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1.
Dielectric relaxations of Tb0.91Yb1.38Bi0.71Fe5O12 ceramics were investigated. A Debye-type relaxation was observed in the temperature range of 125-620 K with an activation energy of 0.29 eV. This activation energy agreed well with that of carriers hopping between Fe2+ and Fe3+, indicating that this relaxation might be a dipolar-type relaxation associated with the hopping carries. A high relaxorlike dielectric peak with a very strong frequency dispersion in the high temperature range of 400-620 K might be originate from the oxygen vacancies related dielectric relaxation. 相似文献
2.
Effects of O2/Ar ratio and annealing temperature on electrical properties of Ta2O5 film prepared by magnetron sputtering
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The effects of the oxygen-argon ratio on electric properties of Ta2O5 film prepared by radio-frequency magnetron sputtering were investigated.The Ta2O5 partially transforms from the amorphous phase into the crystal phase when annealing temperatures are 800℃ or higher.The lattice constant of Ta2O5 decreases with the increase of the O2/Ar ratio,which indicates that oxygen gas in the working gas mixture contributes to reducing the density of oxygen vacancies during the deposition process.For the films deposited in working gas mixtures with different O2/Ar ratios and subsequently annealed at 700℃,the effective dielectric constant is increased from 14.7 to 18.4 with the increase of the O2/Ar ratio from 0 to 1.Considering the presence of an SiO2 layer between the film and the silicon substrate,the optimal dielectric constant of Ta2O5 film was estimated to be 31.Oxygen gas in the working gas mixture contributes to reducing the density of oxygen vacancies,and the oxygen vacancy density and leakage current of Ta2O5 film both decrease with the increase of the O2/Ar ratio.The leakage current decreases after annealing treatment and it is minimized at 700℃.However,when the annealing temperature is 800℃ or higher,it increases slightly,which results from the partially crystallized Ta2O5 layer containing defects such as grain boundaries and vacancies. 相似文献
3.
Due to the fault of the first author, this article entitled “The coexistence of ferroelectricity and ferromagnetism in Mn-doped BaTiO3 thin films”, published in “Chinese Physics B”, 2011,Vol.20, Issue 12, Article No. 127701, has been found to copy from the article entitled“Decisive role of oxygen vacancy in ferroelectric versus ferromagnetic Mn-doped BaTiO3 thin films”, published in “Journal of Applied Physics”, 2011,Vol.109, Issue 8, article No. 084105.
So the above article in “Chinese Physics B” has been withdrawn from the publication.< 相似文献
4.
采用Sol-Gel工艺低温制备了Si基Bi3.25La0.75Ti3O12铁电薄膜.研究了退火温度对薄膜微观结构、介电特性与铁电性能的影响.500℃退火处理的Bi3.25La0.75Ti3O12薄膜未能充分晶化,晶粒细小且有非晶团聚,介电与铁电性能均较差.高于550℃退火处理的Bi3.25La0.75
关键词:
铁电薄膜
3.25La0.75Ti3O12')" href="#">Bi3.25La0.75Ti3O12
Sol-Gel工艺 相似文献
5.
Hongwei Chen Chuanren Yang Jihua Zhang Bo Wang Hong Ji 《Applied Surface Science》2009,255(8):4585-4589
BaZr0.1Ti0.9O3 and BaZr0.2Ti0.8O3 (BZT) thin films were deposited on Pt/Ti/LaAlO3 (1 0 0) substrates by radio-frequency magnetron sputtering, respectively. The films were further annealed at 800 °C for 30 min in oxygen. X-ray diffraction θ-2θ and Φ-scans showed that BaZr0.1Ti0.9O3 films displayed a highly (h 0 0) preferred orientation and a good cube-on-cube epitaxial growth on the LaAlO3 (1 0 0) substrate, while there are no obvious preferential orientation in BaZr0.2Ti0.8O3 thin films. The BaZr0.1Ti0.9O3 films possess larger grain size, higher dielectric constant, larger tunability, larger remanent polarization and coercive electric field than that of BaZr0.2Ti0.8O3 films. Whereas, BaZr0.1Ti0.9O3 films have larger dielectric losses and leakage current density. The results suggest that Zr4+ ion can decrease dielectric constant and restrain non-linearity. Moreover, the enhancement in dielectric properties of BaZr0.1Ti0.9O3 films may be attributed to (1 0 0) preferred orientation. 相似文献
6.
