cuo 4 y thin film formed on a polycrystal substrate in which a thin about 0 1 micrometer continuous film coats the individual grains of aluminum oxide this film is also completely dense except for where cracks have occurred between grains fig3 shows a thicker film of the same material which is not fully dense but rather is porous derived from a thicker polymer film coating fig4 shows a yba 2 cu 3 o 7 x film formed on an amorphous sio 2 substrate which is completely continuous and very smooth fig5 shows the yba 2 cu 3 o 7 x thin film formed on an mgo single crystalline substrate in which a small defect in a thicker portion of the film shows some cracking while the adjacent film region is thin continuous and smooth a substrate flat or otherwise is first coated with a citrate precursor to srtio 3 which is made as follows a solution containing is stirred and heated to less than 100 u00b0 c until the isopropanol present has evaporated this solution is assayed to determine the exact concentration of ti per unit volume or unit weight of the solution and then srco 3 is added in the correct amount to obtain a molar sr ti ratio of 1 1 this citrate solution is used to coat the substrate in one of the ways described above and fired to 600 u00b0 c in air or oxygen to yield a thin dense film of srtio 3 then the polymer solution which yields the superconductivity oxide is used to coat the srtio 3 film after firing a second time a layer of superconducting oxide on top of the srtio 3 film is formed a batio 3 film can.