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Your search keyword '"Govindaraj, G."' showing total 11 results
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11 results on '"Govindaraj, G."'

1. Combination of distinct conduction and dielectric relaxation processes in LiCoO2.

Author

Kumar, N. S. K. and Govindaraj, G.

Subjects
*DIELECTRIC relaxation, *ELECTRIC conductivity, *LITHIUM cobalt oxide, *DIELECTRIC loss, *TEMPERATURE effect
Abstract

The dielectric loss peaks are rarely seen in highly conducting solids due to conductivity contribution to the dielectric loss of material. LiCoO2 for the temperature range of l48K to 248K show dielectric relaxation at high frequencies with dc conductivity contribution. Conduction and dielectric relaxation of the material is studied with Cole-Cole type combined 'pinned dipole' relaxation from hopping charges and 'free dipole' relaxation due to host matrix. [ABSTRACT FROM AUTHOR]

Published
2016
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2. Combination of distinct conduction and dielectric relaxation processes in LiCoO2.

Author

Kumar, N. S. K. and Govindaraj, G.

Subjects
DIELECTRIC relaxation, ELECTRIC conductivity, LITHIUM cobalt oxide, DIELECTRIC loss, TEMPERATURE effect
Abstract

The dielectric loss peaks are rarely seen in highly conducting solids due to conductivity contribution to the dielectric loss of material. LiCoO2 for the temperature range of l48K to 248K show dielectric relaxation at high frequencies with dc conductivity contribution. Conduction and dielectric relaxation of the material is studied with Cole-Cole type combined 'pinned dipole' relaxation from hopping charges and 'free dipole' relaxation due to host matrix. [ABSTRACT FROM AUTHOR]

Published
2016
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3. Electrical relaxation studies on Na2NbMP3O12 (M=Zn, Cd, Pb and Cu) phosphate glasses

Author

Vinoth Rathan, S. and Govindaraj, G.

Subjects
*DIELECTRIC relaxation, *PHOSPHATES, *TEMPERATURE effect, *TRANSITION metals, *NIOBIUM, *GLASS, *METAL quenching, *ELECTRIC conductivity, *SODIUM compounds
Abstract

Abstract: Niobium based glasses of composition Na2NbMP3O12 (where M=Cd, Zn, Pb and Cu) have been synthesized by melt quenching method and characterized by XRD, FTIR and DSC. The ac conductivity measurements have been carried out over wide range of frequencies at different temperatures on these glassy systems. Ac conductivity data are analyzed using conductivity and electric modulus formalisms. The bulk dc conductivity obtained from complex impedance plots follow the Arrhenius behavior and its activation energy matches well with the activation energy obtained from electric modulus formalism. The ac conductivity plot exhibits universal power law features and the temperature dependence of dc and ac conductivity is discussed. The scaling behavior of the ac conductivity and electric modulus spectra with respect to temperature are discussed and reported for these glassy systems. [Copyright &y& Elsevier]

Published
2010
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4. Ce-substituted Lithium Ferrite: Preparation and Electrical Relaxation Studies.

Author

Mohanty, Viswarupa, Cheruku, Rajesh, Vijayan, Lakshmi, and Govindaraj, G.

Subjects
CESIUM, LITHIUM, FERRITES, THERMOGRAVIMETRY, TEMPERATURE effect, ERROR analysis in mathematics
Abstract

Ce-substituted lithium ferrite, Li0.5Ce x Fe2.5−x O4 (x = 0, 0.05 and 0.1) compositions were synthesized from metal nitrates and citric acid by the solution combustion process by keeping the oxidizer to fuel ratio at unity. The thermal decomposition process was investigated by thermogravimetry–differential thermal analysis, which showed a stable phase formation above 600 °C. The phase composition and molecular bonding of Li0.5Ce x Fe2.5−x O4 were characterized by X-ray powder diffraction analysis and Fourier transform infrared spectroscopy, respectively. An extensive study of electrical relaxation process has been represented with impedance and modulus as a function of frequency at different temperatures. The activation energy obtained from both the formalisms was found to be equal within the error. The dc conductivity and hopping frequency were thermally activated and their activation energies were found to be in the range of 0.69–0.64 eV for x = 0.05. The scaling of modulus and impedance were used to understand the electrical relaxation behaviour of the compositions and they suggest the time temperature superposition principle. [ABSTRACT FROM AUTHOR]

Published
2014
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5. Analysis of ion dynamics on Na2NbZnP3O12 glass using anomalous relaxation function.

