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Guohua Dong Guoqiang Tan Wenlong Liu Ao Xia Huijun Ren 《Journal of Materials Science: Materials in Electronics》2013,24(11):4445-4451
BiFeO3 and Bi0.92Tb0.08Fe1?xCrxO3 (BTFCO) thin films were successfully prepared on SnO2: F (FTO)/glass substrates by a chemical solution deposition technique. The influences of Tb and Cr co-doping on the structure, the leakage current, charge defects, the dielectric and the ferroelectric properties of the BTFCO thin films were investigated systematically. X-ray diffraction and Raman spectra results clearly reveal the structural distortion in the co-doped thin films. The X-ray photoelectron spectroscopy measurements show the absence of Fe2+ ions indicating the suppression of oxygen vacancies due to Tb and Cr co-doping. The electrical conduction mechanism of the BTFCO thin film is dominated by the Ohmic conduction in the low resistance state and trap-controlled space charged limited current in the high resistance state. With 8 %Tb and 1 %Cr co-doping, the film exhibits the superior ferroelectric (2P r = 105 μC/cm2) and dielectric properties. All the results show the film is very promising in the practical application. 相似文献
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Wenlong Liu Guoqiang Tan Xu Xue Guohua Dong Huijun Ren 《Journal of Materials Science: Materials in Electronics》2013,24(12):4827-4832
Pure BiFeO3 (BFO) and (Mn, Cr) co-doped BiFe0.96?yMn0.04CryO3 thin films were prepared on FTO/glass (SnO2:F) substrates by using a sol–gel method. The effects of (Mn, Cr) co-doped on the microstructure and electric properties of the BiFeO3 thin films were studied. The result indicates that the co-doped BiFe0.94Mn0.04Cr0.02O3 (BFMCO) thin film has a structure transition and better ferroelectric properties compared with the pure BFO thin film. The Rietveld refined XRD patterns of BFO and BFMCO thin films conform the trigonal (R3c:H) and the biphasic (R3c:H + R3m:R) structure, respectively. The co-existence of two phases and the mixed valences of Cr3+/6+ and Mn2+/3+, which apparently improves the electric properties of the (Mn, Cr) co-doped BFMCO thin films. The remnant polarization (P r) of the BFMCO thin film was 93.58 μC/cm2 at 1 kHz in the applied electric field of 636 kV/cm. At an applied electric field of 100 kV/cm, the leakage current density of (Mn, Cr) co-doped BFMCO thin film is 6.2 × 10?6 A/cm2. It is about three orders much lower than that of the BFO thin film (1.43 × 10?3 A/cm2). 相似文献
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Bi0.95Nd0.05Fe1–xCrxO3 (x = 0, 0.01, 0.03, 0.05) samples are synthesised by the sol-gel method. The variation in structure, magnetisation, electrical and photocatalytic properties by Cr doping at Fe site in Bi0.95Nd0.05FeO3 samples is analysed. X-ray diffraction pattern confirms the formation of rhombohedral structure in all the samples. The crystallite size is calculated using the Scherrer relation and found to be in nanometre range. Kubelka-Munk theory is used to determine the direct band gap of the samples from reflectance spectra. The saturation magnetisation is found to enhance the concentration of chromium. Arrott-Belov-Kouvel plot confirms the ferromagnetic nature in the samples. The leakage mechanisms are studied to understand the influence of Cr concentration on the BFO. A good correlation exists between the leakage current and ferroelectric behaviour. Photocatalytic tests show degradation of methylene blue dye in the presence of H2O2. A drastic decrease in photocatalytic activity is observed with the concentration of Cr. 相似文献
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Naganuma H Inoue Y Okamura S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(5):1046-1050
A multiferroic BiFeO(3) film was fabricated on a Pt/Ti/SiO(3)/Si(100) substrate by a chemical solution deposition (CSD) method, and this was followed by postdeposition annealing at 923 K for 10 min in air. X-ray diffraction analysis indicated the formation of the polycrystalline single phase of the BiFeO(3) film. A high remanent polarization of 89 microC/cm(2) was observed at 90 K together with a relatively low electric coercive field of 0.32 MV/cm, although the ferroelectric hysteresis loops could not be observed at room temperature due to a high leakage current density. The temperature dependence of the ferroelectric hysteresis loops indicated that these hysteresis loops lose their shape above 165 K, and the nominal remanent polarization drastically increased due to the leakage current. Magnetic measurements indicated that the saturation magnetization was less than 1 emu/cm(3) at room temperature and increased to approximately 2 emu/cm(3) at 100 K, although the spontaneous magnetization could not appear. The magnetization curves of polycrystalline BiFeO3 film were nonlinear at both temperatures, which is different with BiFeO3 single crystal. 相似文献
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Wenlong Liu Guoqiang Tan Guohua Dong Xia Yan Wei Ye Huijun Ren Ao Xia 《Journal of Materials Science: Materials in Electronics》2014,25(2):723-729
