Microstructural development and properties of solution-chemistry-derived Sr(x)Ba(1-x)Nb(2)O(6) thin films and bulk ceramics.

摘要

Microstructural changes in sol-gel derived SrxBa 1−xNb2O6 (SBN) thin films were monitored as a function of Ba to Sr ratio (from x = 0 to x = 1), choice of substrate (Si, Au, or MgO), and processing variations. Sols were created using Ba, Sr, and Nb alkoxides dissolved in acetic acid. The relatively high decomposition temperature for the organics led to a tendency to form defects, but careful control of thermal process parameters could be used to produce a uniform film microstructure. An unexpected phase interpreted as a hexagonal (pseudo-orthorhombic) variant of hexagonal BaNb2O6 was encountered in Ba rich sol-gel derived SBN powders and thin films annealed at 750°C. Increased (001) orientation was observed in films deposited on (100) MgO and on polycrystalline Au when fast thermally processed.;In addition to fabricating thin films, strontium barium niobate, Sr xBa1−xNb2O6, (SBN) ceramics with a range of Sr/Ba ratios were fabricated using a solution chemistry approach with alkoxides dissolved in acetic acid. Powders obtained from dried gels were calcined at 800°C for three hours, a heat treatment that produced fully crystalline powders. After sintering at 1200°C for 1–24 hours, the tetragonal tungsten bronze (TTB) phase at least partially formed in all compositions between 0 ≤ x ≤ 1, although not predicted by the phase diagram for BaNb2O6 and SrNb2O6. V2O5 additions increased the densification, the amount of tungsten bronze phase, and the dielectric constant for all compositions except for SBN65 ceramics.