γ‐Irradiation Effect on the Thermal Conductivity of Al₂O₃ with Cr or Mn Impurities at Low Temperature

Abstract

Abstract The effect of γ‐irradiation on the thermal conductivity of samples of Mn or Cr‐doped Al 2 O 3 is measured between 1.3 and 300 °K. Ions with an even number of electrons (particularly those with the Mn 3+ configuration) are much more effective in scattering phonons than Kramers' ions. Comparison of the experimental data therefore strongly suggests the presence of Cr 2+ , isoelectronic of Mn 3+ , in irradiated ruby. A preliminary study of the thermal annealing shows that the recovery of the thermal conductivity is rather complicated.