Low‐temperature synchrotron X‐radiation topography is used to investigate the Morin transition in highly perfect flux‐grown crystals of haematite. Domain boundaries are revealed in the topographs of some crystals at temperatures as low as 77 K, well below the accepted spin re‐orientation (Morin) transition temperature. The Morin transition temperature appears to vary greatly with specimen perfection and evidence for magnetic phase coexistence over a large temperature range is obtained. This is attributed to both the influence of impurity variation and local regions of strain.

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A channel plate has been used in the electro‐magnetic and proximity focusing modes for the instantaneous display of X‐ray topographs using CuKα radiation. The resolution is found to be about 100 m̈m when proximity focusing is used and 50 m̈m, limited by the channel pitch, in the electro‐magnetically focused mode. The device is robust, cheap and easy to construct, and insensitive to ambient lighting.

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