Schrader, H.; Boysen, Hans; Frey, Friedrich; Convert, P.
On the phase transformation proto- to clino-/orthoenstatite: Neutron powder investigation.
In: Physics and Chemistry of Minerals, Vol. 17, No. 5: pp. 409-415
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The phase transformation proto- to coexisting ortho- and clino-enstatite has been studied by in-situ neutron powder diffraction with samples from Bamble/ Norway. The evolution with temperature was followed in two subsequent cycles with different cooling rates. Refined structural parameters did not indicate any significant anomalies. The transformation behaviour is different for proto to clino (rapid) and the proto to ortho inversion (sluggish). The latter proceeds in two steps: ortho-enstatite starts to grow slowly below 1180 K on cooling, whereas the main transformation takes place below 800 K simultaneously with the proto-clino inversion. The athermal martensitic character is confirmed for the proto to clino inversion. The diffuse background in the powder diagrams is related to stacking faults which are irreversibly created during the transformation and affect the degree of order.