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1.
Pinyang Fang Huiqing Fan Shaojun Qiu Liajun Liu Jin Chen 《Journal of Sol-Gel Science and Technology》2009,50(3):290-295
Lanthanum-modified bismuth titanate (Bi3.25La0.75Ti3O12, BLTO) powders were prepared by the complex polymerization method. The structure and morphology of BLTO powders were investigated
by X-ray diffraction and scanning electron microscopy. The complexation of citric acid with the metallic cations was detected
by Fourier transformed infrared (FT-IR). The thermal analyses of obtained gels were investigated by differential thermal gravimetric
(DTG). The pure and normally stoichiometric phase of BLTO powders could be obtained at relatively low temperature of 550–700 °C
even if the bismuth content is not excess in the starting precursors, while the secondary phase could be detected at lower
and higher calcination temperatures. The shape of the BLTO grains is similarly to platelet in Bi-layer structure and stoichiometry
BLTO was detected by the analysis of energy dispersive spectrometry. 相似文献
2.
The metal-ferroelectric-semiconductor (MFS) heterostructure has been fabricated using Bi3.25La0.75Ti3O12 (BLT) as a ferroelectric layer by sol-gel processing. The effect of annealing temperature on phase formation and electrical
characteristics of Ag/BLT/p-Si heterostructure were investigated. The BLT thin films annealed at from 500°C to 650°C are polycrystalline,
with no pyrochlore or other second phases. The C-V curves of Ag/BLT/p-Si heterostructure annealed at 600°C show a clockwise C-V ferroelectric hysteresis loops and obtain good electrical properties with low current density of below 2×10−8 A/cm2 within ±4 V, a memory window of over 0.7 V for a thickness of 400 nm BLT films. The memory window enlarges and the current
density reduces with the increase of annealing temperature, but a annealing temperature over 600°C is disadvantageous for
good electrical properties. 相似文献
3.
Highly (111) oriented, phase-pure perovskite Pb(Zr0.3Ti0.7)O3 (or PZT 30/70) thin films were deposited on single-crystal, (0001) wurtzite GaN/sapphire substrates using the sol-gel process
and rapid thermal annealing. The phase, crystallinity, and stoichiometry of annealed PZT films were evaluated by X-ray diffraction
and Rutherford backscattering spectroscopy. The atomic force microscopy revealed a smooth PZT surface (rms roughness ∼1.5 nm)
with striations and undulations possibly influenced by the nature of the underlying GaN surface. The cross-sectional field-emission
scanning electron microscopic images indicated a sharper PZT/GaN interface compared to that of sol-gel derived PZT on (111)
Pt/TiO2/SiO2/(100) Si substrates. The capacitance-voltage (C-V) characteristics for PZT in the Pt/PZT/GaN (metal-ferroelectric-semiconductor
or MFS) configuration were evaluated as a function of annealing temperature and applied voltage. The observed C-V hysteresis
stemmed from trapped charge at defect sites within PZT. Also, the lower capacitance density (C/A = 0.35 μF/cm2, where A is the area of an electrode) and remnant polarization (P
r
∼ 4 μC/cm2) for PZT in the MFS configuration, compared to the values for PZT in the MFM configuration (Pt/PZT/Pt), were attributed to
the high depolarization field within PZT. 相似文献
4.
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
5.
Chen-Chia Chou Shen-Da Tsai Wen-Hsiang Tu Yu-En Yeh-Liu Hsien-Lung Tsai 《Journal of Sol-Gel Science and Technology》2007,42(3):315-322
Fabrication of ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thick films on a Pt/Ti/SiO2/Si substrate using powder-mixing sol-gel spin coating and continuous wave CO2 laser annealing technique to treat the specimens with at a relatively low temperature was investigated in the present work.
PZT fine powders were prepared by drying and pyrolysis of sol-gel solutions and calcined at temperatures from 400 to 750°C.
