共查询到20条相似文献,搜索用时 31 毫秒
1.
A. V. Knyazev N. G. Chernorukov N. Yu. Kuznetsov 《Russian Journal of Inorganic Chemistry》2011,56(12):1875-1878
Compounds of composition Li
x
Na1 − x
VWO6 (0 ≤ x ≤ 1), which are synthetic analogues of brannerite-type minerals, were produced for the first time by solid-state synthesis
at high temperatures. The structure of the compounds and their unlimited miscibility in the solid phase in the LiVWO6-NaVWO6 binary system were determined by X-ray diffraction. The phase equilibrium diagram was studied by differential thermal analysis
together with thermodynamic modeling. It was found that the system under investigation is described by the regular solid solutions
model. 相似文献
2.
A. N. Nadeev S. V. Tsybulya E. Yu. Gerasimov N. A. Kulikovskaya L. A. Isupova 《Journal of Structural Chemistry》2010,51(5):891-897
A synthesis method with the use of polymer-salt compositions (calcination temperature 800°C) provides the preparation of various
solid solutions of a La1−x
Ca
x
FeO3−δ series in the 0≤ x≤ 0.7 range, which belong to the perovskite structure type. A morphotropic phase transition occurs from the orthorhombic perovskite
modification (0≤ x ≤ 0.4) to the cubic one (0.5 ≤ x≤ 0.7). A growing number of microdistortions in the perovskite structure and the formation of a microblock structure in the
morphotropic phase transition region are observed with increasing degree of calcium substitution for lanthanum. Calcination
of solid solutions with x = 0.6 and 0.7 at temperatures above 1000°C in the air or under conditions of reduced oxygen partial pressure (laboratory
vacuum of 10−3 Torr) results in the formation of a nanostructured state with coherently grown blocks of perovskite and Grenier phase, which
is due to irreversible oxygen loss. 相似文献
3.
Wanju Luo Dongliang Wang Xiande Peng Fangwei Wang 《Journal of Sol-Gel Science and Technology》2009,51(1):53-57
Nanosized multiferroic BiFeO3 powders were synthesized by a microwave combustion method. The average crystallite sizes of the samples stay at a same level
with the ratio of fuel glycine 0.5 ≤ G/N ≤ 1.5 and it increases significantly with G/N = 2.0. An inhomogeneity of amorphous
and microcrystallites is observed directly by HRTEM. A ferromagnetic hysteresis loop with a saturation magnetization (M
S) of ~0.09 μ
B
/Fe has been observed at room temperature in the sample with a crystallite size of 53 nm, whereas other powders with much
smaller crystallite size (~20 nm) will not saturate even at 20 kOe. These magnetic behaviors were ascribed to a combination
of the magnetic enhancement effect of a decreased crystallite size and superparamagnetic mechanism. 相似文献
4.
L. F. Brum Malta Marta Eloisa Medeiros 《Journal of Thermal Analysis and Calorimetry》2007,87(3):883-886
This work reports the study of Bi4V2–xBaxO11–1.5x (0.02≤x≤0.50)
series, which is a potential source of solid electrolytes to apply in oxygen
sensors. X-ray powder diffraction was used to point out the formation of major
ionic conductive phases and minor ones. The modifications of vanadate substructure
were probed, at short range, by Fourier-transform infrared spectroscopy. Differential
scanning calorimetry evidenced the formation of tetragonal γ phase, which
can be ionic conductive, for x=0.14. 相似文献
5.
Huaibing Sun Yungui Chen Chenghao Xu Ding Zhu Lihong Huang 《Journal of Solid State Electrochemistry》2012,16(3):1247-1254
Spinel powders of LiMn2−x
RE
x
O4 (RE = La, Ce, Nd, Sm; 0 ≤ x ≤ 0.1) have been synthesized by solid-phase reaction. The structure and electrochemical properties of these electrode materials
were characterized by X-ray diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge–discharge
experiment. The part substitution of rare-earth element RE for Mn in LiMn2O4 decreases the lattice parameter, resulting in the improvement of structural stability, and decreases the charge transfer
resistance during the electrochemical process of LiMn2O4. As a result, the cycle ability, 55 °C high-temperature and high-rate performances of LiMn2−x
RE
x
O4 electrode materials are significantly improved with increasing RE addition, compared to the pristine LiMn2O4. 相似文献
6.
