Electrical Conductivity of Prussian Blue Analogues (Cu, Ni, K Cu, K Ni)

Abstract

Prussian Blue, Fe+3₄[Fe+2₆]₃·xH₂O is a typical hexacyanometalate network, in which cyanide ligand coordinates octahedrally with the metal ion. Interstitial cations and metal vacancies balance the local charge in PB structure. This octahedrally coordinated cyanide ligand with metal ion imparts high electrical conductivity to PB. Other than high electrical conductivity, hexacyanometalate offers interesting redox property. That makes PB suitable material for microelectronics applications such as Resistive Random Access Memories (RRAM). PB shows change in colour during redox transitions when transitions metal cations are associated with it. The change in colour is due to charge transfer between transitions metal cations and hexacyanometalate group. This charge transfer tunes the electrical conductivity of PB compounds. Here we tune the electrical conductivity of PB by adding transition metal cations (Cu, Ni, K Cu, K Ni) into it. Conduction mechanism will be explained based on ab initio and density of states calculations. From these calculation results, we also explain the contribution of each metal on hopping and band transport, which is the responsible conduction mechanism for varying electrical conductivity in PB analogues.