceramics, in the temperature range -100 degrees C-150 degrees C and frequencies () 0.1Hz-1MHz, showed extremely high epsilon(r)>10(4) (above -30 degrees C), and dissipation (tan =epsilon(r)/epsilon(r)) between 0.1 and 5 (for 500Hz1MHz, and -100T150 degrees C). The ac conductivity of Pr2CuO4 ceramics ranged between 10(-6) and 10(-3)Scm(-1) for the measured frequencies and temperatures, and showed frequency-dependent double power law behavior akin to a modified Jonscher's power law

    Impedance and AC conductivity study of nano crystalline, fine grained multiferroic bismuth ferrite (BiFeO3), synthesized by microwave sintering

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    In this paper, major reduction in sintering time, temperautre and significant improvement over final density of sitnered sample is reported for the microwave sintered nanocrystalline BiFeO3 (BFO) ceramic. Also, different sintering time and temperatures have been used to tailor the grain size and the final density of the resulting BFO ceramics synthesized from phase pure BFO nanoparticles ((d) over bar approximate to 10 nm). Microwave sintering resulted in reducing the sintering time substantially (by 1h), and has resulted in submicron sized grains and high resistivity similar to 1.8 G Omega-cm. The AC conductivity is seen to follow the Jonscher's power law behavior, suggesting correlated barrier hopping (CBH) mechanism in the sample. The role of oxygen vacancies at high temperature, due to volatility of bismuth, in dielectric and conductivity behavior is also discussed. Further, the sample displayed dielectric anomaly near magnetic transition temperature (similar to 180 degrees C) indicating bearing of magnetic moments on the dielectric properties. Using Impedance Spectroscopy (IS) we have established, the electrical heterogeneity of the ceramic BFO reavealing semiconducting nature of grains and insulating nature of grain boundary. This, formation of network of insulating grain boundaries and semiconducting grains could lead to formation of internal barrier layer capacitance (IBLC) leading to high dielectric constant in microwave sintered BFO. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License

    Giant dielectric response and magnetoelectric behavior of 95BiFeO(3)-5BaTiO(3) (95BFO-5BT) ceramics

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    A detailed study of electrical behavior of 95BiFeO(3)-5BaTiO(3) (95BFO-5BT) ceramics through comprehensive analysis of temperature and frequency dependent dielectric behavior, ac impedance and magnetodielectric (MD) properties is reported here. Addition of insulating BaTiO3 into BiFeO3 have exhibited enhanced dielectric and ferromagnetic responses. The remnant polarization (P-r) was found to be 6 A mu C/cm(2), while the dielectric constant was found to be very high ( a parts per thousand yen 10(2), for T a parts per thousand yen 140 A degrees C). Along with strong conductivity contribution to , spectroscopic plots of revealed the Maxwell-Wagner type relaxation in the sample, which ultimately could have led to an apparent high in 95BFO-5BT ceramics. Origin of such a high in BFO-BT was further investigated using impedance spectroscopy. MD studies revealed the magneto-electric coupling in the ceramics. The MD studies along with anomaly in dielectric data near antiferromagnetic ordering temperature (T-N = 170 A degrees C) of BFO suggests the magnetic bearing on the electrical properties of 95BFO-5BT ceramics

    The redclaw crayfish: A prominent aquaculture species with invasive potential in tropical and subtropical biodiversity hotspots

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    10.1111/raq.12531Reviews in Aquaculture1331488-153
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