A progress report on the MAB phases: atomically laminated, ternary transition metal borides

ABSTRACT

The MAB phases are atomically layered, ternary or quaternary transition metal (M) borides (TMBs), with the general formula (MB)_2zA_x(MB₂)_y (z = 1–2; x = 1–2; y = 0–2), whose structures are composed of a transition M-B sublattices interleaved by A-atom (A = Al,Zn) mono- or bilayers. Most of the MAB phases were discovered before the 1990s, but recent discoveries of intriguing magnetocaloric properties, mechanical deformation behaviour, catalytic properties, and high-temperature oxidation resistance has led to their ‘re-discovery’. Herein, MAB phase synthesis is reviewed and their magnetic, electronic, thermal, and mechanical properties are summarized. Because the M-B layers in the MAB phases structurally resemble their corresponding binaries of the same M:B stoichiometry, the effects of the A-layers on properties are discussed. Inconsistencies in the literature are critically assessed to gain insights on the processing-structure-property relations, suggest fruitful avenues for future research, and identify limitations for prospective applications.

KEYWORDS:

• MAB phases
• atomically layered solids
• ceramics
• borides
• review
• magnetocaloric effect
• alumina former

Acknowledgements

We acknowledge the following people for their valuable input and discussion: Dr. Louisiane Verger and Varun Natu (Drexel University, USA); Dr. Martin Dahlqvist and Dr. Jun Lu (Linköping University, Sweden), Dr. El’ad Caspi (Nuclear Research Centre-Negev, NCRN, Israel), and Aik Jun Tan (Massachusetts Institute of Technology, USA). Furthermore, we are grateful for the data provided by Professor Michael Shatruk (Florida State University, USA) and Professor Chunfeng Hu (Southwest Jiaotong University, China).

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Sankalp Kota http://orcid.org/0000-0003-3775-3279

Maxim Sokol http://orcid.org/0000-0001-8588-0585

Michel W. Barsoum http://orcid.org/0000-0001-7800-3517

Additional information

Funding

We would like to acknowledge the U.S. National Science Foundation grant DMREF-1729335; Directorate for Engineering.