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Issue 25, 2017
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Epitaxial growth and cationic exchange properties of layered KNb3O8 thin films

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Abstract

The KNb3O8 potassium triniobate phase is a layered compound that shows excellent photocatalytic activity, intercalation properties and electrochemical performances. In this study, we report the synthesis of this niobate in thin film form. Thin films of layered KNb3O8 phase were grown by pulsed laser deposition on (100)-oriented strontium titanate SrTiO3 substrates using targets with different compositions and various deposition parameters. Samples were analyzed by X-ray diffraction, scanning and transmission electron microscopy, X-ray energy dispersive and Rutherford backscattering spectroscopies. This work shows that KNb3O8 films are obtained in a narrow composition range, close to K1.13Nb3O8.7 that can be achieved with several combinations of the elaboration parameters (target composition, deposition temperature, target–substrate distance, laser fluence). Slight potassium amount variations in the film composition lead to the growth of other niobates (i.e. K2Nb8O21, K6Nb10.88O30, K3Nb7O19, K4Nb6O17). The KNb3O8 films are either made of elongated crystals (500 nm long, 50–75 nm wide, and 40 nm thick) or of flat lamellas. In both cases, they are (010)-preferentially oriented with epitaxial relationships with the substrate, namely (010)KNb3O8//(100)SrTiO3, [100]KNb3O8//[010]SrTiO3 and [001]KNb3O8//[001]SrTiO3. Protonation of the KNb3O8 films leads to a complete exchange of K+ ions by H3O+ ions that are themselves exchanged by Sn2+ ions after immersion in a tin chloride solution confirming the exchange reaction capabilities also in thin films. Exchange of K+ by Sn2+ leads to the band gap reduction of 0.33 eV.

Graphical abstract: Epitaxial growth and cationic exchange properties of layered KNb3O8 thin films

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Publication details

The article was received on 07 Jan 2017, accepted on 26 Feb 2017 and first published on 08 Mar 2017


Article type: Paper
DOI: 10.1039/C7RA00261K
Citation: RSC Adv., 2017,7, 15482-15491
  • Open access: Creative Commons BY license
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    Epitaxial growth and cationic exchange properties of layered KNb3O8 thin films

    A. Waroquet, V. Demange, N. Hakmeh, J. Perrière, S. Freslon, S. Députier and M. Guilloux-Viry, RSC Adv., 2017, 7, 15482
    DOI: 10.1039/C7RA00261K

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