as the temperature increases additional frustrated oxygen consuming reactions occur until the material is fully saturated with oxygen or until the last instability point is passed two thick dielectric electroluminescent devices incorporating thin film phosphor layers comprising barium thioaluminate activated with europium were constructed the thick film substrate was comprised of a 5 cm by 5 cm alumina substrate having a thickness of 0 1 cm a gold electrode was deposited on the substrate followed with a thick film high dielectric constant dielectric layer in accordance with the methods exemplified in applicant 39 s co pending international application pct ca00 00561 filed may 12 2000 the entirety of which is incorporated herein by reference a thin film dielectric layer consisting of barium titanate with a thickness of about 100 u2013 200 nanometers was deposited on top of the thick film dielectric layer using the sol gel technique described in applicant 39 s co pending u s patent application ser no 09 761 971 filed jan 17 2001 the entirety of which is incorporated herein by reference the phosphor film was electron beam evaporated on top of the barium titanate layer using dual source electron beam evaporation according to the methods described in applicant 39 s co pending u s patent application ser no 09 747 315 filed dec 22 2000 the entirety of which is incorporated herein by reference the two.