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1.
The efficiency of simultaneous application of chemically-derived starting powders and melt-forming sintering aids in low temperature
sintering has been demonstrated. Doping of cryochemically processed BiNbO4 powders with CuO/V2O5 causes reducing sintering temperatures from 850–900∘C to 700–720∘C. Similar doping of Zn3Nb2O8 fine powders allows to obtain ceramics with density 97–98% and Q × F values up to 40 000 GHz at T > 720∘C. The sintering of solution-derived BaCeO3 powders doped with CuO results in dense ceramics at T = 1000∘C. Morphological evolution during sintering was observed using hot stage SEM. Low temperature liquid phase sintering of fine
powders is rather sensitive to the traces of secondary phases and to the micromorphology of starting powders though observed
reduction of sintering temperatures is substantially larger than for traditional liquid phase sintering of coarse-grained
oxide powders. 相似文献
2.
Wei-Kuo Chia Ying-Chung Chen Cheng-Fu Yang San-Lin Young Wang-Ta Chiang Yu-Tarng Tsai 《Journal of Electroceramics》2006,17(2-4):173-177
Bi4Ti3O12 thin films are deposited on ITO/glass and Pt/Ti/Si(100) substrates by R.F. magnetron sputtering at room temperature. The
films are then heated by a rapid thermal annealing (RTA) process conducted in oxygen atmosphere at temperatures ranging from
550–700∘C. X-ray diffraction examination reveals that the crystalinity of the films grown on Pt/Ti/Si is better than that of the films
grown on ITO/glass under the same fabrication conditions. SEM observation shows that the films grown on Pt/Ti/Si are denser
than those grown on ITO/glass substrates. Interactive diffusion between the Bi4Ti3O12 film and the ITO film increases with the increase of annealing temperature. The optical transmittance of the thin film annealed
at 650∘C is found to be almost 100% when the effect of the ITO film is excluded. The relative dielectric constants, leakage currents
and polarization characteristics of the two films are compared and discussed. 相似文献
3.
C. K. Tan Gregory K. L. Goh D. Z. Chi Albert C. W. Lu B. K. Lok 《Journal of Electroceramics》2006,16(4):581-585
Polycrystalline BaTiO3 films were hydrothermally grown on Ti-coated substrates from 80∘C to 200∘C. Films grown at 200∘C exhibited the lowest dielectric loss of around 0.1. Proton incorporation was more severe for the 80∘C film resulting in higher dielectric losses and leakage currents about two orders of magnitude higher. Post deposition oxygen
plasma treatment removed incorporated protons and reduced the loss tangent but did not reduce defect density. As such, the
leakage current of the 80∘C film remained high. The films had dielectric constants of 275 to 675 from 100 Hz to 100 kHz and a value of 67 from 100 MHz
to 3 GHz. 相似文献
4.
Kyoung R. Han Soyoung Park Young-Soon Kwon Chang Sam Kim 《Journal of Electroceramics》2006,17(2-4):965-970
Low-temperature-sinterable PMN-PT-BT [0.96 (0.91Pb(Mg1/3Nb2/3)O3-0.09PbTiO3)-0.04BaTiO3] powder was first prepared by the modified mixed oxide method and then metal (M = Cu, Mg, Ag) oxides were introduced as their
nitrate salts. Precalcined PMN-PT-BT/MO composite powders were surface modified with the magnesia sol to suppress diffusion
of Ag or metal oxides. Such prepared composite powders were sintered > 98% T.D. at 850–900∘C and showed homogeneous microstructures with <100 nm Ag or metal oxide particles. Nanoparticles were located mostly in grains
and some on grain boundaries. Grain growth was substantially inhibited and resulted in grain size of ∼2 μm. The nanocomposites
of PBT/Ag and PBT/MgO showed substantially improved sintered densities and dielectric properties at sintering temperature
below 1000∘C, but the PBT/CuO composite was hardly affected. The PBT/Ag composites treated with the MgO sol showed good handling strength
of MOR > 120 MPa. The proper amount of the magnesia sol for surface modification seemed to be 0.5–1.0 wt. 相似文献
5.