Jun Wang Tianjin Zhang Hongying Xia Junhuai Xiang Wenkui Li Shuwang Duo 《Journal of Sol-Gel Science and Technology》2008,47(1):102-106
Compositionally graded Ba1−x
Sr
x
TiO3 (BST) (0 ≤ x ≤ 0.4) thin films were fabricated on Pt/Ti/SiO2/Si and YSZ/Pt/Ti/SiO2/Si substrates by a modified sol–gel technique. The YSZ buffer layer was prepared by RF magnetron sputtering. The microstructure
of the graded BST films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force
microscopy (AFM). The results showed that all the films have uniform and crack-free surface with a perovskite structure. The
graded BST film with an YSZ buffer layer has larger dielectric constant and lower dielectric loss. The leakage current density
of the graded BST film with an YSZ buffer layer lowers two orders than the film without buffer layer. The improved electric
properties of the graded films with an YSZ buffer layer was attributed to the YSZ buffer layer act as an excellent seeding
layer to enhance the graded BST film growth. 相似文献
7.
T. I. Krasnenko M. V. Rotermel’ S. A. Petrova R. G. Zakharov O. V. Sivtsova A. N. Chvanova 《Russian Journal of Inorganic Chemistry》2008,53(10):1641-1647
Phase relations in the Zn2V2O7-Cu2V2O7 system were studied by high-temperature X-ray diffraction and differential thermal analysis. The major phase constituents
of the system are solid solutions based on Zn2V2O7 and Cu2V2O7 polymorphs and their coexistence regions. The generation of α-Zn2 − 2x
Cu2x
V2O7 solid solution, where 0 ≤ x ≤ 0.30, leaves almost unchanged the stabilization temperature of the high-temperature zinc pyrovanadate phase. The α-Cu2 − 2x
Zn2x
V2O7 homogeneity range is 5 mol % Zn2V2O7. In the range 0.050 ≤ x ≤ 0.09 from 20 to ∼ 620°C, there is the two-phase field of α-Cu2V2O7 and β-Cu2V2O7 base solid solutions. At still higher temperatures, β-Zn2 − 2x
Cu2x
V2O7 and α-Cu2 − 2x
Zn2x
V2O7 coexist in the mixed-phase region. β-Zn2 − 2x
Cu2x
V2O7 solid solution, where 0 ≤ x ≤ 0.30, exists above 610 ± 5°C. The extent of the β′-Cu2V2O7-base solid solution is 9 to 65 mol % Zn2V2O7 at 615 ± 5°C, expanding to 0 mol % Zn2V2O7 with rising temperature.
Original Russian Text ¢ T.I. Krasnenko, M.V. Rotermel’, S.A. Petrova, R.G. Zakharov, O.V. Sivtsova, A.N. Chvanova, 2008, published
in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 10, pp. 1755–1762. 相似文献
8.
V. Ya. Kavun L. A. Zemnukhova A. I. Ryabov A. B. Podgorbunskii S. V. Gnedenkov S. L. Sinebryukhov V. I. Sergienko 《Russian Journal of Electrochemistry》2012,48(1):104-110
The methods of NMR, thermogravimetric analysis, and impedance spectroscopy were used to study ion mobility, phase transitions,
and ion conductivity in crystal phases in the KF-CsF-SbF3-H2O system. Analysis of 19F NMR spectra allowed tracing the dynamics of ion movement in the fluoride sublattice under temperature variations, determining
their types and temperature ranges, in which they are implemented. The observed phase transitions in potassium-cesium fluoroantimonates(III)
are phase transitions to the superionic state. It is found that the predominant form of ion movement in the high-temperature
modifications formed as a result of phase transitions becomes diffusion of fluoride ions. According to the results of electrophysical
studies the K1 − x
Cs
x
SbF4 (x ≤ 0.2) high-temperature phases are superionic. Their conductivity reaches the values of ∼10−2 to 10−3 S/cm at 463–483 K. The high-temperature phases are stabilized under cooling, which results in a significant increase in conductivity
at the room temperature. 相似文献
9.
