共查询到20条相似文献,搜索用时 31 毫秒
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A. I. Klyndyuk E. A. Tugova O. N. Karpov E. A. Chizhova M. V. Tomkovich V. M. Kononovich 《Russian Journal of General Chemistry》2016,86(10):2282-2287
The sequence of phases appearance during the formation of Bi1–xNdxFeO3 solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO3 or NdFeO3) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi1–xNdxFeO3 as the final product, due to the prevalence of various interphase contacts in the starting reaction zone. 相似文献
3.
I. B. Bakhtiyarly G. M. Fatullaeva O. Sh. Kerimli 《Russian Journal of Inorganic Chemistry》2018,63(7):962-965
The boundaries of the glass formation region in the ternary system La2O3–As2S3–Er2O3 were found. Transparent glass of composition (La2O3)0.03(As2S3)0.90(Er2O3)0.07 was studied by X-ray photoelectron and Raman spectroscopy. The intensities of the bands characterizing As–S, La–O, and Er–O bonds increased, and these bands were shifted toward higher energies. This was due to an increase in the covalence of these bonds and probably due to the formation of new bonds in the glasses. Samples in the glass formation region are resistant at 300 K to air, water, and organic solvents. 相似文献
4.
P. Mošner K. Vosejpková L. Koudelka L. Beneš 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1129-1135
The effect of TeO2 additions on the thermal behaviour of zinc borophosphate glasses were studied in the compositional series (100 − x)[0.5ZnO–0.1B2O3–0.4P2O5]–xTeO2 by differential scanning calorimetry, thermodilatometry and heating microscopy thermal analysis. The addition of TeO2 to the starting borophosphate glass resulted in a linear increase of glass transition temperature and dilatometric softening
temperature, whereas the thermal expansion coefficient decreased. Most of glasses crystallize under heating within the temperature
range of 440–640 °C. The crystallization temperature steeply decreases with increasing TeO2 content. The lowest tendency towards crystallization was observed for the glasses containing 50 and 60 mol% TeO2. X-ray diffraction analysis showed that major compounds formed by annealing of the glasses were Zn2P2O7, BPO4 and α-TeO2. Annealing of the powdered 50ZnO–10B2O3–40P2O5 glass leads at first to the formation of an unknown crystalline phase, which is gradually transformed to Zn2P2O7 and BPO4 during subsequent heating. 相似文献
5.
M. Kış M. Arı Y. Polat B. Erdoğan T. Karaaslan 《Journal of Structural Chemistry》2018,59(5):1133-1140
In the present work, Dy2O3 and Sm2O3 double-doped Bi2O3-based materials are synthesized by exploiting the solid-state synthesis method. The structural and temperature dependent electrical properties of these ternary ceramic samples, which are candidate materials for solid oxide fuel cell (SOFCs) electrolyte, are determined by means of a powder X-ray diffractometer (XRD), the four point-probe method (FPPM), and the thermal-gravimetry/differential thermal analysis (TG/DTA). As a result of the XRD measurements, the fluorite-type fcc δ-phase with a stable structure is obtained for higher values of the dopant oxide material, which are the samples with the maximum content of fixed 20% Dy2O3 and 15% and 20% Sm2O3. The samples with the stable δ-phase structure have higher conductivities. The highest electrical conductivity is found for the (Bi2O3)0.6(Dy2O3)0.2(Sm2O3)0.2 sample, which was 2.5×10–2 (Ohm cm)–1 at 750 °C. The activation energies are also calculated from the Arrhenius charts, which were determined from the FPPM measurements. The lowest activation energy is found as 0.85 eV for the sample with the highest electrical conductivity. 相似文献
6.
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
7.
