Conventional solid state reaction technique was used to synthesize Ca1-xSrx(Fe0.5Ta0.5)O3 multiferroic ceramics (where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5). Powder of ingredients was mixed thoroughly in stoichiometric...Conventional solid state reaction technique was used to synthesize Ca1-xSrx(Fe0.5Ta0.5)O3 multiferroic ceramics (where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5). Powder of ingredients was mixed thoroughly in stoichiometric amount and calcined at 1150°C for 5 h. Disk and toroid shaped samples prepared from each composition were sintered at 1450°C for 5 h. The XRD analysis confirms that all compositions are single phase cubic perovskite structure. The theoretical and bulk density increases with increase of Sr content, which may be attributed to the fact that the atomic weight and density of Sr are larger than those of Ca. The average grain size increased with increasing Sr content up to x = 0.2, and then decreased with further increase of Sr content. Frequency dependent dielectric constant shows usual dielectric dispersion at lower frequencies due to Maxwell-Wagner type interfacial polarization. The higher values of real and imaginary part of impedance at lower frequencies are also due to the fact that all kinds of polarization mechanism are present and increase with Sr content indicating the enhancement property of the composition. The continuous dispersion on increasing frequency contributes to the conduction phenomena. Two semicircles correspond to the grain boundary and grain resistance separately. The complex modulus analysis reveals the polaron hopping and negligibly small contribution of electrode effect. The continuous dispersion on increasing frequency may be contributed to the conduction phenomena. The ac conductivity, σac, was derived from the dielectric measurement and it increases with increase of frequency for all the compositions and can also be explained on the basis of polaron hopping mechanism. At higher frequencies conductive grains are more active, and thereby increases of hopping of charge carrier contribute to rise in conductivity. The real part of initial permeability increased with increasing Sr content up to x = 0.2, and then decreased further increasing the Sr content. Firstly, it increased due to the higher values of grain size, and then decreased with the Sr content due to the lowering the grain size. The saturation magnetization, Ms, increases for x = 0.2 and then decreases with increasing Sr content due to the pore acted as a pinning centre of electron spin;thereby Ms decreases also due to the grain size which is well supported by the permeability results. The decrease of magnetoelectric voltage coefficient αME with content may be attributed to the increased porosity in the sample. The presence of the pores breaks the magnetic contacts between the grains. The highest value of αME is 42.22 mV·cm-1·Oe-1 for the composition x = 0.2 which is attributed to the enhanced mechanical coupling. It was revealed that there is a dramatic influence of Sr with content x = 0.2 and also has strong correlations on grain size as well as magnetic and magnetoelectric properties.展开更多
Spinel cubic ferrites have huge applications in me mory and high frequency devices.For the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the import...Spinel cubic ferrites have huge applications in me mory and high frequency devices.For the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important issues.This article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and 0.10.The X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),energy dispersive X-ray(EDX),vibrating sample magnetometer(VSM),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the samples.The XRD patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped samples.The densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu concentration.The FTIR analysis also proves the spinel cubic phase of the samples.The average grain size of the ferrites is obtained via FESEM images,and it is increased from 121 to 198 nm.VSM analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites.Particularly,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EDX study shows that there is no impurity contamination in the ferrites.The permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric losses.Frequency dependent resistivity and impedance analysis also show the improved nature.From the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.展开更多
