Abstract
The thermal conductivity from 3° to 300°K of single crystals of the two spinels, diamagnetic MgAl2 O4 and paramagnetic Fe3 O4, has been measured and analyzed. The heat is transported by phonons in both cases. The phonon scattering processes in the two crystals are quite similar except that the phonons in Fe3 O4 are also scattered by the magnetic lattice in its disordered state. The thermal conductivity of Fe3 O4 falls abruptly with increasing temperature at the 121±2°K transition.