Segregation of hydrogen at internal Ag/MgO (metal/oxide)-interfaces as observed by small angle neutron scattering |
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| Affiliation: | 1. Georg-August-Universität Göttingen, Institut für Materialphysik, Tammanstraße 1, 37077 Göttingen, Germany;2. NIST, Center for Neutron Research, Gaithersburgh, MD, USA;3. FZ Jülich, Institut für Festkörperforschung, Germany;1. School of Mater. Sci. & Eng./Eng. Res. Cent. of Mater. Behav. & Des., MOE/Eng. Train. Cent., Nanjing University of Science & Technology, Nanjing 210094, PR China;2. Key Laboratory of Polar Materials and Devices, East China Normal University, Shanghai, 200241, PR China;3. Department of Physics, Institute of Materials Science & Engineering, Washington University, 1 Brookings Drive, St. Louis, MO 63130-4899, USA;4. Cent. for Adv. Struc. Mater., MBE, College of Sci. & Eng., City University of Hong Kong, Hong Kong, China;5. Dept. of Mater. Sci. & Eng., University of Tennessee, Knoxville 37996, USA;6. International Institute of Green Materials, Josai International University, Togane 283-8555, Japan;7. Department of Physics, King Abdulaziz University, Jeddah 22254, Saudi Arabia;1. N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian Federation;2. A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 119991 Moscow, Russian Federation;1. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA;2. Center for Research in Computational Thermochemistry, Department of Chemical Engineering, École Polytechnique de Montréal, C.P. 6079, Station Downtown, Montréal, Québec H3C 3A7, Canada |
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| Abstract: | The chemical composition of metal/oxide (M/O)-interfaces was studied for an internally oxidized Ag–1at.%Mg-alloy with small MgO nanoprecipitates in a dilute Ag matrix. This composition was varied by exposing the sample to oxygen (p(O2) = 2 × 104 Pa), hydrogen (p(H2) = 105 Pa) or vacuum (p<10−4 Pa). By means of small angle neutron scattering (SANS) we were able to show that hydrogen segregates at the internal Ag/MgO-interfaces. The average hydrogen occupancy at the Ag/MgO-phase boundary can be determined to be ΘH=(7.1±0.5)×1014 H/cm2. In addition it could be shown that for each segregated hydrogen atom one Ag atom is displaced from the M/O-interface. The amount of hydrogen at the interfaces is in agreement with a model of structural vacancies at densely packed interface planes. To the best of our knowledge these are the first SANS-measurements that provide information about the segregation of hydrogen and deuterium at internal interfaces. |
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