The effect of a small amount Fe2O3 (0.1-2 mol%) doping on the electrical properties of (Na0.5K0.5)0.96Li0.04Nb0.86Ta0.1Sb0.04O3 (NKLNTS) ceramics was investigated. It was found that the B-site substitution of Fe3+ does not change the crystal structure within the studied doping level and all modified ceramics have a pure tetragonal perovskite structure at room temperature. The addition of Fe2O3 can promote the sintering of NKLNTS ceramics, and simultaneously cause the grain growth so that Fe3+-doped NKLNTS compositions show degraded densification at higher doping level. Furthermore, the dielectric properties of the NKLNTS ceramics do not show a significant change by Fe2O3 doping. However, the addition of Fe2O3 was found to have a significant influence on the electric fatigue resistance and the durability against water. The presence of oxygen vacancies caused by the replacement of Fe3+ for B-site ions makes the NKLNTS ceramics harder. 相似文献
7.
Ba(Ti0.3Fe0.7)O3 ceramic was prepared by solid-state reaction and post-annealed in vacuum and oxygen, respectively. The as-prepared and annealed samples are all single-phase, crystallizing in a 6H-BaTiO3-type hexagonal perovskite structure. Room-temperature ferromagnetism is exhibited in all ceramics. For the as-prepared sample, the super-exchange interactions of Fe3+ in different occupational sites (pentahedral and octahedral sites) are expected to produce the ferromagnetism observed. After annealing in vacuum, the magnetization is reduced while the exchange mechanism remains unchanged. On the contrary, O2 annealing can effectively enhance the magnetization due to the presence of Fe4+, an unusual valence for iron. The simultaneous presence of Fe3+ and Fe4+ allows new exchange mechanism responsible for the ferromagnetic interaction. The exchange couplings of Fe ions with mixed valences (Fe3+ and Fe4+) determine the magnetic behavior. 相似文献
8.
Annealing effects on the structure and electrical characteristics of amorphous Er2O3 films
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Amorphous Er 2 O 3 films are deposited on Si (001) substrates by using reactive evaporation.This paper reports the evolution of the structure,morphology and electrical characteristics with annealing temperatures in an oxygen ambience.X-ray diffraction and high resolution transimission electron microscopy measurement show that the films remain amorphous even after annealing at 700 C.The capacitance in the accumulation region of Er 2 O 3 films annealed at 450 C is higher than that of as-deposited films and films annealed at other temperatures.An Er 2 O 3 /ErO x /SiO x /Si structure model is proposed to explain the results.The annealed films also exhibit a low leakage current density (around 1.38 × 10 4 A/cm 2 at a bias of 1 V) due to the evolution of morphology and composition of the films after they are annealed. 相似文献
9.
The CaCu3Ti4O12/SiO2/CaCu3Ti4O12 (CCTO/SiO2/CCTO) multilayered films were prepared on Pt/Ti/SiO2/Si substrates by pulsed laser deposition method. It has been demonstrated that the dielectric loss and the leakage current density were significantly reduced with the increase of the SiO2 layer thickness, accompanied with a decrease of the dielectric constant. The CCTO film with a 20 nm SiO2 layer showed a dielectric loss of 0.065 at 100 kHz and the leakage current density of 6×10−7 A/cm2 at 100 kV/cm, which were much lower than those of the single layer CCTO films. The improvement of the electric properties is ascribed to two reasons: one is the improved crystallinity; the other is the reduced free carriers in the multilayered films. 相似文献
10.
Jie SuXiaomei Lu Chao ZhangJunting Zhang Hui SunChangcheng Ju Zhijun WangKangli Min Fengzhen HuangJinsong Zhu 《Physica B: Condensed Matter》2012,407(3):485-488
Ho3Fe5O12 ceramics with garnet structure were prepared by the solid-state reaction method. The results revealed the existence of Fe2+ ions have intensive influence on dielectric and magnetic properties of Ho3Fe5O12 ceramics, which could be further confirmed by oxygen treatment. With a magnetic field lower than 10 kOe, the ME coefficient reaches 33 ps m−1 at room temperature. And the ME coupling was further verified by dielectric anomaly near Néel temperature. 相似文献
11.
