Weissenberg-type neutron diffraction camera and its application to the structural and magnetic phase transitions of KMnF3

A Weissenberg-type neutron diffraction camera (W-NDC) equipped with a neutron imaging-plate (NIP) has been developed. The W-NDC gives Weissenberg-type and rotational diffraction patterns at low-temperature (10 K6LiF powder is continuously oscillated around the specimen during measurements. A test structural analysis for a single crystal NaCl suggests that the integrated intensities of reflections obtained from the Weissenberg-type diffraction patterns adequately satisfy a structural refinement by means of a least square method, though a fading effect of the photon energy stored in the NIP should be regarded during measurements. Structural and magnetic phase transitions in KMnF₃ have been studied by using the W-NDC, to eliminate an inconsistency for temperature, and to enable an ordering of the phase transition as reported. PACS 61.12.Ld; 64.70.Kb; 61.72.-y