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Papers by Avishek Satapathy

Journal of Alloys and Compounds, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Materials Research Express, 2019

The oxygen deficient BaZr0.85Sc0.15−xYbxO3-δ (x = 0, 0.05, 0.10) ceramics were synthesized via co... more The oxygen deficient BaZr0.85Sc0.15−xYbxO3-δ (x = 0, 0.05, 0.10) ceramics were synthesized via conventional solid state reaction route. The Rietveld analysis of the x-ray diffraction profile proved that all the prepared compositions presents single phase cubic perovskite symmetry and space group. The actual oxygen occupancy of the materials has been derived from the Rietveld study. Thermo-gravimetric study of the pre-hydrated samples revealed a considerable mass loss, indicating more than 90% of the oxygen vacancies have been successfully filled by protonic defects upon hydration. FESEM images of the fractured surfaces of sintered ceramics showed dense microstructures with sub-micron sized grains and well resolved grain boundaries. The Nyquist plots differentiated the bulk, grain boundary and electrode response at lower temperatures (≤300 °C). The bulk conductivity of the Sc and Yb co-doped barium zirconate was higher compared to that of the respective Sc-doped perovskite oxide. The activation energy of bulk conductivity and total conductivity decreased with the increase in Yb content. The total conductivity of (4.01 × 10−3 Scm−1) at 600 °C has been achieved for BaZr0.85Sc0.10Yb0.05O3, suggesting the composition suitable for SOFC applications.

Journal of Alloys and Compounds, 2019

A comparative proton conductivity study on Yb-doped BaZrO 3 perovskite at intermediate temperatur... more A comparative proton conductivity study on Yb-doped BaZrO 3 perovskite at intermediate temperatures under wet N 2 environment

Ceramics International, 2016

Barium bismuth titanate ceramics doped with different concentration of samarium −() Ba Sm Bi Ti O... more Barium bismuth titanate ceramics doped with different concentration of samarium −() Ba Sm Bi Ti O x x 1 3/2 4 4 15 , (x¼ 0, 0.05, 0.10, 0.20, 0.30, and 0.40) were prepared by solid state reaction route. X-ray diffraction pattern confirmed that all compositions have a bismuth-layered perovskite structure with an orthorhombic phase of space group A2 1 am. The plate-like grain morphology was observed for the compositions upto (x¼0, 0.05, and 0.10) and the shape changed for higher samarium () + Sm 3 concentration. FT-IR study confirmed the presence of Bi-O stretching vibrations. The temperature dependent dielectric behavior showed a frequency dependent diffused phase transition above 400°C and a broadening of phase transition with increasing + Sm 3 content. The phase transition temperature shifted to higher temperatures with increasing + Sm 3 content. Ferroelectric studies revealed that the remanent polarization (P r) first increased, and then decreased with rising in dopant concentration. The maximum value of remanent polarization (P r) was found to be 2.40 μC/cm 2 for = x 0.05 composition at an applied electric field of 80 kV/cm.

Metallurgical and Materials Transactions A, 2015

The ceramics with general formula Ba (1Àx) Nd (2x/3) ZrO 3 (x = 0.0,0.02, 0.04, 0.06, 0.08, and 0... more The ceramics with general formula Ba (1Àx) Nd (2x/3) ZrO 3 (x = 0.0,0.02, 0.04, 0.06, 0.08, and 0.1) were prepared by solid-state reaction. The phase formation of the powders was analyzed by means of X-ray diffraction (XRD), Fourier transform-Raman (FT-Raman), and Fourier transform infrared (FTIR) spectroscopy. XRD patterns revealed that all powders show a perovskite-type cubic structure with space group Pm-3m. FT-Raman and FTIR spectra suggested the formation of higher degree of symmetry in the crystal. The optical bandgap was found to be decreasing while Urbach energy was found to be increasing with an increase of Nd 3+ content. The surface morphology of sintered pellets was studied by scanning electron microscope. Microwave dielectric constant and quality factor were investigated by the TE 01d mode dielectric resonator method. The microwave dielectric constant and temperature coefficient of resonant frequency decreases with increase in of Nd 3+ content. The irregular nature of quality factor (Q 9 f) was observed due to the extrinsic losses in materials. The dielectric resonator antenna (DRA) characteristics were investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft's high-frequency structure simulator software, respectively. The resonant frequency and bandwidth of DRAs were also investigated for the ceramics.

