Dielectric properties of Li doped Li-Nb-O thin films

Lithium niobate LiNbO3 was prepared as a thin film layered structure deposited on stainless steel substrate using e-gun evaporation. The Li doping was provided for by the formation of Li-Nb-O/Li/LiNb-O sandwich structure and annealing at about 250 C. AC impedance spectroscopy measurements were performed on the samples at temperatures from the interval between 28 and 165 C and in a frequency range of 10-3 to 106 Hz. Using the values Z' and Z'' at different frequencies, the dielectric parameters - parts of the complex permittivity ε' and ε'' and loss tangent tan δ were calculated. The results prove validity of the proposed equivalent circuit containing parallel RC elements connected in series where the first RC element represents the bulk of material and the second RC element belongs to the double layer at the metal interface. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)