Asghari Maqsood - Profile on Academia.edu (original) (raw)

Papers by Asghari Maqsood

ZnTe Thin Films Prepared by Two Source Evaporation Method

Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used t... more Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used to miniaturize the size of the high frequency devices which is the order of the day. Nanocrystalline Ni-Co ferrites having general formula Ni 1−x Co x Fe 2 O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by coprecipitation method. The structural morphology of the prepared samples was carried out using scanning electron microscopy. The results showed the spherical shaped nanoparticles varying in the range of 16-40 nm. The complex relative permittivity (ε r ) and complex relative permeability ( r ) were measured using vector network analyzer for all the samples in the frequency range of 1 MHz to 3 GHz. The variation of complex relative permittivity (ε r ) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. The effect of frequency and cobalt concentration on permeability are reported. The reflectivity (R) of nanoferrites is also calculated. The value of minimum reflection loss (RL) is about −18 dB at 2.45 GHz with a thickness of 2.1 ± 0.1 mm. The results indicate that Ni 1−x Co x Fe 2 O 4 nanoparticles have excellent microwave absorbing properties and have a great potential for military use.

Acoustic Properties of Ho2Si2O7 Single Crystal Investigated by Brillouin Light Scattering

Key Engineering Materials, May 22, 2012

ABSTRACT

Indian Journal of Physics, Mar 14, 2014

This e-offprint is for personal use only and shall not be self-archived in electronic repositorie... more This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Preparation and characterization of superconducting material in the Ho-Ba-Cu-O system

J Mater Sci Lett, 1990

Journal of Alloys and Compounds, Oct 1, 2010

The effect of sintering time variation on grain size, density, porosity, dc electrical resistivit... more The effect of sintering time variation on grain size, density, porosity, dc electrical resistivity, activation energy, drift mobility, dielectric constant, loss factor, maximum magnetic flux density and coercivity of Cu 0.6 Zn 0.4 Fe 2 O 4 ferrites has been reported. Grain size, density and drift mobility increased with the increase in sintering time. Porosity, dc electrical resistivity and activation energy decreased with the increase in sintering time. Dielectric constant decreased by increasing frequency for all the samples and it follows the Maxwell-Wagner's interfacial polarization. Loss factor was also studied. It has a decreasing trend followed by resonance peak with the rise of frequency.

Influence of sintering time on structural, magnetic and electrical properties of Si Ca added Sr-hexa ferrites

Journal of Magnetism and Magnetic Materials, Sep 1, 2007

Sr-hexa ferrites with the addition of Si (0.5 wt%) and Ca (0.5 wt%) have been prepared by solid-s... more Sr-hexa ferrites with the addition of Si (0.5 wt%) and Ca (0.5 wt%) have been prepared by solid-state reaction method with sintering time variation ranging from 2 to 10 h. The structural characterization of the samples confirmed the major phase of Sr-hexa ferrite. Average grain size was found within the range of 1-4 μm. Vicker hardness increased from 512 to 1187 Hv. The coercivity and remanence had the ranges from 596 to 4255 Oe and 324 to 516 G, respectively. The DC electrical resistivity measurements were carried out by two-probe method as a function of temperature from 303 to 723 K. The room temperature DC resistivity increased from 1.67×10 6 to 2.89×10 8 Ω cm in turn the activation energy also increased from 0.314 to 0.495 eV. The DC electrical resistivity decreased while drift mobility increased with the rise in temperature, ensuring the semi-conducting behavior. Dielectric properties were studied as a function of frequency in the range of 80 Hz to 1 MHz at room temperature.

Thermal Conductivity and Thermoelectric Power of Vanadium-Substituted Bi-Based (2223) High-Tc Superconductor as a Function of Temperature

Journal of Superconductivity and Novel Magnetism, 2008

ABSTRACT Superconducting samples with nominal composition Bi1.3V0.3Pb0.4Sr2Ca2Cu3O δ are prepared... more ABSTRACT Superconducting samples with nominal composition Bi1.3V0.3Pb0.4Sr2Ca2Cu3O δ are prepared by the solid state reaction method. The samples are characterized by X-ray diffraction, scanning electron microscopy, DC electrical resistivity, critical current density, AC magnetic susceptibility, thermal conductivity and thermoelectric measurements. The room temperature X-ray diffraction pattern of the sample indicated the presence of large amount of Bi-(2223) phase along with minor amount of Bi-(2212) phase. The standard four-probe technique is applied to measure DC electrical resistivity in the temperature range from 300 to 77 K. The onset temperature T c (onset) and zero resistivity critical temperature T c (R=0) are found to be 112±1 K and 106±1 K, respectively. The low field AC magnetic susceptibility is also measured as a function of temperature. Thermal conductivity and thermoelectric power of large disc-shaped cylindrical samples are measured as a function of temperature from 300 to 77 K. The increase in thermal conductivity is observed below and above T c (R=0). The estimation of the resistivity change due to scattering by phonons and impurities has been discussed.

