Growth and characterization of ternary Ni, Mg–Al and Ni–Al layered double hydroxides thin films deposited by pulsed laser deposition

Abstract

Layered double hydroxides (LDHs) are a class of layered materials consisting of positively charged brucite-like layers and exchangeable interlayer anions. Layered double hydroxides containing a transition metal which undergoes a reversible redox reaction in the useful potential range have been proposed as electrode coating materials due to their properties of charge transport and redox catalysts in basic solutions.Ni–Al,(Ni,Mg)–Al and, as reference, non-electronically conductive Mg–Al double hydroxides thin films were obtained via pulsed laser deposition technique. The thin films were deposited on different substrates (Si, glass) by using a Nd:YAG laser (1064nm) working at a repetition rate of 10Hz. X-ray diffraction, Atomic Force Microscopy, Energy Dispersive X-ray spectroscopy, Fourier Transform Infra-Red Spectroscopy, Secondary Ions Mass Spectrometry, Impedance Analyzer and ellipsometry were the techniques used for the as deposited thin films investigation. The optical properties of Ni based LDH thin films and the effect of the Ni amount on the structural, morphological and optical response are evidenced.The optical band gap values, covering a domain between 3.84eV and 4.38eV, respond to the Ni overall concentration: the higher Ni amount the lower the band gap value.