T. N. Afonasenko N. N. Leont’eva V. P. Talzi N. S. Smirnova G. G. Savel’eva A. V. Shilova P. G. Tsyrul’nikov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(10):1939-1945
The textural and structural properties of mixed oxides Ga2O3–Al2O3, obtained via impregnating γ-Al2O3 with a solution of Ga(NO3)3 and subsequent heat treatment, are studied. According to the results from X-ray powder diffraction, gallium ions are incorporated into the structure of aluminum oxide to form a solid solution of spinel-type γ-Ga2O3–Al2O3 up to a Ga2O3 content of 50 wt % of the total weight of the sample, accompanied by a reduction in the specific surface area, volume, and average pore diameter. It is concluded that when the Ga2O3 content exceeds 50 wt %, the β-Ga2O3 phase is observed along with γ-Ga2O3–Al2O3 solid solution. 71Ga and 27Al NMR spectroscopy shows that gallium replaces aluminum atoms from the tetrahedral position to the octahedral coordination in the structure of γ-Ga2O3–Al2O3. 相似文献
8.
A quaternary super-ion-conducting system, 20CdI2 − 80[xAg2O − y(0.7V2O5 − 0.3B2O3)] where 1 ≤ x/y ≤ 3, has been prepared by melt quenching technique. The electrical conductivity measured was the order of 10−4 S/cm at room temperature. The values of silver-ion transport number obtained by electromotive force technique are nearly
unity. The thermoelectric power and electrochemical studies were done on the CdI2–Ag2O–V2O5–B2O3 system. The discharge and polarization characteristics were examined for different cathodes to evaluate the utility of these
cells as power sources for low energy applications. 相似文献
9.
B. Li Y. Y. Wang W. Q. Luo Y. H. Zhang 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(3):1619-1625
Radiation-induced degradation of the weakly and strongly 4-vinylpyridine basic ion exchange resins by gamma radiolysis was investigated in the presence of air and liquid water. This study is focused on evaluating the radiolytic gases (H2, CO, CO2 and CH4) and liquid products (water-solute TOC and NH4 +). The weakly basic resin yielded lower amounts of H2 and CO and higher amounts of CO2 than those of the strongly basic resin. Moreover, the strong basic resin tended to yield greater amounts of NH4 +. Resins were characterized by the FTIR spectroscopy technique and the results showed that the resins structures are relatively stable. 相似文献
10.
A. R. El-Sersy A. Hussein H. M. El-samman N. E. Khaled A. El-Adawy H. Donya 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):65-69
The total mass attenuation coefficients, partial interaction and the effective atomic numbers (Zeff) of glass system (80−x)B2O3–10Al2O3–10SiO2–xCaF2 (where x = 5, 10, 20, 25, 30, 35 and 40 mol %) have been calculated at photon energies 0.662 and 1.25 MeV using the WinXCom software
on the basis of mixture rule. Results indicated that the total mass attenuation coefficients showed a decrease with increasing
the CaF2 concentration, due to a decrease in Compton scattering probability, which gave a dominant contribution to the total mass
attenuation coefficients for the studied glass samples at both energies. However, the photoelectric absorption and coherent
scattering showed an increase with increasing the CaF2, concentrations at same energies. For a comparison, the total mass attenuation coefficients of the glass system had lower
values at the energy 1.25 MeV than that at 0.662 MeV. Zeff was found to increase linearly with the increase of CaF2 concentrations. It was concluded that low CaF2 concentrations in glass system, under study, have Zeff close to that of human tissue and have higher total absorption coefficients at energy of 0.662 MeV than that at 1.25 MeV.
These results are very useful in designing gamma radiation detectors using thermoluminescence technique. Therefore, it is
recommended to use low CaF2 concentration of our glass system as good gamma detectors at energy of 1.25 MeV. 相似文献
11.
The concentration space of homogeneous garnet in the system Ga2O3–(Y, Bi)3(Fe, Ga)5O12–Fe2O3 was determined by X-ray powder diffraction analysis. The obtained results expand the knowledge of the possible variations of cation ratios Y : Bi : Fe : Ga in garnet, which can be used for searching for and creating new stable magneto-optical materials. 相似文献
12.
