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1.
Malgorzata Adamczyk Lucjan Kozielski Dariusz Bochenek Daria Radoszewska Marian Pawełczyk Beata Wodecka-Duś 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(2):37
In recent years a wide range of Aurivillius layered materials have been introduced. These novel materials are produced in many various forms such as fibers, thin films as well as bulk by using a number of processing routes. As advanced materials they are they have many interesting properties which include a number of useful electrical properties related to separated grain and grain boundary conductivity, impedance, activation energies, etc. In this paper these properties are described and discussed in detail. The electrical properties of the vanadium doped BaBi2Nb2O9 ceramic was measured over a wide range of temperatures by impedance spectroscopy (IS). The separated grain activation energy, calculated from Arrhenius characteristics at temperatures between room temperature and 600 °C, was 1 eV for 0 at.% of vanadium dopant and 1.2 eV for 10 at.%, whereas the activation energies in the grain boundary region were 0.97 and 1.15 eV, respectively. The obtained results suggest the significant role of vanadium dopant, causing ordering the crystalline structure. 相似文献
2.
M. Kodu T. Avarmaa H. Mändar R. Jaaniso 《Applied Physics A: Materials Science & Processing》2008,93(3):801-805
This paper reports the first results obtained on monobarium gallate thin films grown on silicon and platinum coated substrates
by pulsed laser deposition. The influence of oxygen background pressure and substrate (or post-annealing) temperature on the
film properties was studied. The films were characterized by XRD, RHEED, AFM, photoelectron and electrical impedance spectroscopy.
The structure analysis showed that the films crystallized into a hexagonal phase, most probably into (metastable) α-BaGa2O4. Depending on deposition conditions, films with different (from nearly epitaxial to polycrystalline) textures were obtained. 相似文献
3.
Bi3.25Pr0.75Ti3O12 (BPT) ferroelectric thin films have been prepared by chemical solution deposition on platinized Si substrates. Well-crystallized BPT films can be achieved by 600 °C rapid thermal annealing. The film surface is smooth and crack-free, composed of uniform spherical grains around 90–100 nm in diameter. The electrical properties of Pt/BPT/Pt thin film capacitors were characterized by hysteresis and impedance measurements. The remanent polarization of 700 °C annealed BPT films is around 20 C/cm2 at 120-kV/cm stimulus field. The dielectric constant is around 380 at 10 kHz, 100-mV amplitude. The remanent polarization of BPT film showed a slight reduction, 10% of its original value, after 2.8×109 cycles, while a 30% reduction of non-volatile polarization was observed. PACS 81.15.-z; 77.55.+f; 77.22.Gm 相似文献
4.
The lithium dihydrogen phosphate LiH2PO4 has been investigated by X-ray powder diffraction, scanning electron microscopy (SEM), and electrical impedance spectroscopy. The Rietveld refinements based on the XRD patterns show that the compound is crystallized in the orthorhombic system with Pna21 space group, and the refined unit cell parameters are a = 6.2428 Å, b = 7.6445 Å, and c = 6.873 Å. The electrical properties were studied using complex impedance spectroscopy as a function of frequency (104–107 Hz) at various temperatures (300–400 K). The Nyquist plots are well fitted to an equivalent circuit consisting of a series of combination of grains and inhomogeneous electrode surface effect. The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. Moreover, the near value of the activation energies obtained from the equivalent circuit and analysis of M″ confirms that the transport is through ion hopping mechanism dominated by the motion of the proton in the structure of the investigated material. 相似文献
5.