Author

Krishna Kumar, N. S., Govindaraj, G., and Rathan, S. Vinoth

Subjects
*GLASS, *SODIUM compounds, *IMPEDANCE spectroscopy, *IONIZATION (Atomic physics), *RADIO frequency, *CHARGE transfer, *TEMPERATURE effect
Abstract

Ion conducting Na2NbZnP3O12 glass is investigated for the mechanism of the ion dynamics and non-Debye relaxation. The impedance spectroscopic data of the sample is taken for a frequency range of 100Hz to 1MHz for a temperature range of 393K to 513K. Anomalous relaxation function is used to study the microscopic mechanism of ion dynamics through the complex relaxation time. The physical picture of the ion dynamics have studied with the trapped and hopping charge carriers. The many particle displacement function and its scaling are used to understand the length scale of ion dynamics. [ABSTRACT FROM AUTHOR]

Published
2013
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6. Synthesis, characterization and ion conductivity study of nanocrystalline LiNaSO4.

Author

Ganesha, K. N. and Govindaraj, G.

Subjects
*IONIC conductivity, *NANOCRYSTALS, *LITHIUM compounds, *PRECIPITATION (Chemistry), *TEMPERATURE effect, *X-ray diffraction
Abstract

The nanocrystallites of LiNaSO4 were prepared by co-precipitation method at room temperature and characterized by XRD, SEM and TG-DSC measurements. The average crystallite size is found to be 46 nm. The DSC curve shows two endothermic peaks at 255.8 °C and 508.8 °C. The electrical conductivity is studied as functions temperature and frequency and results are reported. The activation energy obtained for the stable phase of LiNaSO4 is 1.19 eV. The material becomes superionic conductor at high temperature phase. [ABSTRACT FROM AUTHOR]

Published
2013
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7. Synthesis, characterization and ion conductivity study of nanocrystalline LiNaSO4.

Author

Ganesha, K. N. and Govindaraj, G.

Subjects
IONIC conductivity, NANOCRYSTALS, LITHIUM compounds, PRECIPITATION (Chemistry), TEMPERATURE effect, X-ray diffraction
Abstract

The nanocrystallites of LiNaSO4 were prepared by co-precipitation method at room temperature and characterized by XRD, SEM and TG-DSC measurements. The average crystallite size is found to be 46 nm. The DSC curve shows two endothermic peaks at 255.8 °C and 508.8 °C. The electrical conductivity is studied as functions temperature and frequency and results are reported. The activation energy obtained for the stable phase of LiNaSO4 is 1.19 eV. The material becomes superionic conductor at high temperature phase. [ABSTRACT FROM AUTHOR]

Published
2013
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8. Ac Conductivity and Electrical Relaxation in ion conducting Li4Nb1-x Zn2.5xP3O12 glasses.

Author

Rathan, S. Vinoth, Shah, Aashaq Hussain, and Govindaraj, G.

Subjects
ELECTRIC conductivity, RELAXATION phenomena, METALLIC oxides, METALLIC glasses, QUENCHING (Chemistry), DISPERSION (Chemistry), TEMPERATURE effect
Abstract

We report the electrical relaxation in ion conducting Li4Nb1-xZn 2.5xP3O12. These glasses were prepared by conventional melt quenching method. The electrical relaxation has been investigated both in ac conductivity as well as electric modulus formalisms. The conductivity isotherms show a transition from frequency independent dc region to dispersive region where the conductivity increases with increasing frequency. The power law dispersion of the ac conductivity scales regardless of the variation of x in TTSP scheme, and therefore suggests that relaxation in these glasses is independent of the temperature and composition.. [ABSTRACT FROM AUTHOR]

Published
2011
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9. Physical and electrical properties of combustion synthesized NASICON type Na3Cr2(PO4)3 crystallites: Effect of glycine molar ratios

Author

Vijayan, Lakshmi, Cheruku, Rajesh, Govindaraj, G., and Rajagopan, S.

