MICROWAVE CHARACTERIZATION OF HYDROTHERMALLY CRYSTALLIZED BARIUM STRONTIUM TITANATE SOL-GEL COMPOSITE THIN FILMS USING A COPLANAR WAVEGUIDE TECHNIQUE

ABSTRACT

Barium strontium titanate (BST) and BST doped with 5 at% Mn films have been fabricated on gold-patterned alumina substrates by hydrothermal sol-gel composite recrystallization at < 200°C. A spun-on sol-gel BST composite film is hydrothermally treated in an alkaline aqueous solution at elevated pressure. The dielectric constant and loss tangent between 5 and 40 GHz has been determined using the response of a series of coplanar waveguide spur-line band stop filters. The film shows a maximum dielectric constant between 15–40 GHz of 94 ± 5 for a film 2.6 μ m in thickness. The loss tangent at 15 GHz is 0.07.

Keywords::

• Hydrothermal crystallization
• sol gel composite coatings
• barium strontium titanate
• microwave characterization