The Ac electrical conductivity and the dielectric relaxation properties of the [(C3H7)4N]2Cd2Cl6 polycrystalline sample have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies
and temperatures, 209 Hz–5 MHz and 361–418 K, respectively. The purpose is to make a difference between the electrical and
dielectric properties of the polycrystalline sample and single crystal. Besides, a detailed analysis of the impedance spectrum
suggests that the electrical properties of the material are strongly temperature-dependent. Plots of (Z" versus Z') are well
fitted to an equivalent circuit model consisting of a series combination of grains and grains boundary elements. Moreover,
the temperature dependence of the electrical conductivity in the different phases follows the Arrhenius law and the frequency
dependence of σ (ω) follows the Jonscher’s universal dynamic law. Furthermore, the modulus plots can be characterized by full
width at half height or in terms of a nonexperiential decay function φ(t) = exp(t/t)β. Finally, the imaginary part of the permittivity constant is analyzed with the Cole–Cole formalism. 相似文献
6.
D.Y. Wang Y.L. Cheng J. Wang X.Y. Zhou H.L.W. Chan C.L. Choy 《Applied Physics A: Materials Science & Processing》2005,81(8):1607-1611
Lead lanthanum zirconate titanate (PLZT 9/65/35) thin films were deposited on MgO (00l) substrates using a sol–gel method. X-ray diffraction measurements reveal that the PLZT film has epitaxially grown on the substrate and has a pure perovskite structure. Using gold interdigital electrodes the in-plane dielectric properties of the films were measured as a function of frequency (1 kHz to 10 GHz), temperature (293–435 K) and dc electric field (0–20 MV/m). The PLZT (9/65/35) thin film exhibits a diffuse phase transition, which indicates a relaxor-like ferroelectric behavior. The temperature dependence of the characteristic relaxation time was analyzed in terms of the Vögel–Fulcher relation. The relative permittivity has a high tunability of 34–42% in the frequency range of 10 MHz to 1 GHz. 相似文献
7.
The Rb3(HSeO4)2.5(H2PO4)0.5 compound was prepared and its thermal behavior and electric properties were investigated. The thermogravimetry (TGA) analysis and the differential scanning calorimetric (DSC) show the presence of a structural phase transition of the title compounds at 374 K which is confirmed by the variation of fp and σdc as a function of temperature. The complex impedance of the Rb3(HSeO4)2.5(H2PO4)0.5 compound has been investigated in the temperature range of 295–453 K and in the frequency range 209 Hz–1 MHz. The impedance plots show semicircle arcs at different temperatures, and an electrical equivalent circuit has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance Rp and constant phase elements CPE1 in series with fractal capacity CPE2. The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. The conductivity dc follows the Arrhenius relation. The near value of activation energies obtained from the analysis of modulus, conductivity data, and circuit equivalent confirm that the transport is through the ion hopping mechanism, dominated by the motion of the H+ proton in the structure of the investigated materials. 相似文献
8.
P. Myllymäki M. Roeckerath M. Putkonen S. Lenk J. Schubert L. Niinistö S. Mantl 《Applied Physics A: Materials Science & Processing》2007,88(4):633-637
Gadolinium scandium oxide (Gd-scandate, GdScO3) thin films were grown by atomic layer deposition (ALD) from β-diketonate precursors M(thd)3 (M=Gd, Sc; thd=2,2,6,6-tetramethyl-3,5-heptanedionato) and ozone. The deposition parameters were optimized to produce films with the stoichiometric 1:1 metal ratio and a series of samples with nominal thicknesses of 5, 10, 15, and 20 nm were prepared. At 300 °C the metal precursor pulsing ratio Gd:Sc=5:6 yielded amorphous stoichiometric films and a growth rate of 0.21 Å/cycle. The films stayed amorphous up to 900 °C. The surface was probed with an AFM and the rms roughness was found to be 0.3 nm for the 5–20 nm thick films. The electrical properties of the as-deposited films proved to be very promising, with a dielectric constant of ~22 and leakage current density of 340 μA/cm2, measured at -2 V. 相似文献
9.