Z. Branković K. Đuriš A. Radojković S. Bernik Z. Jagličić M. Jagodič K. Vojisavljevic G. Branković 《Journal of Sol-Gel Science and Technology》2010,55(3):311-316
Substituted lanthanum manganites with the general formula A1−x
B
x
MnO3 (A = La, B = Ca, Sr…) have attracted a lot of attention due to their exceptional electric and magnetic properties. In this
work, pure and Ca2+, Sr2+-doped LaMnO3 (LMO) with the concentrations of dopants 30% Ca2+ (LCMO), 30% Sr2+ (LSMO) and 15% Ca2+ + 15% Sr2+ (LCSMO) (in mol. %) were synthesized by polymerizable complex method. Bulk samples were prepared by sintering at 1300 °C
for 4 h in oxygen atmosphere. It was found that sintering in oxygen atmosphere enables preparation of single phase ceramics
with rhombohedral crystal structure. Chemically prepared fine, submicronic precursor powders provided uniform microstructure
and grain size distribution in final ceramics. As a result, pure and doped LMO ceramics with excellent microstructural and
magnetic properties were obtained. Depending on the composition, magnetic measurements showed high saturation magnetizations
(up to 93 emu/g), with values of the Curie temperature in the range 180–390 K and magnetoresistance up to 67%. 相似文献
10.
P. Tabero 《Journal of Thermal Analysis and Calorimetry》2007,88(1):37-41
Solid solution phases of a formula Fe8V10W16–xMoxO85 where 0≤x≤4, have been obtained, possessing a structure
of the compound Fe8V10W16O85.
It was found on the base of XRD and DTA investigations that these solution
phases melted incongruently, with increasing the value of x, in the temperature
range from 1108 (x=0) to 1083 K (x=4) depositing Fe2WO6
and WO3. The increase of the Mo6+
ions content in the crystal lattice of Fe8V10W16O85
causes the lattice parameters a=b contraction with cbeing
almost constant. IR spectra of the Fe8V10W16–xMoxO85 solid solution phases have been recorded. 相似文献
11.
Anna Maria Cardinale Daniele Macciò Adriana Saccone 《Journal of Thermal Analysis and Calorimetry》2012,108(2):817-823
The isothermal section at 500 °C of the Dy–Al–Si system was studied in the whole concentration range. The alloys were characterized
by X-ray powder diffraction, scanning electron microscopy and electron micro-probe analysis. A few samples were analysed by
differential thermal analysis. The following intermetallic compounds, some of them showing variable composition, were found:
DyAl2Si2 (τ1), hP5-CaAl2O2 structure type, Dy2Al3Si2 (τ2) mS14-Y2Al3Si2 structure type, Dy2Al1+x
Si2−x
(τ3), 0 ≤ x ≤ 0.25, oI10-W2CoB2 structure type and Dy6Al3Si (τ4), tI80-Tb6Al3Si structure type. A number of binary phases dissolve the third element forming ternary solid solutions: Dy(Al1−x
Si
x
)3, 0 ≤ x ≤ 0.5, hP16-Ni3Ti structure type, Dy(Al
x
Si1−x
)2, 0 ≤ x ≤ 0.1, oI12-GdSi2 structure type, Dy(Al
x
Si1−x
)1.67, 0 ≤ x ≤ 0.2, oI12-GdSi2 structure type, DyAl
x
Si1−x
, 0 ≤ x ≤ 0.2, oC8-CrB, and Dy5(Al
x
Si1−x
)3, 0 ≤ x ≤0.3, hP16-Mn5Si3 structure type. The melting point of Dy6Al3Si was determined. 相似文献
12.
B. Bhushan A. Basumallick N.Y. Vasanthacharya S. Kumar D. Das 《Solid State Sciences》2010,12(7):1063-1069
Multiferroic nanoparticles of Bi1?xSrxFeO3 (x = 0, 0.01, 0.03, 0.05 and 0.07) were prepared by a facile sol–gel route and the variation of their structural, optical, dielectric and magnetic properties on strontium concentration has been studied. XRD and TEM results confirm the phase purity of the samples having high degree of crystallinity and monodispersity. The average particle size shows an exponential decline with increase in Sr concentration. A shape transformation from a multifaceted polygon to a spherical one has been observed as Sr concentration in the sample increases to 5%. In the second derivative FTIR spectra, the intensity of vibration peak at ~593 cm?1 that is characteristic of rhombohedral BiFeO3 is seen to decrease after Sr doping. All the samples showed typical M–H behavior of a ferromagnet with saturation magnetization achieved within an applied magnetic field of 10 kOe. The sample with 3% Sr substitution displayed saturation and remanent magnetization values 1.37 emu/g and 0.32 emu/g respectively that are highest among all the samples studied. Presence of exchange coupling produced due to interaction between the antiferromagnetic core and ferromagnetic shell is also observed in all Bi1?xSrxFeO3 nanoparticles. 相似文献
13.
