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P. Pasierb Ewa Drożdż-Cieśla R. Gajerski S. Łabuś S. Komornicki M. Rękas 《Journal of Thermal Analysis and Calorimetry》2009,96(2):475-480
The purpose of this work was to investigate the influence of titanium and yttrium dopants on chemical stability of selected
Ba(Ce1−xTix)1−yYyO3 compounds. The presented results are the part of wider research concerning the crystallographic structure, microstructure,
electrical and transport properties of these groups of materials.
Samples of Ba(Ce1−xTix)1−yYyO3 with x=0.05, 0.07, 0.10, 0.15, 0.20, 0.30 and y=0.05, 0.10, 0.20 (for x=0.05) were prepared by solid-state reaction method. Initially, differential thermal analysis (DTA) and thermogravimetry (TG)
were used for optimization of preparation conditions. Subsequently, DTA-TG-MS (mass spectrometry) techniques were applied
for evaluation of the stability of prepared materials in the presence of CO2. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results were used to determine the phase composition,
structure and microstructure of materials and to assist the interpretation of DTA-TG-MS results.
The strong influence of Ti and Y dopants contents (x and y) on the properties was found. The introduction of Ti dopant led to the improvement of chemical stability against CO2. The lower Ti concentration the better resistance against CO2 corrosion was observed. Doping by Y had the opposite effect; the decrease of chemical stability was determined. In this case
the higher Y dopant concentration the better resistance was observed. The attempt to correlate the influence of dopant on
structure and chemical stability was also presented. 相似文献
3.
D. V. Korchagin E. I. Zhilyaeva G. V. Shilov N. S. Ovanesyan S. M. Aldoshin 《Russian Journal of Inorganic Chemistry》2009,54(2):226-231
Single crystals of the Na4[Na2Cr2(C2O4)6] · 10H2O complex were synthesized for the first time. The structure of the complex was determined by X-ray diffraction analysis. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 17.290(4) Å, b = 12.521(3) Å, c = 15.149(3) Å, β = 100.45(3)°, Z = 4, space group Cc. Anionic layers [NaCr(C2O4)3] 2n 4n? can be distinguished in the crystal structure of the complex. The Na+ cations and water molecules, involved in the formation of a hydrogen bond network, are located between the anionic layers. 相似文献
4.
A new potassium cadmium hydrogen diphosphate dihydrate, KCdHP2O7?2H2O (1), has been synthesized by slow evaporation at room temperature and characterized by FT-IR, Raman, TG-DTA, and single crystal X-ray diffraction. Compound (1) crystallizes in the orthorhombic Pcmn space group with the unit cell parameters a = 6.5814(8) Å, b = 7.9428(9) Å, c = 15.961(6) Å, V = 834.4(3) Å3 and Z = 4. Its structure consists of polyhedral layers parallel to the ab plane where each CdO6 octahedron (m position) shares four edges with three different diphosphate groups. In the Cd octahedron, two oxygen atoms residing in (m) special positions belong to coordinated water molecules. These layers are joint by K+ cations (4c Wyckoff position) and hydrogen bonds, leading thus to a two-dimensional framework. The structural model is supported by the bond-valence-sum validation tool as calculated valences are close to the formal oxidation numbers. 相似文献
5.
