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1.

Вид документа : Статья из журнала
Шифр издания : 54/A 10
Автор(ы) : Istomin S. Ya., Antipov E. V., Svensson G., Attfield J. P., Kozhevnikov V. L., Leonidov I. A., Patrakeev M. V., Mitberg E. B.
Заглавие : A Novel Complex Cobalt Gallium Oxide Ca2Co0.8Ga1.2O4.8: Synthesis and High-Temperature Electron Transport Properties
Параллельн. заглавия :A Novel Complex Cobalt Gallium Oxide Ca2Co0.8Ga1.2O4.8: Synthesis and High-Temperature Electron Transport Properties
Место публикации : Journal of Solid State Chemistry. - 2002. - V. 167, N 1. - С. 196-202. - ISSN 0022-4596. - ISSN 0022-4596
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Аннотация: A new complex oxide with the cation ratio Ca:Co:Ga = 2:0.8:1.2 has been synthesized in air at 1150oC. The cobalt atoms adopt oxidation states 2+ and 3+ in equal amounts giving an oxygen content corresponding to the composition Ca2Co0.8Ga1.2O4.8. It crystallizes in F-centered cubic structure with a = 15.0558 Angstrom. Conductivity measurements performed at high temperatures revealed that the temperature increase gives a charge disproportionation of Co3+ species resulting in a small concentration of Co4+ species and thus a small p-type conductivity in the oxide. A decrease of the oxygen pressure promotes oxygen depletion from the oxide and a deterioration of the conductivity. The electric properties are interpreted within a small polaron conduction mechanism. An unusually large mobility activation energy of 0.45 eV can be explained by a large spatial separation of cobalt cations in the structure
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2.

Вид документа : Статья из журнала
Шифр издания : 54/A 29
Автор(ы) : Akashev L. A., Kononenko V. I.
Заглавие : Optical properties of liquid La, Ce, Pr and Nd
Место публикации : Physics and chemistry of novel materials: 4th Bilateral Russian-German Symposium (Febr. 24-March 1, 1999): Progr. and abstr. - Ekaterinburg, 1999. - С. 4.1
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): свойства оптические--оптические свойства--проводимость оптическая--оптическая проводимость--la--лантан--ce--церий--pr--празеодим--nd--неодим--металлы твердые--твердые металлы--металлы жидкие--жидкие металлы--оптические проводники--проводники оптические
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3.

Вид документа : Статья из журнала
Шифр издания : 54/A 90
Автор(ы) : Melnikova N. V., Kurochka K. V., Kheifets O. L., Volkova Y. Y., Kadyrova N. I.
Заглавие : Atomic structure and ionic conductivity of glassy materials based on silver sulfide
Место публикации : Bulletin of the Russian Academy of Sciences: Physics. - 2015. - Vol. 79, № 6. - С. 719-722
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): ионные проводники--нанотрубки--проводимость
Аннотация: The effect of the composition of glassy ionic conductors AgGe1 + x As1–x S3 and the composites based on these materials containing single-walled carbon nanotubes (CNT) AgGe1+x As1–x (S + CNT)3, on the atomic structure and ionic conductivity is analyzed.
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4.

Вид документа : Статья из журнала
Шифр издания : 54/E 43
Автор(ы) : Patrakeev M. V., Bahteeva J. A., Mitberg E. B., Leonidov I. A., Kozhevnikov V. L., Poeppelmeier K. R.
Заглавие : Electron/hole and ion transport in La1-xSrxFeO3-delta
Место публикации : Journal of Solid State Chemistry. - 2003. - V. 172, N 1. - С. 219-231. - ISSN 0022-4596. - ISSN 0022-4596
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): электронные дырки--ионный перенос--la1-xsrxfeo3-дельта--ферриты лантаностронциевые--кислородная проводимость--проводимость кислородная--электронная проводимость--проводимость электронная--лантан-стронций
Аннотация: The conductivity of the entire solid solution La1-xSrxFeO3-delta, where x = 0.2, 0.4, 0.5, 0.7 and 0.9, in the oxygen partial pressure range 10(-19)-0.5 atm and temperatures between 750°C and 950°C is reported. The partial contributions from different charge carriers and the energetic parameters governing transport of charged species reveal that the lanthanum-strontium ferrites can be characterized as mixed, ion-electron conductors in the low oxygen pressure/high oxygen deficiency limit. The partial contributions to conductivity from oxygen ions, electrons and holes increase with strontium content and attain maximal values at x = 0.5. Further increase in doping results in development of oxygen vacancy ordering phenomena and deterioration of conducting properties
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5.

