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1.
Synthetic spinels of the system MgO-Cr2O3-Al2O3-Fe2O3 are considered and the desirability of organizing their production for the refractory industry is demonstrated.
Translated from Novye Ogneupory, No. 6, pp. 32–35, June 2008. 相似文献
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Cerium oxide is one of the most important rare earth elements that is introduced into glass compositions due to its great effects on the optical properties. CeO2 was introduced in Hench’s patented SiO2-Na2O-CaO-P2O5 glasses with different concentrations in order to study its effect on the optical behavior of this glass including optical band gap, transmittance, reflectance and refractive index and to give a complete view for the optical properties on cerium oxide-doped silicate glasses. 相似文献
4.
Jingfu Wang Yan Wang 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(4):913-918
In the present study, the crystallization behavior and thermal stability of amorphous Zr55Cu20Ni10Al10Ti5 alloy, obtained by melt-spinning, have been investigated using X-ray diffraction (XRD), differential thermal analysis (DTA)
and transmission electron microscopy (TEM). The activation energy for crystallization has been evaluated by the Kissinger
method, and it has been found that E
x obtained from the crystallization onset temperature (T
x) is lower than E
p determined by the crystallization peak temperature (T
P). During the continuous annealing process, ZrO and h-Al3Zr5 phases firstly precipitate from the amorphous matrix, then Zr2Ni0.66O0.33 phase forms continuously and its relative content increases with increasing annealing temperature. However, no crystalline
phases have been observed during the isothermal annealing process at 733 K (below T
x) for 90 min. The atomic clusters can keep the stability state through adjusting the short-range ordering. 相似文献
5.
Yu. K. Startsev A. A. Pronkin I. A. Sokolov I. V. Murin 《Glass Physics and Chemistry》2011,37(3):263-282
The glasses, in which oxygen was partially replaced with sulfur, have been synthesized in the Na2O-P2O5-Na2S system. The chemical and chromatographic analyses of the glasses synthesized have been performed. The temperature-concentration
dependences of electrical conductivity of the glasses have been studied over a wide temperature range; the glass transition
temperatures and the nature of charge carriers have been determined. The IR spectra and Raman spectra have been recorded at
room temperature; the density and microhardness of the glasses and ultrasound velocity have been measured. A comparison of
the electrical conductivities of the investigated glasses with those of the earlier studied glasses in the Na2O-P2O5 system has shown their fair coincidence. The introduction of sodium sulfide into the Na2O-P2O5 system is accompanied by an approximately threefold increase in electrical conductivity, although the concentrations of charge
carriers (sodium ions) in the glasses amount to ∼17 and ∼26 mmol/cm3, respectively. The rise in electrical conductivity has been assumed to be caused by the increase in the degree of dissociation
of polar structural chemical units including sulfide ions and by the higher mobility of sodium ions in the oxygen-free matrix. 相似文献
6.
V. F. Popova E. A. Tugova A. S. Isaeva I. A. Zvereva V. V. Gusarov 《Glass Physics and Chemistry》2007,33(5):498-501
The phase formation is investigated and the phase diagram of the Ho2O3-SrAl2O4 system is constructed. A ternary compound, namely, Ho2SrAl2O7, is revealed. It is established that this compound undergoes incongruent melting. 相似文献
7.
I. A. Zvereva V. F. Popova E. A. Tugova N. S. Pylkina V. V. Gusarov 《Glass Physics and Chemistry》2005,31(6):808-811
The phase equilibria are investigated and the phase diagram is constructed for the Gd2O3-SrAl2O4 pseudobinary join of the Gd2O3-SrO-Al2O3 ternary oxide system. One ternary compound, namely, Gd2SrAl2O7, is revealed in the Gd2O3-SrAl2O4 join. It is found that this compound undergoes congruent melting. 相似文献
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9.
V. G. Vyatchina L. A. Perelyaeva M. G. Zuev I. V. Baklanova 《Glass Physics and Chemistry》2009,35(6):580-585
A glass formation region has been established in the MgSO4-Na2B4O7-KPO3 system. This region is located in the borate-phosphate part of the concentration triangle and occupies ∼40% of the triangle
area. Based on the spectral data obtained (nuclear magnetic resonance, IR and Raman spectroscopy), a model is proposed in
terms of which the physicochemical properties (such as the linear thermal expansion coefficient, the softening temperature,
and the glass transition temperature) of the samples are discussed. 相似文献
10.
