  The magnetic susceptibility between 1.5 and 800 K, the infrared reflectivity
at room temperature and the temperature dependence of the dielectric constant
at mm-wavelengths are reported for single crystalline BiFeO3. A well developed
anomaly in the magnetic susceptibility signals the onset of antiferromagnetic
order close to 640 K. Beside this anomaly, no further indications of phase or
spin-glass transitions are found in the susceptibility down to the lowest
temperatures. From infrared reflectivity we were able to identify all 9 phonon
modes which are expected to be infrared active within the ab plane of the
crystal. The temperature dependence of the dielectric constant was measured
contact free in the 100 GHz range yielding e' = 54 at room temperature. The
loss is substantial and strongly frequency dependent indicating the
predominance of hopping conductivity.