Via sol–gel processing metal–organic fibers were produced and dried up to 140 °C. For these gel fibers the influence of a
treatment in different atmospheres was investigated for the temperature range of 200–850 °C. The atmospheres were nitrogen,
water vapor, evaporated nitric and hydrochloric acid and evaporated hydrogen peroxide. In the presence of moisture and especially
with acidic moisture fibers were transformed almost completely to their oxide composition (82 mol% Al2O3·18 mol% Y2O3). In these inorganic amorphous structures considerable differences were observed on several structural levels. On the atomic
scale, the coordination of Al ions was investigated by 27Al MAS NMR and skeletal density by He-pycnometry. Porosity in the nm scale was characterized by N2-sorption. As a macroscopic effect of different treatment atmospheres, the longitudinal shrinkage was observed. For fibers
treated at 500 °C the relative shrinkage varied by 100% (comparing water vapor and nitrogen atmosphere). No simple correlation
between the release of organic constituents, the formation of porosity and the shrinkage could be found. These aspects were
controlled by the rigidity of the inorganic network against atomic reconstitution. The kind of atmosphere was found to be
an effective parameter to control various aspects of the xerogel structure. 相似文献
13.
In this study, mechanical activation process was used for intimate mixing as well as producing finely ground particles, increased surface area and improved chemical reactivity of milled materials for producing SrTiO3 from commercially pure strontium carbonate and TiO2 as a contributive process. Characterization of milled powder mixture by X-ray diffraction analysis showed that disappearing, decreasing and/or shifting of the patterns occurred with mechanical activation that means amorphization was taken place. Amorphization was also demonstrated by FT-IR analysis where shift of band centers as well as the decrement of transmittance related to CO3 was observed. Advantage of amorphization was established with high-temperature XRD analysis which showed 1300 °C was not enough for non-activated mixture to form SrTiO3, whereas structure only composed of SrTiO3 at 1000 °C for activated ones. The reason for this phenomenon was investigated by DTA-TG analysis, and it was based on energy accumulation originated from mechanical activation that corresponds to peak temperature shifting to the lower temperatures and CO2 liberation at mechanical activation step arising from local temperature rising at the vial during high-energy milling that was understood from peak temperature, and area decrement of endothermic peak corresponds to decomposition of SrCO3. 相似文献
14.
L. M. Delitsyn 《Doklady Chemistry》2017,477(1):265-270
The system LaPO4–SiO2–NaF–Nb2O5–Fe2O3 is characterized by immiscibility fields in the liquid state region. Addition of iron expands fields of immiscibility of melts and decreases the temperature of their coexistence. A fraction of 87–90% of niobium is extracted into iron silicate melt, and 92–98% of lanthanum is extracted into phosphate salt melt. 相似文献
15.
The purpose of this work was to employ the differential thermal analysis (DTA) technique to compare variations in the collapse
energy of the zeolite Y crystalline structure in a fresh catalyst and in the same catalyst impregnated with nickel and vanadium.
A small exothermic signal in the DTA curve at 950–1150 °C indicated the collapse of the crystalline structure. The areas of
the exothermic signals in the DTA curves of the two samples indicated a reduction in the curve of the metal impregnated catalyst.
These results were compared with X-ray data, leading to the conclusion that metal impregnation affects the zeolite Y crystalline
structure and that the DTA technique is a potentially useful tool for measuring the integrity of zeolite Y in catalysts. 相似文献
16.
A. S. Ulikhin N. F. Uvarov K. B. Gerasimov A. A. Iskakova Yu. G. Mateishina 《Russian Journal of Electrochemistry》2017,53(8):834-837
Composite solid electrolytes were synthesized from the organic salt dimethylammonium chloride (1–x)C2H8NCl–xAl2O3. Their physicochemical properties were studied. In the starting C2H8NCl salt, there is a phase transition at 39°C accompanied by an increase in conductivity by two orders of magnitude. The conductivity of the high-temperature phase is 9.3 × 10–6 S/cm at 160°C. A differential scanning calorimetry study showed that the salt in the composites spreads over the oxide surface and at x > 0.6 the salt melting enthalpy decreases to zero. The conductivity of the resulting composites was studied by impedance spectroscopy. It was shown that heterogeneous doping leads to a sharp increase in ion conductivity to 7.0 × 10–3 S/cm at 160°C and a decrease in the activation energy to 0.55 eV. 相似文献
17.
