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1.
The layered LiNi0.5Mn0.47Al0.03O2 was synthesized by wet chemical method and characterized by X-ray diffraction and analysis of magnetic measurements. The
powders adopted the α-NaFeO2 structure. This substitution of Al for Mn promotes the formation of Li(Ni0.472+Ni0.033+Mn0.474+Al0.033+)O2 structures and induces an increase in the average oxidation state of Ni, thereby leading to the shrinkage of the lattice
unit cell. The concentration of antisite defects in which Ni2+ occupies the (3a) Li lattice sites in the Wyckoff notation has been estimated from the ferromagnetic Ni2+(3a)–Mn4+(3b) pairing observed below 140 K. The substitution of 3% Al for Mn reduces the amount of antisite defects from 7% to 6.4–6.5%.
The analysis of the magnetic properties in the paramagnetic phase in the framework of the Curie–Weiss law agrees well with
the combination of Ni2+ (S = 1), Ni3+ (S = 1/2) and Mn4+ (S = 3/2) spin-only values. Delithiation has been made by the use of K2S2O8. According to this process, known to be softer than the electrochemical one, the nickel ions in the (3b) sites are converted into Ni4+ in the high spin configuration, while Ni2+(3a)–Mn4+(3b) ferromagnetic pairs remain, as the Li+(3b) ions linked to the Ni2+(3a) ions in the antisite defects are not removed. The results show that the antisite defect is surrounded by Mn4+ ions, implying the nonuniform distribution of the cations in agreement with previous NMR and neutron experiments. 相似文献
2.
S.K. Rout T. Badapanda E. Sinha S. Panigrahi P.K. Barhai T.P. Sinha 《Applied Physics A: Materials Science & Processing》2008,91(1):101-106
BaTi0.6Zr0.4O3 (BTZ) ceramic was synthesized by a soft chemical route. X-ray diffraction at room temperature shows that the sample has cubic
perovskite structure with space group Pm-3m. Temperature dependent dielectric study of the sample has been investigated in
the frequency range from 50 Hz to 1 MHz. The density of the sample was determined using Archimedes’ principle and found to
be ∼ 97% of the X-ray density. The average grain size in the pallet was found to be ∼ 1 μm. The dielectric constant peaks
at temperature Tm which is dependent on the frequency. The dielectric relaxation rate follows the Vogel–Fulcher relation with activation energy = 0.0185 eV,
and freezing temperature = 186 K. All these measurements confirm that BTZ is a relaxor ferroelectric.
PACS 77.22.Jp; 77.84.-s; 77.80.Bh; 77.22.Gm 相似文献
3.
V.M. Sreekumar R.M. Pillai B.C. Pai M. Chakraborty 《Applied Physics A: Materials Science & Processing》2008,90(4):745-752
The present study analyzes the morphological transformations of reaction products i.e., MgO, MgAl2O4 occurring during the reaction between SiO2 and Al-Mg alloy in Al-Mg-SiO2 composite processed by the liquid metallurgy technique. Different phases of platelet and hexagonal morphologies are detected
and their composition analysis by EDS has confirmed them as being transition phases existing between MgO, MgAl2O4 and Al2O3. This study has also revealed the gradual transformation of (i) MgO needles to octahedral MgAl2O4 through Mg-Al-Si-O and Mg-Al-O transition phases having platelet morphologies and (ii) MgAl2O4 to Al2O3 through hexagonal transition phases on holding of Al-5Mg-SiO2 and Al-1Mg-SiO2 composites respectively at 1023K. Fully developed α-Al2O3 crystals are not observed under the present experimental conditions, wherein the Mg content is well above the equilibrium
Mg content required for the formation of stable Al2O3 (<0.05 wt. %).
PACS 05.70.Np 相似文献
4.
There has been an increasing interest towards the incorporation of nanosize ceramic fillers in polymer electrolytes. Solid
polymer electrolytes based on polyvinylidene fluoride (PVDF), silver triflate (AgCF3SO3), and x wt% of aluminum oxide (Al2O3) nanopowders (where x = 1, 3, 5, and 10, respectively) have been prepared using solution casting technique. The structural characteristics of these
thin film specimens were studied using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) patterns at room temperature.
