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1.
Perovskite Bi1−x
Y
x
FeO3 (0.0 ≤ x ≤ 0.1) oxides were prepared by a citrate-gel method. The crystal structure examined by X-ray powder diffraction indicates
that the samples were single-phase and crystallize in a rhombohedral (space group, R-3c no. 161) structure. The structural phase transition from rhombohedral to orthorhombic phase was observed at x = 0.10. Increase in magnetization was observed as a result of Y doping. The optical band-gap of (Bi, Y)FeO3 materials were determined. The observed increase in magnetization and low band-gap of (Bi, Y)FeO3 ceramics position them for potential magenotoelectric and photocatalytic applications, respectively. 相似文献
2.
María Luisa Ojeda Monserrat Bizarro Antonio Campero 《Journal of Sol-Gel Science and Technology》2011,60(2):108-115
Nanostructured TiO2 films were synthesized by a modified sol–gel method using Pluronics P-123 (EO20PO70EO20) as templating agent, titanium n-butoxide [Ti(OC4H9)4] as inorganic precursor, and ammonium fluoride (NH4F) as the source of N and F dopant atoms in order to prepare sols of x(NF) TiO2 (x=2, 5, 10, 20 wt%). The thin film preparation was made by spin coating, followed by calcination at 400 °C. The as-prepared
TiO2 and xNF-TiO2 films were characterized by XRD, Raman spectroscopy, FTIR, TGA-DTA, SEM, UV–Vis diffuse reflectance spectroscopy and EPR.
XRD and Raman spectroscopy show that the crystalline structure of these samples consists exclusively of the anatase phase.
The band gap (E
g
) values for the doped 10 and 20 NF-TiO2 film systems were found to be significantly smaller than those corresponding to the rest of the other TiO2 films. The photocatalytic properties of these films are investigated by following the degradation of methyl orange in aqueous
solution under UV irradiation. The photodecomposition is mainly a direct function of the amount of NF present in the TiO2 matrix. The 20NF-TiO2 sample shows the highest activity of all the samples studied. 相似文献
3.
Petra Šulcová Jan Večeřa Pavel Bystrzycki 《Journal of Thermal Analysis and Calorimetry》2012,108(2):525-529
New environmentally inorganic pigments based on Bi2O3 doped by metal ions, such as Zr4+ and Dy3+ have been developed and characterized using the methods thermal analysis, X-ray powder diffraction, and spectral reflectance
data. The compounds having formula Bi2−x
Dy
x/2Zr3x/8O3 (x = 0.2, 0.6, 1.0, and 1.2) were prepared by the solid state reaction. Methods of thermal analysis were used for determination
of the temperature region of the pigment formation and thermal stability of compounds. The incorporation of doped ions in
Bi2O3 changes the color from yellow to orange and also contributes to a growth of their thermal stability. This property gives
a direction for coloring ceramic glazes. 相似文献
4.
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
5.
Tatiana Nedoseykina Pavel Plyusnin Yuri Shubin Sergey Korenev 《Journal of Thermal Analysis and Calorimetry》2010,102(2):703-708
Thermolysis of double complex salt [Pd(NH3)4][AuCl4]2 has been studied in helium atmosphere from ambient to 350 °C. The XAFS of Pd K and Au L3 edges and thermogravimetry measurements have been carried out to characterize the intermediates and the final product. In
the temperature range 115–160 °C the complex is decomposed to form Pd(NH3)2Cl2 and AuCl4−x
N
x
species with x ranging from 2 to 3. Subsequent heating of the intermediate up to 300 °C leads to the total loss of NH3. The Au–Cl and Au–Au bonds form the local environment of Au at the stage of decomposition while only four chlorine atoms
are around Pd. At the temperature of 330 °C the Au and Pd nanoparticles as well as residues of palladium chloride are detected.
The final product consists of separated Au and Pd nanoparticles. 相似文献
6.
Yuko Ichiyanagi Yuki Moro Hikaru Katayanagi Shinji Kimura Daiki Shigeoka Tomoyuki Hiroki Toshiyuki Mashino 《Journal of Thermal Analysis and Calorimetry》2010,99(1):83-86
Magnetic nanoparticles were prepared by a wet chemical method. Precursors of MFe2O4 (M = Co, Mn, Zn) were prepared from a mixture of metal chloride and metasilicate nonahydrate aqueous solutions. The precipitates
obtained in the wet chemical method were calcined to obtain MFe2O4 nanoparticles encapsulated by amorphous SiO2. The blocking temperatures T
B’s were between 20 and 320 K, in this temperature range, the anisotropy energy of the particles decreased below their thermal
energy. T
B increased with the particle size. In order to clarify the nanoparticle formation process, differential thermal analysis and
thermogravimetric (TG-DTA) measurements were performed for the as-prepared samples. 相似文献
7.