S. Palanichamy J. Raj Mohamed P. S. Satheesh Kumar S. Pandiarajan L. Amalraj 《Optical and Quantum Electronics》2018,50(9):346
Undoped SnO2 thin films have been deposited on amorphous glass substrates with different precursor solution volume (10, 15, 20 and 25 ml) using simple and cost-effective nebulized spray pyrolysis technique. The influence of precursor solution on structural, optical, photoluminescence and electrical properties had been studied. The X-ray diffraction spectra prove the polycrystalline nature of SnO2 with tetragonal structure. All the films show a preferred growth orientation along (110) diffraction plane. The average transmittance of SnO2 thin films varied between 82 and 75% in the visible as well as IR region. The band gap energy decreases from 3.74 to 3.64 eV corresponding to direct transitions with the precursor solution volume had increased from 10 to 20 ml and then increased as 3.72 eV for 25 ml. SEM pictures demonstrated polyhedrons like grains. EDX confirmed the existence of Sn and O elements in all the prepared SnO2 thin films. Photoluminescence spectra at room temperature revealed that the four emission bands in all the samples such as sharp dominant peak at 361 nm with shoulder peak at 377 nm (UV region), a broad and low intensity peak at 492 nm (blue region) and 519 nm (green region). The electrical parameters were examined by Hall effect measurements, which demonstrated that the film prepared at 20 ml precursor solution volume possess minimum resistivity 2.76?×?10?3 Ω-cm with activation energy 0.10 eV and maximum figure of merit 1.54?×?10?2 (Ω/sq)?1. 相似文献
10.
D. Do S. S. Kim S. W. Yi J. W. Kim 《Applied Physics A: Materials Science & Processing》2009,94(3):697-701
Ferroelectric and dielectric properties of bilayered ferroelectric thin films, SrBi4Ti4O15 grown on Bi4Ti3O12, were investigated. The thin films were annealed at 700°C under oxygen atmosphere. The bilayered thin films were prepared
on a Pt(111)/Ti/SiO2/Si substrate by a chemical solution deposition method. The dielectric constant and dielectric loss of the bilayered thin
films were 645 and 0.09, respectively, at 100 kHz. The value of remnant polarization (2P
r) measured from the ferroelectric thin film capacitors was 60.5 μC/cm2 at electric field of 200 kV/cm. The remnant polarization was reduced by 22% of the initial value after 1010 switching cycles. The results showed that the ferroelectric and dielectric properties of the SrBi4Ti4O15 on Bi4Ti3O12 ferroelectric thin films were better than those of the SrBi4Ti4O15 grown on a Pt-coated Si substrate suggesting that the improved properties may be due to the different nucleation and growth
kinetics of SrBi4Ti4O15 on the c-axis-oriented Bi4Ti3O12 layer or on the Pt-coated Si substrate. 相似文献
11.
Proton-conducting solid polymer blend electrolytes based on methylcellulose-polyvinyl alcohol:ammonium nitrate (MC-PVA:NH4NO3) were prepared by the solution cast technique. The structural and electrical properties of the samples were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electrical impedance (EI) spectroscopy. The shifting and change in the intensity of FTIR bands of the electrolyte samples confirm the complex formation between the MC-PVA polymer blend and the NH4NO3 added salt. The observed broadening in the XRD pattern of the doped samples reveals the increase of the amorphous fraction of polymer electrolyte samples. The increase in electrical conductivity of polymer electrolyte samples with increasing salt concentration attributed to the formation of charge-transfer complexes, and to increase in the amorphous domains. A maximum ionic conductivity of about 7.39 × 10?5 S cm?1 was achieved at room temperature for the sample incorporating 20 wt% of NH4NO3. The DC conductivity of the present polymer system exhibits Arrhenius-type dependence with temperature. The decrease in the values of activation energies with increasing salt concentration indicates the ease mobility of ions. The decrease in dielectric constant with increasing frequency was observed at all temperatures. Optical properties such as absorption edge, optical band gap, and tail of localized state were estimated for polymer blend and their electrolyte films. It was found that the optical band gap values shifted towards lower photon energy from 6.06 to 4.75 eV by altering the NH4NO3 salt content. 相似文献
12.
