Discovery of Two Polymorphs of TiP₄N₈Synthesized from Binary Nitrides

Abstract

TiP4N8 was obtained from the binary nitrides TiN and P3N5 upon addition of NH4F as a mineralizer at 8 GPa and 1400 °C. An intricate interplay of disorder and polymorphism was elucidated by in situ temperature‐dependent single‐crystal X‐ray diffraction, STEM‐HAADF, and the investigation of annealed samples. This revealed two polymorphs, which consist of dense networks of PN4 tetrahedra (degree of condensation κ=0.5) and either augmented triangular TiN7 prisms or triangular TiN6 prisms for α‐ and β‐TiP4N8, respectively. The structures of TiP4N8 exhibit body‐centered tetragonal (bct) framework topology. DFT calculations confirm the measured band gaps of α‐ and β‐TiP4N8 (1.6–1.8 eV) and predict the thermochemistry of the polymorphs in agreement with the experiments.

Characterization of the Binary Nitrides VN and ScN by Solid‐State NMR Spectroscopy

“…In general, research and development involving nitride compounds is still a vibrant field, as partly reviewed in the Introduction of this paper. In particular, the group of Wolfgang Schnick has been very productive in this field of research over the last decades [15,16,54–56] …”

“…Aluminium nitride is a precursor in the production of SiAlON ceramics [14] . Titanium nitride has been reacted to obtain a range of target compounds, such as an oxonitridophosphate, [15] TiP 4 N 8 polymorphs, [16] and both titanium pernitride [17] and cubic phase Ti 3 N 4 under extreme pressure conditions [18] . Scandium nitride has long been considered mostly inert, but has recently been utilized for the synthesis of an oxonitridophosphate [15] .…”

“…Scandium nitride has long been considered mostly inert, but has recently been utilized for the synthesis of an oxonitridophosphate [15] . Due to the refractory character [19] of TiN and ScN, it has been necessary to activate these compounds under both high‐pressure and high‐temperature conditions, using NH 4 F as mineralizing agent and HF source [15,16] . Obviously, it is of vital importance to monitor synthetic procedures by appropriate analytics.…”

Trendbericht Festkörperchemie 2023

“…24) Unter 8 GPa Druck stellten die Gruppen um Johrendt, Oeckler und Schnick erstmals zwei neue Polymorphe des ternären Titannitridophosphats Ti[P 4 N 8 ] her; sie nutzten (NH 4 )F als Mineralisierungsreagenz. 25) Die Verbindung bildet rote Kristalle, und die Struktur ist durch vollständig eckenverknüpfte [PN 4 ] 7--Tetraeder und ein kondensiertes Netzwerk mit einem Kondensationsgrad von κ 0,5 charakterisiert.…”

From Framework to Layers Driven by Pressure – The Monophyllo‐Oxonitridophosphate β‐MgSrP3N5O2and Comparison to its α‐Polymorph

“…This strategy has been revived and modified recently by Eisenburger et al for synthesis of transition metal oxonitridophosphates, starting from binary nitride precursors like ScN and TiN by adding NH 4 F as activation reagent. [16,17] Based on this, a combination of both nitride and azide approaches, appears to be a promising method to synthesize new oxonitridophosphates, as exemplified by the synthesis of MgSrP 3 N 5 O 2 . The latter was obtained starting from stoichiometric amounts of Mg 3 N 2 , Sr(N 3 ) 2 , PON and P 3 N 5 , as well as NH 4 Cl as mineralizer, performed under HP/HT conditions (6 GPa, approx.…”