共查询到20条相似文献,搜索用时 15 毫秒
1.
Cabrera Edgar J. Amade Roger Jaller Lina Pascual Esther Bertran Enric 《Journal of nanoparticle research》2014,16(1):1-7
The thermal stability of nanocrystalline 3R-CuCrO2 obtaining by hydrothermal method was investigated by annealing treatment, XRD, FT-IR, XPS and TG. The three temperature domains corresponding to thermal stability of 3R-CuCrO2 nanocrystals (25–400 °C), destabilization of nanocrystalline 3R-CuCrO2 phase (400–800 °C) and recrystallization of 3R-CuCrO2 in microcrystalline state over 800 °C, were determined by the specific hydrothermal synthesis conditions. This study has indicated that nanocrystals with delafossite structure synthesized by hydrothermal method exhibit nanocrystalline state up to a reasonably high temperature, about 390 °C, which could be interesting for technical applications and the classical theory of the grain growth. 相似文献
2.
Yusuke Kondo Yasuko Okumura Chifumi Oi Wataru Sakamoto Toshinobu Yogo 《Journal of nanoparticle research》2008,10(7):1203-1208
Transparent BaTiO3 nanoparticle/polymer composite films were synthesized from titanium-organic film and barium ion in aqueous solution under
direct current (DC) field. Titanium-organic precursor was synthesized from titanium isopropoxide, acetylacetone and methacrylate
derivative. The UV treatment was effective to increase the anti-solubility of the titanium-organic film during DC processing.
BaTiO3 nanoparticles were crystallized in the precursor films on stainless substrates without high temperature process, as low as
40°C. The crystallite size of BaTiO3 increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. BaTiO3 nanoparticles also grew in size with increasing reaction time from 15 min to 45 min at 3.0 V/cm and 50 °C. Transparent BaTiO3 nanoparticle/polymer films were synthesized on stainless substrates at 3.0 V/cm and 50°C for 45 min. 相似文献
3.
Alessio Bassano Vincenzo Buscaglia Mohamed Sennour Maria Teresa Buscaglia Massimo Viviani Paolo Nanni 《Journal of nanoparticle research》2010,12(2):623-633
Nanocoatings (5–20 nm) of different compounds on fine BaTiO3 particles were obtained by means of precipitation processes. Homogeneous and smooth shells of Y(OH)CO3 and Dy(OH)CO3 were grown from nitrate solutions in the presence of urea. An irregular coating consisting of zirconia nanoparticles was
produced from zirconyl nitrate solution using ammonia as a precipitating agent after adsorption of a polymeric polyelectrolyte
on the BaTiO3 surface. Composite particles with a peculiar morphology were obtained by inducing heterogeneous nucleation and growth of
Ni(OH)2 lamellae on the BaTiO3 surface. The different shells can be transformed in a nanocrystalline coating of the corresponding oxide (Y2O3, Dy2O3, ZrO2, NiO) by calcination at moderate temperatures (400–700 °C). The overall results indicate that precipitation from solution
represents a versatile process to grow a second-phase layer on the surface of BaTiO3 particles. This approach can be used as an alternative to mechanical wet mixing for controlled doping of ferroelectric materials
and for the fabrication of composite materials with specific geometry of the two-phase assembly. 相似文献
4.
I. Vrejoiu J.D. Pedarnig M. Dinescu S. Bauer-Gogonea D. Bäuerle 《Applied Physics A: Materials Science & Processing》2002,74(3):407-409
BaTiO3–polymer composite layers have been produced by the spin-on technique (thickness 3–10 μm). The dielectric permittivity of
the layers at room temperature can be tuned from 2.8 to approximately 33 by varying the ceramic filling from 0 to 60% by volume.
The dielectric properties of the films are almost insensitive to temperature variations in the range 20–180 °C. Free-standing
composite layers with ceramic content ≤50% are flexible without noticeable change of permittivity after repeated mechanical
bending.
Received: 22 November 2001 / Accepted: 24 November 2001 / Published online: 23 January 2002 相似文献
5.
