共查询到20条相似文献,搜索用时 796 毫秒
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2.
Dr. Veronika Kovacova Dr. Jung In Yang Leonard Jacques Dr. Song Won Ko Dr. Wanlin Zhu Prof. Susan Trolier-McKinstry 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(42):9356-9364
(K0.5Na0.5)NbO3 (KNN) is a promising lead-free alternative for ferroelectric thin films such as Pb(Zr,Ti)O3. One main drawback is its high leakage current density at high electric fields, which has been previously linked to alkali non-stoichiometry. This paper compares three acetate-based chemical solution synthesis and deposition methods for 0.5 mol % Mn-doped KNN film fabrication, using lower crystallization temperature processes in comparison to the sintering temperatures necessary for fabrication of KNN ceramics. This paper shows the crucial role of the A site homogenization step during solution synthesis in preserving alkali chemical homogeneity of Mn doped KNN films. Chemically homogeneous films show a uniform grain size of 80 nm and a leakage current density under 2.8×10−8 A cm−2 up to electric fields as high as 600 kV cm−1, which is the highest breakdown strength reported for KNN thin films. Solution synthesis involving two-step pyrolysis resulted in films with dense, columnar microstructures, which are interesting for orientation control and enhancement of piezoelectric properties. This study reports detailed solution synthesis and deposition processes with good dielectric, ferroelectric and breakdown field properties. An optimized fabrication method that should couple low leakage current density with dense and oriented microstructures is proposed. 相似文献
3.
Photocatalytic Activity and Characterization of the Sol-Gel Derived Pb-Doped TiO2 Thin Films 总被引:1,自引:0,他引:1
Yu Jiaguo Yu Jimmy C. Cheng Bei Zhao Xiujian 《Journal of Sol-Gel Science and Technology》2002,24(1):39-48
Photocatalytically active Pb-doped TiO2 thin films were prepared on a soda-lime glass substrate by sol-gel dip-coating technique using TiO2 sols containing lead(II) nitrate. The thin films were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), UV-VIS spectroscopy and X-ray diffraction (XRD). A shift of the UV-VIS absorption towards longer wavelengths was observed, which indicated a decrease in the band-gap of TiO2 upon Pb doping. XRD results showed both pure and Pb-doped TiO2 thin films were polycrystalline, anatase type, and oriented predominantly to the (101) plane. A slight shift in the d-spacing for the Pb-doped film indicated the incorporation of Pb into the TiO2 lattice to form Pb
x
Ti1–x
O2 solid solution. AFM results showed Pb-doped TiO2 thin films were composed of larger TiO2 particles and had rougher surface, compared with un-doped TiO2 thin films. XPS results showed that except for the enrichment of Pb near the surface, Pb exists in the forms of Pb
x
Ti1–x
O2 and PbO. Dimethyl-2,2-dichlorovinyl phosphate (DDVP) was efficiently degraded in the presence of the Pb-doped TiO2 thin films by exposing the insecticide solution to sunlight. The mechanism of photocatalytic activity enhancement of the Pb-doped TiO2 thin films was discussed. 相似文献
4.
Synthesis,Ferroelectric and Optical Properties of (Pb,Ca)TiO3 Thin Films by Soft Solution Processing
Pontes F.M. Pontes D.S.L. Leite E.R. Longo E. Santos E.M.S. Mergulhão S. Varela J.A. 《Journal of Sol-Gel Science and Technology》2003,27(2):137-147
Calcium modified lead titanate sol was synthesized using a soft solution processing, the so-called polymeric precursor method. In soft chemistry method, soluble precursors such as lead acetate trihydrate, calcium carbonate and titanium isopropoxide, as starting materials, were mixed in aqueous solution. Pb0.7Ca0.3TiO3 thin films were deposited on platinum-coated silicon and quartz substrates by means of the spinning technique. The surface morphology and crystal structure, dielectric and optical properties of the thin films were investigated. The electrical measurements were conducted on metal-ferroelectric-metal (MFM) capacitors. The typical measured small signal dielectric constant and dissipation factor at a frequency of 100 kHz were 299 and 0.065, respectively, for a thin film with 230 nm thickness annealed at 600°C for 2 h. The remanent polarization (2Pr) and coercive field (E
c) were 32 C/cm2 and 100 kV/cm, respectively. Transmission spectra were recorded and from them, refractive index, extinction coefficient, and band gap energy were calculated. Thin films exhibited good optical transmissivity, and had optical direct transitions. The present study confirms the validity of the DiDomenico model for the interband transition, with a single electronic oscillator at 6.858 eV. The optical dispersion behavior of PCT thin film was found to fit well the Sellmeir dispersion equation. The band gap energy of the thin film, annealed at 600°C, was 3.56 eV. The results confirmed that soft solution processing provides an inexpensive and environmentally friendly route for the preparation of PCT thin films. 相似文献
5.
