In order to control oxygen fugacities in solid-gas reactions at high temperatures and hydrostatic pressures, Eugster introduced the use of solid assemblages, as oxygen buffers in presence of water, with a platinum tube acting as a semipermeable membrane and a gold tube as an exterior protection. These assemblages control the oxygen fugacities in discontinuous steps. A simple variation of that method is here proposed to obtain a control of oxygen fugacities in continuous steps: one of the phases is a binary solid solution of two oxides which have very different values of the standard free energy of formation. Because the composition may have continuous variations and the oxygen fugacities are a function of the composition, it is possible to prepare all the intermediate buffers between two extreme values.
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Con il contributo del Ministero per i Beni e le Attività Culturali