This article reports on the impedance spectroscopic study of lithium substituted niobo vanadate g... more This article reports on the impedance spectroscopic study of lithium substituted niobo vanadate glasses and their nickel ferrite doped counterparts using Cole–Cole (Nyquist) plots and electrical conductivity analysis. The glass samples were prepared using the melt quenching technique. Differential scanning calorimetry and x-ray diffractometry were used to determine the thermal properties and the amorphous nature of the glass samples, respectively. Using impedance spectroscopy, the nature and extent of inhomogeneity were investigated and correlated with transport properties in the glasses at different temperature ranges (120–240 °C). Equivalent circuit analysis was adopted to study the glass materials further. The introduction of a constant phase element (Q) in a modified RQ circuit describes the Cole–Cole plot well, which accounts for the frequency dependence of dielectric response. The electrical conductivity analysis is performed using Jonscher’s law and Arrhenius plots. The expon...
Rare-earth (RE) doped glasses are widely used for laser and optoelectronic applications and their... more Rare-earth (RE) doped glasses are widely used for laser and optoelectronic applications and their optical properties depend on the host glass matrix to a large extent. RE doped alkali borate glasses are interesting to observe the effect of network modifiers on the RE environment. In spite of several studies on RE doped glasses, a consensus on the RE environment is still elusive. In this communication we are able to show the effect of the modifier ion on the RE environment in 30R2O-69.5B2O3-0.5Nd2O3 ( R=Li , Na, K, Rb and the composition is in mol %) by measuring B11 Nuclear Spin Lattice (NSLR) time over a temperature range 100-4.2K . These measurements allow us to evaluate the crystal field splitting (Delta) of the two lowest lying multiplets of the ground state (4I9/2) of Nd3+ . We show here that a systematic variation of Delta with the type of alkali can be correlated to the findings from optical and EXAFS measurements. Our results suggest that the next nearest neighbour of RE is ...
We have built a low cost and versatile pulsed internal field nuclear magnetic resonance (IFNMR) s... more We have built a low cost and versatile pulsed internal field nuclear magnetic resonance (IFNMR) spectrometer and used it to study ferromagnetic materials. Initially optimization of the instrument has been tested with nuclear quadrupole resonance (NQR) active nuclei. Ferromagnetic materials like bulk iron, bulk cobalt and carbon coated cobalt nanopowder have been used as the testing materials for our spectrometer. Preliminary results obtained from the present spectrometer have been compared with the earlier reports and are in good agreement. The specifications and performance standard of the instrument match quite well with standard instruments elsewhere in the world which is testified with the observation of NMR echo signals in the above mentioned materials confirming the quality of the spectrometer. Additionally NMR signals from the grain boundaries are observed in Co@C nanomaterials which prove the sensitivity of the spectrometer.
Influence of a split double concentric ring resonator elements axial rotation on the microwave tr... more Influence of a split double concentric ring resonator elements axial rotation on the microwave transmission line frequency-selective characteristics AIP Advances 11, 035209 (2021);
Novel nanocomposite polymeric membranes containing nanosized (30–100nm) polyaniline (PANI) partic... more Novel nanocomposite polymeric membranes containing nanosized (30–100nm) polyaniline (PANI) particles dispersed in poly(vinyl alcohol) (PVA) were prepared and used in the pervaporation separation of water–isopropanol feed mixtures ranging from 10 to 50mass% of water at 30°C. Of the three nanocomposite membranes prepared, the membrane containing 40:60 surface atomic concentration ratio of PANI:PVA produced the highest selectivity of 564 compared to
Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation o... more Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation of LaMnO3+δ (LM) nanopowders. The powders were well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface area and Fourier transform infrared spectroscopy (FTIR). The PXRD of as-formed LM showed a cubic phase but, upon calcination (900°C, 6 h), it transformed into a
3d-metal fluorosulphates that have a tavorite-type structure (e.g., LiFeSO 4 F) were recently rep... more 3d-metal fluorosulphates that have a tavorite-type structure (e.g., LiFeSO 4 F) were recently reported as attractive positive electrode candidates for future Li-ion batteries aimed at large volume markets. These new fluorosulphates had to be synthesized via ionothermal synthesis owing to both their thermal instability at temperatures greater than 300°C and their water solubility. In an attempt to depart from ionothermal synthesis, low-temperature solid-state reactions and solvothermal processes were successfully tried. The latter technique, which is reported herein, proceeds with water as the solvent and has led to a new family of fluorosulphates NaMSO 4 F 3 2H 2 O that crystallize in a monoclinic unit cell (SG =P2 1 /m) similar to the uklonskovite-type structure earlier proposed for NaMgSO 4 F 3 2H 2 O. These new phases show no electrochemical activity with either Li or Na metal and have room temperature ionic conductivities on the order of 1 Â 10 -9 S cm -1 . Additionally, we have discovered the feasibility, upon controlled dehydration of the NaMSO 4 F.2H 2 O phases, to prepare NaMSO 4 F phases adopting a derived tavoritetype structure and displaying ionic conductivities around 10 -7 S cm -1 . Finally, this finding opens the possibility to achieve Li-based fluorosulphates via two-step synthetic pathways.
Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation o... more Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation of LaMnO3+δ (LM) nanopowders. The powders were well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface area and Fourier transform infrared spectroscopy (FTIR). The PXRD of as-formed LM showed a cubic phase but, upon calcination (900°C, 6 h), it transformed into a
This article reports on the impedance spectroscopic study of lithium substituted niobo vanadate g... more This article reports on the impedance spectroscopic study of lithium substituted niobo vanadate glasses and their nickel ferrite doped counterparts using Cole–Cole (Nyquist) plots and electrical conductivity analysis. The glass samples were prepared using the melt quenching technique. Differential scanning calorimetry and x-ray diffractometry were used to determine the thermal properties and the amorphous nature of the glass samples, respectively. Using impedance spectroscopy, the nature and extent of inhomogeneity were investigated and correlated with transport properties in the glasses at different temperature ranges (120–240 °C). Equivalent circuit analysis was adopted to study the glass materials further. The introduction of a constant phase element (Q) in a modified RQ circuit describes the Cole–Cole plot well, which accounts for the frequency dependence of dielectric response. The electrical conductivity analysis is performed using Jonscher’s law and Arrhenius plots. The expon...
Rare-earth (RE) doped glasses are widely used for laser and optoelectronic applications and their... more Rare-earth (RE) doped glasses are widely used for laser and optoelectronic applications and their optical properties depend on the host glass matrix to a large extent. RE doped alkali borate glasses are interesting to observe the effect of network modifiers on the RE environment. In spite of several studies on RE doped glasses, a consensus on the RE environment is still elusive. In this communication we are able to show the effect of the modifier ion on the RE environment in 30R2O-69.5B2O3-0.5Nd2O3 ( R=Li , Na, K, Rb and the composition is in mol %) by measuring B11 Nuclear Spin Lattice (NSLR) time over a temperature range 100-4.2K . These measurements allow us to evaluate the crystal field splitting (Delta) of the two lowest lying multiplets of the ground state (4I9/2) of Nd3+ . We show here that a systematic variation of Delta with the type of alkali can be correlated to the findings from optical and EXAFS measurements. Our results suggest that the next nearest neighbour of RE is ...
We have built a low cost and versatile pulsed internal field nuclear magnetic resonance (IFNMR) s... more We have built a low cost and versatile pulsed internal field nuclear magnetic resonance (IFNMR) spectrometer and used it to study ferromagnetic materials. Initially optimization of the instrument has been tested with nuclear quadrupole resonance (NQR) active nuclei. Ferromagnetic materials like bulk iron, bulk cobalt and carbon coated cobalt nanopowder have been used as the testing materials for our spectrometer. Preliminary results obtained from the present spectrometer have been compared with the earlier reports and are in good agreement. The specifications and performance standard of the instrument match quite well with standard instruments elsewhere in the world which is testified with the observation of NMR echo signals in the above mentioned materials confirming the quality of the spectrometer. Additionally NMR signals from the grain boundaries are observed in Co@C nanomaterials which prove the sensitivity of the spectrometer.
Influence of a split double concentric ring resonator elements axial rotation on the microwave tr... more Influence of a split double concentric ring resonator elements axial rotation on the microwave transmission line frequency-selective characteristics AIP Advances 11, 035209 (2021);
Novel nanocomposite polymeric membranes containing nanosized (30–100nm) polyaniline (PANI) partic... more Novel nanocomposite polymeric membranes containing nanosized (30–100nm) polyaniline (PANI) particles dispersed in poly(vinyl alcohol) (PVA) were prepared and used in the pervaporation separation of water–isopropanol feed mixtures ranging from 10 to 50mass% of water at 30°C. Of the three nanocomposite membranes prepared, the membrane containing 40:60 surface atomic concentration ratio of PANI:PVA produced the highest selectivity of 564 compared to
Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation o... more Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation of LaMnO3+δ (LM) nanopowders. The powders were well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface area and Fourier transform infrared spectroscopy (FTIR). The PXRD of as-formed LM showed a cubic phase but, upon calcination (900°C, 6 h), it transformed into a
3d-metal fluorosulphates that have a tavorite-type structure (e.g., LiFeSO 4 F) were recently rep... more 3d-metal fluorosulphates that have a tavorite-type structure (e.g., LiFeSO 4 F) were recently reported as attractive positive electrode candidates for future Li-ion batteries aimed at large volume markets. These new fluorosulphates had to be synthesized via ionothermal synthesis owing to both their thermal instability at temperatures greater than 300°C and their water solubility. In an attempt to depart from ionothermal synthesis, low-temperature solid-state reactions and solvothermal processes were successfully tried. The latter technique, which is reported herein, proceeds with water as the solvent and has led to a new family of fluorosulphates NaMSO 4 F 3 2H 2 O that crystallize in a monoclinic unit cell (SG =P2 1 /m) similar to the uklonskovite-type structure earlier proposed for NaMgSO 4 F 3 2H 2 O. These new phases show no electrochemical activity with either Li or Na metal and have room temperature ionic conductivities on the order of 1 Â 10 -9 S cm -1 . Additionally, we have discovered the feasibility, upon controlled dehydration of the NaMSO 4 F.2H 2 O phases, to prepare NaMSO 4 F phases adopting a derived tavoritetype structure and displaying ionic conductivities around 10 -7 S cm -1 . Finally, this finding opens the possibility to achieve Li-based fluorosulphates via two-step synthetic pathways.
Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation o... more Single-step low-temperature solution combustion (LCS) synthesis was adopted for the preparation of LaMnO3+δ (LM) nanopowders. The powders were well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), surface area and Fourier transform infrared spectroscopy (FTIR). The PXRD of as-formed LM showed a cubic phase but, upon calcination (900°C, 6 h), it transformed into a
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