Oxygen ion transference numbers for Gd2−xCaxTi2O7
−δ (x=0.10–0.14) pyrochlore ceramics were determined at 973–1223 K by the modified e.m.f. and faradaic efficiency techniques, taking
into account electrode polarization, and from the results on oxygen permeation. The ion transference numbers vary in the range
0.95–0.98 in air, increasing when the temperature or oxygen partial pressure decreases. The activation energies for the ionic
and p-type electronic transport in air are 74–77 and 87–91 kJ/mol, respectively. The p-type conductivity and oxygen permeability
of Gd2Ti2O7-based pyrochlores can be adequately described by relationships common for other solid electrolytes. At temperatures below
1273 K under a gradient of 10%H2+90%N2/air, average ion transference numbers for doped gadolinium titanate are not less than 0.97. Thermal expansion coefficients
for Gd2−xCaxTi2O7
−δ ceramics, calculated from dilatometric data in air, are in the range (10.4–10.6)×10−6 K−1 at 400–1300 K. 相似文献
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Antonín Klečka Šárka Langová Pavel Raška Juraj Leško Roman Pěnčík 《Chemical Papers》2015,69(10):1312-1318
Thermodynamic activity of sodium oxide and oxidation potential in NaOH—Na2O—Na2O2—H2O—NaH melt at the temperature of 400°C was investigated. Galvanic cell for the potentiometric measurements consisted either of a sodium electrode formed by β and β″-alumina semi-closed tube filled with liquid sodium or a platinum wire and of an oxygen electrode made from ZrO2 (Y2O3) solid electrolyte with the Bi—Bi2O3 reference mixture. The number of exchanged electrons determined from the electromotive force measurements was in good agreement with the assumed reactions. The activity coefficient of sodium oxide was lower than one. Voltammetric measurements were carried out with a sodium reference electrode and a nickel auxiliary electrode. Behaviour of platinum, gold, silver and nickel as working electrodes was studied. The experiments were carried out in nitrogen atmosphere. Several types of zirconia semi-closed tubes were tested for long-term measurements under the process conditions. 相似文献
8.
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
9.
Thomas Dippong Erika Andrea Levei Oana Cadar Firuta Goga Gheorghe Borodi Lucian Barbu-Tudoran 《Journal of Thermal Analysis and Calorimetry》2017,128(1):39-52
The thermal behavior of CoxFe3?xO4/SiO2 nanocomposites obtained by direct synthesis starting from nonahydrate ferric nitrate and hexahydrate cobalt nitrate in different ratios with and without the addition of 1,4-butanediol was studied. For the synthesis of CoxFe3?xO4 (x = 0.5–2.5) dispersed in the silica matrix a wide Co/Fe molar ratio was used. The decomposition processes, formation of crystalline phases, gases evolvement and mass changes during gels annealing at different temperatures were assessed by thermal analysis. The absence of succinate precursor and a low mass loss were observed in the case of the gel obtained in the absence of 1,4-butanediol. In case of gels obtained using a stoichiometric ratio of Co/Fe, no clear delimitation between Co and Fe succinates was observed, while for samples with a Fe or Co excess, the formation of the two succinates was observed. The evolution of the crystalline phase after annealing (673, 973 and 1273 K) investigated by X-ray diffraction analysis and Fourier transformed infrared spectrometry revealed that in samples with Fe excess, stoichiometric Fe/Co ratio or low Co excess, the cobalt ferrite (CoFe2O4) was obtained as a single phase, while in samples with higher cobalt excess, olivine (Co2SiO4) as a main phase, cobalt oxide and CoFe2O4 as secondary phases were obtained after annealing at 1273 K. The SEM images confirmed the nanoparticles embedding in the silica matrix, while the TEM and X-ray diffraction data showed that the obtained nanoparticles’ size was below 10 nm in most samples. 相似文献
10.
Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates.
These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC2O4 as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite
Na2Cu2+(C2O4)2·2H2O.
High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two
higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and
857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison
the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost
at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II)
oxalate as compared to the synthetic compound which is the dihydrate. 相似文献
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The synthesis of new compounds based on Bi2O3 is investigated because they can be used as new ecological inorganic pigments. Chemical compounds of the (Bi2O3)1−x(Y2O3)x type were synthesized. The host lattice of these pigments is Bi2O3 that is doped by Y3+ ions. The incorporation of doped ions provides the interesting colours and contributes to a growth of the thermal stability
of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment
formation and thermal stability of pigments. This paper also contains the results of the pigment characterization by X-ray
powder diffraction and their colour properties. 相似文献
13.
