The crystal structure of the lowest-temperature -phase of has been determined as a function of temperature by neutron powder diffraction. The diffraction measurements show that there are no additional phases at low temperatures. Magnetic measurements suggest that no superconductivity exists at temperatures as low as , but instead, an increase of the magnetic susceptibility according to a paramagnetic Curie law was found. This observation indicates that unpaired carriers persist in the sample after cooling to very low temperatures.