Zuci Quan Hao Hu Sheng Xu Wei Liu Guojia Fang Meiya Li Xingzhong Zhao 《Journal of Sol-Gel Science and Technology》2008,48(3):261-266
Bi1−x
Ce
x
FeO3 (x = 0, 0.05, 0.1, 0.15 and 0.20) (BCFO) thin films were deposited on Pt/TiN/Si3N4/Si substrates by sol–gel technique. Crystal structures, surface chemical compositions and bonding states of BCFO films were
investigated by X-ray diffraction and X-ray photoelectron spectroscopy (XPS), respectively. Compared to BiFeO3 (BFO) counterparts, the fitted XPS narrow-scan spectra of Bi 4f7/2, Bi 4f5/2, Fe 2p3/2, Fe 2p1/2 and O 1s peaks for Bi0.8Ce0.2FeO3 film shift towards higher binding energy regions by amounts of 0.33, 0.29, 0.43, 0.58 and 0.49 eV, respectively. Dielectric
constants and loss tangents of the BCFO (x = 0, 0.1 and 0.2) film capacitors are 159, 131, 116, 0.048, 0.041 and 0.035 at 1 MHz, respectively. Bi0.8Ce0.2FeO3 film has a higher remnant polarization (P
r = 2.04 μC/cm2) than that of the BFO (P
r = 1.08 μC/cm2) at 388 kV/cm. Leakage current density of the Bi0.8Ce0.2FeO3 capacitor is 1.47 × 10−4 A/cm2 at 388 kV/cm, which is about two orders of magnitude lower than that of the BFO counterpart. Furthermore, Ce cations are
feasibly substituted for Bi3+ in the Bi0.8Ce0.2FeO3 matrix, possibly resulting in the enhanced ferroelectric properties for the decreased grain sizes and the reduced oxygen
vacancies. 相似文献
14.
Anna Maria Cardinale Daniele Macciò Stefano Delfino Adriana Saccone 《Journal of Thermal Analysis and Calorimetry》2011,103(1):103-109
The isothermal section of the Nd–Al–Si ternary system at 500 °C has been investigated using differential thermal analysis,
X-ray diffraction analysis, scanning electron microscopy and electron micro-probe analysis. Four ternary intermetallic compounds
were confirmed: NdAl2Si2 (τ1), hP5-CaLa2O2 structure type, Nd2Al3Si (τ2), hP3-AlB2 structure type, NdAl1−x
Si1+x
, 0.25 ≤ x ≤ 0.3 (τ3), tI12-αThSi2 structure type and Nd2Al1−x
Si1+x
, 0 ≤ x ≤ 0.2, (τ5), oS8-CrB structure type. A new ternary intermetallic phase (τ4) was found: Nd4Al3Si3, orthorhombic oS20, isotypic with Pr4Al3Ge3. 相似文献
15.
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
16.
D. R. Mane D. D. Birajdar Swati Patil Sagar E. Shirsath R. H. Kadam 《Journal of Sol-Gel Science and Technology》2011,58(1):70-79
Cu0.7−
x
Co
x
Zn0.3Fe2O4 (0 ≤ x ≤ 0.5) nanoparticles are prepared by sol–gel auto combustion method, using copper nitrate, zinc nitrate, ferric nitrate,
cobalt nitrate, and citric acid as the starting materials. The process takes only a few minutes to obtain as-received Co-substituted
Cu–Zn ferrite powders. X-ray diffraction (XRD), vibrational sample magnetometer and thermo gravimetric analysis are utilized
in order to study the effect of variation in the Co substitution and its impact on particle size, lattice constant, density,
cation distribution and magnetic properties like magnetization, coercivity, remanent magnetization, ferritization temperature
and associated water content. Lattice parameter found to increase with increasing Co content, whereas X-ray density, bulk
density, particle size showed decreasing trend with the Co content. Cation distribution indicates that the Co and Cu ion show
preference towards octahedral [B] site, Zn occupy tetrahedral (A) site whereas Fe occupy both tetrahedral (A) and octahedral
[B] site. Redistribution of cations takes place for x > 0.3. Saturation magnetization (Ms) increases from 52.99 to 79.62 emu/g (x ≤ 0.3), for x > 0.3 Ms decreases with increase in Co content x. However, coercivity, magnetocrystalline anisotropy and remanent magnetization increases with the Co2+ substitution. 相似文献
17.