The thermal stability and crystallization behaviour of metallic glass Fe85.5B14.5 were investigat... more The thermal stability and crystallization behaviour of metallic glass Fe85.5B14.5 were investigated by Dynamic Temperature Resistivity Measurement (DTRM) technique from room temperature to 1050K in forward and reverse mode at a heating rate of 40 K/hr. The slope of Resistivity-Temperature-Curve (RTC) changes sign and magnitude at the temperature where the transition takes place.

Cu 1Àx Tl x Ba 2 Ca 2 Cu 3 O 10Ày (Cu 1Àx

Electronic Materials Letters, 2012

The nano-crystalline erbium oxide powder was synthesized through the sol-gel technique. The effec... more The nano-crystalline erbium oxide powder was synthesized through the sol-gel technique. The effect of sintering temperature from 250°C to 1400°C on structure, morphology, and electrical properties was studied. The results were compared with the microcrystalline erbium oxide purchased from the market. The synthesized erbium oxide showed fiber like nanostructures. Dielectric properties at different sintering temperatures were measured in the frequency range 100 Hz to 5 MHz. The synthesized erbium oxide had the highest dielectric constant at 650°C. The behavior of the dissipation factor tan δ for sol-gel synthesized material was distinct from that of the purchased material; it was higher at low frequencies and then decreased with the increase in frequency. The synthesized material sintered at different temperatures exhibited a similar sort of frequency-dependent response for permittivity ( ) and resistivity (ρ). This was in accordance with Koop's theory of dielectrics. For the microcrystalline material, frequency dependence of permittivity and resistivity was not uniform. The results showed that sol-gel synthesized erbium oxide could be a good candidate for high-k applications.

The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks ... more The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.

This e-offprint is for personal use only and shall not be self-archived in electronic repositorie... more This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Microsystem Technologies

The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks ... more The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.

The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks ... more The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.

Journal of Alloys and Compounds

Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used t... more Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used to miniaturize the size of the high frequency devices which is the order of the day. Nanocrystalline Ni-Co ferrites having general formula Ni 1−x Co x Fe 2 O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by coprecipitation method. The structural morphology of the prepared samples was carried out using scanning electron microscopy. The results showed the spherical shaped nanoparticles varying in the range of 16-40 nm. The complex relative permittivity (ε r ) and complex relative permeability ( r ) were measured using vector network analyzer for all the samples in the frequency range of 1 MHz to 3 GHz. The variation of complex relative permittivity (ε r ) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. The effect of frequency and cobalt concentration on permeability are reported. The reflectivity (R) of nanoferrites is also calculated. The value of minimum reflection loss (RL) is about −18 dB at 2.45 GHz with a thickness of 2.1 ± 0.1 mm. The results indicate that Ni 1−x Co x Fe 2 O 4 nanoparticles have excellent microwave absorbing properties and have a great potential for military use.

Determination of thickness

Effects of MOSFET mismatch on the performance of single supply low voltage operational amplifiers

Microelectronics International, 2005

ABSTRACT

ZnTe Thin Films Prepared by Two Source Evaporation Method

Structural, optical and electrical characterization of HgxCd1-xTe polycrystalline films fabricated by two-source evaporation technique

Crystal Research and Technology

Two-source thermal evaporation technique was used to prepare HgxCd1-xTe thin films onto scratch f... more Two-source thermal evaporation technique was used to prepare HgxCd1-xTe thin films onto scratch free transparent glass substrates. The structural investigations revealed that thin films were polycrystalline in nature. Transmittance measurements in the wavelength range (500-2700 nm) were used to calculate optical constants. The analysis of the optical absorption data showed that the optical band gap was of indirect type. In the composition range 0.05< x < 0.25 the films exhibited an optical band gap between 1.29 and 0.98 eV. In the same composition range the films were p-type and exhibited a resistivity, which varied between 102 and 10-1 Ω-cm.