Y. Akishige H. Shigematsu T. Tojo H. Kawaji T. Atake 《Journal of Thermal Analysis and Calorimetry》2005,81(3):537-540
Summary Specific heats on the single crystals of Sr2Nb2O7, Sr2Ta2O7 and (Sr1-xBax)2Nb2O7 were measured in a wide temperature range of 2-600 K. Heat anomalies of a λ-type were observed at the incommensurate phase transition of TINC (=495 K) on Sr2Nb2O7 and at the super-lattice phase transition of TSL (=443 K) on Sr2Ta2O7; the transition enthalpies and the transition entropies were estimated. Furthermore, a small heat anomaly was observed at the low temperature ferroelectric phase transition of TLOW (=95 K) on Sr2Nb2O7. The transition temperature TLOW decreases with increasing Ba content x and it vanishes for samples of x>2%. 相似文献
8.
Noble metal-free, Cd1 − x
Zn
x
S-based photocatalysts for hydrogen evolution from aqueous solutions of sodium sulfide and sodium sulfite upon irradiation
with visible light (λ > 420 nm) have been synthesized and characterized by a complex of physicochemical methods. The effects
of pH and catalyst and substrate concentrations on the rate of photocatalytic hydrogen evolution have been investigated. Under
the optimal conditions, the quantum efficiency of the process is up to 12.9%. 相似文献
9.
H. Y. He 《Research on Chemical Intermediates》2010,36(2):155-161
The photocatalytic activity of S-doped TiO2 powder depends on the S content. To synthesize S-doped TiO2 powders with high S content, solvothermal processes were used in this work. The S-doped TiO2 powder contains 2.0 M% sulfur and has an absorption edge of 460 nm (2.7 eV). The pure TiS2 powder also synthesized by a solvothermal process has an absorption edge of 595 nm (2.08 eV) and broad absorption above 595 nm.
The photocatalysis experiments indicate that the degradation of methyl orange is associated with the light adsorption edge.
The photocatalytic activity is much larger for the pure TiS2 powder than for partially S-doped TiO2 powder. 相似文献
10.
Gold catalysts with loadings ranging from 0.5 to 7.0 wt% on a ZnO/Al2O3 support were prepared by the deposition–precipitation method (Au/ZnO/Al2O3) with ammonium bicarbonate as the precipitation agent and were evaluated for performance in CO oxidation. These catalysts
were characterized by inductively coupled plasma-atom emission spectrometry, temperature programmed reduction, and scanning
transmission electron microscopy. The catalytic activity for CO oxidation was measured using a flow reactor under atmospheric
pressure. Catalytic activity was found to be strongly dependent on the reduction property of oxygen adsorbed on the gold surface,
which related to gold particle size. Higher catalytic activity was found when the gold particles had an average diameter of
3–5 nm; in this range, gold catalysts were more active than the Pt/ZnO/Al2O3 catalyst in CO oxidation. Au/ZnO/Al2O3 catalyst with small amount of ZnO is more active than Au/Al2O3 catalyst due to higher dispersion of gold particles. 相似文献
11.
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
12.
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
13.
L. V. Yakovkina T. P. Smirnova V. O. Borisov S. Jeong-Hwan N. B. Morozova V. N. Kichai A. V. Smirnov 《Journal of Structural Chemistry》2011,52(4):743-747
The results of the investigation of the chemical constitution and structure of (HfO2)
x
(Sc2O3)1−x
thin films are reported. The films are obtained by chemical vapor deposition (CVD) from hafnium 2,2,6,6-tetramethyl-3,5-heptandionate
(Hf(thd)4) and scandium 2,2,6,6-tetramethyl-3,5-heptandionate (Sc(thd)3) coordination compounds. It is demonstrated by powder X-ray diffraction and infrared spectroscopy that depending on the scandium
content in the films the structure is changed from monoclinic to cubic. Voltage-capacity dependences of test Al/(HfO2)
x
(Sc2O3)1−x
/Si structures are used to calculate the dielectric constant of the films. For the films with the cubic structure it is found
that k = 21, while for the films with the monoclinic structure k = 9. 相似文献
14.
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
15.
Yun Zhou Can Guo Shengqi Xi Chongfeng Sun Hongjing Wu Feihu Shang 《Research on Chemical Intermediates》2017,43(3):1495-1512
ZnFe2O4 nanoparticles sensitized by C-modified TiO2 hybrids (ZnFe2O4–TiO2/C) were successfully prepared by a feasible method. The ZnFe2O4 nanoparticles were prepared by mechanical alloying and annealing. The residual organic compounds in the synthetic process of TiO2 were selected as the carbon source. The as-prepared composites were characterized by X-ray diffraction, Raman spectroscopy, X-ray fluorescence, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible light diffuse reflectance spectroscopy (UV–Vis) and N2 adsorption–desorption analysis. The photocatalytic activity of the photocatalysts was measured by degradation of methyl orange under ultraviolet (UV) light and simulated solar irradiation, respectively. The results show that the carbon did not enter the TiO2 lattice but adhered to the surface of TiO2. The photocatalytic activity of the as-prepared C-modified TiO2 (TiO2/C) improved both under UV and simulated solar light irradiation, but the improvement was not dramatic. Introduction of ZnFe2O4 into the TiO2/C could enhance the absorption spectrum range. The ZnFe2O4–TiO2/C hybrids exhibited a higher photocatalytic activity both than that of the pure TiO2 and TiO2/C under either UV or simulated solar light irradiation. The complex synergistic effect plays an important role in improving the photocatalytic performance of ZnFe2O4–TiO2/C composites. The optimum photocatalytic performance was obtained from the ZnFe2O4(0.8 wt%)–TiO2/C sample. 相似文献
16.