M. Yu. Shilova A. V. Vologzhanina L. B. Serezhkina V. N. Serezhkin 《Russian Journal of Inorganic Chemistry》2009,54(11):1763-1767
Single crystals of Li(H3O)[UO2(C2O4)2(H2O)] · H2O (I) have been synthesized and studied by X-ray diffraction. Compound I crystallizes in the monoclinic crystal system with the unit cell parameters: a = 7.1682(10) Å, b = 29.639(6) Å, c = 6.6770(12) Å, β= 112.3(7)°, space group P 21/c, Z = 4, R = 4.36%. Structure I contains discrete mononuclear groups [UO2(C2O4)2(H2O)]2? ascribed to the crystal-chemical group AB 2 01 M1 (A = UO2 2+, B01 =C2O 4 2? , M1 = H2O), which are “cross-linked” by the lithium ions into infinite layers {Li(UO2)(C2O4)2(H2O)2}? perpendicular to [010]. The hydroxonium ions are located between adjacent uranium-containing layers. A hydrogen bond system involving water molecules, oxalate ions, and hydroxonium combines the anionic layers into a three-dimensional framework. 相似文献
14.
N. A. Sanina S. M. Aldoshin T. N. Rudneva N. I. Golovina G. V. Shilov Yu. M. Shul’ga V. M. Martynenko N. S. Ovanesyan 《Russian Journal of Coordination Chemistry》2005,31(5):301-306
Binuclear iron nitrosyl complex Na2[Fe2(S2O3)2(NO)4] · 4H2O (I) was synthesized by the reaction of iron(II) sulfate with sodium thiosulfate in the flow of NO gas. According to X-ray diffraction data, the [Fe2(S2O3)2(NO)4]2– anion has binuclear centrosymmetric structure with Fe atoms bonded by the µ-S atoms of thiosulfate groups. The isomeric shift for complex I =0.168(1) mm/s and quadrupole splitting E
Q
=1.288 mm/s at T=80 K. When heated, complex I transforms to Na2[Fe2(S2O3)2(NO)4] (II), whose unit cell parameters found by X-ray diffraction method differ from those of complex I. The process of transformation of I to II was studied by calorimetric method. Complex I transforms to complex II without chemical decomposition, which was confirmed by IR and mass spectroscopy data.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 323–328.Original Russian Text Copyright © 2005 by Sanina, Aldoshin, Rudneva, Golovina, Shilov, Shulga, Martynenko, Ovanesyan. 相似文献
15.
L. B. Serezhkina E. V. Peresypkina A. V. Virovets I. V. Medrish D. V. Pushkin 《Russian Journal of Inorganic Chemistry》2009,54(10):1577-1580
Single crystals of Cs[(UO2)2(C2O4)2(OH)] · H2O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P21/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) Å3, R = 0.0444. The main building units of crystals are [(UO2)2(C2O4)2(OH)]? layers of the A2K 2 02 M2 (A = UO 2 2+ , K02 = C2O 4 2? , and M2 = OH?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules. 相似文献
16.
Dong-Yong Chung Heui-Seung Seo Jae-Won Lee Han-Beom Yang Eil-Hee Lee Kwang-Wook Kim 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(1):123-129
A feasibility and basic study to find a possibility to develop such a process for recovering U alone from spent fuel by using
the methods of an oxidative leaching and a precipitation of U in high alkaline carbonate media was newly suggested with the
characteristics of a highly enhanced proliferation-resistance and more environmental friendliness. This study has focused
on the examination of an oxidative leaching of uranium from SIMFUEL powders contained 16 elements (U, Ce, Gd, La, Nd, Pr,
Sm, Eu, Y, Mo, Pd, Ru, Zr, Ba, Sr, and Te) using a Na2CO3 solution with hydrogen peroxide. U3O8 was dissolved more rapidly than UO2 in a carbonate solution. However, in the presence of H2O2, we can find out that the leaching rates of the reduced SIMFUEL powder are faster than the oxidized SIMFUEL powder. In carbonate
solutions with hydrogen peroxide, uranium oxides were dissolved in the form of uranyl peroxo-carbonato complexes. UO2(O2)
x
(CO3)
y
2−2x−2y
, where x/y has 1/2, 2/1. 相似文献
17.
