One disorder out of two orders: Synthesis and crystal structures of cation-ordered PbNaF 2 NO 3 , anion-ordered Pb 2 OFNO 3 , and continuous disordered (Pb, Na) 2 (O,F) 2-$\updelta$ NO 3 solid solution with Sillén-derived structuresстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 21 сентября 2017 г.
Аннотация:Two new Sillén–like layered lead fluoride nitrates, PbNaF2NO3 and Pb2OFNO3, have been prepared at 300 °C. PbNaF2NO3 is a structural analog of alkaline earth – bismuth oxyhalides, BaBiO2X and SrBiO2X (X = Cl – I), but not the corresponding nitrates, SrBiO2NO3 or BaBiO2NO3. Pb2OFNO3 is analogous to the corresponding halides, Pb2OFX (X = Cl, Br, I). Both structures belong to orthorhombic symmetry and demonstrate Na/Pb and O/F ordering, respectively. A continuous solid solution is formed between PbNaF2NO3 and Pb2OFNO3 which demonstrates neither cation nor anion ordering; the structure of intermediate composition Pb1.5Na0.5F1.5O0.5NO3 was refined in tetragonal symmetry and is indeed very close to that of PbBiO2NO3 and CaBiO2NO3. In PbNaF2NO3, the O:F ratio may be varied to a slight extent, PbNaF2-2yOyyNO3, which also breaks the Na – Pb cation ordering. Analogous fluoride halides could not be prepared. Structural analogies to lead, bismuth, and antimony oxyhalides are discussed.