Two new heteropolyoxovanadoborates (H2dap)2H6{(VO)12O6[B3O6(OH)]6(H2O)}·13H2O (1, dap = 1,2-diaminopropane) and {[Zn(dien)]2[Zn(dien)(H2O)]4(VO)12O6[B3O6(OH)]6(H2O)}2·15H2O (2, dien = diethylenetriamine) have been hydrothermally synthesized and structurally characterized. Both 1 and 2 contain {(VO)12O6[B3O6(OH)]6(H2O)} cluster (denoted on V12B18), which is constructed by a puckered B18O36(OH)6 ring sandwiched between two triangles of six alternating cis and trans edge-sharing vanadium atoms, and a central water molecule. 1 consists of discrete [V12B18]10− cluster anions with H2dap2+ as counterions, while 2 consists of discrete neutral {[Zn(dien)]2[Zn(dien)(H2O)]4[V12B18]} clusters, which are built from two types of zinc(II) complex fragments connecting with V12B18 cluster through two Zn-(μ
3-O)-B bonds. Interestingly, 2 is the only example of the V12B18 cluster decorated by two types of zinc(II) complex fragments. 相似文献
17.
Marcela Stoia C. Caizer M. Stefanescu P. Barvinschi I. Julean 《Journal of Thermal Analysis and Calorimetry》2007,88(1):193-200
This article presents the results
of our investigation on the obtaining of Ni0.65Zn0.35Fe2O4 ferrite nanoparticles embedded in a SiO2 matrix using
a modified sol–gel synthesis method, starting from tetraethylorthosilicate
(TEOS), metal (FeIII,NiII,ZnII)
nitrates and ethylene glycol (EG). This method consists in the formation of
carboxylate type complexes, inside the silica matrix, used as forerunners
for the ferrite/silica nanocomposites. We prepared gels with different compositions,
in order to obtain, through a suitable thermal treatment, the nanocomposites
(Ni0.65Zn0.35Fe2O4)x–(SiO2)100–x (where x=10,
20, 30, 40, 50, 60 mass%). The synthesized gels were studied by differential
thermal analysis (DTA), thermogravimetry (TG) and FTIR spectroscopy.
The formation of Ni–Zn ferrite in the silica matrix and the behavior
in an external magnetic field were studied by X-ray diffraction (XRD) and
quasi-static magnetic measurements (50 Hz). 相似文献
18.
Mohammad El-khateeb Khalil J. Asali Ibrahim Jibril Anas Abuseni Helmar Görls Wolfgang Weigand 《Transition Metal Chemistry》2009,34(4):419-424
A controlled substitution reaction of the chlorine atoms of 1,3,5-benzenetricarbonyl trichloride by the organoiron fragment
(CpFe(CO)2S) has been achieved. The complexes CpFe(CO)2SCO-3,5-C6H3(COCl)2 (1), 1,3-[CpFe(CO)2SCO]2-5-C6H3COCl (2) and 1,3,5-[CpFe(CO)2SCO]3C6H3 (3) were prepared from the reaction of (μ-S
x
)[CpFe(CO)2]2 (x = 3, 4) with 1,3,5-C6H3(COCl)3 in a 1:1, 2:1, or 3:1 metal to ligand molar ratio. The reactions of (1) with amines, thiols, and carboxylic acids produce the trifunctional mono-iron complexes CpFe(CO)2SCO-3,5-C6H3(COY)2 [Y = NR2 (4), SR (5), OCOR (4)]. The X-ray structure determination of (1) is reported. 相似文献
19.
Weiming Wu Shijing Liang Zhengxin Ding Huarong Zheng Ling Wu 《Journal of Sol-Gel Science and Technology》2012,61(3):570-576
Nanosized ZnNb2O6 photocatalysts (band gaps ~4.0 eV) were successfully synthesized via a citrate complex method. Their particle sizes ranged
from 50 to 150 nm. The result of Mott–Schottky measurement revealed that the flat-band potential of ZnNb2O6 was ca. −1.3 V versus Ag/AgCl at pH 6.6. The photocatalytic activities of the samples for the degradation of methyl orange
were evaluated under UV-light (λ = 254 nm). It was found that the sample obtained at 850 °C showed the highest photocatalytic
activity due to its opportune crystallinity and surface area. Furthermore, ·OH radicals were detected as the major oxidation
agents responsible for the decomposition of methyl orange. 相似文献
20.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献