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Study of complex impedance spectroscopic properties of La <sub/> 0.7? <i>x</i> </sub> Dy <i> <sub/>x</sub></i> Sr <sub/>0.3</sub> MnO <sub/>3</sub> perovskite oxides
摘要： The dysprosium perovskite La0.72xDyxSr0.3MnO3 [LSMO] and 0.03 [LDSMO]) compounds were prepared by the sol–gel reaction and characterized by the X-ray diffraction technique. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 311–356 K and 209–5 (cid:2) 107 Hz, respectively, by means of impedance spectroscopy. The ac and dc conductivities were studied to explore the mechanisms of conduction of LSMO and LDSMO. The insertion of a small amount of Dy3t in the La-site of LSMO perovskite oxide increases the value of the activation energy from 0.2106 to 0.5357 eV and enhances electrical resistivity values for almost two orders of magnitude.
关键词： the non-overlapping small polaron tunneling,impedance spectroscopy,correlated barrier hopping,modulus,ac conductivity
更新于2025-09-10 09:29:36
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Incarceration of iodine in a pyrene-based metal-organic framework
摘要： A pyrene-based metal–organic framework (MOF) SION-8 captures iodine (I2) vapour with a capacity of 460 mg g–1 MOF and 250 mg g–1 MOF at room temperature and at 75 °C, respectively. Single-crystal X-ray diffraction analysis and van der Waals-corrected density functional theory calculations confirm the presence of I2 molecules within the pores of SION-8 and their interaction with the pyrene-based ligands. The I2-pyrene interactions in the I2-loaded SION-8 lead to a 104-fold increase of its electrical conductivity compared to the bare SION-8. Upon adsorption, ≥95% of I2 molecules are incarcerated and cannot be washed out, signifying the potential of SION-8 towards the permanent capture of radioactive I2 at room temperature.
关键词： charge transfer,conductivity,impedance spectroscopy,iodine capture,metal–organic framework
更新于2025-09-10 09:29:36
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Structural and dielectric properties of BaTi0.5 (Co0.33 Mo0.17) O3 perovskite ceramic
摘要： The polycrystalline sample BaTi0.5 (Co0.33 Mo0.17) O3 was synthesized by the sol-gel method. The effect of replacing titanium by cobalt and molybdenum on the structural and electrical properties of our compound was investigated. The results of X-ray diffraction (XRD) at room temperature showed a pure tetragonal perovskite. The electrical response was studied by complex impedance spectroscopy over a broad frequency range (30 - 106 Hz) at different temperatures. The values of ac conductivity were fitted by Jonscher’s law σ(ω) = σDC + Aωn and supported by the correlated barrier hopping (CBH) mechanism. Complex impedance analysis confirmed the existence of an electrical relaxation in the compound. The dielectric constant and the dielectric loss decreased with the increase in frequency. This behavior can be explained by the presence of the Maxwell–Wagner type of polarization responsible for the electric conduction. The modulus plots were characterized by the Havriliak–Negami (H-N) and the empirical Kohlrausch–Williams–Watts (K.W.W.) functions. The Normalized plot of the imaginary part of modulus indicates that the dynamical processes are temperature independent.
关键词： Impedance spectroscopy,Sol-gel processes,Permittivity,X-ray diffraction,Conductivity
更新于2025-09-10 09:29:36
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Improvement of charge transport for hydrothermally synthesized Cd0.8Fe0.2S over co-precipitation method: A comparative study of structural, optical and magnetic properties
摘要： Here, we have elucidated the structural, optical, magnetic and electrical properties of Cd0.8Fe0.2S which is considered as diluted magnetic semiconductor (DMS). Cd0.8Fe0.2S materials were synthesized using co-precipitation (compound 1) and hydrothermal (compound 2) method. The particle size and the polycrystalline phase of the synthesized materials are significantly influenced by the synthesis procedures. Presence of anti-ferromagnetic coupling confirms the magnetic behavior of materials. The current-voltage (I-V) characteristics exhibit lower barrier height for the device based on compound 2 (0.59 eV) than the other device (0.64 eV). Furthermore, the 19 times enhanced mobility and lesser density of states near the Fermi level for the Al/compound 2/ITO configured device is enlightened by the space charge conduction mechanism. But, the interface resistances of the devices cannot be distinguished by the I-V characteristics. Therefore, we have tackled the problem by simulating the Nyquist plots obtained from impedance spectroscopy. We have fitted the Nyquist plots with the appropriate equivalent circuit and explained the mechanism of charge transport through the Schottky interface. The higher dc conductivity and lower relaxation time of diode fabricated by compound 2 confirm the outcomes obtained from I-V characteristics. The effect of particle size on charge transport was also analyzed.
关键词： Schottky diode characteristics,Diluted magnetic semiconductor,Chemical synthesis,Impedance spectroscopy
更新于2025-09-10 09:29:36
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Structural, Dielectric and Impedance Spectroscopic Studies on Fe Doped BaTiO <sub/>3</sub>
摘要： Compositions with x=0.03, 0.05 and 0.10 are synthesized in the system BaFexTi1–xO3 using conventional solid state reaction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). XRD patterns reveal the coexistence of tetragonal and hexagonal phases which are strongly affected by the level of Fe doping. The hexagonal phase increases with increasing x, being maximum for x=0.10. SEM images show the presence of agglomerated grains which increase in size with amount of Fe doping. SEM for x=0.10 shows mostly rod-like or rectangular grains indicating predominantly hexagonal phase. Dielectric and impedance measurements have been carried out in the frequency range 20 Hz-1 MHz as a function of temperature (300-650 K). The samples with x=0.03 and 0.05 exhibit diffuse phase transition. Using complex impedance analysis equivalent circuit models have been developed which represent the data well and successfully separate out the contributions of tetragonal phase, hexagonal phase, grain boundaries and electrodes.