F. M. Sapountzi S. Brosda K. M. Papazisi S. P. Balomenou D. Tsiplakides 《Journal of Applied Electrochemistry》2012,42(9):727-735
The performance of La0.75Sr0.25Cr0.9M0.1O3 (M = Mn, Fe, Co, and Ni) perovskitic materials as anodes was studied for a CO-fueled solid oxide fuel cell. The electrocatalytic performance and the tolerance to carbon deposition were investigated, while electrochemical characterization was carried out via AC impedance spectroscopy and cyclic voltammetry. The La0.75Sr0.25Cr0.9Fe0.1O3 perovskite showed the best anode performance at temperatures above 900 °C; while at temperatures below 900 °C, the best performance was achieved with the La0.75Sr0.25Cr0.9Co0.1O3 material. AC impedance spectroscopy was used for a semi-quantitative analysis of the LSC-M0.1 anodes performance in view of total cell and charge transfer resistance. All anode materials exhibit high electronic conductivity and presumably do not substantially contribute to the overall cell resistance and concomitant ohmic losses. 相似文献
11.
Junyeong Kim Jeong Yeon Do No-Kuk Park Seung Jong Lee Jin-Pyo Hong Misook Kang 《Korean Journal of Chemical Engineering》2018,35(5):1089-1098
Nano-sized bismuth sulfide (Bi2S3) and titanium dioxide (TiO2) with the orthorhombic and anatase tetragonal structures, respectively, were synthesized for application as catalysts for the reduction of carbon dioxide (CO2) to methane (CH4). Four double-layered dense films were fabricated with different coating sequences—TiO2 (bottom layer)/Bi2S3 (top layer), Bi2S3/TiO2, TiO2/Bi2S3: TiO2 (1 : 1) mix, and Bi2S3: TiO2 (1 : 1) mix/Bi2S3: TiO2 (1 : 1) mix—and applied to the photoreduction of CO2 to CH4; the catalytic activity of the fabricated films was compared to that of the pure TiO2/TiO2 and Bi2S3/Bi2S3 doubled-layered films. The TiO2/Bi2S3 double-layered film exhibited superior photocatalytic behavior, and higher CH4 production was obtained with the TiO2/Bi2S3 double-layered film than with the other films. A model of the mechanism underlying the enhanced photoactivity of the TiO2/Bi2S3 double-layered film was proposed, and it was attributed in effective charge separation. 相似文献
12.
Structure and crystalline behavior of the ternary system ZnO-B2O3-P2O5 glasses were investigated by means of X-ray diffraction (XRD) and infrared Raman spectra. The research showed that number
of the planar [BO3] units increases with the increase of B2O3 content. When the B2O3 content is above ≥10 mol %, the relative content of planar [BO3] units increases rapidly and causes weakening of the glass structure and decrease in the chemical stability. In the crystallized
glasses the predominant crystal phase Zn2P2O7 decreases with the increase of B2O3 content, while the crystal phase BPO4 increases with it, which cause the declining of chemical stability and the decrease of thermal coefficients of expansion. 相似文献
13.
Pharatree Jaita Anucha Watcharapasorn Sukanda Jiansirisomboon 《Nanoscale research letters》2012,7(1):24
Lead-free piezoelectric compositions of the (1-x)Bi0.5(Na0.40K0.10)TiO3-x(Ba0.7Sr0.3)TiO3 system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050°C and
1,175°C for 2 h. The effect of (Ba0.7Sr0.3)TiO3 [BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was
1,125°C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that
showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain
size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the
BNKT ceramic. A large room-temperature dielectric constant, ε
r
(1,609), and piezoelectric coefficient, d
33 (214 pC/N), were obtained at an optimal composition of x = 0.10. 相似文献
14.
Amorphous La2O-TiO2 powders were synthesized by the polymerized complex (PC) method. The activation energies for crystallization and grain growth
of La2Ti2O7 from these precursors were determined from results of XRD and DTA and compared with those for La2Ti2O7 precursors by the conventional solid-state reaction (SSR). Activation energy of grain growth of La2Ti2O7 in PC-sample was determined to be 7.1 kJ/mol while that of SSR sample was 14.8 kJ/mol. The energy required for the phase
transformation from amorphous PC sample to layered perovskite was 432 kJ/mol, while the SSR sample did not show this transition
below 900‡C. It was clearly demonstrated that the La2Ti2O7 crystals were formed at a lower temperature and they grew in size faster in the sample prepared by the PC method relative
to the sample prepared by the SSR method. Mixing of elements in molecular level in PC preparation appeared responsible for
these differences. 相似文献
15.
