Figure 2
Structural representations of the β-Pna21 (a), (b) and the hypothetical α-Pna21 structure (c), (d). Views are along the crystallographic c axis (a), (c) and as a general view (b), (d). All crystallographically independent cation positions are highlighted as large spheres in different colours, while the nitrogen atoms are very small to increase visibility of the cations. The crystal structure of the α-Pna21 structure was constructed from the wurtzite type using the TRANSTRU tool of the Bilbao Crystallographic server (Aroyo, Perez-Mato et al., 2006; Aroyo, Kirov et al., 2006; Aroyo et al., 2011). |