Journal of Alloys and Compounds, 2014

ABSTRACT Structural, optical band gap, microwave dielectric properties and dielectric resonant an... more ABSTRACT Structural, optical band gap, microwave dielectric properties and dielectric resonant antenna studies of Ba (1Àx) La (2x/3) ZrO 3 (0 6 x 6 0.1) ceramics Band gap Microwave dielectric properties Dielectric resonator antenna (DRA) High frequency structure simulator software (HFSS) a b s t r a c t The structural properties of the Ba (1Àx) La (2x/3) ZrO 3 system were investigated by means of XRD, FT-Raman and FTIR. The XRD analysis demonstrated that lattice parameter gradually decreased with increase of La content. Raman analysis intended the formation of higher degree of symmetry to increase of La 3+ content. It was also confirmed from FTIR analysis. The optical band gap was found to be decreased from 3.55 eV to 3.01 eV with increase of La 3+ content. The surface morphology was studied by the SEM. The microwave dielectric constant and quality factor were investigated by the method as proposed by Hakki–Coleman. The microwave dielectric constant decreased from 38.40 to 30.47 and the value of s f changed from 384.71 ppm/°C to 165.41 ppm/°C. The Q Â f values increased from 5731 to 9031 with increase of La 3+ content. The dielectric resonator antenna (DRA) was investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft's high frequency structure simulator software, respectively. The required resonance frequency and bandwidth of DRA were investigated in the composition between 0 6 x 6 0.1.

Journal of Solid State Electrochemistry, 2019

Journal of Alloys and Compounds, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Materials Research Express, 2019

The oxygen deficient BaZr0.85Sc0.15−xYbxO3-δ (x = 0, 0.05, 0.10) ceramics were synthesized via co... more The oxygen deficient BaZr0.85Sc0.15−xYbxO3-δ (x = 0, 0.05, 0.10) ceramics were synthesized via conventional solid state reaction route. The Rietveld analysis of the x-ray diffraction profile proved that all the prepared compositions presents single phase cubic perovskite symmetry and space group. The actual oxygen occupancy of the materials has been derived from the Rietveld study. Thermo-gravimetric study of the pre-hydrated samples revealed a considerable mass loss, indicating more than 90% of the oxygen vacancies have been successfully filled by protonic defects upon hydration. FESEM images of the fractured surfaces of sintered ceramics showed dense microstructures with sub-micron sized grains and well resolved grain boundaries. The Nyquist plots differentiated the bulk, grain boundary and electrode response at lower temperatures (≤300 °C). The bulk conductivity of the Sc and Yb co-doped barium zirconate was higher compared to that of the respective Sc-doped perovskite oxide. The activation energy of bulk conductivity and total conductivity decreased with the increase in Yb content. The total conductivity of (4.01 × 10−3 Scm−1) at 600 °C has been achieved for BaZr0.85Sc0.10Yb0.05O3, suggesting the composition suitable for SOFC applications.

