In this work films were prepared by reactive magnetron sputtering at room temperature and deposited on a silicon wafer. It was found that the diffractograms of the nitrogen-rich rhenium film are consistent with those produced by high-pressure high-temperature methods, under the assumption that the film is oriented on the substrate. Using density functional calculations it was found that the composition of this compound could be ReN3, instead of ReN2, as stated on previous works. The ReN3 compound fits in the Ama2 (40) orthorhombic space group, and due to the existence of N3 anions between Re layers it should be categorized as an azide. The material is exceptionally brittle and inherently unstable under indentation testing. 1. Introduction In recent years, reports on the synthesis of novel materials by high-pressure and high temperature (HPHT) methods have become common. The use of extreme pressures and temperatures, combined with compositional variables, provides an opportunity to synthesize uncommon materials and/or to tune the physical properties of materials for a wide range of applications [1]. HPHT methods were pioneered by researchers looking to synthesize diamonds, but now are often applied to discover materials that might have mechanical, chemical or thermal resistance comparable to those of diamond. Many transition metal nitrides are poised as promising hard materials principally for machining of ferrous alloys. Using HPHT methods, novel nitrides of heavy metals such as platinum, osmium, and iridium [2, 3] have been synthesized. Due to the observed high bulk modulus of these materials, some HPHT studies have sought to discover novel nitrides of heavy metals. An example of this effort is the work of Kawamura et al., who recently published an article describing the HPHT synthesis of ReN2 [4]. In direct competition with HPHT methods for the synthesis of artificial diamond are methods using plasma [5]. These have been successful in terms of the quality and purity of the obtained diamond, with the added advantage that these materials can be applied as coatings directly from the synthesis. Similarly, the plasma methods are used to discover alternative materials that can replace diamond. The success of plasmas for producing new materials originates from the high reactivity obtained by breaking molecular bonds after multiple ionization events. Using laser ablation experiments—a very energetic plasma method—it was possible to grow films composed of [6], [7], and [8]. The main limitations of plasma synthesis are the low growth rates and the textured
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