Jong-Bong Lim Sahn Nahm Hyo-Tae Kim Jong-Hee Kim Jong-Hoo Paik Hwack-Joo Lee 《Journal of Electroceramics》2006,17(2-4):393-397
The effect of B2O3 and CuO on the sintering temperature and microwave dielectric properties of BaTi4O9 ceramics was investigated. The BaTi4O9 ceramics were able to be sintered at 975∘C when B2O3 was added. This decrease in the sintering temperature of the BaTi4O9 ceramics upon the addition of B2O3 is attributed to the formation of BaB2O4 second phase whose melting temperature is around 900∘C. The B2O3 added BaTi4O9 ceramics alone were not sintered below 975∘C, but were sintered at 875∘C when CuO was added. The formation of BaCu(B2O5) second phase could be responsible for the decrease in the sintering temperature of the CuO and B2O3 added BaTi4O9 ceramics. The BaTi4O9 ceramics containing 2.0 mol% B2O3 and 5.0 mol% CuO sintered at 900∘C for 2 h have good microwave dielectric properties of εr = 36.3, Q× f = 30,500 GHz and τf = 28.1 ppm/∘C 相似文献
6.
Bo-Yun Jang Beom-Jong Kim Young-Hun Jeong Sahn Nahm Ho-Jung Sun Hwack-Ju Lee 《Journal of Electroceramics》2006,17(2-4):387-391
BaTi4O9 thin films were grown on a Pt/Ti/SiO2/Si substrate using RF magnetron sputtering. A homogeneous BaTi4O9 crystalline phase developed in the films deposited at 550∘C and annealed above 850∘C. When the thickness of the film was reduced, the capacitance density and leakage current density increased. Furthermore,
the dielectric constant was observed to decrease with decreasing film thickness. The BaTi4O9 film with a thickness of 62 nm exhibited excellent dielectric and electrical properties, with a capacitance density of 4.612
fF/μm2 and a dissipation factor of 0.26% at 100 kHz. Similar results were also obtained in the RF frequency range (1–6 GHz). A low
leakage current density of 1.0 × 10−9 A/cm2 was achieved at ± 2 V, as well as small voltage and temperature coefficients of capacitance of 40.05 ppm/V2 and –92.157 ppm/∘C, respectively, at 100 kHz. 相似文献
7.
Anatase TiO2 films were deposited on glass substrates at 50 and 200∘C to investigate the effect of growth temperature on the photocatalytic acitivity of the films. It was observed that the films
grown at 200∘C were composed of columnar crystallites and were more porous than the films grown at 50∘C which had more compact structures. Also, the film crystallinity increased from 75 to 90% if the higher growth temperature
was used. Despite the higher crystallinity, it was observed that for crystallinities between 60 and 90%, the photocatalytic
behavior of the films was more significantly affected by changes in the surface area. 相似文献
8.
Thin films of Pb(Mg1/3,Nb2/3)O3 (PMN) and Pb(Mg1/3,Nb2/3)O3-PbTiO3 (PMN-PT) were fabricated on Si and Pt/Ti/SiO2/Si substrates by MOCVD using ultrasonic nebulization and their characteristics were investigated. PMN-PT films deposited
at 350∘C were annealed in a RTA (Rapid Thermal Annealing) system at 650∘C for 30 sec to improve the micostructural properties. The crystallographic properties of PMN-PT films strongly depend on
the content ratio of PbTiO3. The content of pyrochlore phase in PMN-PT films decreased with the increase of Ti content and nearly single phase perovskite
films were obtained at the composition of 80PMN-20PT. The PMN-PT films with perovskite phase showed a typical butterfly type
C-V curve which verifies the ferroelectricity and had the relative dielectric constant of about 60. 相似文献
9.
