TiO-2 thin films have bee deposited on p-Si(111) substrates by pulsed-laser ablation of metallic Ti target in the O-3 ambient. The current-voltage and capacitance-voltage of the Al/TiO-2/Si capacitors are measured. Th...TiO-2 thin films have bee deposited on p-Si(111) substrates by pulsed-laser ablation of metallic Ti target in the O-3 ambient. The current-voltage and capacitance-voltage of the Al/TiO-2/Si capacitors are measured. The results show that the dielectric constant of thin film after being annealed at 700℃ is found to be 46, and the border trap density and the interface state density at the TiO-2/p-Si interface are 1.8×10 12 cm -2 and 2×10 12 eV -1·cm -2, respectively. The conduction mechanisms of as-deposited films are also discussed.展开更多
Bi_4Ti_3O_(12) is an important lead-free ferroelectric material.Doping modification of Bi_4Ti_3O_(12)has attracted great attention to improving its performances.In this work,the effect of Sr dopants on the microstruct...Bi_4Ti_3O_(12) is an important lead-free ferroelectric material.Doping modification of Bi_4Ti_3O_(12)has attracted great attention to improving its performances.In this work,the effect of Sr dopants on the microstructure,dielectric,and conductivity of Bi_4Ti_3O_(12) ceramic was investigated by XRD,SEM,and AC impedance spectroscopy.Substitution of 1 at%Sr for Bi decreased the grain size,suppressed the dielectric dispersion of Bi_4Ti_3O_(12) ceramic at room temperature,and resulted in different effects on the conductivity of grains and grain boundaries.The conductivity of grains in Bi_4Ti_3O_(12) ceramic was increased by the small amount of Sr dopants in the whole experimental temperature range.While the grain boundaries of 1 at%Sr-doped Bi_4Ti_3O_(12) exhibited lower conductivity than pure Bi_4Ti_3O_(12) below～380℃and higher conductivity above～380℃.The experimental phenomena were interpreted in term of compensating defects for Sr dopants.展开更多
In the current research work Ba_(1-x)La)xMn)yFe_(12-y)O_(19) hexa-ferrite nanoparticles of different compositions were synthesized using chemical co-precipitation technique. The structural properties were explored usi...In the current research work Ba_(1-x)La)xMn)yFe_(12-y)O_(19) hexa-ferrite nanoparticles of different compositions were synthesized using chemical co-precipitation technique. The structural properties were explored using X-ray diffractions(XRD), scanning electron microscopy(SEM) and Fourier transmission infrared spectroscopy(FTIR). XRD indexed pattern confirms the formation of M-type hexagonal phase. The crystallite size of synthesized samples ranges from 13 to 34 ± 2 nm. FTIR peaks observe also confirmed the presence of metaloxygen bond of the desired product. The position of peak at 467 cm^(-1) corresponds to A_2 u vibration for octahedral Fe(4+)-O and peak position E1 u corresponds to vibration of Fe(3+)O4 octahedral bonds. The band v_1 in range(677-559 cm^(-1)) and v_2 in frequency range(356-419 cm^(-1)) are associated to A and B sites.Dielectric properties of all compositions were measured with frequency. The dielectric constant, loss and tangent loss decrease from 26 to 9, 25 to 2 and 0.94 to 0.14, respectively with frequency. DC electrical resistivity is increased with dopant concentration increasing from 2.15 × 10~4 to 1.92 ×10~5 Ω·cm.展开更多
Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism. It is found that a Lorenz-type law can be used to describe the dielectric permit- tivity of ...Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism. It is found that a Lorenz-type law can be used to describe the dielectric permit- tivity of either the normal ferroelectrics with or without diffuse phase transitions (DPT) or the typical ferroelectric relaxors. The ferroelectric DPT can be well described by just one fitting process using the Lorenz-type law, while the relaxor ferroelectric transition needs two independent fitting processes. The Lorenz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition. Above the transition temperature, the dielectric curves of all the studied materials can be well described by a Lorenz-type law.展开更多
The effects of TiO2 on sintering and nonlinear electrical properties of（98.5-x）ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2（x = 0.3,0.5,0.7,0.9 mol%） ceramic varistors prepared by the ceramic technique are investigated ...The effects of TiO2 on sintering and nonlinear electrical properties of（98.5-x）ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2（x = 0.3,0.5,0.7,0.9 mol%） ceramic varistors prepared by the ceramic technique are investigated in this work.The optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption percentages.The optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water absorption.Also minimum water absorption appears in a sample of x = 0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase sintering.The crystal size of ZnO decreases with increasing TiO2 doping.The addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x = 0.7 mol% of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 kHz.The temperature and composition dependences of the dielectric constant and AC conductivity are also studied.The increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.展开更多