ZnTe Thin Films Prepared by Two Source Evaporation Method

Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used t... more Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used to miniaturize the size of the high frequency devices which is the order of the day. Nanocrystalline Ni-Co ferrites having general formula Ni 1−x Co x Fe 2 O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by coprecipitation method. The structural morphology of the prepared samples was carried out using scanning electron microscopy. The results showed the spherical shaped nanoparticles varying in the range of 16-40 nm. The complex relative permittivity (ε r ) and complex relative permeability ( r ) were measured using vector network analyzer for all the samples in the frequency range of 1 MHz to 3 GHz. The variation of complex relative permittivity (ε r ) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. The effect of frequency and cobalt concentration on permeability are reported. The reflectivity (R) of nanoferrites is also calculated. The value of minimum reflection loss (RL) is about −18 dB at 2.45 GHz with a thickness of 2.1 ± 0.1 mm. The results indicate that Ni 1−x Co x Fe 2 O 4 nanoparticles have excellent microwave absorbing properties and have a great potential for military use.

Acoustic Properties of Ho2Si2O7 Single Crystal Investigated by Brillouin Light Scattering

Key Engineering Materials, May 22, 2012

ABSTRACT

Indian Journal of Physics, Mar 14, 2014

This e-offprint is for personal use only and shall not be self-archived in electronic repositorie... more This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Preparation and characterization of superconducting material in the Ho-Ba-Cu-O system

J Mater Sci Lett, 1990

Journal of Alloys and Compounds, Oct 1, 2010

The effect of sintering time variation on grain size, density, porosity, dc electrical resistivit... more The effect of sintering time variation on grain size, density, porosity, dc electrical resistivity, activation energy, drift mobility, dielectric constant, loss factor, maximum magnetic flux density and coercivity of Cu 0.6 Zn 0.4 Fe 2 O 4 ferrites has been reported. Grain size, density and drift mobility increased with the increase in sintering time. Porosity, dc electrical resistivity and activation energy decreased with the increase in sintering time. Dielectric constant decreased by increasing frequency for all the samples and it follows the Maxwell-Wagner's interfacial polarization. Loss factor was also studied. It has a decreasing trend followed by resonance peak with the rise of frequency.

Influence of sintering time on structural, magnetic and electrical properties of Si Ca added Sr-hexa ferrites

Journal of Magnetism and Magnetic Materials, Sep 1, 2007

Sr-hexa ferrites with the addition of Si (0.5 wt%) and Ca (0.5 wt%) have been prepared by solid-s... more Sr-hexa ferrites with the addition of Si (0.5 wt%) and Ca (0.5 wt%) have been prepared by solid-state reaction method with sintering time variation ranging from 2 to 10 h. The structural characterization of the samples confirmed the major phase of Sr-hexa ferrite. Average grain size was found within the range of 1-4 μm. Vicker hardness increased from 512 to 1187 Hv. The coercivity and remanence had the ranges from 596 to 4255 Oe and 324 to 516 G, respectively. The DC electrical resistivity measurements were carried out by two-probe method as a function of temperature from 303 to 723 K. The room temperature DC resistivity increased from 1.67×10 6 to 2.89×10 8 Ω cm in turn the activation energy also increased from 0.314 to 0.495 eV. The DC electrical resistivity decreased while drift mobility increased with the rise in temperature, ensuring the semi-conducting behavior. Dielectric properties were studied as a function of frequency in the range of 80 Hz to 1 MHz at room temperature.

Thermal Conductivity and Thermoelectric Power of Vanadium-Substituted Bi-Based (2223) High-Tc Superconductor as a Function of Temperature

Journal of Superconductivity and Novel Magnetism, 2008

ABSTRACT Superconducting samples with nominal composition Bi1.3V0.3Pb0.4Sr2Ca2Cu3O δ are prepared... more ABSTRACT Superconducting samples with nominal composition Bi1.3V0.3Pb0.4Sr2Ca2Cu3O δ are prepared by the solid state reaction method. The samples are characterized by X-ray diffraction, scanning electron microscopy, DC electrical resistivity, critical current density, AC magnetic susceptibility, thermal conductivity and thermoelectric measurements. The room temperature X-ray diffraction pattern of the sample indicated the presence of large amount of Bi-(2223) phase along with minor amount of Bi-(2212) phase. The standard four-probe technique is applied to measure DC electrical resistivity in the temperature range from 300 to 77 K. The onset temperature T c (onset) and zero resistivity critical temperature T c (R=0) are found to be 112±1 K and 106±1 K, respectively. The low field AC magnetic susceptibility is also measured as a function of temperature. Thermal conductivity and thermoelectric power of large disc-shaped cylindrical samples are measured as a function of temperature from 300 to 77 K. The increase in thermal conductivity is observed below and above T c (R=0). The estimation of the resistivity change due to scattering by phonons and impurities has been discussed.

