Masroor Ahmad Bhat | Barkatulla University (original) (raw)
Uploads
Papers by Masroor Ahmad Bhat
We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.... more We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites for the first time for identifying the transport properties as a function of the composition and temperature. Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) samples exhibit a single phase nature with an orthorhombic structure and a Pbnm space group. These materials show colossal magnetoresistance effect (CMR) and have wide technological applications such as magnetic sensors, reading head devices, spintronics, bolometers, magnetic refrigeration, etc. The computed transport properties such as cohesive energy, Reststrahlen frequency, Debye temperature, Grüneisen parameter and temperature dependence of specific heat of Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites are discussed in detail in the present work by applying extended rigid ion model (ERIM) and have shown significant agreement with the corresponding available results.
We have reported the synthesis of polycrystalline samples of R0.67Sr0.33MnO3 (R Pr, Nd) from th... more We have reported the synthesis of polycrystalline samples of R0.67Sr0.33MnO3 (R Pr, Nd) from the precursors of PrMnO3, NdMnO3 and SrMnO3 by using solid state reaction method. These samples were sintered at 1200 °C and 1400 °C. Some of samples were also undergone oxygen annealing at 950 °C for 6 h. All the synthesized samples were characterized by X-Ray diffraction (XRD) technique, scanning electron microscopy (SEM) and low temperature resistivity versus temperature (R-T) measurement. The XRD patterns show the monophasic nature of the sintered and annealed samples. The sintered samples of Nd0.67Sr0.33MnO3 has metal-insulator transition at 250 K, while the sample annealed in oxygen shows two peaks, one sharp peak at 250 K and other broad peak at 200 K. The sintered samples of Pr0.67Sr0.33MnO3 has only one peak at 290 K, while the sample annealed in oxygen shows two peaks, one sharp peak at 290 K and another broad peak at 225 K. The two peak behavior in the annealed samples has been explained by inhomogeneous diffusion of oxygen in the core of the grain and at the grain boundaries region.
We report the structural and magnetic properties of Ag substituted Sm 0.55 Sr 0.45-x Ag x MnO 3 (... more We report the structural and magnetic properties of Ag substituted Sm 0.55 Sr 0.45-x Ag x MnO 3 (x = 0, 0.15) synthesized via solid state reaction method. The XRD patterns using Full Prof Rietveld analysis shows that the samples have single phase nature without any detectable impurity. SEM results shows that the grain size increases upto sharper instant. The magnetic studies reveals Neil temperature (T N ) and Curie Temperature (T c ) get decreased with the lowering of temperature. The hysteresis loss which is dominant in pure sample disappears in Ag doped one. This shows that Ag helps in achieving the homogeneity thereby decreasing the disorder.
We have synthesized and investigated the effect of Ag doping in Pr 0.67 Sr 1 À x Ag x MnO 3 (0 r ... more We have synthesized and investigated the effect of Ag doping in Pr 0.67 Sr 1 À x Ag x MnO 3 (0 r x r0.3) perovskite materials via solid state reaction route. The structural, transport and magnetoresistance behavior have been studied. The Rietveld refinement of X-ray diffraction data shows that the compounds crystallize in an orthorhombic structure with Pnma space group with systematic non-linear variation in unit cell volume and lattice parameters. The grain morphology confirms that silver enhances conducting channels and reacts well with the compound only upto a certain doping level. The temperature dependent zero-field and in-field resistivity have been measured between 5 K and 300 K. The samples exhibit a systematic variation in metal to insulator transition temperature and a large magnetoresistance at x ¼ 0.10. The highest value of temperature coefficient of resistance has been observed by us for the first time. The results revealed that Ag takes part in the reaction only when the doping amount is small and at higher doping the system becomes a two phase composite.
We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.... more We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites for the first time for identifying the transport properties as a function of the composition and temperature. Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) samples exhibit a single phase nature with an orthorhombic structure and a Pbnm space group. These materials show colossal magnetoresistance effect (CMR) and have wide technological applications such as magnetic sensors, reading head devices, spintronics, bolometers, magnetic refrigeration, etc. The computed transport properties such as cohesive energy, Reststrahlen frequency, Debye temperature, Grüneisen parameter and temperature dependence of specific heat of Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites are discussed in detail in the present work by applying extended rigid ion model (ERIM) and have shown significant agreement with the corresponding available results.