Вид документа : Статья из журнала
Шифр издания : 54/E 43
Автор(ы) : Zainullina V. M., Volkov V. L., Podvalnaya N. V., Ivanovskii A. L.
Заглавие : Electronic structure and chemical bonding in K2V3O8
Место публикации : Journal of Structural Chemistry. - 2005. - Vol. 46, № 2. - С. 340-342
Примечания : Библиогр. : с. 342 (14 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): поливанадат калия--ионная проводимость
Аннотация: The calculations of the electronic structure of layered polyvanadate K2V3O8 were made employing the spinpolarized tight-binding LMTO method. Calculated magnetic moment for K4V6O16 compound phase equals 1.97 мB. V-O interactions were established to be dominating in the chemical bonding generation in this polyvanadate according to the estimated crystal orbital overlap population. The covalent bonds V(2)-V(2) in V(2)2O7 groups and electron density localization on vanadium atoms in isolated pyramids V(1)O were found.
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6.

Вид документа : Статья из журнала
Шифр издания : 54/F 42
Автор(ы) : Lazoryak B. I., Belik A. A., Stefanovich S. Yu., Morozov V. A., Malakho A. P., Baryshnikova O. V., Leonidov I. A., Leonidova O. N.
Заглавие : Ferroelectric–Ionic Conductor Phase Transitions in Optical Nonlinear Ca9R(VO4)7 Vanadates
Место публикации : Doklady Physical Chemistry. - 2002. - vol. 384, № 4-6. - С. P. 144-148: il.
Примечания : Bibliogr. : p. 148 (15 ref.)
ISSN: 0012-5016
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): ферроэлектрики--ионная проводимость--фазовый переход--ванадаты
\\\\Expert2\\nbo\\Doklady Physical Chemistry\\2002, V. 384, N 4-6, p.144-148.pdf
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7.

Вид документа : Статья из журнала
Шифр издания : 54/H 65
Автор(ы) : Mitberg E. B., Patrakeev M. V., Leonidov I. A., Kozhevnikov V. L., Poeppelmeier K. R.
Заглавие : High-temperature electrical conductivity and thermopower in nonstoichiometric La1-xSrxCoO3-delta (x = 0.6)
Место публикации : Solid State Ionics. - 2000. - V. 130, N 3-4. - С. 325-330. - ISSN 0167-2738. - ISSN 0167-2738
Примечания : Библиогр.: 18 назв.
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): электропроводность высокотемпературная--высокотемпературная электропроводность--нестехиометрия--термоэдс--лантан--стронций--кобальт--проводники смешанные--смешанные проводники--кобальтиты--проводимость электронная--электронная проводимость--la--sr--co
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8.

Вид документа : Статья из журнала
Шифр издания : 54/H 65
Автор(ы) : Bahteeva Ju. A., Leonidov I. A., Patrakeev M. V., Mitberg E. B., Kozhevnikov V. L., Poeppelmeier K. R.
Заглавие : High-temperature ion transport in La1-xSrxFeO3-delta
Параллельн. заглавия :High-temperature ion transport in La1-xSrxFeO3-delta
Место публикации : Journal of Solid State Electrochemistry . - 2004. - V. 8, N 9. - С. 578-584. - ISSN 1432-8488 . - ISSN 1432-8488
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Аннотация: The conductivity of the entire solid solution La1-xSrxFeO3-delta, where x = 0.2, 0.4, 0.5, 0.7 and 0.9, in the oxygen partial pressure range 10(-19) to 0.5 atm and temperatures between 750 and 950 °C is reported. The analysis of the isothermal pressure dependences of the conductivity reveal that the lanthanum-strontium ferrites can be characterized as mixed ion-electron conductors in the low-oxygen pressure/high-oxygen deficiency limit. The partial contribution to conductivity from oxygen ions increases with strontium content and attains a maximal value at x = 0.5. Further increase in doping results in the development of oxygen vacancy ordering phenomena and deterioration of the conducting properties
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9.