Rosa Maria Rojas K. Petrov G. Avdeev J. M. Amarilla L. Pascual J. M. Rojo 《Journal of Thermal Analysis and Calorimetry》2007,90(1):67-72
Chromium doped spinels LiCrYMn2−YO4 (0.2≤Y≤0.8) has been synthesized by the sucrose-aided combustion procedure. The thermal behaviour, phase homogeneity and structural
characteristics of the samples were studied by thermal analysis, coupled mass spectrometry, and room-and high-temperature
X-ray diffraction methods. It was found that the ‘as prepared’ samples contained residual organic impurities undetectable
for X-ray diffraction, that burn out completely at 400°C. Samples treated between 400 and 750°C are single phase spinels,
whose crystallites size increase from 10 to 50 nm on increasing the temperature. Cr-doping enhances the thermal stability
of the spinels, which augments on increasing the Cr content Y. The enhanced thermal stability of the spinels has been accounted
for based on the high excess stabilization energy of Cr3+ in octahedral ligand field. 相似文献
18.
L. F. da Silva M. I. B. Bernardi L. J. Q. Maia G. J. M. Frigo V. R. Mastelaro 《Journal of Thermal Analysis and Calorimetry》2009,97(1):173-177
This work reports on the synthesis of a SrTi1−x
Fe
x
O3 nanostructured compound (0.0 ≤ x ≤ 0.1) using a modified polymeric precursor method. The effect of the addition of iron on the thermal, structural and morphological
properties of the nanoparticles was investigated by FT-IR spectroscopy, X-ray diffraction, and field emission scanning electron
microscopy (FE-SEM). A thermogravimetric analysis indicated that the crystallization process preceded by three decomposition
steps. Differential thermal analysis experiments showed that decomposition occurred in a broad range of temperatures from
400 to 600 °C. It was observed that iron ions acted as catalysts, promoting rapid organic decomposition and phase formation
at a lower temperature than in SrTiO3. Moreover, the addition of iron decreased the crystallite size and increased the lattice parameter of the SrTi1−x
Fe
x
O3 structure. 相似文献
19.
Thermal behavior of xGa2O3–(50 − x)PbO–50P2O5 (x = 0, 10, 20, and 30 mol.% Ga2O3) and xGa2O3–(70 − x)PbO–30P2O5 (x = 0, 10, 20, 30, and 40 mol.% Ga2O3) glassy materials were studied by thermo-mechanical analysis (TMA) and differential thermal analysis (DTA). Replacement of
PbO for Ga2O3 is accompanied by increasing glass-transition temperature (263 ≤ T
g/°C ≤ 535), deformation temperature (363 ≤ T
d/°C ≤ 672), crystallization temperature (396 ≤ T
c/°C ≤ 640) and decreasing of coefficient of thermal expansion (5.1 ≤ CTE/ppm K−1 ≤ 16.7). Values of Hruby parameter were determined (0.1 ≤ K
H ≤ 1.3). The thermal stability of prepared glasses increases with increasing of concentration of Ga2O3. 相似文献
20.
Deuk Yong Lee Kyong-Ho Lee Myung-Hyun Lee Nam-Ihn Cho Bae-Yeon Kim 《Journal of Sol-Gel Science and Technology》2010,53(1):43-49
Ba1−x
Sr
x
TiO3(x = 0–0.5, BST) nanofibers with diameters of 150–210 nm were prepared by using electrospun BST/polyvinylpyrrolidone (PVP) composite
fibers by calcination for 2 h at temperatures in the range of 650–800 °C in air. The morphology and crystal structure of calcined
BST/PVP nanofibers were characterized as functions of calcination temperature and Sr content with an aid of XRD, FT-IR, and
TEM. Although several unknown XRD peaks were detected when the fibers were calcined at temperatures less than 750 °C, they
disappeared with increasing the temperature (above 750 °C) due to its thermal decomposition and complete reaction in the formation
of BST. In addition, the FT-IR studies of BST/PVP fibers revealed that the intensities of the O–H stretching vibration bands
(at 3430 and 1425 cm−1) became weaker with increasing the calcination temperature and a broad band at 540 cm−1, Ti–O vibration, appeared sharper and narrower after calcination above 750 °C due to the formation of metal oxide bonds.
However, no effect of Sr content on the crystal structure of the composites was detected. 相似文献