BST/BSLaT/BST multiplayer (ML) films were prepared by sol-gel method on the Pt/Ti/SiO2/Si substrate. X-ray diffraction analysis and atomic force microscopy showed that dopant La causes decreased grain size of
BST thin films obviously, and ML films were similar to BST films in size. The dielectric constant versus temperature curve
of ML films becomes sharper comparing with that of BST films near the phase transition point, which indicated that the pyroelectric
coefficient is propitious to be enhanced. The ML films also improve the leakage current characteristics of BST thin films
and the linear relationship of the log J versus E1/2 curves shows in a good agreement with the Schottky thermionic emission model. This work clearly reveals the highly promising
potential of BST/BSLaT/BST multiplayer films compared with BST films for application in uncooled infrared focal plane arrays
system. 相似文献
6.
The CaCu3Ti4O12 (CCTO) thin films were synthesized via a metal‐organic solution containing stoichiometric amounts of the metal cations at 700 °C for 1 h. The stable metal‐organic solution was prepared by dissolving calcium nitrate, copper nitrate, and tetrabuty titanate in grain alcohol. The phases, microstructures, and electric properties of CCTO thin films were characterized by X‐ray diffraction, scanning electron microscopy, atomic force microscope, and electric measurements. The results show that the CCTO thin films have homogeneous microstructure, smooth surface, low leakage current, and high values of dielectric constant. The low leakage current can be attributed to the small surface roughness. The high value of dielectric constant can be attributed to the internal barrier layer capacitor mechanism and metal‐insulator‐semiconductor junction of CCTO thin films. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
Polycrystalline β-zinc sulfide thin films were prepared by solution pyrolysis of an ethylzinc isopropylthiolate–zinc bis(dibutyldithiocarbamate) combined precursor (EtZnSiPr–Zn(S2CNnBu2)2) in chloroform solution on glass or silicon(111) substrates at 300°C. Homogeneous but amorphous indium sulfide thin films were obtained from butylindium bis(isopropylthiolate) (nBuInSiPr2) in P-xylene on these substrates at 300°C similarly. The sulfide thin films obtained were characterized by means of X-ray photoelectron spectroscopy (XPS), X-ray fluorescence Microanalysis, scanning electron microscopy (SEM) and optical band gap measurements. 相似文献
8.
Ferroelectric Properties of New Chemical Solution Derived SBT Thin Films for Non-Volatile Memory Devices 总被引:1,自引:0,他引:1
Kim Seung-Hyun Kim D.J. Im J. Kim C.E. Kingon Angus I. 《Journal of Sol-Gel Science and Technology》1999,16(1-2):57-63
Ferroelectric SBT (Sr/Bi/Ta = 0.8/2.3/2) thin films on Pt/ZrO2/SiO2/Si were successfully prepared by using an alkanolamine modified chemical solution deposition method. Acetic acid as a solvent led to the formation of water in the solution, which might continuously induce the hydrolysis and condensation of the precursors, leading to reducing the stability of the solution with aging time. It was observed that alkanolamine provided the stability to the SBT solution by retarding the hydrolysis and condensation rates. This solution could be used as long as up to 30 days without any appreciable change of the solution properties. The typical hysteresis loop of SBT thin films was obtained at 2 V, and it was fully saturated even below an applied voltage of 3 V (2Pr 16 C/cm2). The measured 2Pr value of the SBT thin film at 5 V was almost 20 C/cm2. Fatigue and breakdown characteristics of the films, measured at 5 V, showed a stable behavior, and negligible degradation was observed up to 1010 cycles. 相似文献
9.
