The $Pb_{1-X}La_XTi_{1-0.25X}O_3$ (PLT) solutions have been prepared by two different mixings of lead acetate, titanium isopropoxide and lanthanum nitrate in 2-methoxyethanol. One is the solution in which two PT and La solutions were mixed.(PLT) The other is the solution in which Pb, La, Ti solutions were mixed separately.(sPLT) The decomposition characteristics of the solutions have been examined by using Thermal analysis, Mass spectrometry, FT-IR and NMR. Also, the solutions have been spin-coated on glass and $SiO_2$/Si substrates for application of optical waveguide.
The different coating behavior and characteristics of the solutions have been investigated and the optimum solution and process conditions have been found for coating of thick and plain optical films. The refractive indices and transmissions of the films were examined using Ellipsometer and UV-VIS spectrophotometer.
Organics and nitrates were burned off at 350℃ and PbO and $PbCO_3$ were decomposed and volatilized at 500℃. PLT solution h as been found to be more stable and decomposed completely at definite temparature range than sPLT because PLT solution reacted between Pb acetate and Ti isopropoxide and left byproducts such as isopropylacetate but sPLT solution were merely mixed without these reaction.
No cracks were shown in the films dried at 350℃. However, the films dried at high temperature have cracks due to the differences of thermal expansion coefficients between PLT films and substrates. Also, the films dried at low temperature have defects and cracks due to organic residues. The films of the thickness up to 4100Å can be coated without cracks when heated at slower heating rates because organics and nitrates were completely decomposed and volatilized. Also, thick films without cracks up to the thickness of 7500Å can be coated when heated at 500℃ on plain heater in every spin-coating. It was found that the films using PLT solution were more plain and homogeneous than the films using sPLT solution.
Inspite of various heat treatment, only single perovskite phase was produced. The more thickness of films, the more intensity of XRD peak due to increased crystallinity.