关键词： Impedance spectroscopy,Fe doped BaTiO3,Dielectric response,Diffuse phase transition
更新于2025-09-09 09:28:46
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Hybrid and pristine polyalkylthiophene Langmuir-Schaefer films: Relationships of electrical impedance spectroscopy measurements, barrier properties and polymer nanostructure
摘要： Molecular organization in solid state plays a central role on organic devices performance. In this sense, a thorough investigation of thin films with application in organic electronics is imperative. This work addressed the fabrication and the morphological, optical and electrical characterization of Langmuir-Schaefer (LS) films of poly(3-hexylthiophene) (P3HT), pristine and mixed with stearic acid (SA), and their use as the active layer in organic Schottky diodes. The floating materials isotherms showed the SA molecules acting as a stabilizer for the P3HT in the Langmuir trough. Moreover, deposited P3HT:SA films present significant morphological changes, an improvement of the films overall structural ordering and a more effective charge transport within the active layer through electrical outcome. The alternating current measurements along with theoretical fitting, using equivalent electrical circuits, provided a good alternative to investigate the interfacial effects of the P3HT and P3HT:SA films deposited onto Al and Au electrodes.
关键词： Electrical impedance spectroscopy,Structure-property relations,Polythiophene,Langmuir-Schaefer,Thin films
更新于2025-09-09 09:28:46
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Dielectric, electrical and impedance study of single perovskite Pb(Ni1/3Mn1/3W1/3)O3
摘要： A multiferroic material Pb(Ni1/3Mn1/3W1/3)O3 with ferroelectric and ferromagnetic properties at room temperature is designed for multifunctional applications. A orthorhombic perovskite crystal structure has been assigned for the present perovskite according to the X-ray diffraction patterns. At 1 kHz, dielectric constant (er) increases from 1655 at 298 K to its ?rst maximum 3514 at 457 K referred as magnetic transition. The high values of er in the low frequency range show better dispersion, and with the increase in frequency, a gradual decrease in the er values was observed. The contribution of grain and/or electrode/interface effects in the resistive/capacitive properties was ascertained by the Nyquist plots. An equivalent circuit has been suggested consisting of resistive and capacitive components (R, C, Q) estimates the bulk (grain) and grain boundary resistance and capacitance. The activation energy was found to be greater than 0.2 eV, supporting the conduction mechanism due to hopping of charge carriers.
关键词： Solid-state reaction,Multiferroic material,Dielectric response,Electrochemical impedance spectroscopy,Ceramics
更新于2025-09-09 09:28:46
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Effect of Environmental Humidity in the Electrical Properties of Lead Halide Perovskites
摘要： In large quantities, water is detrimental to lead halide perovskite solar cells, mainly because of the decomposition of the perovskite layer. On the contrary, the presence of small quantities of water has been observed to play a key role in the crystallization of the perovskite and in the performance of the corresponding devices. However, it is still under debate the exact role of water during the operation of perovskite solar cells. In this paper, impedance spectroscopy is used to analyze the changes produced by environmental humidity in the electronic properties of methylammonium lead triiodide perovskite. Our results show that water absorbed from environmental humidity induces a huge increase in the capacitance of this material. This capacitance can reach values as large as the accumulation capacitance found in devices based in perovskite, which is the responsible of the characteristic large hysteresis observed between forward and reverse J-V curves. In parallel to this outstanding rise of the capacitance, water absorption produces a significant rise of the conductivity, in agreement with previous reports in the literature. Activation energy of 0.52 eV is found for electronic transport, a value in line with activation energy of ionic transport found in literature, what suggests ambipolar diffusion as the transport mechanism that links these two phenomena.
关键词： impedance spectroscopy,environmental humidity,electrical properties,lead halide perovskites,capacitance,conductivity
更新于2025-09-09 09:28:46
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[IEEE 2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro) - Bento Gon?alves, Brazil (2018.8.27-2018.8.31)] 2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro) - Characterization by GISAXS and Electrochemical Impedance Spectroscopy of porous oxide films
摘要： Porous oxide films were deposited by reactive sputtering. Some films received UV cures and/or a Si cap. The FTIR analyses show that the deposited films were very hydrophilic. Standard ellipsometric porosimetry was not able to determine porosity nor pore size. With GISAXS, the porosity of different films was determined (approximately 13%) and the (mostly spherical pores with a radius of approximately 5 nm). Electrochemical Impedance Spectroscopy completed the pore analysis, indicating mostly open porosity. These techniques were sufficiently sensitive to show that the Si cap closed the pores somewhat while the UV cure increased the porosity.
关键词： porous oxide,electrochemical impedance spectroscopy,GISAXS
更新于2025-09-09 09:28:46
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Detection of abnormality occurring over the whole cable length by frequency domain reflectometry
摘要： In previous papers, the authors reported that a combination of frequency domain reflectometry and inverse fast Fourier transform can locate the position of occurrence of degradation or abnormality in a polymer-insulated electric cable. This paper demonstrates that this method is also applicable even if the degradation or abnormality occurs uniformly over the entire cable length.
关键词： frequency domain reflectometry,broadband impedance spectroscopy,fault location,characteristic impedance,aging
更新于2025-09-04 15:30:14