The amorphous films were annealed in a wide temperature range (250–1000∘C) and film properties of TiO2 thin films were studied. Nano-sized anatase polycrystallites had been induced by thermal annealing for the films annealed
at and above 300∘C as confirmed by X-ray diffraction. Strong LO-phonon Raman modes, especially B1g
(395 cm−1) and E
g
(636 cm−1) in Raman spectra and the absorption peak at 436 cm−1 in absorbance spectra by Fourier transform infrared spectroscopy also indicated the existence of anatase phase in crystalline
thin films. In addition, with the increase of the annealing temperature, the wettability of the film surface was enhanced
as shown by the decrease of water contact angle from over 90∘ to less than 40∘. Moreover, upon UV laser irradiation on film surface, the water contact angle saturated at 10∘ indicative of a highly hydrophilic surface for all the films, which arose from the dissociative adsorption of water molecules
on the defect sits of the surface generated by the photocatalysis reactions of TiO2. This behavior makes the film a good potential candidate for self-clean coatings. 相似文献
10.
Films of (1−x)Pb(Zn1/3Nb2/3)O3-xPb(Zr0.4Ti0.6) O3 (x = 0.6, 40PZN-60PZT) were deposited on Pt/TiO2/ SiO2/Si substrate through spin coating. Using a combination of homogeneous precursor solution preparation and two-step pyrolysis
process, we were able to obtain the 40PZN-60PZT thin films of perovskite phase virtually without pyrochlore phase precipitation
after annealing above 650∘C. But since annealing done at the high temperatures for extended time can cause diffusion of Pt, TiO2 and Si, and precipitation of nonstoichiometric PbO, we adopted 2-step annealing method to circumvent these problems. The
2-step annealed films show dense microstructure than the 1-step films annealed at higher temperature. Furthermore, the root-mean-square
surface roughness of 220 nm thick films which are annealed at 720∘C for 1 min and then annealed at 650∘C for 5 min was found to be 3.9 nm by atomic force microscopy as compared to the 12 nm surface roughness of the film annealed
only at 720∘C for 5 min. The electrical properties of 2-step annealed films are virtually same and those of the 1-step annealed films
annealed at high temperature. The film 2-step annealed at 720∘C for brief 1 min and with subsequent annealing at 650∘C for 5 min showed a saturated hysteresis loop at an applied voltage of 5 V with remanent polarization (P
r) and coercive voltage (V
c) of 25.3 μC/cm2 and 0.66 V respectively. The leakage current density was lower than 10−5A/cm2 at an applied voltage of 5 V. 相似文献
11.
Byung-Teak Lee Sang-Hun Jeong Myong-Ho Kim Min-Ho Kuk Dong-Sik Bae Tae-Kwon Song Won-Jeong Kim 《Journal of Electroceramics》2006,17(2-4):305-310
In this article, it is shown that high quality ZnO films were grown on Si(111) and Al2O3(0001) substrates using a conventional rf magnetron sputtering. High-resolution X-ray diffractometry (HR-XRD), transmission
electron microscopy (TEM), scanning electron microscopy (SEM), and photoluminescence (PL) investigations clearly confirmed
that the ZnO films grown on Al2O3 (0001) at substrate temperatures above 650∘C are single crystal as well as high optical quality. It is also estimated in both cases grown on Si and Al2O3 that an introduction of template pre-grown at 500∘C can induce a homogeneous interface and improvement of emission characteristic by relaxing the strain caused by large lattice
and thermal mismatch between the film and substrate and by reducing defect density in interface region. 相似文献
12.
Spray pyrolysis has been used to prepare La0.6 Sr0.4Co0.2Fe0.8O3-δ thin film cathodes for solid oxide fuel cell (SOFC) applications. The films are polycrystalline with nano-meter sized grains
and less than 1 μm in thickness. Deposition parameters for film deposition have been established. The ratio of deposition
temperature to solvent boiling point is found to be the most important processing parameter that determines whether a crack
free homogeneous and coherent film is obtained. The morphology can be tailored by the deposition parameters. Annealing at
650∘C for four hours in air results in coherent films of the desired perovskite phase. The films are potential cathodes for thin
film micro-solid oxide fuel cells. 相似文献
13.
