Evidence for tunneling states in the oxygen conductor Zr${\mathrm{O}}_2$: ${\mathrm{Y}}_2$${\mathrm{O}}_3$

A linear specific-heat term in Zr${\mathrm{O}}_2$ + 8 wt.% ${\mathrm{Y}}_2$ ${\mathrm{O}}_3$ below 6 K is reported and attributed to tunneling motions in this oxygen conductor. The linear coefficient is 3.08 × ${10}^{-5\mathrm{}}$ cal ${\mathrm{mole}}^{-1\mathrm{}}$ ${\mathrm{K}}^{-2\mathrm{}}$ and is considerably smaller than the corresponding coefficient found in the $\beta$-aluminas.