Вид документа : Статья из журнала
Шифр издания : 54/H 99
Автор(ы) : Kharton V. V., Marques F. M. B., Tsipis E. V., Viskup A. P., Vyshatko N. P., Patrakeev M. V., Naumovich E. N., Frade J. R.
Заглавие : Interfacial effects in electrochemical cells for oxygen ionic conduction measurements. III. Transference numbers vs. grain-boundary resistivity
Место публикации : Solid State Ionics. - 2004. - V. 168, N 1-2. - С. 137-151. - ISSN 0167-2738. - ISSN 0167-2738
Примечания : Bibliogr.: p. 151 (35 ref.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Аннотация: Resistive grain boundaries may significantly influence transference numbers of oxygen ion-conducting ceramics due to a distinct blocking effect on the ionic transport with respect to the electronic conduction. This may lead to remarkable uncertainties, particularly in the boundary resistance estimates obtained using impedance spectroscopy without a separation of the ionic and electronic contributions, and in the interpretation of transport parameters determined by DC techniques. The role of grain boundaries was examined by the example of "pure" and SiO2-containing pyrochlore ceramics Gd2-xCaxTi2O7-delta (x = 0.05-0.14), studied at 973-1223 K using impedance spectroscopy, faradaic efficiency and e.m.f. methods. The oxygen ion transference numbers of "pure" materials in air vary in the range 0.95-0.98, increasing when temperature decreases. As expected, minor additions of SiO2 result in segregation of siliceous phase and highly resistive grain boundaries.The total ion transference numbers of silicaenriched ceramics become considerably lower, 0.76-0.89, and increase with increasing temperature due to relatively high activation energy for the boundary resistivity; the bulk transference numbers extracted from the impedance spectroscopy and faradaic efficiency data are similar for all compositions, with and without SiO2 additions. The results, including dependence of the transport properties on oxygen pressure, suggest that a simplified description of the boundaries as a passive transport-limiting barrier is sufficiently adequate
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10.

Вид документа : Статья из журнала
Шифр издания : 54/I-76
Автор(ы) : Patrakeev M. V., Markov A. A., Leonidov I. A., Kozhevnikov V. L., Kharton V. V.
Заглавие : Ion and electron conduction in SrFe1-xScxO3-delta
Место публикации : Solid State Ionics. - 2006. - Vol. 177, № 19-25. - С. P.1757-1760
Примечания : Bibliogr. : p. 1760 (12 ref.)
ISSN: 0167-2738
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): ионная проводимость, электронная проводимость--стронций--железо--скандий--нестехиометрия
Аннотация: The oxygen ion and electron transport in SrFe1-xScxO3-delta (x =0.1–0.3) system at 700–950 -C were studied analyzing the total conductivity dependencies on the oxygen partial pressure, pO2. The conductivity measurements were performed both under reducing conditions (10(-19)
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11.

