Kermesite, Sb2S2O: crystal structure revision and order–disorder interpretation

Hybler, J.; Ďurovič, S.

doi:10.1107/S2052519213024238

Figure 13
Diffraction pattern of the twinned MDO1 (4A) polytype of kermesite, with sections of the reciprocal space reconstructed from the CCD frames. The orientation of sections corresponds to Fig. 12

. The unit cells of both twin domains are indicated. (a) Pz21, hk10 (hk $[\overline {10}]$ of the second twin domain); (b) Pz24, hk10 (hk $[\overline {10}]$ ), family reflections of both specimens (corresponding to large full circles in Fig. 12

); (c) Pz21, hk11 ( $[hk\overline {11}]$ of the second twin domain); (d) Pz24, hk11 ( $[hk\overline {11}]$ ), characteristic reflections of both specimens (corresponding to small black and red circles). Unit cells, reciprocal lattice directions and indices of selected diffraction spots of the first and second twin domains are indicated in black and red, respectively. Family reflections on the hk10 plane are common for both domains, thus both corresponding indices are indicated. In the hk11 ( $[hk \overline {11}]$ ) planes, the indices of reflections of respective domains allowed by the reflection rules of Kupčík's cell are indicated. Note the differences in intensities of the reflections of both domains in the hk11 plane of Pz21, and the intensities are much closer to being equal in the hk11 plane of Pz24. In Fig. 12

, layers containing the family and characteristic reflections are projected into the same picture, while in these images the reciprocal lattice sections are separated. The reciprocal lattice planes with a relatively high l index were selected for this demonstration, because they are more populated by observed reflections than planes with a low l index.

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ISSN: 2052-5206

Volume 69| Part 6| October 2013| Pages 570-583

doi:10.1107/S2052519213024238

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