The aim of the present work is to investigate the effect of the He-Ne laser irradiation on the whole human blood (HB) in order to enhance the conditions of conservation. The HB was irradiated by He-Ne laser;(λ = 632 ...The aim of the present work is to investigate the effect of the He-Ne laser irradiation on the whole human blood (HB) in order to enhance the conditions of conservation. The HB was irradiated by He-Ne laser;(λ = 632 nm, continuous wave, power 30 mW, 2 mm diameter beam spot), electrical properties and complete blood count CBC were measured at three doses (0.0287, 0.0563 and 0.198 J/cm3) to the relevant best exposure dose during storage periods 9, 24, 30, 35 & 50 days. The irradiation process with the selected dose was performed by the exposure of the laser beam on the blood sample flow through narrow tube of cross section area, 0.0831 cm2. Blood dielectric parameters, (electric conductivity, dielectric constant, dielectric loss and dipole moment) and CBC, (red blood cell, white blood cell, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, and mean cell or corpuscular hemoglobin in concentration) were measured. The obtained results were compared with that of the control and showed that the best irradiation exposure dose suitable for increasing the time of blood storage with minimum changes in properties is 0.198 J/cm3 and storage period of about 50 days. The present study revealed that irradiation by He-Ne laser could be considered a good means to improve the conservation conditions of human blood.展开更多
Nanocrystalline cadmium-zinc ferrite samples were prepared by ball milling method and its electrical transport property were investigated within a temperature range 77 K ≤ T ≤ 300 K in presence of a magnetic field u...Nanocrystalline cadmium-zinc ferrite samples were prepared by ball milling method and its electrical transport property were investigated within a temperature range 77 K ≤ T ≤ 300 K in presence of a magnetic field up to 1T and in a frequency range 20 Hz to 1 MHz. The investigated samples follow a simple hopping type charge transport. The dc magnetoconductivity has been explained in terms of orbital magnetoconductivity theory. The alternating current conductivity follows the universal dielectric response σ'/(f) ∝ Tnfs. The values of ‘s’ have a decreasing trend with temperature. The temperature exponent ‘n’ depends on frequency. The dielectric permittivity of the samples depends on the grain resistance and interfacial grain boundary resistance. The ac magnetoconductivity is positive which can be explained in terms of impedance of the sample.展开更多
Aluminum-oxide films deposited as gate dielectrics on germanium （Ge） by atomic layer deposition were post oxidized in an ozone atmosphere. No additional interfacial layer was electron microscopy and X-ray photoelect...Aluminum-oxide films deposited as gate dielectrics on germanium （Ge） by atomic layer deposition were post oxidized in an ozone atmosphere. No additional interfacial layer was electron microscopy and X-ray photoelectron spectroscopy detected by the high-resolution cross-sectional transmission measurements made after the ozone post oxidation （OPO） treatment. Decreases in the equivalent oxide thickness of the OPO-treated Al2O3/Ge MOS capacitors were confirmed. Furthermore, a continuous decrease in the gate leakage current was achieved with increasing OPO treatment time. The results can be attributed to the film quality having been improved by the OPO treatment.展开更多
文摘TiO-2 thin films have bee deposited on p-Si(111) substrates by pulsed-laser ablation of metallic Ti target in the O-3 ambient. The current-voltage and capacitance-voltage of the Al/TiO-2/Si capacitors are measured. The results show that the dielectric constant of thin film after being annealed at 700℃ is found to be 46, and the border trap density and the interface state density at the TiO-2/p-Si interface are 1.8×10 12 cm -2 and 2×10 12 eV -1·cm -2, respectively. The conduction mechanisms of as-deposited films are also discussed.
基金supported by National Basic Research Program of China (No. 2016YFB0700502) National Natural Science Foundation of China (No. 51372024)
文摘Bi_4Ti_3O_(12) is an important lead-free ferroelectric material.Doping modification of Bi_4Ti_3O_(12)has attracted great attention to improving its performances.In this work,the effect of Sr dopants on the microstructure,dielectric,and conductivity of Bi_4Ti_3O_(12) ceramic was investigated by XRD,SEM,and AC impedance spectroscopy.Substitution of 1 at%Sr for Bi decreased the grain size,suppressed the dielectric dispersion of Bi_4Ti_3O_(12) ceramic at room temperature,and resulted in different effects on the conductivity of grains and grain boundaries.The conductivity of grains in Bi_4Ti_3O_(12) ceramic was increased by the small amount of Sr dopants in the whole experimental temperature range.While the grain boundaries of 1 at%Sr-doped Bi_4Ti_3O_(12) exhibited lower conductivity than pure Bi_4Ti_3O_(12) below～380℃and higher conductivity above～380℃.The experimental phenomena were interpreted in term of compensating defects for Sr dopants.
基金Project supported by Higher Education Commission(HEC)Pakistan(1326,6018)
文摘In the current research work Ba_(1-x)La)xMn)yFe_(12-y)O_(19) hexa-ferrite nanoparticles of different compositions were synthesized using chemical co-precipitation technique. The structural properties were explored using X-ray diffractions(XRD), scanning electron microscopy(SEM) and Fourier transmission infrared spectroscopy(FTIR). XRD indexed pattern confirms the formation of M-type hexagonal phase. The crystallite size of synthesized samples ranges from 13 to 34 ± 2 nm. FTIR peaks observe also confirmed the presence of metaloxygen bond of the desired product. The position of peak at 467 cm^(-1) corresponds to A_2 u vibration for octahedral Fe(4+)-O and peak position E1 u corresponds to vibration of Fe(3+)O4 octahedral bonds. The band v_1 in range(677-559 cm^(-1)) and v_2 in frequency range(356-419 cm^(-1)) are associated to A and B sites.Dielectric properties of all compositions were measured with frequency. The dielectric constant, loss and tangent loss decrease from 26 to 9, 25 to 2 and 0.94 to 0.14, respectively with frequency. DC electrical resistivity is increased with dopant concentration increasing from 2.15 × 10~4 to 1.92 ×10~5 Ω·cm.
