Direct Observation of Short-Range Structural Coherence During a Charge Transfer Induced Spin Transition in a CoFe Prussian Blue Analogue by Transmission Electron Microscopy

详细信息    查看全文

• 作者：Miho Itoi ; Toyoharu Jike ; Daisuke Nishio-Hamane ; Seiichi Udagawa ; Tetsuya Tsuda ; Susumu Kuwabata ; Kamel Boukheddaden ; Matthew J. Andrus ; Daniel R. Talham
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：November 25, 2015
• 年：2015
• 卷：137
• 期：46
• 页码：14686-14693
• 全文大小：514K
• ISSN：1520-5126

文摘

The local structure within the Co鈥揊e atomic array of the photoswitchable coordination polymer magnet, K_0.3Co[Fe(CN)₆]_0.77路nH₂O, is directly observed during charge transfer induced spin transition (CTIST), a solid鈥搒olid phase change, using high-resolution transmission electron microscopy (HRTEM). Along with the low-spin (LS) or thermally quenched high-spin (HS) states normally observed in CTIST solids at low temperature, slow cooling of K_0.3Co[Fe(CN)₆]_0.77路nH₂O results in an intermediate phase containing both HS and LS domains with short coherence length. By mapping individual metal鈥搈etal distances, the nanometer-scale HS domains are directly visualized within the LS array. Temperature-dependent analyses allow monitoring of HS domain coarsening along the warming branch of the CTIST, providing direct visualization of the elastic process and insight into the mechanism of phase propagation. Normally sensitive to electron beam damage, the low-temperature TEM measurements of the porous coordination polymer are enabled by using appropriate ionic liquids instead of usual conductive thin-film coatings, an approach that should find general utility in related classes of materials.