I.?A.?Santos R.?G.?Mendes J.?A.?Eiras J.?de?Los?S.?Guerra E.?B.?Araújo 《Applied Physics A: Materials Science & Processing》2009,95(3):757-760
The dielectric properties of Sr0.75Ba0.25Nb2O6 relaxor ferroelectric thin films were carefully analyzed. In contrast to bulk samples which present three distinct dielectric
relaxation phenomena Sr0.75Ba0.25Nb2O6 thin films present only two of them. The suppression of the third anomaly can be mainly attributed to the narrow grain size
distribution of nanograins and weak tensile strains imposed to the film from the substrate. The whole set of results point
to the interpretation of a dielectric response characteristic of mesoscopic structure, which is composed of clusters and nanodomains. 相似文献
13.
Soumya R. Deo Ajaya K. Singh Lata Deshmukh Narendra Pratap Singh Mariya P. Aleksandrova 《Journal of fluorescence》2016,26(2):459-469
The thin films of CdS1-xSex were successfully deposited over glass substrates by chemical bath deposition technique. Cadmium acetate, thiourea and sodium selenosulfate were used as source materials for Cd2+, S2? and Se2? ions, while 2-mercaptoethanol was used as capping agent. The various deposition conditions such as precursor concentration, deposition temperature, pH and deposition time were optimized for the deposition of CdS1-xSex thin films of good quality and the films were annealed at 200° and 300 °C. The structural, morphological, chemical and optical properties were examined by various characterization techniques and discussed in detail. The optical band gap of CdS1-xSex thin film samples were estimated and found in the range from 2.11 to 1.79 eV for as-deposited and annealed thin films. 相似文献
14.
Microstructures and impedance characteristics of chemical-solution-derived Bi3.15Nd0.85Ti3O12 thin films were studied as functions of temperature. A dielectric anomaly was found at around 450°C, corresponding to the
paraelectric to ferroelectric transition. Via complex impedance studies, grain and grain boundary contributions to the impedance
were separated. The resistance of grain and grain boundaries is found governed by the same kind of space charge with an activation
energy around 1.1 eV, close to that of oxygen vacancies in perovskite ferroelectrics. The low temperature ac conductance of
BNdT thin films shows a frequency dispersion, which can also be ascribed to space charges mainly due to oxygen vacancies.
The results were compared with SrBi2Ta2O9 in terms of oxygen vacancy conductivity. 相似文献
15.
Zineb Essalhi Bouchaib Hartiti Abderrazak Lfakir Bernabé Mari Philippe Thevenin 《Optical and Quantum Electronics》2017,49(9):301
In this research, Cu-doped TiO2 thin films have been successfully deposited onto a glass substrate by Sol–gel technique using dip coating method. The films were annealed at different annealing temperatures (400–500 °C) for 1 h. The structural, optical and electrical properties of the films were investigated and compared using X-ray Diffraction, UV–visible spectrophotometer and 4-point probe method. Optical analysis by mean transmittance T(λ) and absorption A(λ) measurements in the wavelength range between 300 to 800 nm allow us to determine the indirect band gap energy. DRX analysis of our thin films of TiO2:Cu shows that the intensities of the line characteristic of anatase phase increasing in function of the temperature. 相似文献
16.
We report a method for producing BST films with consistently high figures of merit for tunable microwave applications. (Ba1-x,Srx)TiO3 (x=0.4, target doped with 1% W) thin films have been deposited using pulsed laser deposition onto (100)MgO substrates. Films were deposited at low partial pressures of oxygen (50 mTorr) at a substrate temperature of 730 °C. An analysis of the X-ray diffraction data indicates that the film has a nearly cubic structure, with the overall lattice parameter enlarged relative to the bulk material due to the presence of oxygen vacancies. A post-deposition anneal of the film in flowing oxygen (1000 °C for 6 h) resulted in a decrease in the lattice parameter while remaining nearly cubic. An analysis of the microwave dielectric properties (1–20 GHz) showed that the annealed film exhibited about 10% tunability for an applied bias field of 67 kV/cm with a dielectric Q(1/tan)>600. Investigation of the films by time-resolved confocal scanning optical microscopy (CSOM) has revealed that there is an out-of-plane polarization at zero applied field (EDC=0). The results show that the paraelectric response is relatively insensitive to applied field, while the ferroelectric response is correlated with the growth of in-plane nanodomains. We find these results to be consistent with a large number of studies that show that strain-relief is of paramount importance if ferroelectric films are to be developed as microwave circuit components. PACS 81.15.Fg; 85.50.-n 相似文献
17.
