Tuning the Sign of Photoinduced Changes in Magnetization: Spin Transitions in the Ternary Metal Prussian Blue Analogue NaαNi1−xCox[Fe(CN)

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• 作者：Daniel M. Pajerowski ; Justin E. Gardner ; Daniel R. Talham ; Mark W. Meisel
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：September 16, 2009
• 年：2009
• 卷：131
• 期：36
• 页码：12927-12936
• 全文大小：387K
• 年卷期：v.131,no.36(September 16, 2009)
• ISSN：1520-5126

文摘

Tuning the composition of the ternary transition-metal Prussian blue analogue Na_αNi_1−xCo_x[Fe(CN)₆]_β·nH₂O allows the sign of the photoinduced change in magnetization to be controlled. The parent cobalt hexacyanoferrate material is well-known to display photoinduced and thermal charge-transfer-induced spin transitions (CTISTs). Upon partial replacement of Co ion sites with Ni^II, irradiation with halogen light can cause either an increase or a decrease in magnetization, depending upon the extent of Ni^II substitution, the applied field, and the temperature. For all compositions with x > 0, photoexcitation generates new moments according to the same mechanism observed for the parent x = 1 compound. However, the presence of Ni^II introduces a superexchange of opposite sign, providing a mechanism for controlling the sign of the change in magnetization with applied light. Additionally, dilution of the spin-crossover material reduces the magnitude and hysteresis of the thermal CTIST effect. These effects can be qualitatively explained by simple mean-field models.