Indium tin oxide(ITO) thin film was deposited on glass substrate by means of vacuum evaporation technique and annealed at 200 ℃, 300℃ and 400 ℃ in air for 1 h. The characterization and properties of the deposited f...Indium tin oxide(ITO) thin film was deposited on glass substrate by means of vacuum evaporation technique and annealed at 200 ℃, 300℃ and 400 ℃ in air for 1 h. The characterization and properties of the deposited film samples were analyzed by X-ray diffraction(XRD), scanning electron microscopy(SEM), and UV-VIS-NIR spectroscopy techniques. From the XRD patterns, it was found that the deposited thin film was of crystalline at an annealing temperature of 400℃. The crystalline phase was indexed as cubic structure with lattice constant and crystallite size of 0.511 nm and 40 nm, respectively. The SEM images showed that the films exhibited uniform surface morphology with well-defined spherical grains. The optical transmittance of ITO thin film annealed at 400 ℃ was improved from 44% to 84% in the wavelength range from 250 nm to 2 100 nm and an optical band gap was measured as 3.86 e V. Hall effect measurement was used to measure the resistivity and conductivity of the prepared film.展开更多
In this research,influence of adding Li_(2)CO_(3)(at 0%,2%,4%,6%)on electrical and magnetic properties of Ni_(0.6)Mg_(0.4)Fe_(2)O_(4)(with 60%Ni and 40%Mg)ferrite has been studied.The samples are prepared by solid sta...In this research,influence of adding Li_(2)CO_(3)(at 0%,2%,4%,6%)on electrical and magnetic properties of Ni_(0.6)Mg_(0.4)Fe_(2)O_(4)(with 60%Ni and 40%Mg)ferrite has been studied.The samples are prepared by solid state reaction method and sintered at 1300℃ for 6 h.X-ray diffraction(XRD)patterns show the samples belong to single-phase cubic structure without any impurity phase.The magnetic properties(saturation magnetization and coercivity)of the samples have been investigated by VSM and found that the higher concentration of Li_(2)CO_(3)reduces the hysteresis loss.DC resistivity increases with Li_(2)CO_(3)contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor.The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime,which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers.Notably,the loss peaks are shifted to the lower frequency with Li_(2)CO_(3)additions.展开更多
文摘Conventional solid state reaction technique was used to synthesize Ca1-xSrx(Fe0.5Ta0.5)O3 multiferroic ceramics (where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5). Powder of ingredients was mixed thoroughly in stoichiometric amount and calcined at 1150°C for 5 h. Disk and toroid shaped samples prepared from each composition were sintered at 1450°C for 5 h. The XRD analysis confirms that all compositions are single phase cubic perovskite structure. The theoretical and bulk density increases with increase of Sr content, which may be attributed to the fact that the atomic weight and density of Sr are larger than those of Ca. The average grain size increased with increasing Sr content up to x = 0.2, and then decreased with further increase of Sr content. Frequency dependent dielectric constant shows usual dielectric dispersion at lower frequencies due to Maxwell-Wagner type interfacial polarization. The higher values of real and imaginary part of impedance at lower frequencies are also due to the fact that all kinds of polarization mechanism are present and increase with Sr content indicating the enhancement property of the composition. The continuous dispersion on increasing frequency contributes to the conduction phenomena. Two semicircles correspond to the grain boundary and grain resistance separately. The complex modulus analysis reveals the polaron hopping and negligibly small contribution of electrode effect. The continuous dispersion on increasing frequency may be contributed to the conduction phenomena. The ac conductivity, σac, was derived from the dielectric measurement and it increases with increase of frequency for all the compositions and can also be explained on the basis of polaron hopping mechanism. At higher frequencies conductive grains are more active, and thereby increases of hopping of charge carrier contribute to rise in conductivity. The real part of initial permeability increased with increasing Sr content up to x = 0.2, and then decreased further increasing the Sr content. Firstly, it increased due to the higher values of grain size, and then decreased with the Sr content due to the lowering the grain size. The saturation magnetization, Ms, increases for x = 0.2 and then decreases with increasing Sr content due to the pore acted as a pinning centre of electron spin;thereby Ms decreases also due to the grain size which is well supported by the permeability results. The decrease of magnetoelectric voltage coefficient αME with content may be attributed to the increased porosity in the sample. The presence of the pores breaks the magnetic contacts between the grains. The highest value of αME is 42.22 mV·cm-1·Oe-1 for the composition x = 0.2 which is attributed to the enhanced mechanical coupling. It was revealed that there is a dramatic influence of Sr with content x = 0.2 and also has strong correlations on grain size as well as magnetic and magnetoelectric properties.