Journal of Alloys and Compounds, 2019

A comparative proton conductivity study on Yb-doped BaZrO 3 perovskite at intermediate temperatur... more A comparative proton conductivity study on Yb-doped BaZrO 3 perovskite at intermediate temperatures under wet N 2 environment

Ceramics International, 2016

Barium bismuth titanate ceramics doped with different concentration of samarium −() Ba Sm Bi Ti O... more Barium bismuth titanate ceramics doped with different concentration of samarium −() Ba Sm Bi Ti O x x 1 3/2 4 4 15 , (x¼ 0, 0.05, 0.10, 0.20, 0.30, and 0.40) were prepared by solid state reaction route. X-ray diffraction pattern confirmed that all compositions have a bismuth-layered perovskite structure with an orthorhombic phase of space group A2 1 am. The plate-like grain morphology was observed for the compositions upto (x¼0, 0.05, and 0.10) and the shape changed for higher samarium () + Sm 3 concentration. FT-IR study confirmed the presence of Bi-O stretching vibrations. The temperature dependent dielectric behavior showed a frequency dependent diffused phase transition above 400°C and a broadening of phase transition with increasing + Sm 3 content. The phase transition temperature shifted to higher temperatures with increasing + Sm 3 content. Ferroelectric studies revealed that the remanent polarization (P r) first increased, and then decreased with rising in dopant concentration. The maximum value of remanent polarization (P r) was found to be 2.40 μC/cm 2 for = x 0.05 composition at an applied electric field of 80 kV/cm.

Metallurgical and Materials Transactions A, 2015

The ceramics with general formula Ba (1Àx) Nd (2x/3) ZrO 3 (x = 0.0,0.02, 0.04, 0.06, 0.08, and 0... more The ceramics with general formula Ba (1Àx) Nd (2x/3) ZrO 3 (x = 0.0,0.02, 0.04, 0.06, 0.08, and 0.1) were prepared by solid-state reaction. The phase formation of the powders was analyzed by means of X-ray diffraction (XRD), Fourier transform-Raman (FT-Raman), and Fourier transform infrared (FTIR) spectroscopy. XRD patterns revealed that all powders show a perovskite-type cubic structure with space group Pm-3m. FT-Raman and FTIR spectra suggested the formation of higher degree of symmetry in the crystal. The optical bandgap was found to be decreasing while Urbach energy was found to be increasing with an increase of Nd 3+ content. The surface morphology of sintered pellets was studied by scanning electron microscope. Microwave dielectric constant and quality factor were investigated by the TE 01d mode dielectric resonator method. The microwave dielectric constant and temperature coefficient of resonant frequency decreases with increase in of Nd 3+ content. The irregular nature of quality factor (Q 9 f) was observed due to the extrinsic losses in materials. The dielectric resonator antenna (DRA) characteristics were investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft's high-frequency structure simulator software, respectively. The resonant frequency and bandwidth of DRAs were also investigated for the ceramics.

Journal of Alloys and Compounds, 2014

ABSTRACT Structural, optical band gap, microwave dielectric properties and dielectric resonant an... more ABSTRACT Structural, optical band gap, microwave dielectric properties and dielectric resonant antenna studies of Ba (1Àx) La (2x/3) ZrO 3 (0 6 x 6 0.1) ceramics Band gap Microwave dielectric properties Dielectric resonator antenna (DRA) High frequency structure simulator software (HFSS) a b s t r a c t The structural properties of the Ba (1Àx) La (2x/3) ZrO 3 system were investigated by means of XRD, FT-Raman and FTIR. The XRD analysis demonstrated that lattice parameter gradually decreased with increase of La content. Raman analysis intended the formation of higher degree of symmetry to increase of La 3+ content. It was also confirmed from FTIR analysis. The optical band gap was found to be decreased from 3.55 eV to 3.01 eV with increase of La 3+ content. The surface morphology was studied by the SEM. The microwave dielectric constant and quality factor were investigated by the method as proposed by Hakki–Coleman. The microwave dielectric constant decreased from 38.40 to 30.47 and the value of s f changed from 384.71 ppm/°C to 165.41 ppm/°C. The Q Â f values increased from 5731 to 9031 with increase of La 3+ content. The dielectric resonator antenna (DRA) was investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft's high frequency structure simulator software, respectively. The required resonance frequency and bandwidth of DRA were investigated in the composition between 0 6 x 6 0.1.

Journal of Solid State Electrochemistry, 2019