Characterization and electrical properties of new perovskite films of Ba(Ti,Zr)O₃ type doped with lanthanum (BLZT)

Abstract

Abstract In the current work, we characterized a new family of compounds with perovskite‐type structure with the general formula: Ba 1–y La 2y/3 Ti 1–x Zr x O 3 (BLZT). Through XRD on crystalline powder we detected a single perovskite cubic phase, Pm3m (221), for the compounds with zirconium content (x) lower than 0.15 and lanthanum content (La) lower than 0.17. Upon increasing the x value in BLZT compounds, the value of La falls to 0.13. Morphology studies through SEM revealed that the incorporation of lanthanum into the composition of Ba(Ti,Zr)O 3 (BZT) compounds produces the formation of bigger grains and materials with greater density. The stoichiometry for each compound was corroborated by atomic emission spectroscopy (AES‐ICP). The lanthanum‐doped compounds demonstrated higher relative permittivity values with respect to the BZT and a decrease of the Curie temperature (T c ) with relation to the amount of La 3+ ion present in the structure. Finally, we grew thin films by using a target of the compound Ba 0.90 La 0.067 Ti 0.91 Zr 0.09 O 3 over three different substrates under two atmospheres (Ar and O 2 ), using the Magnetron Sputtering technique by Radio Frequency (RF), showing the best results when growth is over the substrate SrTiO 3 .Nb 0.1% in the [00l] direction under an O 2 atmosphere. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)