Defect chemistry of oxides in partially frozen-in states: case studies forZrO2(Y2O3), SrZrO3(Y2O3), and SrTiO3

The low temperature defect chemistry is analyzed for ZrO2(Y2O3), SrZrO3(Y2O 3), and SrTiO3. In this temperature regime, the oxygen incorporation is no longer in equilibrium but the internal ionization reaction of electrons (ho les) with redox-active impurities is still reversible. The concentration of ions with a specific valence state is quantified by EPR for ZrO2(Y2O3), wh ile the electrical conductivity is considered for SrZrO3(Y2O3) and SrTiO3. It is shown that the experimental low-temperature results can well be expla ined in this way. If the experiments are appropriately conducted, an additi onal degree of freedom is introduced, which is the freezing-in temperature. The technological and scientific relevance with respect to materials resea rch is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.