C.J. Xiao W.W. Zhang S.M. Feng X.H. Wang L.T. Li 《Journal of Physics and Chemistry of Solids》2007,68(2):311-314
Dense nanocrystalline BaTiO3 ceramics with uniform grain sizes of 30 nm was obtained by pressure assisted sintering. The phase transitions were investigated by Raman scattering at temperatures ranging from −190 to 200 °C. With increasing temperature, similar to 3 μm BaTiO3 normal ceramics, the successive phase transitions from rhombohedral to orthorhombic, orthorhombic to tetragonal, tetragonal to cubic were also observed in 30 nm BaTiO3 ceramics. Especially, the coexistence of ferroelectric tetragonal and orthorhombic phases was found at room temperature. The ferroelectric behavior was further characterized by P-E hysteresis loop. The experimental results indicate that the critical grain size of the disappearance of ferroelectricity in nanocrystalline BaTiO3 ceramics fabricated by pressure assisted sintering is below 30 nm. 相似文献
6.
P. Jenouvrier E. Cela C. Coutier M. Langlet R. Rimet J. Fick 《Applied physics. B, Lasers and optics》2001,73(5-6):463-466
This work deals with the low-temperature preparation of optically active silica-based materials. Tb3+-doped silica monolithic gels were elaborated at 40 °C. Tb3+–SSA-doped SiO2–TiO2 thin films were deposited by an original sol–gel approach, the aerosol–gel process, and heat-treated at 150 °C. Organic complexation
of terbium ions was used to improve the active properties of doped silica gels and thin-film samples. Spectroscopic characterisations
are reported for these samples. Photoluminescence increase by a factor two was observed for complexation by sulphosalicylic
acid.
Received: 16 May 2001 / Revised version: 31 August 2001 / Published online: 23 October 2001 相似文献
7.
L. Mancic B. A. Marinkovic K. Marinkovic M. Dramicanin O. Milosevic 《Journal of nanoparticle research》2011,13(11):5887-5897
Phosphors of (Y0.75Gd0.25)2O3:Eu3+ (5 at.%) have been prepared through soft chemistry routes. Conversion of the starting nitrates mixture into oxide is performed
through two approaches: (a) hydrothermal treatment (HT) at 200 °C/3 h of an ammonium hydrogen carbonate precipitated mixture
and (b) by thermally decomposition of pure nitrate precursor solution at 900 °C in dispersed phase (aerosol) within a tubular
flow reactor by spray pyrolysis process (SP). The powders are additionally thermally treated at different temperatures: 600,
1000, and 1100 °C for either 3 or 12 h. HT—derived particles present exclusively one-dimensional morphology (nanorods) up
to the temperatures of 600 °C, while the leaf-like particles start to grow afterward. SP—derived particles maintain their
spherical shape up to the temperatures of 1100 °C. These submicron sized spheres were actually composed of randomly aggregated
nanoparticles. All powders exhibits cubic Ia-3 structure (Y0.75Gd0.25)2O3:Eu and have improved optical characteristics due to their nanocrystalline nature. The detailed study of the influence of
structural and morphological powder characteristics on their emission properties is performed based on the results of X-ray
powder diffractometry, scanning electron microscopy, X-ray energy dispersive spectroscopy, transmission electron microscopy,
and photoluminescence measurements. 相似文献
8.
Nanocrystalline BaTiO3 particles modified with polarizable ligands were synthesized through hydrolysis of modified metal–organics below 100°C. BaTiO3 precursor was synthesized from barium metal, titanium isopropoxide and polarizable ligands in a mixture of ethanol and 2-ethoxyethanol.
The modified Ba–Ti complex alkoxide was hydrolyzed yielding BaTiO3 particles modified with organics. The crystallinty of nanometer-sized particles was dependent upon the hydrolysis conditions,
and increased with increasing water amount and time. The nanocrystalline particles were identified to be BaTiO3 by X-ray diffraction (XRD) and electron diffraction. A fluid consisting of modified BaTiO3 particles and silicone oil revealed a typical electrorheological (ER) behavior on applying DC field. The ER behavior was
found to depend upon the kind of ligand. 4-Fluorobenzyloxy modifier revealed the highest yield stress in the ER measurement
among 4-substitued benzyloxy ligands examined. 相似文献
9.