Wataru Sakamoto Yu-ki Mizutani Naoya Iizawa Toshinobu Yogo Takashi Hayashi Shin-ichi Hirano 《Journal of Electroceramics》2006,17(2-4):293-297
Ferroelectric Si-doped (Bi,Nd)4Ti3O12 thin films have been prepared on Pt/TiOx/SiO2/Si substrates through metal-organic compounds by the chemical solution deposition. The Bi3.25Nd0.75Ti2.9Si0.1O12 (BNTS) precursor films were found to crystallize into the Bi-layered perovskite Bi4Ti3O12 single-phase above 600∘C. The synthesized BNTS films revealed a random orientation having a strong 117 reflection. The BNTS thin films prepared between
600∘C and 700∘C showed well-saturated P-E hysteresis loops with P
r of 13–14 μ C/cm2 and E
c of 100–110 kV/cm at an applied voltage of 5 V. The surface roughness of the BNTS thin films was improved by Si doping compared
with that of undoped Bi3.35Nd0.75Ti3O12 films. 相似文献
14.
ZnGa2O4 thin film phosphors have been synthesized on ITO coated glass and soda-lime glass at a firing temperature of 500∘C and an annealing temperature of 500∘C and 600∘C via a chemical solution method using Zinc acetate dihydrate, Gallium nitrate hydrate and 2-methoxiethanol as a solution.
XRD patterns of the film phosphors synthesized showed the peaks of ZnGa2O4 crystalline phases. AFM surface morphologies of the ZnGa2O4 thin film phosphors revealed marked differences according to an annealing temperature of 500∘C and 600∘C under an annealing atmosphere (3% H2/Ar). On the other hand, the sheet resistance of ZnGa2O4 thin film phosphors, which were measured by four-point probe instrument, was approximately 5.76 Ω /square and 7.86 Ω /square
with annealing temperature, respectively. The ZnGa2O4 thin film phosphors exhibited blue emission spectra with peak wavelength of 434 nm and 436 nm by ultra-violet excitation
around 230 nm. 相似文献
15.
Fransiska Cecilia Kartawidjaja Zhaohui Zhou John Wang 《Journal of Electroceramics》2006,16(4):425-430
Heterolayered Pb(Zr1 − x
Ti
x
)O3 thin films consisting of alternating PbZr0.7Ti0.3O3 and PbZr0.3Ti0.7O3 layers were successfully deposited via a multistep sol-gel route assisted by spin-coating. These heterolayered PZT films,
when annealed at a temperature in the range of 600–700∘C show (001)/(100) preferred orientation, demonstrate desired ferroelectric and dielectric properties. The most interesting
ferroelectric and dielectric properties were obtained from the six-layered PZT thin film annealed at 650∘C, which exhibits a remanent polarization of 47.7 μC/cm2 and a dielectric permittivity of 1002 at 100 Hz. Reversible polarization constituents a considerably high contribution towards
the ferroelectric hysteresis of the heterolayered PZT films, as shown by studies obtained from C-V and AC measurement. 相似文献
16.
I. H. Kim D. Y. Ku J. H. Ko D. Kim K. S. Lee J.-h. Jeong T. S. Lee B. Cheong Y.-J. Baik W. M. Kim 《Journal of Electroceramics》2006,17(2-4):241-245
To improve the stability of sputter-deposited ZnO:Al (AZO) films at high temperature above 300∘C, an amorphous Zn-Sn-O (ZTO) film was deposited on the top of AZO films as an protective layer by co-sputtering of pure ZnO
and SnO2 targets. Amorphous ZTO films had resistivity in the range from 10−2 to 10−3 Ωcm and were stable up to temperature of 400∘C. Heat treatments of bare AZO films in the atmosphere at 400∘C resulted in a dramatic increase in the resistivity accompanied by substantial decrease in carrier concentration and Hall
mobility. The AZO films covered with the ZTO film showed remarkable improvement in thermal stability for subsequent heat treatments
in the temperature range from 200 to 400∘C in the atmosphere as well as chemical stability in weak acidic solution. X-ray photoelectron spectroscopy analysis showed
that the improvement was attained by ZTO layer acting as diffusion barrier of oxygens and/or water vapors. 相似文献
17.