The thermal stability and crystallization behaviour of metallic glass Fe85.5B14.5 were investigat... more The thermal stability and crystallization behaviour of metallic glass Fe85.5B14.5 were investigated by Dynamic Temperature Resistivity Measurement (DTRM) technique from room temperature to 1050K in forward and reverse mode at a heating rate of 40 K/hr. The slope of Resistivity-Temperature-Curve (RTC) changes sign and magnitude at the temperature where the transition takes place.

Cu 1Àx Tl x Ba 2 Ca 2 Cu 3 O 10Ày (Cu 1Àx

Electronic Materials Letters, 2012

The nano-crystalline erbium oxide powder was synthesized through the sol-gel technique. The effec... more The nano-crystalline erbium oxide powder was synthesized through the sol-gel technique. The effect of sintering temperature from 250°C to 1400°C on structure, morphology, and electrical properties was studied. The results were compared with the microcrystalline erbium oxide purchased from the market. The synthesized erbium oxide showed fiber like nanostructures. Dielectric properties at different sintering temperatures were measured in the frequency range 100 Hz to 5 MHz. The synthesized erbium oxide had the highest dielectric constant at 650°C. The behavior of the dissipation factor tan δ for sol-gel synthesized material was distinct from that of the purchased material; it was higher at low frequencies and then decreased with the increase in frequency. The synthesized material sintered at different temperatures exhibited a similar sort of frequency-dependent response for permittivity ( ) and resistivity (ρ). This was in accordance with Koop's theory of dielectrics. For the microcrystalline material, frequency dependence of permittivity and resistivity was not uniform. The results showed that sol-gel synthesized erbium oxide could be a good candidate for high-k applications.

The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks ... more The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.

This e-offprint is for personal use only and shall not be self-archived in electronic repositorie... more This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Microsystem Technologies

The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks ... more The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.

The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks ... more The thermal conductivity, thermal diffusivity, and heat capacity per unit volume of dunite rocks taken from Chillas near Gilgit, Pakistan, have been measured simultaneously using the transient plane source technique. The temperature dependence of the thermal transport properties was studied in the temperature range from 303 K to 483 K. Different relations for the estimation of the thermal conductivity are applied. A proposed model for the prediction of the thermal conductivity as a function of temperature is also given. It is observed that the values of the effective thermal conductivity predicted by the proposed model are in agreement with the experimental thermal conductivity data within 9 %.

Journal of Alloys and Compounds

Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used t... more Ni-Co nanoferrites show excellent magneto-dielectric properties and these materials can be used to miniaturize the size of the high frequency devices which is the order of the day. Nanocrystalline Ni-Co ferrites having general formula Ni 1−x Co x Fe 2 O 4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by coprecipitation method. The structural morphology of the prepared samples was carried out using scanning electron microscopy. The results showed the spherical shaped nanoparticles varying in the range of 16-40 nm. The complex relative permittivity (ε r ) and complex relative permeability ( r ) were measured using vector network analyzer for all the samples in the frequency range of 1 MHz to 3 GHz. The variation of complex relative permittivity (ε r ) as a function of frequency is explained in accordance with Maxwell-Wagner model and Koop's phenomenological theory. The effect of frequency and cobalt concentration on permeability are reported. The reflectivity (R) of nanoferrites is also calculated. The value of minimum reflection loss (RL) is about −18 dB at 2.45 GHz with a thickness of 2.1 ± 0.1 mm. The results indicate that Ni 1−x Co x Fe 2 O 4 nanoparticles have excellent microwave absorbing properties and have a great potential for military use.

Determination of thickness

Effects of MOSFET mismatch on the performance of single supply low voltage operational amplifiers

Microelectronics International, 2005

ABSTRACT

ZnTe Thin Films Prepared by Two Source Evaporation Method

Structural, optical and electrical characterization of HgxCd1-xTe polycrystalline films fabricated by two-source evaporation technique

Crystal Research and Technology

Two-source thermal evaporation technique was used to prepare HgxCd1-xTe thin films onto scratch f... more Two-source thermal evaporation technique was used to prepare HgxCd1-xTe thin films onto scratch free transparent glass substrates. The structural investigations revealed that thin films were polycrystalline in nature. Transmittance measurements in the wavelength range (500-2700 nm) were used to calculate optical constants. The analysis of the optical absorption data showed that the optical band gap was of indirect type. In the composition range 0.05< x < 0.25 the films exhibited an optical band gap between 1.29 and 0.98 eV. In the same composition range the films were p-type and exhibited a resistivity, which varied between 102 and 10-1 Ω-cm.