The appearance of new absorption bands and gradual shifts observed in some characteristic peaks confirmed the complex formation
between polyvinylidene fluoride and silver triflate. Furthermore, the addition of nanosized filler Al2O3 has also indicated the interaction of the filler with the polymer salt complex. The XRD patterns obtained for all these samples
in the 2θ range 10° to 70° showed the amorphous nature of these samples.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, December 7–9,
2006. 相似文献
5.
Four nanocrystalline ZrO2(Y)- and Al2O3-based powders synthesized by plasma spray pyrolysis have been studied. It has been shown that the ZrO2(3Y)-based system with second component Al2O3 forms a nonequilibrium solid solution ZrO2(3Y, Al) with the tetragonal structure. It has been found that the existence of an component (ZrO2(Y)) insoluble in the coarse-grained state in Al2O3-based systems causes the delay of the γ → α transformation and decreases the size of the coherently scattering domains of
formed nanosized modifications of Al2O3. 相似文献
6.
Photopyroelectric spectroscopy of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> - ZnO ceramics
A. Zakaria Z. Rizwan M. Hashim A. Halim Shaari W. Mohmood Mat Yunus 《The European physical journal. Special topics》2008,153(1):33-35
Photopyroelectric spectroscopy is used to study the
band-gap energy of the ceramic (ZnO + xSb2O3), x = 0.1 - 1.5 mol%
and the ceramic (ZnO + 0.4 mol% Bi2O3 + xSb2O3), x = 0 - 1.5 mol% sintered at isothermal temperature, 1280 °C, for 1 and 2 hours. The wavelength of incident light, modulated
at 9 Hz, is kept in the visible range and the photopyroelectric spectrum with
reference to doping level is discussed. The band-gap energy is reduced from
3.2 eV, for pure ZnO, to 2.86, 2.83 eV for the samples without
Bi2O3at 0.1 mol% of Sb2O3 for 1 and 2 hours of
sintering time, respectively. It is reduced to 2.83, 2.80 eV for the samples
with Bi2O3 at 0 mol% of Sb2O3 for 1 and 2 hours of
sintering time, respectively. The steepness factor σA which
characterizes the slop of exponential optical absorption is discussed with
reference to the doping level. The phase constitution is determined by XRD
analysis; microstructure and compositional analysis of the selected areas
are analyzed using SEM and EDX. 相似文献
7.
Xiao-Ping Shen Hua-Juan Miao Hui Zhao Zheng Xu 《Applied Physics A: Materials Science & Processing》2008,91(1):47-51
Well-aligned Co3O4 nanotubes were synthesized within the nanochannels of porous anodic alumina membranes using a single-source chemical vapor
deposition method. Scanning electron microscopy and transmission electron microscopy showed that the Co3O4 nanotubes are highly ordered with uniform diameter in the range of 100–300 nm and length up to tens of microns. X-ray diffraction,
the Raman spectrum, energy-dispersive spectroscopy and selected-area electron diffraction demonstrated that the nanotubes
are composed of pure cubic phase polycrystalline Co3O4. Magnetic measurements using a SQUID magnetometer suggested the presence of a strong antiferromagnetic interaction with Weiss
constant θ= -248 K. The real and imaginary parts of the ac susceptibility at f= 10 Hz had a maximum at 4.0 K, and the field
dependence of the magnetization at 1.8 K showed a small hysteresis loop with a coercivity of ∼ 98 Oe.
PACS 81.07.De; 81.15.Gh; 78.30.-j; 75.75.+a; 61.46.Np 相似文献
8.
Q. Zhang J. Yang X. Wu S. Qin 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(1):11-16
An investigation into the high-pressure behavior of Sc2O3 was
conducted using first-principle calculations based on density functional theory within the
generalized gradient approximation. Nine candidate phases were considered and simulated,
C-, B-, A-RES, Rh2O3(II), Gd2S3,
U2S3, Al2Er3, corundum and PPv respectively.