Zirconium oxide layers have been successfully deposited by photo-CVD at low temperatures. ZrO2 growth was observed at temperatures as low as 100 °C. When deposited at 250 °C and above, these films exhibited a polycrystalline
structure with a mixture of different crystal phases. Deposition at 300 °C was found to form moisture-free ZrO2 films with a high refractive index of 2.1, a very low effective density of trapped electrons of ∼8.8×108 cm-2 and an interface trap density of 6.6×109 cm-2 eV-1 being readily obtained.
Received: 17 December 2001 / Accepted: 6 January 2002 / Published online: 3 June 2002 相似文献
10.
B.K. Gan J.M. Xue D.M. Wan J. Wang 《Applied Physics A: Materials Science & Processing》1999,69(4):433-436
For the first time, the perovskite phase in 0.9Pb (Zr0.52Ti0.48)O3-0.1BaTiO3(0.9PZT-0.1BT) is triggered to form in an oxide matrix consisting of PbO, ZrO2, BaO, and TiO2. Unlike in the solid-state reaction activated by calcination at an intermediate temperature, intermediate phases, such as
PbTiO3, were not observed with increasing degree of mechanical activation prior to the formation of perovskite 0.9Pb(Zr0.52Ti0.48)O3-0.1BaTiO3 phase. This suggests that the nucleation and subsequent growth of perovskite crystallites in the activated oxide composition
are not a result of the interfacial reactions that normally occur in the temperature-driven solid-state reaction. The mechanical
activation-derived powders can be sintered to a relative density of >97% theoretical at 1100 °C. Sintered 0.9Pb(Zr0.52Ti0.48)O3-0.1BaTiO3 derived from mechanical activation of constituent oxides exhibits a maximum dielectric constant of 775 and a minimum dielectric
loss of <2% at room temperature when measured at 1.0 kHz.
Received: 3 December 1998 / Accepted: 18 March 1999 / Published online: 24 June 1999 相似文献
11.
Y.G. Cao X.L. Chen Y.C. Lan J.Y. Li Y.P. Xu T. Xu Y. Zhang J.K. Liang 《Applied Physics A: Materials Science & Processing》2000,71(3):351-352
A new condensed form of AlN nanocrystalline solids was obtained directly from reactions of metal Al and (NH4Cl+NH4I) in liquid ammonia at 550 °C, without the subsequent consolidation process as in the conventional method. The synthesized
product is a transparent bulk solid, while the constituted nanocrystals have an average size of about 18 nm and possess the
same wurtzite structure as bulk AlN. (NH4Cl+NH4I), which plays a role of a catalyst in the present synthetic route, is indispensable. The photoluminescence spectrum of the
AlN nanocrystalline solids shows a broad blue band centered at 400 nm.
Received: 20 June 2000 / Accepted: 22 June 2000 / Published online: 9 August 2000 相似文献
12.
C. Du Z. Wang J. Liu X. Xu K. Fu G. Xu J. Wang Z. Shao 《Applied physics. B, Lasers and optics》2002,74(2):125-127
Intracavity sum-frequency mixing of 1.06 μm and 532 nm in YCa4O(BO3)3 (YCOB) crystals cut for different type-I phase-matching directions of (θ,ϕ)=(106°,77.2°), (111°, 79.6°) and (65°, 82.8°)
was investigated in a compact diode-end-pumped acousto-optical Q-switched Nd:YVO4/KTP laser formed with a three-mirror folded resonator. The maximum 355-nm average output power of 124 mW was obtained in
the phase-matching direction of (106°, 77.2°) with a pump-to-ultraviolet conversion efficiency of 3.3% at the repetition frequency
of 20 kHz.
Received: 17 September 2001 / Revised version: 27 November 2001 / Published online: 17 January 2002 相似文献
13.
Synthesis of nanocrystalline material by sputtering and laser ablation at low temperatures 总被引:1,自引:0,他引:1
P. Ayyub R. Chandra P. Taneja A.K. Sharma R. Pinto 《Applied Physics A: Materials Science & Processing》2001,73(1):67-73
Physical vapor deposition techniques such as sputtering and laser ablation – which are very commonly used in thin film technology
– appear to hold much promise for the synthesis of nanocrystalline thin films as well as loosely aggregated nanoparticles.
We present a systematic study of the process parameters that facilitate the growth of nanocrystalline metals and oxides. The
systems studied include TiO2, ZnO, γ-Al2O3, Cu2O, Ag and Cu. The mean particle size and crystallographic orientation are influenced mainly by the sputtering power, the substrate
temperature and the nature, pressure and flow rate of the sputtering gas. In general, nanocrystalline thin films were formed
at or close to 300 K, while loosely adhering nanoparticles were deposited at lower temperatures.
