Evidence of Magnetoresistance in the Prussian Blue Lattice during a Voltammetric Scan

Abstract

This manuscript reports evidence of magnetoresistance effects in the Prussian Blue lattice during a voltammetric scan at room temperature. Accordingly, the PB is a well-known semiconductor that becomes surprisingly an almost metallic conductor in the presence of an internal magnetic field induced during the voltammetric scan. This offers appealing perspectives for the control of this interesting phenomenon from electrochemical techniques that could be used for the fabrication of the recent phase-change computational memories, which are electronically configurable. Herein, the PB magnetic properties have been monitored in situ by means of resonating magnetic microsensors based on the shift in the resonant frequency of microelectromechanical systems.

Identification of electroactive sites in Prussian Yellow films

“…Prussian Blue was deposited from 0.02 M K 3 Fe(CN) 6 All experiments were carried out in KCl 0.5M, pH= 3.0 solutions and at the controlled temperature of 25 ºC.…”

“…Among others, electrochromic and magnetic properties, their possible use as a biosensor or their electrocatalytic behavior are of special interest [1][2][3][4][5][6][7][8][9].…”

“…In these works, it has been proved that some electrochemical properties are dependent on the rate of electrogeneration, obtaining narrower and sharper voltammetric peaks for the higher current deposited PB films. These PB films were galvanostatically generated from FeCl 3 and K 3 Fe(CN) 6 The crystal structure of these i-PB films has been reported to be cubic face centered [15][16][17][18][19][20][21][22] with space group symmetry Fm3m. i-PB films present structural vacancies, 1/4 of the ferrocyanide sites.…”

Electronic Perspective on the Electrochemistry of Prussian Blue Films

“…60 Furthermore, both arrangements imply a high electrical resistivity, in agreement with the resistivity observed in PB films. 40,50,61 An important increase in the exchange integral between iron ions located in high-and low-spin sites has recently been detected during the PB ES scan when the system reaches a ␣ Х 0.30, implying the optimization of double-exchange efficiency at this fractional content. 50 As a result, the Fe͑III͒/͓Fe͑II͒ + Fe͑III͔͒ ratio around 0.30 leads to the easier electronic exchange between neighboring iron ions.…”

“…25 Finally, Fig. 4 shows how the electric current caused by the PB changeover ͑which is characterized by the presence of an internal magnetic field induced 8,50 ͒ during their voltammetric scan is observed when almost all Fe 3+ ͑NC͒ 5 OH − and Fe 3+ ͑NC͒ 5 OH 2 sites are reduced. Conversely, the electrochemical reduction reactions of Fe͑II͒ low-spin -CN-Fe͑III͒ high-spin and Fe͑III͒ low-spin -CNFe͑II͒ high-spin sites occur mainly at more cathodic potentials.…”