The Long-Periodic Loop-Branched Chain Structure of the Oxonitridophosphate La21P40O46N57, Elucidated by a Combination of TEM and Microfocused Synchrotron Radiation |
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| Authors: | Markus Nentwig Dr Simon D Kloß Dr Lukas Neudert Lucien Eisenburger Prof Dr Wolfgang Schnick Prof Dr Oliver Oeckler |
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| Institution: | 1. Institute of Mineralogy, Crystallography and Materials Science, Leipzig University, Scharnhorststraße 20, 04275 Leipzig, Germany;2. Department of Chemistry, University of Munich (LMU), Butenandtstraße 5–13 (D), 81377 Munich, Germany |
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| Abstract: | The lanthanum oxonitridophosphate La21P40O46N57 was synthesized by high-pressure metathesis from partially hydrolysed LiPN2 and LaCl3 at 750–950 °C and 7–9 GPa. The combination of transmission electron microscopy (TEM) and diffraction using microfocused synchrotron radiation revealed a monoclinic crystal structure (space group P21/n, a=14.042(4), b=7.084(3), c=41.404(10) Å, β=97.73(3)° and Z=2), which is characterized by loop-branched 21 member single chains of P(O,N)4 tetrahedra that extend along 2 0 1]. These chains are related to the loop-branched dreier single chains with dreier-ring loops in stillwellite (CeBSiO5). In La21P40O46N57, these chains are characterized by a complex long-periodic conformation and exhibit disorder that involves La/N and P split positions. This is an extraordinarily long periodicity with respect to branched single chains of tetrahedra. La21P40O46N57 constitutes the first rare-earth oxonitridophosphate exhibiting a chain structure. Single-crystal data are consistent with electron and powder X-ray diffraction. |
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| Keywords: | chain structures high-pressure/high-temperature chemistry metathesis microcrystals rare-earth oxonitridophosphate |
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