A. Hardy M. K. Van Bael H. Van den Rul D. Vangenechten J. Mullens J. DHaen L. Goux D. J. Wouters 《Journal of Sol-Gel Science and Technology》2007,42(3):239-245
Lanthanum substituted bismuth titanate thin films were deposited using an aqueous chemical solution deposition method. Varying
the composition of Bi4−x
La
x
Ti3O12, with x = 0.5, 0.65, 0.75 and 0.85, is shown to have a large influence on the microstructure and properties of the films. Increasing
the amount of La3+, x, from 0.5 to 0.85 led to a decrease of the remanent polarization (P
r) from 6.2 to eventually 0 μC/cm2. This decrease of P
r is explained by means of X-ray diffraction (XRD) study, which shows that there is an increased preference for c-axis orientation upon increasing the La3+ concentration. Furthermore, a strong decrease of the grain size upon increasing x is observed in a scanning electron microscopic (SEM) study. The concurrent increase of domain pinning on the grain boundaries
is a second effect which may be responsible for the deterioration of the ferroelectric property at larger x. 相似文献
10.
《化学物理学报(中文版)》2010,23(5):582-586
Thin films of CuInS2 were grown on glass substrate by successive ionic layer adsorption and reaction method with different [Cu]/[In] ratios and annealed at 400 °C for 30 min. The crystal structure and grain sizes of the thin films were characterized by X-ray diffraction method. Atomic force microscopy was used to determine surface morphology of the films. Optical and electrical properties of these films were investigated as a function of [Cu]/[In]ratios. The electrical resistivity of CuInS2 of thin films was determined using a direct current-two probe method in the temperature range of 300—470 K. It is observed that, the electrical resistivity values show a big decreasing with increasing [Cu]/[In] ratio. Hence, the [Cu]/[In] ratio in the solution can drastically affect the structural, electrical, and optical properties of thin films of CuInS2. 相似文献
11.
Control of microstructure and functional properties of PZT thin films via UV assisted pyrolysis 总被引:1,自引:0,他引:1
S. R. Kumar S. Habouti V. Zaporojtchenko M. Es-Souni 《Journal of Sol-Gel Science and Technology》2007,42(3):309-314
The influence of ultraviolet (UV) light during pyrolysis of sol-gel fabricated Pb(Zr0.52Ti0.48)O3 thin films on (111)Pt/Ti/SiO2/Si substrates has been investigated. The UV treated films show a homogeneous fine grain structure with (100) preferential
orientation, whereas a bimodal grain structure and (111) preferential orientation were found for the untreated film. This
is explained in terms of specific template layers formed during pyrolysis. The ferroelectric, dielectric and piezoelectric
properties are also reported for both films. It is shown that while the ferroelectric properties are higher for the (111)
films, the (100) films show better dielectric and piezoelectric properties with an effective piezoelectric coefficient, d
33eff, of 183 pm/V vs. 101.8 pm/V for the (111) films. 相似文献
12.
Priyabrata Sahoo Bikesh Gupta Ramesh Chandra Sahoo Dr. Kiran Vankayala Dr. H. S. S. Ramakrishna Matte 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(44):11326-11334
Solution processing of nanomaterials is a promising technique for use in various applications owing to its simplicity and scalability. However, the studies on liquid-phase exfoliation (LPE) of tungsten oxide (WO3) are limited, unlike others, by a lack of commercial availability of bulk WO3 with layered structures. Herein, a one-step topochemical synthesis approach to obtain bulk layered WO3 from commercially available layered tungsten disulfide (WS2) by optimizing various parameters like reaction time and temperature is reported. Detailed microscopic and spectroscopic techniques confirmed the conversion process. Further, LPE was carried out on topochemically converted bulk layered WO3 in 22 different solvents; among the solvents studied, the propan-2-ol/water (1 : 1) co-solvent system appeared to be the best. This indicates that the possible values of surface tension and Hansen solubility parameters for bulk WO3 could be close to that of the co-solvent system. The obtained WO3 dispersions in a low-boiling-point solvent enable thin films of various thickness to be fabricated by using spray coating. The obtained thin films were used as active materials in supercapacitors without any conductive additives/binders and exhibited an areal capacitance of 31.7 mF cm−2 at 5 mV s−1. Photo-electrochemical measurements revealed that these thin films can also be used as photoanodes for photo-electrochemical water oxidation. 相似文献
13.