Вид документа : Статья из журнала
Шифр издания : 54/I-76
Автор(ы) : Patrakeev M. V., Leonidov I. A., Kozhevnikov V. L., Kharton V. V.
Заглавие : Ion-electron transport in strontium ferrites: relationships with structural features and stability
Место публикации : Solid State Sciences. - 2004. - Vol. 6, № 9. - С. 907-913
Примечания : Bibliogr. : p. 913 (27 ref.)
ISSN: 1293-2558
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): феррит стронция--нестехиометрия кислородная--проводимость ионная--ионный перенос--электронный транспорт
Аннотация: The total electrical conductivity of strontium ferrites, including intergrowth Sr4Fe6O13+delta, Sr3Fe2O6+delta with a Ruddlesden-Popper??structure, and SrFeO2.5+delta where the cubic perovskite lattice transforms into vacancy-ordered brownmillerite at p(O2) 10 Pa and??T 850 .C, was measured at 650.1000 .C in the oxygen partial pressure range 10.15 Pa to 50 kPa. The data were used in order to determine partial ion, p- and n-type electron contributions in the vicinity of electron.hole equilibrium point. The ferrites with brownmillerite and Ruddlesden-Popper structures exhibit substantial ion transport due to thermally-activated disordering of oxygen vacancies and??oxygen ions in the perovskite structural slabs, whereas the ion conductivity of Sr4Fe6O13+delta remains below 0.01 S cm.1 in the studied??conditions. The bonding energy of oxygen ions, evaluated from the formation enthalpy of n-type charge carriers, increases in the sequence??Sr4Fe6O13+delta SrFeO3+delta Sr3Fe2O6delta. These values correlate with thermodynamic stability of strontium ferrites at low p(O2). The??transition of SrFeO2.5+delta brownmillerite into disordered cubic phase above 850 .C leads to higher stability in reducing atmospheres. The??level of p-type conductivity is mainly governed by the concentration of electron holes, which was calculated from the oxygen content??determined by coulometric titration technique. The hole mobility, which is quite similar for all strontium ferrites and has a temperatureactivated??character, varies in the range 0.005.0.05 cm2 V.1 s.1 indicative of small-polaron conduction mechanism
\\\\Expert2\\nbo\\Solid State Sciences\\2004, v.6, N 9, p.907.pdf
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12.

Вид документа : Статья из журнала
Шифр издания : 54/H 99
Автор(ы) : Yaremchenko A. A., Shaula A. L., Kharton V. V., Waerenborgh J. C., Rojas D. P., Patrakeev M. V., Marques F. M. B.
Заглавие : Ionic and electronic conductivity of La9.83-xPrxSi4.5Fe1.5O26 + or - delta apatites
Параллельн. заглавия :Ionic and electronic conductivity of La9.83-xPrxSi4.5Fe1.5O26 + or - delta apatites
Место публикации : Solid State Ionics. - 2004. - V. 171, N 1-2. - С. 51-59. - ISSN 0167-2738. - ISSN 0167-2738
Примечания : Библиогр.: с. 59 (30 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Аннотация: The incorporation of praseodymium in the apatite-type lattice of La9.83-xPrxSi4.5Fe1.5O26 + or - delta (x = 0-6) decreases the unit cell volume, suppresses Fe4+ formation according to Mossbauer spectroscopy, and increases p- and n-type electronic contributions to total conductivity, studied by the impedance spectroscopy and modified faradaic efficiency (FE) and electromotive force (EMF) methods at 973-1223 K. The additions of praseodymia have no essential effect on the ionic transport, with an activation energy of 99-109 kJ/mol, under oxidizing conditions. Contrary to the Al-containing analogue, La9.83Si4.5Al1.5O26, exhibiting p(O2)-independent conductivity at oxygen pressures from 10(-20) to 0.5 atm, the ionic conductivity of La9.83-xPrxSi4.5Fe1.5O26 + or - delta decreases on reducing p(O2) below 10(-14)-10(-12) atm. The observed behavior suggests a presence of hyperstoichiometric oxygen, critical for the level of ionic conduction and compensated by the formation of Fe4+ or Pr4+. The ion transference numbers in air vary in the range 0.979-0.994 for La9.83-xPrxSi4.5Fe1.5O26+delta, whilst for La9.83Si4.5Al1.5O26 the p-type electronic contribution to the total conductivity is lower than 0.5%. The average thermal expansion coefficients (TECs) of silicate-based solid electrolytes are (8.8-9.4)x10(-6)K(-1) at 300-1200 K and (14.2-15.8)x10(-6)K(-1) at 1200-1350 K
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13.