We have reported the effect of HgO addition on electrical resistivity of La 0.75 Ca 0.25 MnO 3 ma... more We have reported the effect of HgO addition on electrical resistivity of La 0.75 Ca 0.25 MnO 3 manganites. The samples have been synthesised by conventional solid state reaction method. The pellets of these samples were sintered at 1200 °C in ambient atmosphere. These samples were characterized by X-Ray diffraction technique and low temperature four probe resistivity measurement using closed cycle helium cryostat. From XRD analysis, these samples were found to have single phase orthorhombic (Pnma) crystal structure. From the resistivity vs temperature behaviour of these samples, it has been found that the resistivity of HgO added La 0.75 Ca 0.25 MnO 3 decreases considerably in comparison to La 0.75 Ca 0.25 MnO 3 . It has also been observed that HgO addition decreases the metal-insulator transition from 242 K to 232 K which is due to cationic disorder created by HgO in La 0.75 Ca 0.25 MnO 3 .
A modified Rigid Ion Model (MRIM) incorporated by the effect of van der Waal's interaction has be... more A modified Rigid Ion Model (MRIM) incorporated by the effect of van der Waal's interaction has been applied to investigate the thermal expansion of LaGaO 3 .The thermal expansion at low temperature gives an anomalous softening. Also, we have reported the specific heat for temperature 25K ≤ T ≤ 400K and compared with the experimentally measured data.
The thermophysical properties such as structural, transport and elastic properties of the orthorh... more The thermophysical properties such as structural, transport and elastic properties of the orthorhombic perovskite-type titanate system, LaTiO 3 have been explored in detail for the first time by applying extended rigid ion model (ERIM). LaTiO 3 has been subject of recent interest because of the variety of attractive behaviors, including a metal-insulator transition, spin-charge-orbital ordering and high-temperature superconductivity. LaTiO 3 has been suggested to have promising scientific and technological applications. The theoretically computed thermophysical properties of LaTiO 3 compound are in good agreement with the available results.
We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.... more We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites for the first time for identifying the transport properties as a function of the composition and temperature. Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) samples exhibit a single phase nature with an orthorhombic structure and a Pbnm space group. These materials show colossal magnetoresistance effect (CMR) and have wide technological applications such as magnetic sensors, reading head devices, spintronics, bolometers, magnetic refrigeration, etc. The computed transport properties such as cohesive energy, Reststrahlen frequency, Debye temperature, Grüneisen parameter and temperature dependence of specific heat of Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites are discussed in detail in the present work by applying extended rigid ion model (ERIM) and have shown significant agreement with the corresponding available results.
We have reported the synthesis of polycrystalline samples of R0.67Sr0.33MnO3 (R Pr, Nd) from th... more We have reported the synthesis of polycrystalline samples of R0.67Sr0.33MnO3 (R Pr, Nd) from the precursors of PrMnO3, NdMnO3 and SrMnO3 by using solid state reaction method. These samples were sintered at 1200 °C and 1400 °C. Some of samples were also undergone oxygen annealing at 950 °C for 6 h. All the synthesized samples were characterized by X-Ray diffraction (XRD) technique, scanning electron microscopy (SEM) and low temperature resistivity versus temperature (R-T) measurement. The XRD patterns show the monophasic nature of the sintered and annealed samples. The sintered samples of Nd0.67Sr0.33MnO3 has metal-insulator transition at 250 K, while the sample annealed in oxygen shows two peaks, one sharp peak at 250 K and other broad peak at 200 K. The sintered samples of Pr0.67Sr0.33MnO3 has only one peak at 290 K, while the sample annealed in oxygen shows two peaks, one sharp peak at 290 K and another broad peak at 225 K. The two peak behavior in the annealed samples has been explained by inhomogeneous diffusion of oxygen in the core of the grain and at the grain boundaries region.