Eil-Hee Lee Jae-Gwan Lim Dong-Yong Chung Han-Beom Yang Kwang-Wook Kim 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(2):387-395
The removal of Cs and Re (as a surrogate for Tc) by selective precipitation from the simulated fission products which were
co-dissolved with uranium during the oxidative dissolution of spent fuel in a Na2CO3–H2O2 solution was investigated in this study. The precipitations of Cs and Re were examined by introducing sodium tetraphenylborate
(NaTPB) and tetraphenylohosponium chloride (TPPCl), respectively. The precipitation of Cs by NaTPB and that of Re by TPPCl
each took place within 5 min, and an increase in temperature up to 50 °C and a stirring speed up to 1000 rpm hardly affected
their precipitation rates. The most important factor in the precipitation with NaTPB and TPPCl was found to be a pH of the
solution after precipitation. Since Mo tends to co-precipitate with Cs or Re at a lower pH, an effective precipitation with
NaTPB and TPPCl was done at pH of above 9 without the co-precipitation of Mo. More than 99% of Cs and Re were precipitated
when the initial concentration ratio of NaTPB to Cs was above 1 and when that of TPPCl to Re was above 1. The precipitation
of Cs and Re was never affected by the concentration of Na2CO3 and H2O2, even though they were raised up to 1.5 and 1.0 M, respectively. Precipitation yields of Cs and Re in a Na2CO3–H2O2 solution were found to be dependent on the concentration ratios of [NaTBP]/[Cs] and [TPPCl]/[Re]. 相似文献
18.
Zh. V. Akhmerkina E. V. Peresypkina A. V. Virovets L. B. Serezhkina 《Russian Journal of Inorganic Chemistry》2008,53(9):1396-1400
Single crystals of Ba3[UO2(C2O4)2(NCS)]2 · 9H2O are synthesized and studied by X-ray diffraction. The crystals are orthorhombic, space group Fddd, Z = 16, and the unit cell parameters are a = 16.253(3) Å, b = 22.245(3) Å, c = 39.031(6) Å. The main crystal structural units are mononuclear complex groups [UO2(C2O4)2NCS]3? of the crystal-chemical family (AB 2 01 M1 (A = UO 2 2+ , B01 = C2O 4 2? , M1 = NCS?) of the uranyl complexes linked into a three-dimensional framework by electrostatic interactions and hydrogen bonds involving oxalate ions and water molecules. 相似文献
19.
S. K. Dedushenko Yu. D. Perfil’ev M. A. Chuev A. M. Afanas’ev 《Russian Journal of Inorganic Chemistry》2010,55(6):942-949
The first stage of the solid-phase reaction of Na2O2 and Fe2O3 yields a tetravalent iron derivative. The product is unstable and disproportionates to form compounds with different oxidation states of iron. Analysis of their Mössbauer spectra was performed with the DISCVER program based on the Afanas’ev-Chuev method. At the early stage of analysis, the program identifies the maximal possible number of well-defined lines in the spectrum with a specified statistical quality and, thus, discerns a large number of known and unknown iron derivatives (phases) in samples of complex composition. Previously unknown highest oxidation states of iron from +5 to +8 were identified. 相似文献
20.
E. A. Kiseleva S. I. Troyanov Yu. M. Korenev 《Russian Journal of Coordination Chemistry》2007,33(2):85-89
Single crystals of Mg pivalate hydrate, Mg(H2O)6(Piv)2 · 3H2O (HPiv = (CH3)3CCOOH) are synthesized and their structure is determined by X-ray diffraction method. The crystals are rhombic: a = 10.917(2) Å, b = 12.625(2) Å, c = 31.394(8) Å, Z = 8, space group Pbca, R 1 = 0.0525. The Mg atom has octahedral surrounding of the O atoms of water molecules (Mg-O 2.044–2.137 Å). The cationic chains of [Mg(H2O)6] ∞ 2+ lie in the voids of doubled network anionic layers of [(H2O)3(Piv)2] ∞∞ 2? . Inside the layer, the pivalate anions alternate with water molecules in the xy plane, being bonded to them by hydrogen bonds. The cationic chains and the anionic layers are united into layered packs by hydrogen bonds between coordinated water molecules and pivalate anions and between coordinated and crystal hydrate water molecules. 相似文献