Вид документа : Статья из журнала
Шифр издания : 54/K 49
Автор(ы) : Kiselev A. I., Kononenko V. I.
Заглавие : Estimation of the Effective Electron Mass in Cerium from the Data of Optical Experiment
Место публикации : High Temperature (Translation of Teplofizika Vysokikh Temperatur). - 2003. - Vol. 41, № 6. - С. P. 771-777: il.
Примечания : Bibliogr. : p. 777 (16 ref.)
ISSN: 0018-151X
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): жидкие рзм--церий--проводимость оптическая--плотность
Аннотация: The form of the dispersion dependence of the optical conductivity of liquid rare earth metals (REM) in the range of photon energies of about 2 eV is defined by the contribution of the maximum of the density of electron states, which emerges during the Bragg scattering of electrons from the first coordination sphere of a melt. It is shown that, for liquid cerium, the experimental dependence of the optical conductivity in this range of photon energies may be described with due regard for the effective electron mass close to the value of 1.37. It is noted that the inclusion of the effective electron mass in the classical Drude equation for the optical conductivity makes it possible to estimate the value of this parameter on the basis of the data of optical experiment
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14.

Вид документа : Статья из журнала
Шифр издания : 54/L 27
Автор(ы) : Packer R. J., Skinner S. J., Yaremchenko A. A., Tsipis E. V., Kharton V. V., Patrakeev M. V., Bakhteeva Yu. A.
Заглавие : Lanthanum substituted CeNbO4+delta scheelites: mixed conductivity and structure at elevated temperatures
Место публикации : Journal of Materials Chemistry. - 2006. - Vol. 16, № 34. - С. 3503-3511
Примечания : Библиогр. : с. 3511 (17 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): лантан--проводимость--стехиометрия--церий
Аннотация: CeNbO4+d is a room temperature monoclinic material exhibiting a phase change to a tetragonal scheelite polymorph at 1023 K. The material can accommodate oxygen excess up to a composition of CeNbO4.25 in air which is believed to be incorporated on interstitial sites and hence is of interest for solid oxide fuel cell applications. Recent research however pointed to poor stability at low p(O2) making optimisation a necessity. To this end the effect of substituting lanthanum for cerium in CeNbO4+d has been investigated in terms of redox, structural and mixed conductive behaviour. On increasing lanthanum content the overall oxygen hyperstoichiometry of the as-prepared substituted phases was found to decrease. A reduction in the temperature of the monoclinic fergusonite to tetragonal scheelite phase transformation with increasing lanthanum content was also observed. However, the extent of oxidation with increasing temperature was found to decrease. Four probe dc conductivity measurements in the temperature range 923 K to 1223 K showed that the total conductivity decreased and that the p(O2) dependence of the total ionic conductivity increased with increasing lanthanum content. The ionic transference number, ti, was found to increase to a maximum of approximately 0.75 with lanthanum substitution but at low p(O2) the stability of the tetragonal phase was found to decrease
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15.

Вид документа : Статья из журнала
Шифр издания : 54/L 55
Автор(ы) : Leonidov I. A., Leonidova O. N., Slepukhin V. K.
Заглавие : Electronic Conductivity of Sr3 - 3xLa2xvacancyx(VO4)2 Solid Solutions
Место публикации : Inorganic Materials. - 2000. - Vol. 36, № 1. - С. P. 72-75: il.
Примечания : Bibliogr. : p. 75 (8 ref.)
ISSN: 0020-1685
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): электронная проводимость--растворы твердые--ванадаты--стронций--лантан
Аннотация: The electronic conductivity of Sr 3 3xLa2x[vacancylx(VO4)2 solid solutions was measured at oxygen pressures from 10 -13 tO 105 Pa and temperatures from 1070 to 1270 K, and their band gap was determined as a function of composition. The activation energy (~2.85 eV) and enthalpies of electron generation (=,4.2 eV) and migration (~-0.75 eV) were determined. A correlation between the band gap and electronic conductivity of the solid solutions was revealed
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16.

Вид документа : Статья из журнала
Шифр издания : 54/L 55
Автор(ы) : Leonidova O. N., Leonidova E. I.
Заглавие : Synthesis and electrophysical properties of cation conductorsSr3 - 3xLa2x(V1 -yPyO4)2 with palmierite structure
Место публикации : Solid State Ionics. - 2008. - vol. 179, № 1-6. - С. p. 188-191: il.
Примечания : Bibliogr. : p. 191 (8 ref.)
ISSN: 0167-2738
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): катионный перенос--проводимость--фазовые переходы--ортованадат стронция--ортофосфат стронция
Аннотация: The solid solutions Sr2.4La0.4(V1 - yPyO4)2 with palmierite structure were synthesized and characterized. The electrical conductivity was measured depending on temperature and partial pressure of oxygen. Both studies were carried out in the range of partial oxygen pressure 10.15.0.5atm at temperatures 400.1200C. Thermal expansion tests were carried out in air within 20.1200C. The cation transport over Sr2 positions is responsible??for the ion conductivity below 950 C. The disordering of palmierite structure in Sr2.4La0.4(V1 - yPyO4)2, where y=0.3, near 1000 ‹C is accompanied by the conductivity increase in about two times and by the decrease of thermal expansion coefficient. These changes are explained as manifestation of interstitial strontium cations. The substitution of vanadium by phosphorus results in the increase in thermodynamic stability
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17.