La-substituted BiFeO3, Bi0.8La0.2FeO3, thin films were fabricated on Pt/Ti/SiO2/Si substrates by pulsed laser deposition. X-ray diffraction and high-resolution transmission electron microscope were used to analyze the structures of the films. The results show the films fabricated under optimized growth condition are (0 1 2) textured. X-ray photoemission spectroscopy results indicate that the oxidation state of Fe ion is Fe3+ in the films without detectable Fe2+. The films show low leakage current and excellent dielectric characters. Multiferroic properties with a remnant ferroelectric polarization of 5.2 μC/cm2 and a remanent magnetization of 0.02 μB/Fe were established. These results have some implications for further research. 相似文献
12.
Neodymium-substituted Bi4Ti3O12 (BNdT) thin films were prepared by a chemical solution deposition technique on platinum- coated silicon substrates. All of
the samples were annealed at the relatively low temperature of 600 °C by a rapid thermal annealing process in different atmospheres,
such as O2, air, and nitrogen, and vacuum. Irrespective of different annealing atmospheres, all of the BNdT thin films exhibit good
ferroelectric properties, such as a saturated hysteresis loop, good fatigue endurance, and low leakage current density. A
large remanent polarization (Pr) of ∼48 μC/cm2 with an electric field of 240 kV/cm was observed from the BNdT thin film annealed in O2 atmosphere. The BNdT thin films annealed in nitrogen and vacuum, at reduced oxygen partial pressures, exhibit smaller Pr than that annealed in oxygen. The difference of Pr of the BNdT thin films annealed in different atmospheres may originate from differences in the grain sizes and the number
of oxygen vacancies.
PACS 77.55.+f; 77.80.-e; 77.80.Fm; 81.15.-z 相似文献
13.
Ba0.5Sr0.5TiO3 (BST) thin films were deposited on copper foils via sol-gel method with La2O3 as a buffer layer. The films were processed in almost inert atmosphere so that the substrate oxidation was avoided while allowing the perovskite film phase to crystallize. The existence of a La2O3 buffer layer between the BST thin film and Cu foil improved the dielectric constant and reduced the leakage current density of the BST thin film. Meanwhile, the BST thin film exhibited ferroelectric character at room temperature, which was contrast to the para-electric behavior of the film without the buffer layer. Effects of La2O3 buffer layer on the crystallizability and microstructure of BST thin films were also investigated. 相似文献
14.
Nanostructured Gd2O3:Eu3+ and Li+ doped Gd2O3:Eu3+ thin films were prepared by pulsed laser ablation technique. The effects of annealing and Li+ doping on the structural, morphological, optical and luminescent properties are discussed. X-ray diffraction and Micro-Raman investigations indicate a phase transformation from amorphous to nanocrystalline phase and an early crystallization was observed in Li+ doped Gd2O3:Eu3+ thin films on annealing. AFM images of Li+ doped Gd2O3:Eu3+ films annealed at different temperatures especially at 973 K show a spontaneous ordering of the nanocrystals distributed uniformly all over the surface, with a hillocks (or tips) like self-assembly of nanoparticles driven by thermodynamic and kinetic considerations. Enhanced photoemission from locations corresponding to the tips suggest their use in high resolution display devices. An investigation on the photoluminescence of Gd2−xEuxO3 (x=0.10) and Gd2−x−yEuxLiyO3 (x=0.10, y=0.08) thin films annealed at 973 K reveals that the enhancement in luminescence intensity of about 3.04 times on Li+ doping is solely due to the increase in oxygen vacancies and the flux effect of Li+ ions. The observed decrease in the values of asymmetric ratio from the luminescence spectra of Li+ doped Gd2O3:Eu3+ films at high temperature region is discussed in terms of increased EuO bond length as a result of Li+ doping. 相似文献
15.
采用改进的溶胶-凝胶方法在单晶Si(100)衬底上制备了介电性能优异的(Ba0.7Sr0.3)TiO3/LaNiO3异质薄膜.实验发现,在750 ℃下 、O2气氛中晶化的LaNiO3薄膜的电阻率最小.C-V与I-V特性测量表明(Ba0.7Sr0.3)TiO3薄膜具有优异的介电性能,在频率为50kHz、零偏压下的相对介电常数εr>300,偏压为6V时漏电流密度JL<1.2×10-6A/cm2.
关键词:
xSr1-x)TiO3铁电薄膜')" href="#">(BaxSr1-x)TiO3铁电薄膜
3底电极')" href="#">LaNiO3底电极
溶胶-凝胶法 相似文献
16.