After fine powder-containing sol-gel solutions were spin-coated on a substrate and pyrolyzed, CO2 laser annealing was carried out to heat treat the specimens. The results show that laser annealing provides an extremely
efficient way to crystallize the materials, but an amorphous phase may also form in the case of overheating. Thicker films
absorb laser energy more effectively and therefore melt at shorter periods, implying a significant volume effect. A film with
thickness of 1 μm shows cracks and rough surface morphology and it was difficult to obtain acceptable electrical properties,
indicating importance of controlling interfacial stress and choosing appropriate size of the mixing powders. On the other
hand, a thick film of 5 μm annealed at 100 W/cm2 for 15 s exhibits excellent properties (P
r = 36.1 μC/cm2, E
c = 19.66 kV/cm). Films of 10 μm form a melting zone at the surface and a non-crystallized bottom layer easily at an energy
density of 100 W/cm2, showing poor electrical properties. Besides, porosity and electrical properties of thick films can be controlled using appropriate
processing parameters, suggesting that CO2 laser annealing of modified sol-gel films is suitable for fabricating films of low dielectric constants and high crystallinity. 相似文献
6.
Phase-pure nanocrystalline Li4Ti5O12 with BET surface areas between 183 and 196 m2/g was prepared via an improved synthetic protocol from lithium ethoxide and titanium(IV) butoxide. The phase purity was proved by X-ray powder diffraction, Raman spectroscopy and cyclic voltammetry. Thin-film electrodes were prepared from two nanocrystalline samples of Li4Ti5O12 and one microcrystalline commercial sample. Li-insertion behavior of these electrodes was related to the particle size.Presented at the 3rd International Meeting on Advanced Batteries and Accumulators, 16–20 June 2002, Brno, Czech Republic 相似文献
7.
Atomic models are proposed for nanotubes of the titanium silicocarbides Ti2SiC, Ti3SiC2, and Ti4SiC3, and their electronic structure and interatomic interactions are investigated by the density functional tight-binding method
(DFTB) in comparison with the corresponding crystalline phases.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 2, pp. 88-92, March-April, 2009. 相似文献
8.
Lili Chen Mingrong Shen Liang Fang Yu Xu 《Journal of Sol-Gel Science and Technology》2007,42(3):299-303
A TiO2 thin buffer layer was introduced between the (Pb0.4Sr0.6)TiO3 (PST) film and the Pt/Ti/SiO2/Si substrate in an attempt to improve their electrical properties. Both TiO2 and PST layers were prepared by a chemical solution deposition method. It was found that the TiO2 buffer layer increased the (100)/(001) preferred orientation of PST and decreased the surface roughness of the films, leading
to an enhancement in electrical properties including an increase in dielectric constant and in its tunability by DC voltage,
as well as a decrease in dielectric loss and leakage current density. At an optimized thickness of the TiO2 buffer layer deposited using 0.02 mol/l TiO2 sol, the 330-nm-thick PST films had a dielectric constant, loss and tunability of 1126, 0.044 and 60.7% at 10 kHz, respectively,
while the leakage current density was 1.95 × 10−6 A/cm2 at 100 kV/cm. 相似文献
9.
Pb(Zr0.25Ti0.75)O3 (PZT25) thin films were prepared on LaNiO3-coated thermally oxidized silicon substrates by chemical solution deposition method, where LaNiO3 electrodes were also prepared by a chemical solution deposition technique. The dielectric constant and dielectric loss of
the PZT25 thin films were 570 and 0.057, respectively. The remanent polarization and coercive field were 20.11 μC/cm2 and 60.7 kV/cm, respectively. The PZT25 thin films on LaNiO3-coated thermally oxidized silicon substrates showed improved fatigue characteristics compared with their counterparts on
plantium-coated silicon substrates. 相似文献
10.
Nanoparticles of the Aurivillius phase La-substituted BTO (Bi4−xLaxTi3O12, with x=0.75) were obtained through a chemical lithiation process. They have been characterised by X-ray diffraction and transmission electron microscopy (diffraction and imaging at high resolution). The defect-free particles are platelet-shaped with the c large axis perpendicular to the plane. From high-resolution images, it is clear that the delamination process occurs at the level of the (Bi2O2)2+ intermediate layer and is destructive for this layer. The smallest thickness measured corresponds to one cell parameter (3.3 nm) but a large range of thicknesses have been observed: this suggests that the lithium insertion does not take place in all (Bi2O2)2+ layers, despite a large excess of lithium and a long reaction time. This is confirmed by ICP analysis, which leads to a formula Li0.99Bi3.25La0.77Ti3.00O12 for the lithiated compound. This behaviour towards lithium intercalation differs from those observed with BTO in literature, where lithium insertion is reported as occurring in every (Bi2O2)2+ layer. Possible explanations for this difference are advanced based on microstructural and structural considerations. 相似文献
11.