基金supported by the Research and Innovation Centre,Khulna University(KURC ID-47/2020)。
文摘Spinel cubic ferrites have huge applications in me mory and high frequency devices.For the improvement of these modern devices,the magnetic coercivity,permeability,and dielectric properties of a ferrite are the important issues.This article focuses on improving the magnetic coercivity,magnetic permeability,and dielectric properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites,where x=0.00,0.06,and 0.10.The X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),energy dispersive X-ray(EDX),vibrating sample magnetometer(VSM),and an impedance analyzer were used to characterize the structural,magnetic,and dielectric properties of the samples.The XRD patterns indicate the formation of spinel cubic structure of the samples with a secondary peak(EuFeO_(3))for Eu doped samples.The densities and porosities of the samples follow an inverse trend,where the doped samples’lattice parameters are increased with the increment of rare earth Eu concentration.The FTIR analysis also proves the spinel cubic phase of the samples.The average grain size of the ferrites is obtained via FESEM images,and it is increased from 121 to 198 nm.VSM analysis confirms that doping of the Eu content also changes other hysteresis loop properties of Co_(0.2)Zn_(0.3)Ni_(0.5)Eu_(x)Fe_(2-x)O_(4) ferrites.Particularly,the coercivity of the Eu doped samples is greater than that of the mother alloy(x=0.00).The EDX study shows that there is no impurity contamination in the ferrites.The permeability and dielectric measurements show an improved quality factor of the Eu-doped samples with low magnetic and dielectric losses.Frequency dependent resistivity and impedance analysis also show the improved nature.From the observed properties of the samples,all the investigated ferrites might be strong candidates for potential applications in memory devices,magnetic sensors,and high frequency applications.
文摘Indium tin oxide(ITO) thin film was deposited on glass substrate by means of vacuum evaporation technique and annealed at 200 ℃, 300℃ and 400 ℃ in air for 1 h. The characterization and properties of the deposited film samples were analyzed by X-ray diffraction(XRD), scanning electron microscopy(SEM), and UV-VIS-NIR spectroscopy techniques. From the XRD patterns, it was found that the deposited thin film was of crystalline at an annealing temperature of 400℃. The crystalline phase was indexed as cubic structure with lattice constant and crystallite size of 0.511 nm and 40 nm, respectively. The SEM images showed that the films exhibited uniform surface morphology with well-defined spherical grains. The optical transmittance of ITO thin film annealed at 400 ℃ was improved from 44% to 84% in the wavelength range from 250 nm to 2 100 nm and an optical band gap was measured as 3.86 e V. Hall effect measurement was used to measure the resistivity and conductivity of the prepared film.
文摘In this research,influence of adding Li_(2)CO_(3)(at 0%,2%,4%,6%)on electrical and magnetic properties of Ni_(0.6)Mg_(0.4)Fe_(2)O_(4)(with 60%Ni and 40%Mg)ferrite has been studied.The samples are prepared by solid state reaction method and sintered at 1300℃ for 6 h.X-ray diffraction(XRD)patterns show the samples belong to single-phase cubic structure without any impurity phase.The magnetic properties(saturation magnetization and coercivity)of the samples have been investigated by VSM and found that the higher concentration of Li_(2)CO_(3)reduces the hysteresis loss.DC resistivity increases with Li_(2)CO_(3)contents whereas it decreases initially and then becomes constant at lower value with temperature which indicates that the studied samples are semiconductor.The dielectric dispersion occurs at a low-frequency regime and the loss peaks are formed in a higher frequency regime,which are due to the presence of resonance between applied frequency and hopping frequency of charge carriers.Notably,the loss peaks are shifted to the lower frequency with Li_(2)CO_(3)additions.