Pure BiFeO3 (BFO) and Mn-doped BiFe1?yMnyO3 thin films were prepared on FTO/glass (SnO2: F) substrates by using a sol–gel method. The effects of Mn-doping on the structure and electric properties of the BFO thin films were studied. The X-ray diffraction (XRD) analysis reveals a structure transition in the Mn-doped BiFe0.96Mn0.04O3 (BFMO) thin film. The Rietveld refined XRD patterns conform the trigonal (R3c: H) and tetragonal (P422) symmetry for the BFO and BFMO thin films, respectively. The structure transition and the mixed valences of Mn ions substantially improve the electric properties of the BFMO thin film. The remnant polarization (P r) of the BFMO thin film was 105.86 μC/cm2 at 1 kHz in the applied electric field of 865 kV/cm. At an applied electric field of 150 kV/cm, the leakage current density of BFMO thin film is 1.42 × 10?5 A/cm2. It is about two orders of magnitude lower than that of the pure BFO thin film (1.25 × 10?3 A/cm2). And the enhanced saturated magnetization of the BFMO thin film is 4.45 emu/cm3. 相似文献
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《Thin solid films》1986,139(1):33-40
Thin silver films (thickness, 12.5–160 nm) were evaporated under ultrahigh vacuum conditions onto clean glass substrates (substrate temperature, 225 K). During the growth process a large number of lattice defects were incorporated (condensation rate, 0.2 and 0.01 nm s-1). The films were subjected to heat treatment (constant heating rate, 0.1 K s-1) and the variation in the electrical resistance was measured as a function of temperature. Using Vand's theory the initial lattice distortion energy spectra of the films were determined from the resistance-temperature data. The lattice distortion energy function has maximum values. While the number of distortions with a decay energy of about 0.8 eV increases rapidly with decreasing film thickness, the number of distortions with a decay energy of about 0.93 eV varies only slightly. 相似文献
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Renoud R Borderon C Gundel HW 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(9):1975-1980
In this study, the real and imaginary parts of the complex permittivity of lead zirconate titanate ferroelectric thin films are studied in the frequency range of 100 Hz to 100 MHz. The permittivity is well fitted by the Cole-Cole model. The variation of the relaxation time with the temperature is described by the Arrhenius law and an activation energy of 0.38 eV is found. Because of its nonlinear character, the dielectric response of the ferroelectric sample depends on the amplitude of the applied ac electric field. The permittivity is composed of three different contributions: the first is due to intrinsic lattice, the second is due to domain wall vibrations, and the third is due to domain wall jumps between pinning centers. This last contribution depends on the electric field, so it is important to control the field amplitude to obtain the desired values of permittivity and tunability. 相似文献
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The applicability of various convergent beam electron diffraction (CBED) methods to the polarity determination of LiNbO3 crystals in the space group R3c was examined. We show that the method of zone-axis CBED combined with dynamical simulation is applicable to the polarity determination of LiNbO3. The effects of the zone axis, the specimen thickness and the displacement of the homopolar atom on the polarity determination were studied. This method was also successfully applied to the polarity determination of a multiferroic BiFeO3 film deposited on a (111)Pt/TiO2/SiO2/Si substrate by pulsed laser deposition. It shows that about 30% of the grains in the BiFeO3 film are grown along the positive polar direction. 相似文献
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Naganuma H Okubo T Kamishima K Kakizaki K Hiratsuka N Okamura S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(5):1051-1055
BiFeO(3)-based composite films were fabricated onto the Pt/Ti/SiO(2)/Si(100) substrates by a chemical solution deposition (CSD) method using the precursor solutions with various excess iron composition followed by annealing at 923 K for 30 minutes under oxygen gas flow. Coexistence of spontaneous magnetization and remanent polarization could be obtained in the BiFeO(3)-based composite films with high excess iron composition. The remanent magnetization of almost 20 emu/cm(3) and the magnetic coercive field of 1.5 kOe were obtained at the iron composition ratio of Fe/Bi = 1.25. In this specimen, the remanent polarization at 90 K was approximately 10 microC/cm(2) at the electric field of 1500 kV/cm. Structural analysis suggested that the remanent polarization has a possibility to increase by suppressing the formation of the secondary phases of Bi(2)Fe(4)O(9) and alpha-Fe(2)O(3), these are the nonferroelectric material as well as antiferromagnetic phase. 相似文献
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《Materials Letters》2005,59(19-20):2583-2587
Ferroelectric Bi3.33Sm0.67Ti3O12 (BSmT) thin films have been fabricated on Pt/TiOx/SiO2/Si substrates by pulsed laser deposition and their structural and ferroelectric properties have been characterized. The structure and morphology of the films were characterized using X-ray diffraction, atomic force microscopy, and scanning electron microscopy. About 520-nm-thick BSmT films grown at 700 °C exhibit excellent ferroelectric properties with a remanent polarization (2Pr) of 41.8 μC/cm2 and coercive field (Ec) of 91.0 kV/cm, at an applied electric field of 385 kV/cm. The leakage current density was 2.0 × 10− 6 A/cm2 at a dc electric field of 200 kV/cm. The films also demonstrate fatigue-free behavior up to 109 read/write switching cycles with 1 MHz bipolar pulses at an electric field of 192 kV/cm. As a result, Sm-substituted bismuth titanate films with good ferroelectric properties and excellent fatigue resistance are useful candidates for ferroelectric memory applications. 相似文献