Jiwei Zhai Bo Shen Xi Yao Zhengkui Xu Xin Li Haydn Chen 《Journal of Sol-Gel Science and Technology》2007,42(3):369-373
Antiferroelectric (Pb,La)(Zr,Sn,Ti)O3 (PLZST) and Pb(Nb,Zr,Sn,Ti)O3 (PNZST) thin films have been fabricated on LaNiO3/Pt/Ti/SiO2/Si substrates by a sol-gel processing. These films showed highly preferred (100) orientation due to the grain-on-grain local
epitaxial growth. The PLZST films close to the AFE-FE phase boundary showed the electric-field-induced ferroelectric (FE)
state, which could return back to its original AFE state only when the thermal activation was high enough. The AFE to FE phase
transformation in PNZST films can be adjusted by the dc bias field in temperature. Phase transformation behavior of PNZST
and PLZST antiferroelectric thin films were investigated as a function of temperature and dc bias field. 相似文献
12.
The sol-gel processing of lead-free (Na,K) NbO3 ferroelectric films was studied. Sodium ethoxide (NaOC2H5) and potassium ethoxide (KOC2H5) were prepared by reacting solid Na and K with ethanol (99.7%) in a solvent of 2-methoxyethanol. 0.5-μm-thick (Na,K)NbO3 thin films with orthorhombic perovskite structure were obtained by pyrolyzing at 400°C and annealing at 800–900°C. The films
had relatively dense and uniform microstructure with grain size of about 50 nm, whose ferroelectricity was proved by the P-E hysteresis loop measurement. It was found that excess K was effective to reduce the annealing temperature for the crystallization
of sol-gel-derived (Na,K)NbO3 thin films. 相似文献
13.
Nanocrystalline La2Mo2O9 oxide-ion conductor has been successfully synthesized by microwave-assisted combustion method within a very short time duration
using aspartic acid as the newer fuel in a domestic microwave oven. The synthesized nanocrystalline powder showed good sinterability
and reached more than 97% of theoretical density even at low temperature of 800 °C for 5 h. The sintered La2Mo2O9 sample exhibited a conductivity of 0.159 S/cm in air at 750 °C. 相似文献
14.
Yong Hong Wang Yang Zhang Xing Qin Liu Guang Yao Meng 《Journal of Sol-Gel Science and Technology》2007,41(3):267-275
A simple approach namely sol-coated technique has been developed for the low cost fabrication of macroporous ceramic under
a far below common sintering temperature of alumina with large dimension grains. The prepared green support shows higher sinteractive
than the one treated by wet impregnation method under the same sintering conditions. The support possesses great potential
applications with 6.63–7.71 μm in pore size, 39% open porosity as well as >45 MPa mechanical strength at the sintering temperature
range of 1350°– 1500°C. The results indicate that the nitrogen gas flux and pure water permeation value was 51 252.35 m3 m−2 h−1 bar−1, 98.43 m3 m−2 h−1 bar−1, respectively, which were more dependent on the pore structure and pore size distribution than open porosity. 相似文献
15.
Using Fe3O4 nano-particles as seeds, a new type of Fe3O4/Au composite particles with core/shell structure and diameter of about 170 nm was prepared by reduction of Au3+ with hydroxylamine in an aqueous solution. Particle size analyzer and transmission electron microscope were used to analyze
the size distribution and microstructure of the particles in different conditions. The result showed that the magnetically
responsive property and suspension stability of Fe3O4 seeds as well as reduction conditions of Au3+to Au0are the main factors which are crucial for obtaining a colloid of the Fe3O4/Au composite particles with uniform particle dispersion, excellent stability, homogeneity in particle sizes, and effective
response to an external magnet in aqueous suspension solutions. UV-Vis analysis revealed that there is a characteristic peak
of Fe3O4/Au fluid. For particles with d(0.5)=168 nm, the λmax is 625 nm. 相似文献
16.
