Aqueous Solution–Gel Preparation and Dielectric Properties of Ba(Mg1/3Nb2/3)O3 Thin Films with Long‐Range Order

Abstract

In the present research, the Ba(Mg1/3Nb2/3)O3 (BMN) thin films with high 1:2 long‐range order (LRO) were prepared by an entire aqueous solution–gel route and a heat treatment at low temperature. The BMN precursor solutions used for spin‐coating consist of tri‐metal ions citrate complexes, which are formed through the combination of three single citrate complexes with NH4+ acting as crosslinks. The metal‐coordinated bonds of the citrate complexes can be easily broken by heat treatment, which can result in the crystallization of BMN films at low annealing temperature. The crystalline structure and LRO degree of BMN films were also investigated. It is shown that the LRO degrees increase with the increase in annealing temperature. The dielectric constant increases and the dielectric loss decreases with the annealing temperature up to 750°C due to the improvement of the film densification and the LRO degree. The further increase in annealing temperature slightly decreases the dielectric constant and increases the dielectric loss due to the appearance of large aggregates. It is shown that the charge carriers mainly contribute to the dielectric response below 100 KHz, while the dipolar response starts to take effect for the frequency higher than 100 KHz.