Hiroya Kitahata Kiyoharu Tadanaga Tsutomu Minami Norifumi Fujimura Taichiro Ito 《Journal of Sol-Gel Science and Technology》2000,19(1-3):589-593
Hexagonal YMnO3 has a ferroelectric property with an optimal remanent polarization along the c-axis. The c-axis oriented YMnO3 thin films with a small leakage current were prepared by the sol-gel dipping method. The c-axis orientation of the films was promoted by the addition of diethanolamine to the Mn precursor solution. A heat treatment with multiple steps led to a dense film structure with fine grains. The dense structure resulted in the decrease of the leakage current. Furthermore, when the films were heat-treated in a vacuum, the leakage current became considerably small and the ferroelectricity of the YMnO3 thin films was observed even at room temperature. 相似文献
14.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7782-7786
Methylammonium‐mediated phase‐evolution behavior of FA1−xMAxPbI3 mixed‐organic‐cation perovskite (MOCP) is studied. It is found that by simply enriching the MOCP precursor solutions with excess methylammonium cations, the MOCPs form via a dynamic composition‐tuning process that is key to obtaining MOCP thin films with superior properties. This simple chemical approach addresses several key challenges, such as control over phase purity, uniformity, grain size, composition, etc., associated with the solution‐growth of MOCP thin films with targeted compositions. 相似文献
15.
F. Soares-Carvalho P. Thomas J.P. Mercurio B. Frit S. Parola 《Journal of Sol-Gel Science and Technology》1997,8(1-3):759-763
Bi4Ti3O12 thin films were obtained by the sol-gel method. The precursor solution was prepared by allowing the two metallic alkoxides, Bi(OC2H4OCH3)3 and Ti(OC2H4OCH3)4, to react in 2-methoxy-ethanol to form the mixed alkoxide. This stable sol was deposited by spin-coating onto platinized silicon substrates. X-Ray diffraction patterns indicate that the perovskite initial crystallization temperature is 460°C for powder samples and it ranges between 400 and 500°C, for thin films, as a function of the number of coating layers. Dense, smooth and crack free thin films with grain sizes ranging from 20 nm to 500 nm are obtained, depending on the number of coating layers and on the post-deposition temperature annealing. 相似文献
16.
Dan Xie Zhigang Zhang Tianling Ren Litian Liu 《Journal of Sol-Gel Science and Technology》2007,42(3):271-276
Bi-layered ferroelectric Bi3TiTaO9 (BTT) thin films with different thickness (ranging from 100 to 400 nm) were successfully fabricated on Pt(111)/TiO2/SiO2/(100)Si substrates using chemical solution deposition (CSD) technique at different annealing temperatures. The c-axis orientation of the films was affected by film thickness and process temperature. The thinner the film and the higher
the process temperature, the higher the c-axis orientation. With the increase of film thickness, the stress decreased but the film roughness increased, which led to
the decrease of c-axis orientation of films. BTT films annealed at 800°C were found to have much improved remament polarization (P
r
) than that of films annealed at 650 and 750°C. The P
r
and coercive field (E
c
) values were measured to be 2 μC/cm2 and 100 kV/cm, respectively. BTT films showed well-defined ferroelectric properties with grain size larger than 100 nm. 相似文献
17.
