alternativeАльтернативная энергетика и экология (ISJAEE)Alternative Energy and Ecology (ISJAEE)1608-8298Международный издательский дом научной периодики "Спейс10.15518//isjaee.2017.31-36.010-023alternative-1241Research ArticleВОДОРОДНАЯ ЭКОНОМИКАHYDROGEN ECONOMYЛОКАЛЬНЫЕ УРОВНИ В ЗАПРЕЩЕННОЙ ЗОНЕ ОКСИДОВ La1-xSrxScO3-x/2 ПРИ ВЗАИМОДЕЙСТВИИ С КОМПОНЕНТАМИ ГАЗОВОЙ ФАЗЫ O2, H2, H2OLOCAL LEVELS IN THE BAND-GAP OF La1-xSrxScO3-x/2 OXIDES UNDER INTERACTION WITH COMPONENTS O2, H2, H2O GAS PHASESВласовМ. И.VlasovM. I.

канд. физ.-мат. наук, научный сотрудник

in Physics and Mathematics, Researcher

maxim.vlsv@yandex.ruhttps://orcid.org/0000-0002-2254-0193АнаньевМ. В.AnanyevM. V.

д-р хим. наук, зав. лабораторией ТОТЭ, директор Института высокотемпературной электрохимии Уральского отделения РАН

ResearcherID: F-5104-2014 

D.Sc. in Chemistry, the Head of laboratory of SOFC, Director of Institute of High Temperature Electrochemistry of the Ural Branch of the RAS

ResearcherID: F-5104-2014 

maxim.vlsv@yandex.ruФарленковА. С.FarlenkovA. S.

инженер, аспирант

Engineer, Ph.D. student, Institute of HighTemperature Electrochemistry, UB RAS

maxim.vlsv@yandex.ruСлесаревА. И.SlesarevA. I.

канд. физ.-мат. наук, доцент

Ph.D. in Physics and Mathematics, Assistant Professor

maxim.vlsv@yandex.ruСтроеваА. Ю.StroevaA. Y.

канд. хим. наук, старший научный сотрудник

Research ID: 169181

SPIN: 9453-1231

Ph.D. in Chemistry, Senior Researcher, Institute of High-Temperature Electrochemistry, UB RAS

Research ID: 169181

SPIN: 9453-1231

maxim.vlsv@yandex.ruВайнштейнИ. А.WeinsteinI. A.

д-р физ.-мат. наук, профессор, главный научный сотрудник

D.Sc. in Physics and Mathematics, Professor, Chief Researcher, Ural Federal University named after the first President of Russia B.N. Yeltsin

maxim.vlsv@yandex.ruИнститут высокотемпературной электрохимии Уральского отделения РАН; Уральский федеральный университет имени первого Президента России Б.Н. ЕльцинаРоссияInstitute of High-Temperature Electrochemistry of Ural Branch of Russian Academy of Sciences; Ural Federal University named after the First President of Russia B.N. YeltsinRussian FederationУральский федеральный университет имени первого Президента России Б.Н. ЕльцинаРоссияUral Federal University named after the First President of Russia B.N. YeltsinRussian FederationУральский федеральный университет имени первого Президента России Б.Н. Ельцина; Институт химии твердого тела Уральского отделения РАНРоссияUral Federal University named after the First President of Russia B.N. Yeltsin; Institute of Solid State Chemistry of Ural Branch of Russian Academy of SciencesRussian Federation201728012018031-361023Copyright © Международный издательский дом научной периодики "Спейс, 20182018Международный издательский дом научной периодики "СпейсМеждународный издательский дом научной периодики "Спейсhttps://www.isjaee.com/jour/about/submissions#copyrightNoticehttps://www.isjaee.com/jour/article/view/1241