K. A. Aly A. Dahshan Yasser B. Saddeek 《Journal of Thermal Analysis and Calorimetry》2010,100(2):543-549
The present paper reports on the effect of MoO3 on the glass transition, thermal stability and crystallization kinetics for (40PbO–20Sb2O3–40As2O3)100−x
–(MoO3)
x
(x = 0, 0.25, 0.5, 0.75 and 1 mol%) glasses. Differential scanning calorimetry (DSC) results under non-isothermal conditions
for the studied glasses were reported and discussed. The values of the glass transition temperature (T
g) and the peak temperature of crystallization (T
p) are found to be dependent on heating rate and MoO3 content. From the compositional dependence and the heating rate dependence of T
g and T
p, the values of the activation energy for glass transition (E
g) and the activation energy for crystallization (E
c) were evaluated and discussed. Thermal stability for (40PbO–20Sb2O3–40As2O3)100−x
–(MoO3)
x
glasses has been evaluated using various thermal stability criteria such as ΔT, H
r
, H
g and S. Moreover, in the present work, the K
r(T) criterion has been considered for the evaluation of glass stability from DSC data. The stability criteria increases with
increasing MoO3 content up to x = 0.5 mol%, and decreases beyond this limit. 相似文献
18.
T. N. Afonasenko N. S. Smirnova V. L. Temerev N. N. Leont’eva T. I. Gulyaeva P. G. Tsyrul’nikov 《Kinetics and Catalysis》2016,57(4):490-496
The structure of Ga2O3–Al2O3 supports and Pd/Ga2O3–Al2O3 catalysts and the performance of these catalysts in liquid-phase acetylene hydrogenation have been investigated. The deposition of Ga(NO3)3 onto Al2O3 by impregnation followed by calcination of the impregnated support at 600°C yields γ-Ga2O3–Al2O3 solid solutions containing up to 50 wt % Ga2O3. X-ray diffraction characterization of model palladium catalysts and their temperature-programmed reduction with hydrogen have demonstrated that, while palladium in Pd/Ga2O3 is in the form of a Pd2Ga alloy, in the Pd/γ-Ga2O3–Al2O3 catalyst there is no direct interaction between PdО and Ga2O3 particles and palladium is in the monometallic state. The introduction of 10–20 wt % gallium oxide into Al2O3 lowers the activity of the supported palladium catalyst relative to that of the initial Pd/Al2O3 but increases the ethylene yield by enhancing the ethylene formation selectivity. 相似文献
19.
Al2O3–TiO2 nanocrystalline powders were synthesized by sol–gel process. Aluminum sec-butoxide and titanium isopropoxide chemicals were
used as precursors and ethyl acetoacetate was used as chelating agent. Thermal and crystallization behaviors of the precursor
powders were investigated by thermal gravimetric-differential thermal analysis, Fourier-transform infrared spectrum and X-ray
diffraction. The average crystalline size of heat treated Al2O3–TiO2 powders at 1,100 °C is ~100 nm. 相似文献
20.
Magdalena Leśniak Marcin Gajek Janusz Partyka Maciej Sitarz 《Journal of Thermal Analysis and Calorimetry》2017,130(1):165-176
In this work, the structure and thermal properties of aluminosilicate fritted glazes in SiO2–Al2O3–CaO–MgO–Na2O–K2O–ZnO system with (4.0 mol%) and without addition of ZnO were examined by GIXRD, FTIR, MAS-NMR and thermal methods (DTA, DIL). It has been found that the all experimental glazes are amorphous material (transparent glazes). On the base of spectroscopic investigations, it was found that zinc ions exist in the network glazes in the octahedral coordination—Zn2+ ions play a network modifier role in structure of glazes. An analysis of the data obtained from thermal tests showed that addition of ZnO into chemical composition results in decrease in glass transition temperature value (T g) for all glazes (DTA, DIL). The coefficient of thermal expansion (α) is decreased as the whole measurement range for one series of fritted glazes. 相似文献