CeF3 powder produced for use as lubricant is investigated by X-ray pow
der diffraction method and high-resolution transmission electron micro
scopy. It is composed of spherical particles of several ten nanometre
in diameter. Surfaces of the particles arc covered with CeF2 layers wi
th orientation such as [011] (122BAR)CeF3 parallel-to [110] (111BAR)Ce
F2 on the CeF3 particle. The CeF3 particles hardly change in morpholog
y and structure by grinding with an agate mortar. It is concluded that
the lubrication of the CeF3 powder is ascribed to the slip between th
e particles covered with CeF2 under prevailing rotational friction.