Tw on ovel lithium nickel boride polymorphs,R T-LiNiB and HT-LiNiB,w ith layered crystal structures are reported. This family of compounds was theoretically predicted by using the adaptive genetic algorithm (AGA) and subsequently synthesized by ahydride route with LiH as the lithium source.U nique among the knownt ernary transition-metal borides,the LiNiB structures feature Li layers alternating with nearly planar [NiB] layers composed of Ni hexagonal rings with aB -B pair at the center.Acomprehensive study using ac ombination of single crystal/synchrotron powder X-ray diffraction, solid-state 7 Li and 11 BNMR spectroscopy, scanning transmission electron microscopy, quantum-chemical calculations,a nd magnetism has shed light on the intrinsic features of these polymorphic compounds.The unique layered structures of LiNiB compounds make them ultimate precursors for exfoliation studies,t hus paving aw ay toward twodimensional transition-metal borides,MBenes.
Ball milling of polystyrene under ambient conditions in metal containing vials causes scission of macromolecules, resulting in partial dismantling to styrene. Reactions proceeds via intermediate carbon-based free radicals that are detectable by EPR.
The pursuit of two-dimensional (2D) borides, MBenes, has proven to be challenging, not the least because of the lack of a suitable precursor prone to the deintercalation. Here, we studied room-temperature topochemical deintercalation of lithium from the layered polymorphs of the LiNiB compound with a considerable amount of Li stored in between [NiB] layers (33 at. % Li). Deintercalation of Li leads to novel metastable borides (Li∼0.5NiB) with unique crystal structures. Partial removal of Li is accomplished by exposing the parent phases to air, water, or dilute HCl under ambient conditions. Scanning transmission electron microscopy and solid-state 7Li and 11B NMR spectroscopy, combined with X-ray pair distribution function (PDF) analysis and DFT calculations, were utilized to elucidate the novel structures of Li∼0.5NiB and the mechanism of Li-deintercalation. We have shown that the deintercalation of Li proceeds via a “zip-lock” mechanism, leading to the condensation of single [NiB] layers into double or triple layers bound via covalent bonds, resulting in structural fragments with Li[NiB]2 and Li[NiB]3 compositions. The crystal structure of Li∼0.5NiB is best described as an intergrowth of the ordered single [NiB], double [NiB]2, or triple [NiB]3 layers alternating with single Li layers; this explains its structural complexity. The formation of double or triple [NiB] layers induces a change in the magnetic behavior from temperature-independent paramagnets in the parent LiNiB compounds to the spin-glassiness in the deintercalated Li∼0.5NiB counterparts. LiNiB compounds showcase the potential to access a plethora of unique materials, including 2D MBenes (NiB).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.