New nitrides: from high pressure–high temperature synthesis to layered nanomaterials and energy applications

Abstract

We describe work carried out within our group to explore new transition metal and main group nitride phases synthesized using high pressure–high temperature techniques using X-ray diffraction and spectroscopy at synchrotron sources in the USA, UK and France to establish their structures and physical properties. Along with previously published data, we also highlight additional results that have not been presented elsewhere and that represent new areas for further exploration. We also describe new work being carried out to explore the properties of carbon nitride materials being developed for energy applications and the nature of few-layered carbon nitride nanomaterials with atomically ordered structures that form solutions in polar liquids via thermodynamically driven exfoliation. This article is part of the theme issue ‘Fifty years of synchrotron science: achievements and opportunities’.

A Practical Review of the Laser-Heated Diamond Anvil Cell for University Laboratories and Synchrotron Applications

“…In fact, the nature of the XRD (combined with LH) technique, allows the characterization of the structural, textural and chemical evolution of the sample (and the PTM) to be performed in situ as a function of P and T. Furthermore, thanks to the use of fast detectors with an improved signal/noise, it is now possible to probe (in situ) intermediate phases, revealing important crystallographic information. In recent years this technique has been successfully used to (first) synthesize and (successively) characterize new materials, both for geological interest or in the rush for finding new ultra-hard materials [88,89,167,168]. The use of LH-DAC with XRD (and the help of computational methods such as ab initio simulation or thermodynamic modeling) allows detailed characterizations of phase diagrams and thermal equations of state (EoS) of materials at extreme P-T conditions (see Figure 8 for an example) [81,[169][170][171][172][173].…”

Defect rocksalt structures in the La-Na-N system

“…However, synthesis of solid metal nitrides is challenging because of the stability and inertness of the N 2 molecule. High-pressure high-temperature (HPHT) reactions can be used to overcome this issue as illustrated by the notable work of the late Paul McMillan in preparing new highpressure metal nitrides [7][8][9][10]. A recent development has been the use of sodium azide (NaN 3 ) as a versatile nitrogen source in HPHT reactions that can lead to the synthesis of stoichiometric ternary nitrides of transition metals in high-oxidation states such as Ca 4 FeN 4 [11], Ca 2 NiN 2 [12] and the perovskite LaReN 3 [13,14].…”