Our results demonstrate phase transitions of Sc2O3 from C- to B-RES
phase at 15 GPa, then to Gd2S3 phase at 18 GPa. Elastic constants of
Sc2O3 present softening from about 270 GPa to 337 GPa, associated
with a semiconductor-to-metal crossover. The Gd2S3-type
Sc2O3 is both mechanically and dynamical stable at least up to
302 GPa supported by the mechanically stable criteria and the phonon spectrum. 相似文献
9.
Solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 was prepared by sol-gel method under different sintering conditions. The structural identification, surface morphology, electrochemical
window, ionic conductivity, and activation energy of the Li1.3Al0.3Ti1.7(PO4)3 sintered pellets were investigated by X-ray diffraction, scanning electron microscopy, cyclic voltammetry, and electrochemical
impedance spectroscopy. It is found that the sintering temperature and time have considerable effect on the properties of
the Li1.3Al0.3Ti1.7(PO4)3 sintered pellets. The Li1.3Al0.3Ti1.7(PO4)3 pellet sintered at 900 °C for 2 h is denser than the pellets sintered at other conditions. Different sintering conditions
result in the sintered pellet with different porosity. However, the sintering conditions have little effect on the electrochemical
window of Li1.3Al0.3Ti1.7(PO4)3. Among the Li1.3Al0.3Ti1.7(PO4)3 pellets sintered at various conditions, the pellet sintered at 900 °C for 2 h shows the highest ionic conductivity of 3.46 × 10−4 S cm−1 and the lowest activation energy of 0.2821 eV. 相似文献
10.
The preparation of (La9.33−2x/3Sr
x
□0.67−x/3)Si6O24O2 (0 ≤ x ≤ 2) samples with different amounts of cation vacancies is reported. Structure and unit-cell parameters were deduced by Rietveld
analysis of XRD patterns. Structural features that enhance oxygen conductivity in Sr-doped apatites are discussed. Up to three
components were detected in 29Si MAS-NMR spectra which change with the amount and distribution of cation vacancies. In general, oxygen conductivity increases
with the amount of vacancies at La1 (6h) sites, passing through a maximum for x = 0.4. In the case of activation energy, a minimum is detected near x = 1.2, indicating that entropic and enthalpic change in different ways. The presence of cation vacancies should enhance oxygen
hopping along c-axis; however, the analysis of the frequency dependence of conductivity suggests that oxygen motions are produced along three
axes. 相似文献
11.
Christelle Navone Jean-Pierre Pereira-Ramos Rita Baddour-Hadjean Raphael Salot 《Ionics》2010,16(7):577-580
We report for the first time the use of lithiated crystalline V2O5 thin films as positive electrode in all-solid-state microbatteries. Crystalline LixV2O5 films (x ≈ 0.8 and 1.5) are obtained by vacuum evaporation of metallic lithium deposited on sputtered c-V2O5. An all-solid-state lithium microbattery of Li1.5V2O5/LiPON/Li exhibited a typical reversible capacity of 50 μAh/cm2 in the potential range 3.8/2.15 V which exceeds by far the results known on all-solid-state lithium batteries using amorphous
V2O5 films and lithiated amorphous LixV2O5 thin films as positive electrode. Hence, the present work opens the possibility of using high performance crystalline lithiated
V2O5 thin films in rocking-chair solid-state microbatteries. 相似文献
12.
This paper reports on the spectroscopic properties and energy transfer analysis of Tm3+-doped BaF2-Ga2O3-GeO2-La2O3 glasses with different Tm2O3 doping concentrations (0.2, 0.5, 2.0, 2.5, 3.0, 3.5, 3.5, 4.0 wt%). Mid-IR fluorescence intensities in the range of 1,300 nm−2,200 nm
have been measured when excited under an 808 nm LD for all the samples with the same pump power. Energy level structure and
Judd-Ofelt parameters have been calculated based on the absorption spectra of Tm3+, cross-relaxation rates and multi-phonon relaxation rates have been estimated with different Tm2O3 doping concentrations. The maximum fluorescence intensity at around 1.8 μm has been obtained in Tm2O3-3 wt% sample and the maximum value of calculated stimulated emission cross-section of Tm3+ in this sample is about 0.48 × 10−20 cm2 at 1,793 nm, and there is not any crystallization peak in the DSC curve of this sample, which indicate the potential utility
of Tm3+-doped BaF2-Ga2O3-GeO2- La2O3 glass for 2.0-μm optical fiber laser. 相似文献
13.
