Magnetron Sputtering of Nanolaminated Cr2AlB2

Abstract

A ternary Cr2AlB2 phase was deposited as a film using magnetron sputtering. Its anisotropic structure displays both structural and chemical similarities with the nanolaminated MAX phases (Mn+1AXn (n = 1–3) where M usually is an early transition metal, A is typically an element in group 13–14 and X is C or N), and can be described as CrB slabs separated by layers of Al. Combinatorial sputtering was used to optimise the sputtering process parameters for films with the Cr2AlB2 composition. The influences of substrate, temperature and composition were studied using X-ray diffraction, X-ray photoelectron spectroscopy and electron microscopy. Films deposited at room temperature were X-ray amorphous but crystalline films could be deposited on MgO substrates at 680 °C using a composite Al-B, Cr and Al targets. X-ray diffraction analyses showed that the phase composition and texture of the films was strongly dependent on the chemical composition. Films with several phases or with a single Cr2AlB2 phase could be deposited, but an additional Al target was required to compensate for a loss of Al at the high deposition temperatures used in this study. The microstructure evolution during film growth was strongly dependent on composition, with a change in texture in Al-rich films from a preferred [010] orientation to a [100]/[001] orientation. A model based on Al desorption from the surface of the growing grains is proposed to explain the texture variations.

Fabrication of Cr2AlB2 and Cr4AlB4 MAB Phase Coatings by Magnetron Sputtering and Post-Annealing

“…The authors found that as-deposited coatings on Si(100) underwent a reaction with Si and formed Cr-Al-Si phases when subjected to high-temperature post-annealing, in analogy with the findings reported in [24]. Consequently, these coatings were not subjected to further post-annealing and remained as is for measuring the atomic ratio of the Cr, Al, and B elements using inductively coupled plasma optical emission spectrometry (ICP-OES) (iCAP 6300, Thermo Fisher, Waltham, MA, USA).…”

“…The configuration of Al slices overlapping the CrB target can be seen as a variation of the combinatorial approach. However, the general combinatorial sputtering of tilt-fixed multi-targets tends to cause the inhomogeneous distribution of elements in the MAB phase coatings [24,28]. Impurities such as Cr 3 AlB 4 and CrB 2 were found in an attempt to prepare Cr 2 AlB 2 coatings by sputtering tilt-fixed Cr, Al, and AlB 2 targets [24].…”

“…However, the general combinatorial sputtering of tilt-fixed multi-targets tends to cause the inhomogeneous distribution of elements in the MAB phase coatings [24,28]. Impurities such as Cr 3 AlB 4 and CrB 2 were found in an attempt to prepare Cr 2 AlB 2 coatings by sputtering tilt-fixed Cr, Al, and AlB 2 targets [24]. Another MAB phase coating, MoAlB, was generated by combinatorial magnetron sputtering of tilt-fixed MoB and Al targets and crystallized in situ at 700 • C as MoAlB, AlB 2 , and Mo-B binary phases.…”

“…Concerning Cr-Al-B MAB phase coatings, only Cr 2 AlB 2 coatings have been obtained to date [24]. Cr 2 AlB 2 phases were produced in coatings deposited on MgO(100) substrates that were in situ heated to 680 • C, using a combinatorial magnetron sputtering approach involving three tilt-fixed targets (Cr, Al, and AlB 2 ).…”

Lattice dynamics, Raman and IR vibrations of stable Al/Si‐containing MAB phases: An ab initio and experimental study

“…), comprising face-sharing BM 6 trigonal prisms separated by a monolayer or bilayer of A atoms. 8 Various structural phases fall into this category, including 222 phases (Cmcm), [35][36][37] 212 phases (Cmmm), 38,39 314 phases (Pmmm), 34 and 416 phases (Cmmm). 34 Over time, the definition of the MAB phases is expanded to encompass additional phases such as 414 phases (Immm), where M layers are arranged adjacently, 15 as exemplified by Cr 4 AlB 4 , 40 and 512 phases (I4/mcm), [41][42][43] which both deviate from the general formula as mentioned above.…”