Received: 31 October 2000 / Accepted: 9 January 2001 / Published online: 26 April 2001 相似文献
14.
Effect of phase transformation on optical and dielectric properties of zirconium oxide nanoparticles
Rajababu Chintaparty Bhavani Palagiri Venkata subbha Reddy Imma Reddy 《Phase Transitions》2015,88(9):929-938
Zirconium oxide nanoparticle (ZrO2) is synthesized by the hydrothermal method at different calcination temperatures. The structural analysis is carried out by X-ray diffraction and Raman spectra. The sample prepared at 400 °C and 1100 °C showed the cubic and monoclinic phase, respectively, and the sample calcined at 600 °C and 800 °C showed the mixed phase with co-existence of cubic and monoclinic phases. Furthermore, the morphology and particle size of these samples were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. The band gap estimated from UV–Vis spectra of ZrO2 (zirconia) nanocrystalline materials calcined at different temperatures from 400 °C to 1100 °C was in the range of 2.6–4.2 eV. The frequency dependence of dielectric constant and dielectric loss was investigated at room temperature. The low frequency region of dielectric constant is attributed to space charge effects. 相似文献
15.
SrBi2Ta2O9 (SBT) ferroelectric thin films with different preferred orientations were deposited by pulsed laser deposition (PLD). Several
methods have been developed to control the preferred orientation of SBT thin films. For SBT films deposited directly on Pt/TiO2/SiO2/Si substrates and in situ crystallized at the deposition temperature, the substrate temperature has a significant impact
on the orientation and the remnant polarization (Pr) of the films; a higher substrate temperature benefits the formation of
(115) texture and larger grain size. The films deposited on Pt/TiO2/SiO2/Si substrates at 830 °C are (115)-oriented and exhibit 2Pr of 6 μC/cm2. (115)- and (200)-predominant films can be formed by using a La0.85Sr0.15CoO3 (LSCO) buffer layer or by annealing amorphous SBT films deposited on Pt/TiO2/SiO2/Si substrates at 450 °C using rapid thermal annealing (RTA). These films exhibit good electric properties; 2Pr of the films
are up to 12 μC/cm2 and 17 μC/cm2, respectively. The much larger 2Pr of the films deposited on the LSCO buffer layer and of the films obtained by RTA than
2Pr of the films deposited on Pt/TiO2/SiO2/Si substrates at 830 °C is attributed to a stronger (200) texture.
Received: 30 January 2001 / Accepted: 30 May 2001 / Published online: 25 July 2001 相似文献
16.
Wenwei Ge Hong Liu Xiangyong Zhao Xiaobing Li Xiaoming Pan Di Lin Haiqing Xu Xiangping Jiang Haosu Luo 《Applied Physics A: Materials Science & Processing》2009,95(3):761-767
In this paper, a single crystal of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 with dimensions of Φ 30×10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal
possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties
were systematically investigated with 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples. The room-temperature dielectric constants
for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The (T
m, ε
m) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306°C, 3718),
(305°C, 3613) and (307°C, 3600) at 1 kHz for the 〈001〉, 〈110〉 and 〈111〉 oriented crystal. The optimum poling conditions were
obtained by investigating the piezoelectric constants d
33 as a function of poling temperature and poling electric field. For the 〈001〉 and 〈110〉 crystal samples, the maximum d
33 values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80°C were applied
during the poling process. The as-grown 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98×10−11 Ω−1⋅m−1 and 3.95×10−9 Ω−1⋅m−1 at 25°C and 150°C for the 〈001〉 oriented crystal sample. 相似文献
17.
