Pressure effect on the mechanical and electronic properties of the tungsten triboride doped with iron: a first-principle
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THE EUROPEAN PHYSICAL JOURNAL B
Regular Article
Pressure effect on the mechanical and electronic properties of the tungsten triboride doped with iron: a first-principles study Jes´ us Le´on-Flores 1 , Martin Romero 2 , Jos´e Luis Rosas-Huerta 1 , Jaime Eugenio Antonio 3 , and Raul Escamilla 1,a 1
2 3
Instituto de Investigaciones en Materiales, Universidad Nacional Aut´ onoma de M´exico, M´exico CDMX 04510, Mexico Facultad de Ciencias, Universidad Nacional Aut´ onoma de M´exico, M´exico CDMX 04510, Mexico Escuela Superior de Ingenier´ıa Mec´ anica y El´ectrica-Culhuac´ an, Instituto Polit´ecnico Nacional, M´exico CDMX 04430, Mexico Received 9 April 2020 / Received in final form 3 July 2020 / Accepted 16 July 2020 Published online 16 September 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. The crystal structure, mechanical, and electronic properties of W0.71 Fe0.15 B3 under pressure were studied by first principles. Our results show that the structural parameters obtained by geometry optimization are in agreement with other experimental and theoretical results; the main effect of pressure on the structure is compression along the c-axis. The independent elastic constants, mechanical modules, and the Debye temperature increase under pressure, whereas the hardness decreases. Born’s structural stability criteria shows that the structure with space group P63 /mmc is mechanically stable up to 50 GPa; while, Pugh’s and Poisson criteria suggest a transition from brittle to ductile between 30 and 35 GPa. Finally, the density of states at the Fermi energy decreases and a charge transfer from W/Fe to B under pressure is determined.
1 Introduction Tungsten triboride compound (WB3 ) has been under research since it was established as a hard material with a Vickers hardness (Hv ) between 25 GPa and 35 GPa using relatively easy synthesis conditions, becoming a potentially attractive material for technological uses [1–4]. In the early 60s, the structure of the WB3 compound was considered as hexagonal with P63 /mmc space group and with four formula units. The Wyckoff positions for tungsten and boron atoms in this structure are W1 2c (1/3, 2/3, 1/4); W2 2b (0, 0, 1/4); B1 12i (x, 0, 0) and B2 4f (1/3, 2/3, z) [1]. This arrangement is described as a honeycomb-like network of boron atoms separated by tungsten layers with the presence of boron dimmers between the tungsten layers. However, a controversy was generated over the allocation of formula units to WB3 ; this was clarified by a correction utilizing first-principles calculations, establishing just one formula unit for the crystal structure, disappearing the B2 4f(1/3, 2/3, z) Wyckoff position, which was responsible for the boron dimmers formation [5,6]. As a consequence, a wide range of new possible crystal structures of the form hR24-WB3 , hP 16-WB3 , hP 8-WB3 , hP 4-WB3 were proposed and studied experimentally and theoretically [7,8]. The hP 16-WB3 structure was the most a
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