Sandip Halder Theodor Schneller Rainer Waser Florian Thomas 《Journal of Sol-Gel Science and Technology》2007,41(3):203-207
Nickel thin films have been sputtered on standard Si/SiO2 substrates with TiO2 as an adhesive layer. The thermal stability of these substrates was analyzed. SEM images show an increase in grain size with
annealing temperature. They were found to be stable till 800°C, beyond which the nickel layer disintegrated. These substrates
were used for deposition of BaTiO3 and (Ba,Sr)TiO3 dielectric thin films under a reducing atmosphere. The dielectric thin films were processed with various pyrolysis and annealing
temperatures in order to optimize the dielectric properties. Increased pyrolysis temperatures showed an increase in the grain
size. Results on these nickelised substrates were finally compared with dielectric films deposited on platinized silicon substrates
under identical conditions but crystallized in an oxygen atmosphere. 相似文献
18.
A. Bouzidi N. Benramdane S. Bresson C. Mathieu R. Desfeux M. El Marssi 《Vibrational Spectroscopy》2011,57(2):182-186
Vanadium oxide thin films were prepared by spray pyrolysis using solutions of vanadium chloride (VCl3) with different concentrations on glass substrates heated at 200 and 250 °C. The influence of substrate temperature (Ts) and solution concentration (molarity) on structural and vibrational properties is discussed by using X-ray diffraction and Raman spectroscopy. The results revealed that at 0.05 M and Ts = 200 °C, V4O9 thin films are obtained. At 250 °C, V2O5 phases with preferential orientation are observed and the films become polycrystalline when the molarity increases. 相似文献
19.
P. Patil 《Journal of Solid State Electrochemistry》2002,6(4):284-287
The characterisation of electrochemical behaviour of electrochromic (EC) devices based on solution thermolysed (ST) tungsten
oxide (WO3) thin films was carried out using the step potential excitation method. The method, based on generating plots of current
density (J) as a function of passed charge (ΔQ), has been applied for the characterisation of EC-WO3 thin films in proton-containing aqueous electrolyte. EC devices have been fabricated by employing WO3 thin films with variable thickness (T) ranging from 0.04 to 0.52 μm. The J vs time (t) responses (chronoamperometry) of these
devices were recorded at a fixed applied potential (±0.7 V vs S.C.E.) and values of total passed H+ charges (ΔQ) into the WO3 host lattice during the coloration process are calculated. The J-ΔQ curves corresponding to films of different thickness
were plotted as a function of the passed charge volume density, ΔQ /T, and an intercalatable film thickness is calculated
to be 0.13 μm. The modulation in optical transmittance after coloration and bleaching was studied in the wavelength range
between 350 and 850 nm and an optical efficiency (ξλ) is calculated at λ=700 nm. It is found that the ξλ wanes with increasing intercalation.
Electronic Publication 相似文献
20.
Wataru Sakamoto Ken-ichi Mimura Takafumi Naka Tetsuo Shimura Toshinobu Yogo 《Journal of Sol-Gel Science and Technology》2007,42(3):213-220
Ba(Zr,Ti)O3/LaNiO3 layered thin films have been synthesized by chemical solution deposition (CSD) using metal-organic precursor solutions. Ba(Zr,Ti)O3 thin films with smooth surface morphology and excellent dielectric properties were prepared on Pt/TiO
x
/SiO2/Si substrates by controlling the Zr/Ti ratios in Ba(Zr,Ti)O3. Chemically derived LaNiO3 thin films crystallized into the perovskite single phase and their conductivity was sufficiently high as a thin-film electrode.
Ba(Zr,Ti)O3/LaNiO3 layered thin films of single phase perovskite were fabricated on SiO2/Si and fused silica substrates. The dielectric constant of a Ba(Zr0.2Ti0.8)O3 thin film prepared at 700°C on a LaNiO3/fused silica substrate was found to be approximately 830 with a dielectric loss of 5% at 1 kHz and room temperature. Although
the Ba(Zr0.2Ti0.8)O3 thin film on the LaNiO3/fused silica substrate showed a smaller dielectric constant than the Ba(Zr0.2Ti0.8)O3 thin film on Pt/TiO
x
/SiO2/Si, small temperature dependence of dielectric constant was achieved over a wide temperature range. Furthermore, the fabrication
of the Ba(Zr,Ti)O3/LaNiO3 films in alternate thin layers similar to a multilayer capacitor structure was performed by the same solution deposition
process. 相似文献