On the nature of planar defects in transition metal diboride line compounds

Planar defect structures appearing in transition metal diboride (TMB2) thin films, grown by different magnetron sputtering-deposition approaches over a wide compositional and elemental range, were systematically investi-gated. Atomically resolved scanning transmission electron microscopy (STEM) imaging, electron energy loss spec-troscopy (EELS) elemental mapping, and first principles calculations have been applied to elucidate the atomic structures of the observed defects. Two distinct types of antiphase boundary (APB) defects reside on the {1(1) over bar 00} planes. These defects are without (named APB-1) or with (APB-2) local deviation from stoichiometry. APB-2 de-fects, in turn, appear in different variants. It is found that APB-2 defects are governed by the films composition, while APB-1 defects are endemic. The characteristic structures, interconnections, and circumstances leading to the formation of these APB-defects, together with their formation energies, are presented.Funding Agencies|Swedish Research Council [2016-04412, 2021-03652, CTS 21:1272]; Swedish National Infrastructure in Advanced Electron Microscopy [2018-05973]; Knut and Alice Wallenberg Foundation; Fellowship/Scholar grant [2021-00171]; Swedish Foundation for Strategic Research (SSF) through the Research Infrastructure Fellow program [KAW 2015.0043, RIF 14-0074]; Carl Trygger foundation [EM16-0004]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]