Effect of substitution group on dielectric properties of 4H-pyrano [3,2-c] quinoline derivatives thin films
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The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-(3-phenoxyphenyl)-5,6-dihydro-4H-pyrano[3, 2-c]quinoline-3-carbonitrile(Ph-HPQ) and 2-amino-4-(2-chlorophenyl)-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3, 2-c] quinoline-3-carbonitrile(Ch-HPQ) thin films were determined in the frequency range of 0.5 k Hz–5 MHz and the temperature range of 290–443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping(CBH) mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-HPQ and Ch-HPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-HPQ films have higher impedance than the Ph-HPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-HPQ has higher dielectric constants than the Ch-HPQ. 相似文献
18.
In this work platinum thin films deposited by sputtering and electrochemical methods were characterized through physical and electrochemical analysis. The as-grown platinum thin films were characterized through X-ray diffraction (XRD), atomic force microscopy (AFM); scanning electronic microscopy (SEM) and through electrochemical impedance spectroscopy (EIS) measurements. Structural studies indicated that platinum thin films were polycrystalline. Morphological characteristics were significantly affected by the substrate type and synthesis method. Finally the EIS analysis indicated that platinum films were electrochemically stable and present both low resistance of charge transfer and low series resistance; the equivalent circuit of platinum interface has been proposed. 相似文献
19.
İ. A. Kariper 《Optical Review》2016,23(3):401-408
PbI2 thin films were deposited on glass substrates via chemical bath deposition. The characteristics of PbI2 thin films were examined through their structural and optical properties. X-ray diffraction spectra showed the presence of rhombohedral structure and atom planes were subject to change with the pH of the bath. Scanning electron microscope indicated uniform distribution of grains. Optical properties were examined via UV–VIS; optical spectrum of the thin films was measured at the range of 200–1100 nm wavelength. Optimum pH levels for producing thin films were found to be pH 4–5. It has been observed that transmission and optical band gap (E g) increased with the pH of the bath, which varied between 66–95 and 2.24–2.50 %, respectively; on the other hand film thickness of PbI2 thin films was decreased with the pH of the bath. Energy-dispersive X-ray spectroscopy analysis were in accordance with theoretical value of PbI2 at pH = 4 and 5. Refractive index was negatively correlated with pH of the chemical bath; it has been calculated as 1.97, 1.40, 1.29 and 1.24 for the films produced at pH 2, 3, 4 and 5. The results of the study were compared with similar studies in the literature. 相似文献
20.
L. N. Patro N. Ravi Chandra Raju S. R. Meher K. Kamala Bharathi 《Applied Physics A: Materials Science & Processing》2013,112(3):727-732
This article presents the results on the growth and characterization of BaSnF4 thin films on glass substrates prepared by pulsed laser deposition technique. The structural results of BaSnF4 thin film carried out by glancing angle X-ray diffraction technique indicates the formation of the film with similar structure (tetragonal, P4/nmm) to the bulk target material. The absorption coefficient and band gap of the film is determined by suitable analysis of the transmittance spectra. The transport properties of the thin films are studied using impedance spectroscopy in the temperature range of 323–573 K. The frequency-dependent imaginary part of impedance plot shows that the conductivity relaxation is non-Debye in nature. The scaling behavior of the imaginary part of impedance at various frequencies indicates temperature-independent relaxation behavior. 相似文献