P. V. Korolev I. R. Gavrilov M. R. Gavrilov A. V. Korolev 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(11):1495-1499
It is shown that a nonequilibrium solid solution ZrO2(3Y, Al) with tetragonal structure is formed in systems based on ZrO2(3Y) with Al2O3 as a second component. A delay in the γ → α Al2O3 transformation and a reduction in the size of the coherently scattering domain of modifications are observed in systems based
on Al2O3 with ZrO2(Y) as a second component. 相似文献
14.
C. Masingboon S. Maensiri T. Yamwong P.L. Anderson S. Seraphin 《Applied Physics A: Materials Science & Processing》2008,91(1):87-95
Nanocrystalline CaCu3Ti4O12 powders with particle sizes of 50–90 nm were synthesized by a simple method using Ca(NO3)2·4H2O, Cu(NO3)2·4H2O, titanium(diisoproproxide) bis(2,4-pentanedionate) and freshly extracted egg white (ovalbumin) in aqueous medium. The synthesized
precursor was characterized by TG-DTA to determine the thermal decomposition and crystallization temperature which was found
to be at above 400 °C. The precursor was calcined at 700 and 800 °C in air for 8 h to obtain nanocrystalline powders of CaCu3Ti4O12. The calcined CaCu3Ti4O12 powders were characterized by XRD, FTIR, SEM and TEM. Sintering of the powders was conducted in air at 1100 °C for 16 h.
The XRD results indicated that all sintered samples have a typical perovskite CaCu3Ti4O12 structure and a small amount of CuO, although the sintered sample of the 700 °C calcined powders contained some amount of
CaTiO3. SEM micrographs showed the average grain sizes of 12.0±7.8 and 15.5±8.9 μm for the sintered CaCu3Ti4O12 ceramics prepared using the CaCu3Ti4O12 powders calcined at 700 and 800 °C, respectively. The sintered samples exhibit a giant dielectric constant, ε′ of ∼ 1.5–5×104. The dielectric behavior of both samples exhibits Debye-like relaxation, and can be explained based on a Maxwell–Wagner model.
PACS 77.22.Gm; 81.05.Je; 81.07.Wx; 81.20.Ev 相似文献
15.
R. Moubah S. Colis C. Ulhaq-Bouillet G. Schmerber N. Viart M. Drillon A. Dinia D. Muller J. J. Grob 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(3):315-319
Layered cobalt oxides Ca3Co4O9 thin films have been grown directly on c-cut sapphire substrates using pulsed laser deposition. X-ray diffraction and transmission
electron microscopy characterizations show that the deposited films present the expected monoclinic structure and a texture
along the direction perpendicular to the Al2O3(001) plane. The Ca3Co4O9 structure presents six variants in the film plane. Rutherford backscattering spectroscopy shows that the films are stoichiometric
and that the film thickness agrees with the nominal value. The susceptibility χ of the films, recorded along the c-axis of
the substrate, after field cooling and zero field cooling in an applied field of 1 kOe shows two magnetic transitions at 19
and 370 K which agree well with previous findings on single crystal samples. In turn, at low temperature (5 K), the magnetization
curve along the c-axis exhibits coercive field and remanent magnetization much smaller than those reported for bulk samples,
which can be related to the influence of structural variants and structural defects. 相似文献
16.