High-performance pyroelectric infrared detectors have been fabricated using Lithium tantalite (LiTaO3) thin films deposited on Pt(111)/Ti/SiO2/Si(100) substrates by diol-based sol-gel method and rapid thermal annealing (RTA) technique. The dielectric and pyroelectric
properties of IR detectors of LiTaO3 thin films crystallized by conventional and RTA processes are investigated. Experimental results reveal that the heating
rate will influence strongly on dielectricity and pyroelectricity of LiTaO3 thin films. The voltage responsivities (Rv) measured at 80 Hz increase from 5496 to 8455 V/W and the specific detecivities
(D∗) measured at 300 Hz increase from 1.94 × 108 to 2.38 × 108 cmHz1/2/W with an increase of heating rate from 600 to 1800∘C/min. However, the voltage responsivity and the specific detecivity decrease with heating rate in excess of 1800∘C/min. The results show that the LiTaO3 thin film detector with a heating rate of 1800∘C/min exists both the maximums of voltage responsivity and specific detecivity. 相似文献
18.
The effects of Mn-doping on TSDC (Thermally Stimulated Depolarization Current) and electrical degradation of BaTiO3 have been investigated. TSDCs of un-doped BaTiO3 and Ba(Ti1−x
Mnx)O3−δ exhibited the three sharp TSDC peaks around phase transition temperatures. TSDC of Ba(Ti0.995Mg0.005)O2.995 increased gradually from 50∘C and this anomalous depolarization current kept going up well above the Curie temperature (∼130∘C). TSDCs of un-doped BaTiO3 and Ba(Ti0.995Mn0.005)O3−δ decreased in the temperature range above the Curie point, whereas a slight increase in TSDC was confirmed at the specimen
of Ba(Ti0.99Mn0.01)O3−δ. TSDCs of Ba(Ti0.995−y
Mg0.005Mny)O3−δ (y = 0.005, 0.01) were lower than that of Ba(Ti0.995Mg0.005)O2.995. 相似文献
19.
H. Asakura C. D. Madhusoodana Y. Kameshima A. Nakajima K. Okada 《Journal of Electroceramics》2006,17(1):31-36
Faujasite-type zeolite films were prepared on foamed stainless steel by the in-situ crystallization method. Precursor solutions
were prepared by dissolving water glass and NaAlO2in a NaOH solution and aged at room temperature for two days. The concentrations of the starting materials were varied from
0.29 to 2.3 M (in SiO2concentration) keeping the molar ratios of Na2O:SiO2:Al2O3fixed at 3.6:3.0:1.0. The foamed stainless steel substrate had about 90% of porosity and an average pore size of 600 μ m. It was dip-coated in the precursor solution four times, then hydrothermally treated at 80∘, 110∘ and 150∘C for 6–48 h. The XRD patterns and SEM photographs revealed that faujasite-type zeolite was formed predominantly at a SiO2concentration of 1.1 M, temperature of 110∘C and duration of 24 h, with a product particle size of 2–5 μ m. At higher concentrations of the precursor solution, hydroxylsodalite becomes the major product rather than faujasite-type
zeolite. The adherence strength of the zeolite grains deposited on the foamed stainless steel is higher in the in-situ crystallization
method than when a conventional solution method is used. Thus, the in-situ crystallization method is concluded to be effective
for preparing zeolite films even on metal substrates. 相似文献
20.
ZnNb2O6-TiO2 mixture thin films with multilayer structures were fabricated via a sol-gel spin coating process. TiO2 layers were deposited on the pre-crystallized ZnNb2O6 layers in order to suppress the formation of the ixiolite phase which always forms in the bulk system. The phase constitution
of the thin films, confirmed by X-ray diffraction (XRD), could be controlled by the annealing temperatures, which, in turn,
influenced the dielectric properties of the thin films. TiO2 layers crystallized as the anatase phase and then transformed to the rutile phase at temperatures higher than 725∘C. Dielectric constants of the mixture thin films, measured at 1 MHz with an MIM (metal-insulator-metal) structure, increased
from 27 to 41 with dielectric losses below 0.005 as the annealing temperature increased from 700∘C to 900∘C. The increase in the dielectric constants was understood to originate from the increasing amounts of the rutile phase. Temperature
coefficients of capacitance (TCC) were also measured between 25∘C and 125∘C, which showed a decreasing manner from positive values to negative values with increasing annealing temperatures. When annealed
at 850∘C, the TCC of the thin films could be tuned to be approximately 0 ppm/oC with dielectric constant and dielectric loss of 36 and 0.002, respectively. 相似文献