基金Supported by the National Natural Science Foundation of China (Grant No. 50672075)New Century Excellent Talents (Grant No. 05-087)+1 种基金Natural Science Foundation of Northwestern Polytechnical University (Grant No. 200703)Xi’an Science & Technology Foundation (Grant No. CXY08006) and 111 Project (Grant No. B08040)
文摘Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism. It is found that a Lorenz-type law can be used to describe the dielectric permit- tivity of either the normal ferroelectrics with or without diffuse phase transitions (DPT) or the typical ferroelectric relaxors. The ferroelectric DPT can be well described by just one fitting process using the Lorenz-type law, while the relaxor ferroelectric transition needs two independent fitting processes. The Lorenz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition. Above the transition temperature, the dielectric curves of all the studied materials can be well described by a Lorenz-type law.
文摘The effects of TiO2 on sintering and nonlinear electrical properties of（98.5-x）ZnO–0.5MnO2–0.5Co2O3-0.5Bi2O3–xTiO2（x = 0.3,0.5,0.7,0.9 mol%） ceramic varistors prepared by the ceramic technique are investigated in this work.The optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption percentages.The optimum sintering temperature is found to be 1200℃,at which each of the samples shows a maximum firing shrinkage and minimum water absorption.Also minimum water absorption appears in a sample of x = 0.9 mol%.Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase sintering.The crystal size of ZnO decreases with increasing TiO2 doping.The addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x = 0.7 mol% of TiO2,further addition negatively affects it.A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 kHz.The temperature and composition dependences of the dielectric constant and AC conductivity are also studied.The increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.
文摘The aim of the present work is to investigate the effect of the He-Ne laser irradiation on the whole human blood (HB) in order to enhance the conditions of conservation. The HB was irradiated by He-Ne laser;(λ = 632 nm, continuous wave, power 30 mW, 2 mm diameter beam spot), electrical properties and complete blood count CBC were measured at three doses (0.0287, 0.0563 and 0.198 J/cm3) to the relevant best exposure dose during storage periods 9, 24, 30, 35 & 50 days. The irradiation process with the selected dose was performed by the exposure of the laser beam on the blood sample flow through narrow tube of cross section area, 0.0831 cm2. Blood dielectric parameters, (electric conductivity, dielectric constant, dielectric loss and dipole moment) and CBC, (red blood cell, white blood cell, hematocrit, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, and mean cell or corpuscular hemoglobin in concentration) were measured. The obtained results were compared with that of the control and showed that the best irradiation exposure dose suitable for increasing the time of blood storage with minimum changes in properties is 0.198 J/cm3 and storage period of about 50 days. The present study revealed that irradiation by He-Ne laser could be considered a good means to improve the conservation conditions of human blood.
文摘Nanocrystalline cadmium-zinc ferrite samples were prepared by ball milling method and its electrical transport property were investigated within a temperature range 77 K ≤ T ≤ 300 K in presence of a magnetic field up to 1T and in a frequency range 20 Hz to 1 MHz. The investigated samples follow a simple hopping type charge transport. The dc magnetoconductivity has been explained in terms of orbital magnetoconductivity theory. The alternating current conductivity follows the universal dielectric response σ'/(f) ∝ Tnfs. The values of ‘s’ have a decreasing trend with temperature. The temperature exponent ‘n’ depends on frequency. The dielectric permittivity of the samples depends on the grain resistance and interfacial grain boundary resistance. The ac magnetoconductivity is positive which can be explained in terms of impedance of the sample.
基金supported by the National Program for Key Basic Research Projects (973 Program) of China (Grant No. 2011CBA00607)the National Natural Science Foundation of China (Grant Nos. 61106089 and 51102048)+2 种基金the National Science and Technology Major Projects (Grant No. 2009ZX02035)the State Key Laboratory of ASIC and System Project (Grant No. 11MS017)the Open Funds of State Key Laboratory of ASIC and System at Fudan University (Grant No. 10KF001)
文摘Aluminum-oxide films deposited as gate dielectrics on germanium （Ge） by atomic layer deposition were post oxidized in an ozone atmosphere. No additional interfacial layer was electron microscopy and X-ray photoelectron spectroscopy detected by the high-resolution cross-sectional transmission measurements made after the ozone post oxidation （OPO） treatment. Decreases in the equivalent oxide thickness of the OPO-treated Al2O3/Ge MOS capacitors were confirmed. Furthermore, a continuous decrease in the gate leakage current was achieved with increasing OPO treatment time. The results can be attributed to the film quality having been improved by the OPO treatment.
