Two resistance-switchable hybrid polyoxotantalates based on {Co2Ta12} clusters

Abstract

Two inorganic–organic hybrid polyoxotantalates, H₄[Na(H₂O)₅]₂[Co^II(en)₃]₂{[Co^III(en)]₂(Ta₆O₁₉)₂}·22H₂O (1) and H₂K₂Na₆ (H₂O)₂₄{[Co^III(en)]₂(Ta₆O₁₉)₂}·33H₂O (2) have been constructed from {[Co^III(en)(Ta₆O₁₉)]₂}¹⁰⁻ ({Co₂Ta₁₂}) dimers. Compound 1 has a three-dimensional supramolecular framework with a pcu-type topology. Compound 2 possesses a three-dimensional structure composed of {Co₂Ta₁₂} dimers and alkali metal ions (Na⁺/K⁺) via coordination bonds. Polyoxotantalates 1 and 2 have been used as active materials for ITO/1/Ag and ITO/2/Ag RRAM devices. These devices exhibit stable non-volatile storage behavior and rewritable resistive switching with high ON/OFF ratios of 1.43 × 10³ and 2.17 × 10⁴ for 1-based and 2-based RRAM devices, respectively, and stable cyclic performance during 100-cycle stability tests. This discovery opens up new opportunities for the development of electrical bistability materials.