Вид документа : Статья из журнала
Шифр издания : 54/L 81
Автор(ы) : Il’ina E. A., Raskovalov A. A., Shevelin P. Y., Voronin V. I., Berger I. F., Zhyravlev N. A.
Заглавие : Lithium stoichiometry of solid electrolytes based on tetragonal Li7La3Zr2O12
Место публикации : Materials Research Bulletin. - 2014. - Vol. 53. - С. 32-37.
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): керамика--импедансная спектроскопия--рассеяние нейтронов--ионная проводимость
Аннотация: Samples of LixLa3Zr2O8.5+0.5x (x = 6, 7, 8, 9, 10) were synthesized with the citrate–nitrate method. Neutron diffraction studies have shown the presence of lithium carbonate impurities in the synthesized compounds. We propose a simple and effective method to determine the carbonate impurity content in the solid electrolytes. The technique is based on the measurement of the carbon dioxide volume produced from the interaction of the investigated material with acid. Determined in this way, the content of Li2CO3 in the synthesized electrolytes Li7La3Zr2O12, Li8La3Zr2O12.5 and Li9La3Zr2O13 are 1.32 ± 0.04, 1.95 ± 0.06 and 3.49 ± 0.10 wt.%, respectively. From the obtained data, the actual lithium content per formula unit of complex oxide was calculated for the synthesized compounds. The composition with x = 9 had the highest total conductivity, σ = 7.5 × 10−6 S cm−1, at room temperature. All the investigated electrolytes have an activation energy of approximately 50 kJ mol−1.
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18.

Вид документа : Статья из журнала
Шифр издания : 54/N 30
Автор(ы) : Naumovich E. N., Kharton V. V., Yaremchenko A. A., Patrakeev M. V., Kellerman D. G., Logvinovich D. I., Kozhevnikov V. L.
Заглавие : Defect formation in LaGa(Mg,Ni)O3-delta: A statistical thermodynamic analysis validated by mixed conductivity and magnetic susceptibility measurements
Место публикации : Physical Review B: Condensed Matter and Materials Physics. - 2006. - Vol. 74, № 6. - С. 064105/1-064105/12
Примечания : Библиогр. : с. 064105/11 (55 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): магнитная восприимчивость--проводимость--галлат лантана--перовскиты
Аннотация: A statistical thermodynamic approach to analyze defect thermodynamics in strongly nonideal solid solutions was proposed and validated by a case study focused on the oxygen intercalation processes in mixed-conducting LaGa0.65Mg0.15Ni0.20O3−delta perovskite. The oxygen nonstoichiometry of Ni-doped lanthanum gallate, measured by coulometric titration and thermogravimetric analysis at 923–1223 K in the oxygen partial pressure range 5 10−5 to 0.9 atm, indicates the coexistence of Ni2+, Ni3+, and Ni4+ oxidation states. The formation of tetravalent nickel was also confirmed by the magnetic susceptibility data at 77–600 K, and by the analysis of p-type electronic conductivity and Seebeck coefficient as function of the oxygen pressure at 1023–1223 K. The oxygen thermodynamics and the partial ionic and hole conductivities are strongly affected by the pointdefect interactions, primarily the Coulombic repulsion between oxygen vacancies and/or electron holes and the vacancy association with Mg2+ cations. These factors can be analyzed by introducing the defect interaction energy in the concentration-dependent part of defect chemical potentials expressed by the discrete Fermi-Dirac distribution, and taking into account the probabilities of local configurations calculated via binomial distributions
Полный текст
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19.