The electrical conductivity of chalcogenide semiconductor films in the CuI-AsI3-As2Se3 and CuI-SbI3-As2Se3 systems, which have been prepared by chemical deposition from mono-n-butylamine, has been studied as a function of the temperature and film composition. It has been established that the electrical
conductivity of the CuI-AsI3-As2Se3 and CuI-SbI3-As2Se3 films is predominantly determined by the copper iodide content. It has been demonstrated that the electrical properties of
the chalcogenide glasses and the related films are characterized by the same values to within the experimental error, which
is explained by the same model of dissolution of vitreous semiconductors in amines with the retention of the electrical properties
of chalcogenide glasses after the deposition of films from their solutions. 相似文献
16.
Cong Luo Ying Zheng Ning Ding Chuguang Zheng 《Korean Journal of Chemical Engineering》2011,28(4):1042-1046
To improve the stability of CaO adsorption capacity for CO2 capture during multiple carbonation/calcination cycles, modified CaO-based sorbents were synthesized by sol-gel-combustion-synthesis
(SGCS) method and wet physical mixing method, respectively, to overcome the problem of loss-in-capacity of CaO-based sorbents.
The cyclic CaO adsorption capacity of the sorbents as well as the effect of the addition of La2O3 or Ca12Al14O33 was investigated in a fixed-bed reactor. The transient phase change and microstructure were characterized by X-ray diffraction
(XRD) and field emission scanning electron microscopy (FSEM), respectively. The experimental results indicate that La2O3 played an active role in the carbonation/calcination reactions. When the sorbents were made by wet physical mixing method,
CaO/Ca12Al14O33 was much better than CaO/La2O3 in cyclic CO2 capture performance. When the sorbents were made by SGCS method, the synthetic CaO/La2O3 sorbent provided the best performance of a carbonation conversion of up to 93% and an adsorption capacity of up to 0.58 g-CO2/g-sorbent after 11 cycles. 相似文献
17.
The highly ordered mesoporous CoFe2O4 and CuFe2O4 with crystalline walls can be synthesized by hard template with using mesoporous silica SBA-15 as hard template and using ferric nitrate, cobalt nitrate, and copper nitrate as metal precursors. These new mesoporous materials above have high surface areas, narrow pore size distribution, and large pore volumes, which are believed to be valuable for the potential application in the field of sensors, catalysis, message recording, magnetics, and biology. This work provides a method to fabricate the highly ordered mesoporous materials composed of multi-metal oxides with crystalline walls. The development of such versatile approach is of great significance in practical application. It can be envisaged that this established method is significantly expandable to the controlled synthesis of the mesoporous functional materials with diverse compositions. 相似文献
18.
Kamila Michalska Paweł Kowalik Wiesław Próchniak Tadeusz Borowiecki 《Catalysis Letters》2018,148(3):972-978
19.
I. A. Zvereva A. M. Sankovich A. B. Missyul’ V. L. Ugolkov 《Glass Physics and Chemistry》2010,36(2):209-216
The processes of phase formation in the Nd2O3-TiO2-Na2CO3 system have been investigated in the temperature range 500–1100°C. The mechanism of the high-temperature solid-phase reaction
of formation of the complex oxide Na2Nd2Ti3O10 has been studied. It has been established that the Na2Nd2Ti3O10 compound is formed from the intermediate product Na0.5Nd0.5TiO3 with a perovskite structure in the temperature range 830–890°C and from the NaNdTiO4 oxide with a perovskite-like layered structure in the temperature range 960–1100°C. 相似文献
20.
The atomic structure of the amorphous metallic alloy Al83.5Ni9.5Si1.4La5.6 is investigated based on the analysis of the experimental atomic radial distribution function (ARDF) in the fragmentary model. A comparative analysis of the most probable interatomic distances in the alloy and possible compounds based on it has demonstrated the presence of crystalline nuclei of the following phases: Al3La, Al3Ni, Al2.12La0.88, Al3Ni5, and Al. The largest ones (1–2 nm) are nuclei of the Al3Ni and Al compound, while the majority nuclei of all the other phases had sizes of about 7 Å. Al and Al3Ni, as well as Al11La3 and Al5.56LaNi1.44 are observed in the crystallized alloy. 相似文献