Subjects
*ELECTRIC properties of metals, *SELF-propagating high-temperature synthesis, *GLYCINE, *THERMAL analysis, *SOLUTION (Chemistry), *MOLECULAR structure, *TEMPERATURE effect, *ELECTRIC conductivity, *SODIUM compounds
Abstract

Abstract: Thermally stable Na3Cr2(PO4)3 nano-crystallites are synthesized through novel solution combustion technique using glycine fuel in three molar ratios. Effects of fuel molar ratio on structural and electrical properties are investigated. Reaction parameters like fuel molar ratio, flame temperature and number of moles of gases evolved, play a major role in deciding physical and electrical properties. Out of the synthesized samples, one which contains fuel in 1:1 molar ratio shows highest grain conductivity of 2.35×10−6 Scm−1. Improved conductivity is elucidated by least size and highest density of the crystallites, which in turn is decided by the flame temperature. Ac electrical properties are investigated using complex impedance spectroscopy. Activation energies for dc conduction and relaxation are determined and the results are reported. [Copyright &y& Elsevier]

Published
2011
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10. Preparation and characterization of Ce1−x Sm x O2−δ (x = 0.1–0.3) as electrolyte material for intermediate temperature SOFC.

Author

Anjaneya, K.C., Nayaka, G.P., Manjanna, J., Govindaraj, G., and Ganesha, K.N.

Subjects
*SUPERIONIC conductors, *TEMPERATURE effect, *SOLID oxide fuel cells, *CERIUM compounds, *METAL ions, *FOURIER transform infrared spectroscopy, *ABSORPTION spectra
Abstract

Abstract: The effect of Sm doping on CeO2 for its use as a solid electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce1−x Sm x O2−δ (x = 0.1–0.3) samples are successfully synthesized by carbonate co-precipitation method. TG–DTA, XRD, Raman, UV–Vis, FT-IR, SEM and ac-impedance are used for structural and electrical characterization. From the XRD patterns, well-crystalline cubic fluorite structured solid solution is confirmed. Lattice parameters increased with increase in Sm3+ while the crystallite size decreased. The optical absorption spectra exhibits a red shift for Sm3+ doped CeO2. Raman spectra show an intense peak at 463 cm−1, a characteristic peak for doped ceria. SEM shows cluster like particles. Based on ac-impedance data, the total oxygen ionic conductivity is highest for Ce0.8Sm0.2O2−δ in the temperature range of 473–623 K. [Copyright &y& Elsevier]

Published
2013
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11. Preparation and characterization of Ce1− x Gd x O2− δ (x =0.1–0.3) as solid electrolyte for intermediate temperature SOFC.

Author

Anjaneya, K.C., Nayaka, G.P., Manjanna, J., Govindaraj, G., and Ganesha, K.N.

Subjects
*SOLID oxide fuel cells, *SOLID electrolytes, *INTERMEDIATES (Chemistry), *CERIUM oxides, *TEMPERATURE effect, *GADOLINIUM, *DOPED semiconductors, *ELECTRIC conductivity, *PRECIPITATION (Chemistry)
Abstract

Highlights: [•] Gd doped CeO2 was successfully synthesized by carbonate co-precipitation method. [•] Lattice parameters and unit cell volume increases with increase in Gd concentration. [•] The optical absorption spectra of GDC20 exhibits a red shift when compare to pure CeO2. [•] Total conductivity of GDC10 and GDC20 is almost same between 473K and 623K. [ABSTRACT FROM AUTHOR]

Published
2013
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