Direct Observation of Short-Range Structural Coherence During a Charge Transfer Induced Spin Transition in a CoFe Prussian Blue Analogue by Transmission Electron Microscopy.
The local structure within the Co-Fe atomic array of the photoswitchable coordination polymer magnet, K0.3Co[Fe(CN)6]0.77·nH2O, is directly observed during charge transfer induced spin transition (CTIST), a solid-solid 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 K0.3Co[Fe(CN)6]0.77·nH2O results in an intermediate phase containing both HS and LS domains with short coherence length. By mapping individual metal-metal 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.
Division of Physics, Institute of Liberal Education, Nihon University School of Medicine , Tokyo 173-8610, Japan.
Miho
M
Itoi
Division of Physics, Institute of Liberal Education, Nihon University School of Medicine , Tokyo 173-8610, Japan.
Toyoharu
T
Jike
Institute for Solid State Physics, The University of Tokyo , Chiba 277-8581, Japan.
Daisuke
D
Nishio-Hamane
Division of Physics, Institute of Liberal Education, Nihon University School of Medicine , Tokyo 173-8610, Japan.
Seiichi
S
Udagawa
Department of Applied Chemistry, Graduate School of Engineering, Osaka University , Suita, Osaka 565-0871, Japan.
Tetsuya
T
Tsuda
Department of Applied Chemistry, Graduate School of Engineering, Osaka University , Suita, Osaka 565-0871, Japan.
Susumu
S
Kuwabata
Groupe d'Etudes de la Matière Condensée, UMR 8635, CNRS-Université de Versailles Saint-Quentin-en-Yvelines , 45 Avenue des Etats Unis, 78035 Versailles, France.
Kamel
K
Boukheddaden
Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States.
Matthew J
MJ
Andrus
Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611-7200, United States.
Daniel R
DR
Talham