We study the dynamics of ions produced upon ablation of Al and ceramic Al2O3 targets using nanosecond laser pulses at 193 nm (6.4 eV) as a function of the laser fluence from threshold up to 12 J cm−2. An electrical (Langmuir) probe located at 40 mm from the target surface has been used for determining the ion yield and
calculating the kinetic energy distributions. The results for both targets show the existence of a significant amount of ions
having kinetic energies >200 eV (≈20% around threshold fluence), and kinetic energies are up to >1.5 keV. The results are
related with the existence of direct photonionization processes caused by the photon energy of the laser being higher than
the ionization potential of Al (5.98 eV). Comparison of the ion yield when ablating the two types of targets for fluences
above threshold to data reported in the literature suggests that the magnitude of the yield and its threshold are parameters
depending on the thermal properties of the target rather than on the laser wavelength. Around threshold, the different behavior
of ion yield when ablating Al and Al2O3 targets suggests that the threshold for neutral aluminium and ion species in the case of ablation of the Al2O3 target must be similar. 相似文献
17.
Lei Shi Jiang Yin Kuibo Yin Feng Gao Yidong Xia Zhiguo Liu 《Applied Physics A: Materials Science & Processing》2008,90(2):379-384
As potential gate dielectric materials, pseudobinary oxide (TiO2)x(Al2O3)1-x (0.1≤x≤0.6) films (TAO) were deposited on Si (100) substrates by pulsed-laser deposition method and studied systematically
via various measurements. By a special deposition process, including two separate steps, the TAO films were deposited in the
form of two layers. The first layer was deposited at room temperature and the second layer was completed at the substrate
temperature of 400 °C. Detailed data show that the properties of the TAO films are closely related to the ratio between TiO2 and Al2O3. The existence of the first layer deposited at room temperature can effectively restrain the formation of the interfacial
layer. And according to the results of X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy
performed on the films, no other information belonging to the silicon oxide could be observed. For the (TiO2)0.4(Al2O3)0.6 film, the best result has been achieved among all samples and its dielectric constant is evaluated to be about 38. It is
valuable for the amorphous TAO film as one of the promising dielectric materials for high-k gate dielectric applications.
PACS 77.55.+f; 73.40.Qv; 81.15.Fg 相似文献
18.
A new member of the family of garnets with fast lithium ion conduction has been found with the composition Li7La3Hf2O12. The anion arrangement corresponds to the oxygen framework in garnets, e.g., in Ca3Fe2Si3O12. Hafnium is coordinated octahedrally while the lanthanum environment can be described as a distorted cube. Lithium occupies
a large number of positions with tetrahedral, trigonal planar, and metaprismatic coordination. Li7La3Hf2O12 shows a lithium bulk ion conductivity of 2.4 × 10−4 Ω−1 cm−1 at room temperature with an activation energy of 0.29 eV. 相似文献
19.
The effects of dopant on the electrochemical properties of spinel-type Li3.97M0.1Ti4.94O12 (M = Mn, Ni, Co) and Li(4-x/3)CrxTi(5-2x/3)O12(x = 0.1, 0.3, 0.6, 0.9, 1.5) were systematically investigated. Charge-discharge cycling were performed at a constant current
density of 0.5 mA/cm2 between the cut-off voltages of 3.0 and 1.0 V, the experimental results showed that Cr3+ dopant improved the reversible capacity and cycling stability over the pristine Li4Ti5O12. The substitution of the Mn3+ and Ni3+ slightly decreased the capacity of the Li4Ti5O12. Dopants such as Co3+ to some extent worsened the electrochemical performance of the Li4Ti5O12. 相似文献
20.
The lead pyrophosphate, Pb2P2O7, compound was prepared by conventional solid-state reaction and identified by X-ray powder diffractometer. Pb2P2O7 has a triclinic structure whose electrical properties were studied using impedance spectroscopy technique. Both impedance
and modulus analysis exhibit the grain and grain boundary contribution to the electrical response of the sample. The temperature
dependence of the bulk and grain boundary conductivity were found to obey the Arrhenius law with activation energies E
g = 0.66 eV and E
gb = 0.67 eV, respectively. The scaling behavior of the imaginary part of the complex impedance suggests that the relaxation
describes the same mechanism at various temperatures. 相似文献