Исследована электронная структура протонпроводящих оксидов на основе скандата лантана La1-xSrxScO3-x/2 для лучшего понимания механизмов растворения водорода из сухих и влажных атмосфер в решетке оксидов со структурой перовскита. Считается, что процесс инкорпорирования протонов из увлажнённых атмосфер описывается реакцией H2O+ OO× +VO** = 2OHO* . Однако нет устоявшейся концепции о механизме поглощения протонов из атмосферы сухого водорода (H2). При таком поглощении в решетке оксида будет образовываться положительно заряженный протонный дефект, и для компенсации избыточного положительного заряда должен возникать отрицательный заряд. Формально реакцию такого процесса можно представить в виде 1/2 H2O+ OO×=OHO*+e'. В данном случае появляется нескомпенсированный электрон, и для определения его локализации необходимо изучить электронную структуры перовскитов. Установлено, что с ростом концентрации x допанта увеличивается полоса поглощения при 5,6 эВ, перекрывающаяся с краем фундаментального поглощения. Подобная полоса наблюдалась и на других протонпроводящих перовскитах – она может быть связана либо с кислородными вакансиями, либо с акцепторными уровнями, так как количество и тех, и других увеличивается с концентрацией допанта x. При инкорпорировании протонов из атмосферы сухого водорода в решетку La1-xSrxScO3-x/2 интенсивность поглощения в данной полосе снижается, что может быть вызвано переходом обусловливающих ее дефектов в другое зарядовое состояние. Помимо этого, образуются специфические дефекты, поглощающие излучение в красной ИК-области при hν < 2,2 эВ. Установлено, что эти дефекты располагаются достаточно глубоко в запрещенной зоне и не являются электронными ловушками. Показано также, что в La1-xSrxScO3-x/2 имеются электронные ловушки, распложенные на глубине от 2 эВ до 4,5 эВ в запрещенной зоне относительно дна зоны проводимости. На основании полученного комплекса данных можно предположить, что эти ловушки связаны с кислородными вакансиями, однако их зарядовое состояние не очевидно, но важно, что они участвуют в захвате нескомпенсированных электронов при растворении протонов из атмосферы сухого водорода.

 

The paper studies the electronic structure of proton-conducting oxides based on the lanthanum scandate La1-xSrxScO3-x/2 for advancing in understanding the mechanisms of hydrogen uptake from dry and humid atmospheres into the lattice of oxides with a perovskite structure. The process of protons incorporation from watercontaining atmospheres is considered to describe by the reaction H2O+ OO× +VO** = 2OHO*. However, there is no established concept of a mechanism for proton uptake from a dry hydrogen atmosphere. At such an uptake, a positively charged proton defect will be formed in the oxide lattice, and a negative charge must appear for compensation of the excess positive charge. Formally, the reaction of such process can be represented as 1/2 H2O+ OO×=OHO*+e'. In this case, an uncompensated electron appears, and the question arises as to where it is localized. In order to answer this question, it is necessary to study the electronic structure of perovskites. With increasing in concentration of dopant x, the absorption band at 5.6 eV overlapping with the edge of fundamental absorption is found to increase. A similar band has been observed in other proton-conducting perovskites, and it can be related either with oxygen vacancies or with acceptor levels, since the amount of both the ones increases with the concentration of dopant x. When protons are incorporated from the dry hydrogen atmosphere into the La1-xSrxScO3-x/2 lattice, the absorption intensity in this band decreases, that can be due to the transition of the defects causing this band to another charge state. In addition, specific defects that absorb light in the red and infrared region at hν < 2.2 eV are formed. They are found to be located deep enough in the bang-gap and not to be the electronic traps. It is also shown that in La1-xSrxScO3-x/2 there are electron traps located at a depth of 2 eV to 4.5 eV in the band-gap relative to the bottom of the conduction band. On the basis of the data obtained, it can be assumed that these defects are somehow associated with oxygen vacancies, but their charge state is not obvious. It is important that these traps participate in the capture of uncompensated electrons during the proton uptake from the dry hydrogen atmosphere.

 

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The authors declare that there are no conflicts of interest present.