Study of Mg2+-intercalated Nb2O5 thin films for electrochromic applications

The electrochromic behavior of sol-gel-derived Nb2O5 thin films with Mg2+ intercalants has been reported. Films have been intercalated and deintercalated with Mg2+ in the galvanostatic mode using the three-electrode configuration. The ratio of the Mg ions to Nb atoms (referred to as x) has been varied from 0.25 to 0.75. The transmission at 500 nm has changed from 70 to 35% on intercalating to x=0.75. The infrared investigations reveal the presence of adsorbed water, strong interaction between oxygen of the host material and Mg2+, and also formation of Mg(OH)(2) on intercalation. Cyclic voltammetry studies show the existence of irreversible structural changes of lesser magnitudes on cycling. Atomic force microscopy and scanning electron microscopy images show marginal changes in surface morphology on intercalation. (c) 2007 The Electrochemical Society.