  A polycrystalline sample of superconducting LaFePO was prepared in a tin flux
at 1123 K. The structure was determined from single crystal data
(ZrCuSiAs-type, P4/nmm, a = 3.9610(1), c = 8.5158(2) A, Z = 2) and the phase
analysis was performed by the Rietveld method. LaFePO is Pauli-paramagnetic and
becomes superconducting at 7 K after removing the ferromagnetic impurity phase
Fe2P from the sample. 57Fe Moessbauer spectroscopy measurements at 298, 77, 4.2
and 4 K show single signals at isomer shifts around 0.35 mm/s, subject to weak
quadrupole splitting. At 4 K, a symmetric line broadening appears, resulting
from a small transferred magnetic hyperfine field of 1.15(1) T and accompanied
by an angle of 54.7(5) between Bhf and Vzz, the main component of the electric
field gradient tensor.