Вид документа : Статья из журнала
Шифр издания : 54/O-97
Автор(ы) : Kharton V. V., Shaula A. L., Patrakeev M. V., Waerenborgh J. C., Rojas D. P., Vyshatko N. P., Tsipis E. V., Yaremchenko A. A., Marques F. M. B.
Заглавие : Oxygen Ionic and Electronic Transport in Apatite-Type Solid Electrolytes
Параллельн. заглавия :Oxygen Ionic and Electronic Transport in Apatite-Type Solid Electrolytes
Место публикации : Journal of the Electrochemical Society. - 2004. - V. 151, N 8. - С. A1236-A1246. - ISSN 0013-4651. - ISSN 0013-4651
Примечания : Библиогр.: с. A1246 (35 назв.)
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Аннотация: The oxygen ionic conductivity of apatite-type La9.83Si4.5Al1.5-yFeyO26 + - delta (y = 0-1.5), La10-xSi6-yFeyO26 + - delta (x = 0-0.77; y = 1-2), and La7-xSr3Si6O26 + - delta (x = 0-1) increases with increasing oxygen content. The ion transference numbers, determined by faradaic efficiency measurements at 973-1223 K in air, are close to unity for La9.83Si4.5Al1.5-yFeyO26 + - delta and La10Si5FeO26.5, and vary in the range 0.96-0.99 for other compositions. Doping of La9.83(Si, Al)6O26 with iron results in an increasing Fe4+ fraction, which was evaluated by Mossbauer spectroscopy and correlates with partial ionic and p-type electronic conductivities, whereas La-stoichiometric La10(Si, Fe)O26 + delta apatites stabilize the Fe3+ state. Among the studied materials, the highest ionic and electronic transport is observed for La10Si5FeO26.5, where oxygen interstitials are close neighbors of Si-site cations. Data on transference numbers, total conductivity, and Seebeck coefficientas a function of the oxygen partial pressure confirm that the ionic conduction in Fe-substituted apatites remains dominant under solid oxide fuel cell operation conditions. However, reducing p (O2) leads to a drastic decrease in the ionic transport, presumably due to a transition from the prevailing interstitial to a vacancy diffusion mechanism, which is similar to the effect of acceptor doping. Iron additions improve the sinterability of silicate ceramics, increase the n-type electronic conductivity at low p(O2), and probably partly suppress the ionic conductivity drop. The thermal expansion coefficients of apatite solid electrolytes in air are (8.8-9.9)x10(-6) K(-1) at 300-1250 K
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20.

Вид документа : Статья из журнала
Шифр издания : 54/O-97
Автор(ы) : Patrakeev M. V., Leonidov I. A., Kozhevnikov V. L., Kharton V. V.
Заглавие : Oxygen nonstoichiometry and ion-electron transport in SrFe0.9M0.1O3-delta (M = Cr, Ti, Al)
Место публикации : Materials Science Forum. - 2006. - vol. 514-516. - С. 382-386: il.
Примечания : Bibliogr. : p. 386 (9 ref.)
ISSN: 0255-5476
ББК : 54
Предметные рубрики: ХИМИЧЕСКИЕ НАУКИ
Ключевые слова (''Своб.индексиров.''): проводимость ионная--феррит стронция--нестехиометрия кислородная
Аннотация: The total conductivity and oxygen deficiency of partially substituted strontium ferrite,??SrFe0.9M0.1O3-д (M=Cr, Ti, Al), at 700-950°C were measured depending on oxygen partial pressure??varying in ranges 10-19-0.5 and 10-5-0.5 atm. The partial contributions of n- and p-type electronic??charge carriers and oxygen ions to the electrical transport were determined analyzing the total??conductivity vs. oxygen pressure dependencies. Additions of all dopants studied in this work are??found to extend the cubic perovskite phase stability range and to improve oxygen transport in the??intermediate-temperature range. The behavior of hole mobility suggests a polaron conduction??mechanism. Doping with aluminum has a weak influence on the mobility level, while the??incorporation of Cr and Ti cations into the ferrite lattice decreases hole mobility up to four times
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