Photoinduced Ferrimagnetic Systems in Prussian Blue Analogues C^I_xCo₄[Fe(CN)₆]_y (C^I = Alkali Cation). 3. Control of the Photo- and Thermally Induced Electron Transfer by the [Fe(CN)₆] Vacancies in Cesium Derivatives

Abstract

We synthesized a series of CoFe Prussian blue analogues along which we tuned the amount of cesium cations inserted in the tetrahedral sites of the structure. Structure and electronic structure have been investigated, combining XANES, infrared spectroscopy, powder X-ray diffraction experiments, and magnetization measurements. The change of the magnetization induced by light along the series shows that the efficiency of the photoinduced magnetization, evidenced a few years ago in similar compounds by Hashimoto et al. (Sato, O.; Iyoda, T.; Fujishima, A.; Hashimoto, K. Science 1996, 272, 704-705; Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Electrochem. Soc. 1997, 144, L11-L13; Sato, O.; Einaga, Y.; Iyoda, T.; Fujishima, A.; Hashimoto, K. J. Phys. Chem. B 1997, 101, 3903-3905; Einaga, Y.; Ohkoshi, S.-I.; Sato, O.; Fujishima, A.; Hashimoto, K. Chem. Lett. 1998, 585-586; and Sato, O.; Einaga, Y.; Fujishima, A.; Hashimoto, K. Inorg. Chem. 1999, 38, 4405-4412), depends on a compromise between the number of excitable diamagnetic pairs and the amount of [Fe(CN)6] vacancies giving the network flexibility. Besides the efficiency of the photoinduced process, the amount of [Fe(CN)6] vacancies also controls a thermally induced electron transfer.

Metal-to-ligand and ligand-to-metal charge transfer in thin films of Prussian blue analogues investigated by X-ray absorption spectroscopy

“…On the contrary, MnFe Prussian blue analogues show a thermally induced phase transition from the HT cubic Fe(III)(S = 1/2)-CN-Mn(II) (S = 5/2) phase to the LT tetragonal Fe(II)(S = 0)-CN-Mn(III) (S = 2) phase accompanied by a Jahn-Teller distortion on the manganese ion. 13,14 Until now many investigations have been performed on these materials using X-ray techniques, such as X-ray diffraction, 9,13,15 X-ray absorption spectroscopy [5][6][7]10,12,16,17 and X-ray magnetic circular dichroism. 8 However, these studies focused on powder samples and no X-ray data are available so far for Prussian-blue-based thin films.…”

Soft x-ray absorption spectroscopy study of the electronic structures of the MnFe Prussian blue analogs (RbxBay)Mn[3−(Lee1, Seong2, Kim3 et al. 2017Phys. Rev. B8010View full textAdd to dashboardCite

“…Then, as in CoFe PBAs, the valence transition between the Mn 2+ (S = 5/2)−Fe 3+ (S = 1/2) pairs at HT and the Mn 3+ (S = 2)-Fe 2+ (S = 0) pairs at LT has been suggested for MnFe PBAs [6,10,16,17]. However, these models are controversial [3,9,[12][13][14][15][16][17], and the experimental evidence for them is lacking. Therefore, in order to understand the origin of the switching phenomena in PBAs, it is crucial to determine the valence and spin states of M and M ions experimentally.…”

“…The switching phenomena, observed in a CoFe PBA [3], were often ascribed due to a charge transfer between the Co 2+ (S = 3/2)-Fe 3+ (S = 1/2) pairs and the Co 3+ (S = 0)-Fe 2+ (S = 0) pairs through the cyanide C ≡ N bridge. In this interpretation, the low-spin (LS) Co 3+ (t [3,[12][13][14][15]. In certain Rb x Mn z [Fe(CN) 6 ] · mH 2 O PBAs, a temperature (T ) -induced phase transition with a large thermal hysteresis was observed [10,16,17].…”

“…Several studies on the valence states of M and M ions in PBAs have been reported in the literature [7,8,12,17,[20][21][22]. Some of the previous XAS studies on PBAs were done at the K edges of M and M ions [7,8,12,17,22]. K-edge (1s) XAS for M and M ions has the advantage of being bulk-sensitive because of the use of hard x rays.…”

Photoinduced magnetic bound state in an itinerant correlated electron system with a spin-state degree of freedom

“…A well known example of the photo-induced spin state change is seen in the so-called spin cross-over complexes, such as Prussian blue analogue complex. [12][13][14][15] Here, photons bring about a charge transfer from the neighboring Fe ions to Co ions, associated with the spin-state change in Co ions from the low-spin (LS) state to the high-spin (HS) one. A main mechanism of the cooperative spinstate transition in a series of materials is supposed to be the elastic interaction; [16][17][18][19] a local volume change of a metal-ligand cluster propagates over a crystal lattice.…”