R.K. Singhal A. Samariya S.C. Sharma U.P. Deshpande E. Saitovitch 《Applied Surface Science》2010,257(3):1053-1057
We report on the reversible manipulation of room temperature ferromagnetism in Fe (5%) doped In2O3 polycrystalline magnetic semiconductor. The X-ray diffraction and photoemission measurements confirm that the Fe ions are well incorporated into the lattice, substituting the In3+ ions. The magnetization measurements show that the host In2O3 has a diamagnetic ground state, while it shows weak ferromagnetism at 300 K upon Fe doping. The as-prepared sample was then sequentially annealed in hydrogen, air, vacuum and finally in air. The ferromagnetic signal shoots up by hydrogenation as well as vacuum annealing and bounces back upon re-annealing the samples in air. The sequence of ferromagnetism shows a close inter-relationship with the behavior of oxygen vacancies (Vo). The Fe ions tend to a transform from 3+ to 2+ state during the giant ferromagnetic induction, as revealed by photoemission spectroscopy. A careful characterization of the structure, purity, magnetic, and transport properties confirms that the ferromagnetism is due to neither impurities nor clusters but directly related to the oxygen vacancies. The ferromagnetism can be reversibly controlled by these vacancies while a parallel variation of carrier concentration, as revealed by resistance measurements, appears to be a side effect of the oxygen vacancy variation. 相似文献
17.
18.
对高品质单相多晶Bi2Sr2CaCu2O8+δ样品作真空或H2气氛中不同温度下的热处理。由X射线结构分析,其正常态和超导态性质(特别是载流子浓度)的系统测量结果表明:Bi2Sr2CaCu208+δ样品在H2气氛中热处理,其氧的释放可分为两个阶段:一是Bi-O层之间的过量氧原子的逸出,降低系统的载流子浓度,从而调节Tc;二是CuO2面内氧原子的迁移,产生氧空位,使CuO2面内Cu2+的短程二维反铁磁(2D-AFM)有序背景遭到破坏。可以认为:以往文献中报道的Bi2Sr2CaCu2O8+δ超导体的吸氢效应导致Tc的变化,很可能主要的并不是氢原子的电子掺杂行为,而是与吸氢过程中氧含量的变化相联系。
关键词: 相似文献
19.
以十甲基环五硅氧烷(D5)和氧气(O2)作为反应气体,采用电子回旋共振等离子体化学气相沉积(ECR-CVD)方法制备了k=2.62的SiCOH薄膜.研究了O2掺杂对薄膜结构与电学性能的影响.结果表明,采用O2掺杂可以在保持较低介电常数的前提下极大地降低薄膜的漏电流,提高薄膜的绝缘性能,这与薄膜中Si-O立体鼠笼、Si-OH结构含量的提高有关.
关键词:
SiCOH薄膜
2掺杂')" href="#">O2掺杂
介电性能
键结构 相似文献
20.
Xing Li Hong-Liang Lu Hong-Ping Ma Jian-Guo Yang Jin-Xin Chen Wei Huang Qixin Guo Ji-Jun Feng David Wei Zhang 《Current Applied Physics》2019,19(2):72-81
Thin Ga2O3 films were grown on Si (100) using trimethylgallium (TMG) and oxygen as the precursors through plasma-enhanced atomic layer deposition. The depositions were made over a temperature range of 80–250?°C with a growth per cycle of around 0.07 nm/cycle. Surface self-saturating growth was obtained with TMG pulse time ≥20?ms?at a temperature of 150?°C. The root mean square surface roughness of the obtained Ga2O3 films increased from 0.1?nm to 0.3?nm with increasing the growth temperature. Moreover, the x-ray photoelectron spectroscopy analysis indicated that the obtained film was Ga-rich with the chemical oxidation states Ga3+ and Ga1+, and no carbon contamination was detected in the films after Ar+ sputtering. The electron density of films measured by x-ray reflectivity varied with the growth temperature, increasing from 4.72 to 5.80?g/cm3. The transmittance of Ga2O3 film deposited on a quartz substrate was obtained through ultraviolet visible (UV–Vis) spectroscopy. An obvious absorption in the deep UV region was demonstrated with a wide band gap of 4.6–4.8?eV. The spectroscopic ellipsometry analysis indicated that the average refractive index of the Ga2O3 film was 1.91?at 632.8?nm and increased with the growth temperature due to the dense structure of the films. Finally, the I-V and C-V characteristics proved that the Ga2O3 films prepared in this work had a low leakage current of 7.2?×?10?11 A/cm2 at 1.0?MV/cm and a high permittivity of 11.9, suitable to be gate dielectric. 相似文献