Doubly Filled Sandwich Model
Crystal J64
Enlargements from an edge topograph of a thin (147 μm) crystal J64 termed a Doubly filled sandwich containing t
he LPP 42H previously reported by Kuo Chang-Lin (1965).
- A {4150} l = 0 reflection from which the total crystal thickness may be determined.
- A {3142} l ¹
0 reflection reveals a 30μm clear band due to the absence of reflection from the surrounding 6H polytype and indicates a region with either a longer or at least different unit cell c repeat or that is disordered in this direction
- An overexposed region between the 6H reflections on the {314l} row showing the fine LPP repeats and a 6H harmonic reflection. The LPP repeat has been measured with a thickness of 15μm.
- A model, to scale, of the polytypic content in which the 30μm clear band has been assigned a ~ 15μm 42H/126R and ~ 15μm one dimensionally disordered layer.
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