A resonance change in microwave absorption in zero magnetic field, whi
ch is not due to magnetic-field dependence of the energy levels of the
spin systems, is observed for a number of non-Kramers paramagnetic io
ns (Cr2+, Ni2+, Fe2+) in synthetic forsterite. It is shown that these
signals could be due to narrowing of the homogeneous spin packet of an
inhomogeneously broadened EPR line in zero magnetic (C) 1998 American
Institute of Physics. field. [S0021-3640(98)00417-4].