Effect of Annealing on Ferroelectric Properties of Nanometre BaTiO3 Ceramics Prepared by High Pressure Sintering Method
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Dense nanocrystalline BaTiO3 ceramics with a grain size of 5Onto are prepared under 6 GPa at 1273K using a high pressure sintering method. The sintered bulk is uniform and the relative density is above 97%. We anneal the ceramic samples in oxygen with various temperatures and for the annealing, several broadened peaks can be observed at different times without apparent grain growth. After about 378K( by dielectric measurements. However, these peaks are very different from those of coarser-grained ceramics. It is indicated that both the elimination of oxygen vacancies and the release of residual stresses caused by high pressure greatly improve the overall ferroelectric properties of BaTiO3 ceramics. The observation of nearly linear polarization hysteresis loop after anneal provides the solid evidence of ferroelectricity in these nano-sized BaTiO3 ceramics. It is believed that the absence of 90° domains and the existence of poor-permittivity nonferroelectric grain boundaries contribute to the slim loop. 相似文献
18.
Kazuyuki Sumida Kosuke Hiramatsu Wataru Sakamoto Toshinobu Yogo 《Journal of nanoparticle research》2007,9(2):225-232
Transparent BaTiO3 nanoparticle/polymer hybrid was synthesized by polymerization and hydrolysis of barium titanium alkoxide modified with 2-vinyloxyethoxy
ligand. Barium alkoxide, titanium alkoxide and 2-vinyloxyethanol were reacted affording a BaTiO3 precursor, which was then hydrolyzed and polymerized to form BaTiO3 particle/polymer hybrids below 100°C. BaTiO3 particles increased in crystallinity with increasing water amount for hydrolysis. The absorption edge of the hybrid film
on silica plates shifted to shorter wavelength with decreasing crystallite size. Nano-sized BaTiO3 particle/polymer hybrid polymerized with methyl methacrylate (MMA) was shaped into a transparent and self-standing film with
a refractive index of 1.595 at 589 nm. 相似文献
19.
Y.W. Wang G.Z. Wang S.X. Wang T. Gao H. Sang L.D. Zhang 《Applied Physics A: Materials Science & Processing》2002,74(4):577-580
Highly ordered Co-Ag alloy nanowire arrays embedded in the nanochannels of anodic alumina membranes (AAMs) were successfully
fabricated using electrodeposition. Scanning electron microscopy and transmission electron microscopy observations revealed
that the ordered Co-Ag alloy nanowires were uniformly assembled into the hexagonally ordered nanochannels of the AAMs. Magnetic
measurements showed that the perpendicular coercivity (Hc⊥) of the ordered nanowire arrays increased dramatically as the annealing temperature (Ta) rose from 300 °C, reached its maximum (183 Oe) at 400 °C and then decreased sharply as Ta further increased beyond 400 °C. However, there was little change in the parallel coercivity (Hc∥) of the nanowire arrays during the annealing process. The mechanism of this phenomenon was attributed to the special structure
of the AAMs and nanowires.
Received: 27 November 2000 / Accepted: 3 May 2001 / Published online: 25 July 2001 相似文献
20.
X. Zhu S. Lu H.L.W. Chan C.L. Choy K.H. Wong 《Applied Physics A: Materials Science & Processing》2003,76(2):225-229
Compositionally graded (Ba1-xSrx)TiO3 (BST) (x:0.0∼0.25) thin films were grown on Pt (111)/TiO2/SiO2/Si (100) substrates using layer-by-layer pulsed laser deposition in the temperature range 550–650 °C. Both downgraded (Ba/Sr
ratio varying from 100/0 at the bottom surface to 75/25 at the top surface) and upgraded (Ba/Sr ratio varying from 75/25 at
the bottom surface to 100/0 at the top surface) BST films were prepared. Their microstructures were systematically studied
by X-ray diffractometry and scanning electron microscopy. A grain morphology transition from large ‘rosettes’ (>0.30 μm) to
small compact grains (70–110 nm) was observed in the downgraded BST films as the deposition temperature was increased from
550 to 650 °C. No such grain morphology transition was detected in the upgraded BST films. Dielectric measurements with metal
electrodes revealed an enhanced dielectric behavior in the downgraded films. This enhancement is mainly attributed to the
large compressive stress field built up near the interface between the downgraded film and substrate. Furthermore, the BaTiO3 layer in the downgraded BST films not only serves as a bottom layer but also as an excellent seeding layer for enhancing
the crystallization of the subsequent film layers in the downgraded films.
Received: 10 December 2001 / Accepted: 12 March 2002 / Published online: 19 July 2002
RID="*"
ID="*"Corresponding author. Fax: 86-25/359-5535, E-mail: xhzhu@public1.ptt.js.cn 相似文献