Ling Pei Meiya Li Jun Liu Benfang Yu Jing Wang Dongyun Guo Xingzhong Zhao 《Journal of Sol-Gel Science and Technology》2010,53(2):193-198
Ferroelectric thin films of Nd and Mn co-doped bismuth titanate, Bi3.15Nd0.85Ti3−x
Mn
x
O12 (BNTM) (x = 0–0.1), were fabricated on Pt/TiO2/SiO2/Si(100) substrates by a sol–gel technique. The BNTM films had a polycrystalline perovskite structure and uniform and dense
surface morphologies. A lattice distortion was observed in the BNTM films due to Mn ion doping. The ferroelectric measurement
of the films indicated that the values of coercive field (E
c
) decreased gradually with the increase of the Mn content (x), however, the remanent polarization (P
r
) increase firstly and then decrease with the increase of x. The sample with x = 0.05 had optimum electrical properties and a maximum 2P
r
value. The 2P
r
and 2E
c
values of the film at a maximum applied electric field of 400 kV/cm were 38.3 μC/cm2 and 180 kV/cm, respectively. Moreover, this BNTM capacitors did not show fatigue behaviors after 1.0 × 1010 switching cycles at a frequency of 1 MHz, suggesting a fatigue-free character. The main reason for the increase of the 2P
r
and the decrease of the 2E
c
might be attributed to the lattice distortion in BNTM films due to Mn ion doping. 相似文献
17.
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
18.
Anna Blonska-Tabero 《Journal of Thermal Analysis and Calorimetry》2007,88(1):201-205
Thermal properties of Co2FeV3O11
have been reinvestigated. It has been proved that this compound does not exhibit
polymorphism. It melts incongruently at the temperature of 770±5°C
and the phase with lyonsite type structure is the solid product of this melting.
Phase relations in the whole subsolidus area of the CoO–V2O5–Fe2O3 system have been determined. The solidus area projection onto
the component concentration triangle plane of this system has been constructed
using the DTA and XRD methods. 15 subsidiary subsystems can be distinguished
in this system. 相似文献
19.
Ba(Ti1−x
Sn
x
)O3 (x = 0.10 or 0.15) thin films were deposited on Si(100) and Pt(111)/TiO
x
/SiO2/Si(100) substrates via sol–gel spin-coating. Crack-free thin films could be obtained by single-step deposition, where the
thickness was about 0.46 and 0.29 μm at 1000 and 2000 rpm, respectively. Circular delaminated parts 100 μm in diameter, however,
tended to appear in thicker films deposited at 1000 rpm. On both kinds of substrates, the films were crystallized between
500 and 600 °C, where the perovskite phase emerged as the primary phase, and the formation of single-phase perovskite was
basically achieved between 700–800 °C. The films deposited on Pt(111)/TiO
x
/SiO2/Si(100) substrates, however, tended to have small SnO2 and BaCO3 diffraction peaks, which decreased with increasing spinning rate. The dielectric properties were evaluated on the films deposited
on Pt(111)/TiO
x
/SiO2/Si(100) substrates at 2000 rpm. The films prepared by single-step depositions had dielectric constants of 350 and 230, and
dielectric loss of 0.30 and 0.10 at x = 0.1 and 0.15, respectively. The films prepared by two time deposition had dielectric constants of 450 and 250, and dielectric
loss of 0.21 and 0.19 at x = 0.10 and 0.15, respectively. 相似文献
20.
Ca3Co4O9 powder was prepared by a polyacrylamide gel route in this paper. The effect of the processing on microstructure and thermoelectric
properties of Ca3Co4O9 ceramics via spark plasma sintering were investigated. Electrical measurement shows that the Seebeck coefficient and conductivity
are 170 μV/K and 128 S/cm, respectively, at 700 °C, yielding a power factor value of 3.70 × 10−4 W m−1 K−2 at 700 °C, which is larger than that of Ca3Co4O9 ceramics via solid-state reaction processing. The polyacrylamide gel processing is a fast, cheap, reproducible and easily
scaled up chemical route to improve the thermoelectric properties of Ca3Co4O9 ceramics by preparing the homogeneous and pure Ca3Co4O9 phase. 相似文献