Locally controlled Cu-ion transport in layered ferroelectric CuInP2S6
|Title:||Locally controlled Cu-ion transport in layered ferroelectric CuInP2S6||Authors:||Balke, Nina; Neumayer, Sabine M.; Brehm, John A.; Rodriguez, Brian J.; et al.||Permanent link:||http://hdl.handle.net/10197/12001||Date:||23-Jul-2018||Online since:||2021-03-02T16:43:22Z||Abstract:||Metal thiophosphates are attracting growing attention in the context of quasi-two-dimensional van der Waals functional materials. Alkali thiophosphates are investigated as ion conductors for solid electrolytes, and transition-metal thiophosphates are explored as a new class of ferroelectric materials. For the latter, a representative copper indium thiophosphate is ferrielectric at room temperature and, despite low polarization, exhibits giant negative electrostrictive coefficients. Here, we reveal that ionic conductivity in this material enables localized extraction of Cu ions from the lattice with a biased scanning probe microscopy tip, which is surprisingly reversible. The ionic conduction is tracked through local volume changes with a scanning probe microscopy tip providing a current-free probing technique, which can be explored for other thiophosphates of interest. Nearly 90 nm-tall crystallites can be formed and erased reversibly on the surface of this material as a result of ionic motion, the size of which can be sensitively controlled by both magnitude and frequency of the electric field, as well as the ambient temperature. These experimental results and density functional theory calculations point to a remarkable resilience of CuInP2S6 to large-scale ionic displacement and Cu vacancies, in part enabled by the metastability of Cu-deficient phases. Furthermore, we have found that the piezoelectric response of CuInP2S6 is enhanced by about 45% when a slight ionic modification is carried out with applied field. This new mode of modifying the lattice of CuInP2S6, and more generally ionically conducting thiophosphates, posits new prospects for their applications in van der Waals heterostructures, possibly in the context of catalytic or electronic functionalities.||Funding Details:||Science Foundation Ireland||Type of material:||Journal Article||Publisher:||American Chemical Society||Journal:||ACS Applied Materials and Interfaces||Volume:||10||Issue:||32||Start page:||27188||End page:||27194||Copyright (published version):||2018 American Chemical Society||Keywords:||Transition-metal chalcogenophosphate; Copper indium thiophosphate; Layered ferroelectric; Ionic transport; Scanning probe microscopy; Thin-film cathode||DOI:||10.1021/acsami.8b08079||Language:||en||Status of Item:||Peer reviewed||ISSN:||1944-8244||This item is made available under a Creative Commons License:||https://creativecommons.org/licenses/by-nc-nd/3.0/ie/|
|Appears in Collections:||Conway Institute Research Collection|
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