We report the structural and magnetic properties of Ag substituted Sm 0.55 Sr 0.45-x Ag x MnO 3 (... more We report the structural and magnetic properties of Ag substituted Sm 0.55 Sr 0.45-x Ag x MnO 3 (x = 0, 0.15) synthesized via solid state reaction method. The XRD patterns using Full Prof Rietveld analysis shows that the samples have single phase nature without any detectable impurity. SEM results shows that the grain size increases upto sharper instant. The magnetic studies reveals Neil temperature (T N ) and Curie Temperature (T c ) get decreased with the lowering of temperature. The hysteresis loss which is dominant in pure sample disappears in Ag doped one. This shows that Ag helps in achieving the homogeneity thereby decreasing the disorder.
We have synthesized and investigated the effect of Ag doping in Pr 0.67 Sr 1 À x Ag x MnO 3 (0 r ... more We have synthesized and investigated the effect of Ag doping in Pr 0.67 Sr 1 À x Ag x MnO 3 (0 r x r0.3) perovskite materials via solid state reaction route. The structural, transport and magnetoresistance behavior have been studied. The Rietveld refinement of X-ray diffraction data shows that the compounds crystallize in an orthorhombic structure with Pnma space group with systematic non-linear variation in unit cell volume and lattice parameters. The grain morphology confirms that silver enhances conducting channels and reacts well with the compound only upto a certain doping level. The temperature dependent zero-field and in-field resistivity have been measured between 5 K and 300 K. The samples exhibit a systematic variation in metal to insulator transition temperature and a large magnetoresistance at x ¼ 0.10. The highest value of temperature coefficient of resistance has been observed by us for the first time. The results revealed that Ag takes part in the reaction only when the doping amount is small and at higher doping the system becomes a two phase composite.
We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.... more We have investigated the transport studies of the Nb-doped Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites for the first time for identifying the transport properties as a function of the composition and temperature. Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) samples exhibit a single phase nature with an orthorhombic structure and a Pbnm space group. These materials show colossal magnetoresistance effect (CMR) and have wide technological applications such as magnetic sensors, reading head devices, spintronics, bolometers, magnetic refrigeration, etc. The computed transport properties such as cohesive energy, Reststrahlen frequency, Debye temperature, Grüneisen parameter and temperature dependence of specific heat of Pr 0.7 Sr 0.3 Mn 1À x Nb x O 3 (0rxr0.05) manganites are discussed in detail in the present work by applying extended rigid ion model (ERIM) and have shown significant agreement with the corresponding available results.
We have reported the effect of HgO addition on electrical resistivity of La 0.75 Ca 0.25 MnO 3 ma... more We have reported the effect of HgO addition on electrical resistivity of La 0.75 Ca 0.25 MnO 3 manganites. The samples have been synthesised by conventional solid state reaction method. The pellets of these samples were sintered at 1200 °C in ambient atmosphere. These samples were characterized by X-Ray diffraction technique and low temperature four probe resistivity measurement using closed cycle helium cryostat. From XRD analysis, these samples were found to have single phase orthorhombic (Pnma) crystal structure. From the resistivity vs temperature behaviour of these samples, it has been found that the resistivity of HgO added La 0.75 Ca 0.25 MnO 3 decreases considerably in comparison to La 0.75 Ca 0.25 MnO 3 . It has also been observed that HgO addition decreases the metal-insulator transition from 242 K to 232 K which is due to cationic disorder created by HgO in La 0.75 Ca 0.25 MnO 3 .
A modified Rigid Ion Model (MRIM) incorporated by the effect of van der Waal's interaction has be... more A modified Rigid Ion Model (MRIM) incorporated by the effect of van der Waal's interaction has been applied to investigate the thermal expansion of LaGaO 3 .The thermal expansion at low temperature gives an anomalous softening. Also, we have reported the specific heat for temperature 25K ≤ T ≤ 400K and compared with the experimentally measured data.
The thermophysical properties such as structural, transport and elastic properties of the orthorh... more The thermophysical properties such as structural, transport and elastic properties of the orthorhombic perovskite-type titanate system, LaTiO 3 have been explored in detail for the first time by applying extended rigid ion model (ERIM). LaTiO 3 has been subject of recent interest because of the variety of attractive behaviors, including a metal-insulator transition, spin-charge-orbital ordering and high-temperature superconductivity. LaTiO 3 has been suggested to have promising scientific and technological applications. The theoretically computed thermophysical properties of LaTiO 3 compound are in good agreement with the available results.