Effect of technological parameters on the properties of Cuo-TiO2 sol-gel films

Abstract

The effect of technological parameters on the properties of 2-and 42-day film-forming solutions of the system CuO -TiO 2 is analyzed. It is found that the initial components have a strong effect on the maturing of film-forming colloidal solutions (FCS) and the properties of coatings. The properties of coatings obtained from solutions of different age are associated with changes in their microstructure. The index of refraction and the thickness of the films from 42-day FCS are essentially independent of the calcination regime; the variation of the refractive coefficient and chemical stability is inconsistent.It is well-known [1] that thin sol -gel film coatings are nearly glassy so that their properties, just as the properties of glass, should depend on the thermal history -the heat-treatment regime.The film-forming colloidal solutions (FCS) in the form of sols in sol-gel technology age during storage and use. The state of the dispersed phase changes, which should be reflected in the properties of FCS and coatings. In conventional glassmaking, if measures are taken to prevent the separation and contamination of the mixture of raw materials, the mixture can be stored for quite a long time, and the properties of the glass obtained will be constant to within the limits of the experimental error.The objective of the present work is to study the relationship between the age of FCS, the past history of the coating, and the properties of sols and films.Five compositions belonging to the two-component system CuO -TiO 2 differing by the ratio of the film-forming oxides or the raw materials used for preparing the FCS were studied. Copper oxide was introduced in the solution as copper chloride or copper nitrate, TiO 2 was introduced by alkoxides: tetraethoxytitanate Ti(OC 2 H 5 ) 4 (TET) or tetrabutoxytitanate Ti(OC 4 H 9 ) 4 (TBT). Hydrochloric or nitric acid (if the copper oxide was introduced as a chloride or nitrate, respectively) served as the catalyst for the hydrolysis of alkoxides and ethyl alcohol served as the solvent. The total mass content of the film-forming oxides in all solutions (the FCS concentration) was the same and equal to 5%. The aging time of sols was 2 and 42 days.The capillary method was used to measure the viscosity of FCS (VPZh-1 viscosimeter). Samples of heat-polished sheet glass (70´70´5 mm) were immersed in a solution and extracted at a constant rate 1 mm/sec, held for 2 -3 h in air at room temperature to complete the hydrolysis and polycondensation processes, and calcined in a furnace with Silit heaters at temperatures 350, 450, or 550°C for 30 min. All measurements were performed on the side of the glass which during production was in contact with the protective gas atmosphere of the furnace.The structural changes in the films were studied using photomicrographs obtained with magnification´100 (MIM-8M light microscope). The index of refraction n, the thickness h (LÉF-ZM-1 ellipsometer), and the coefficient of mirror reflection R (Pul'sar spectrocolorimeter) were measured. The chemical stabilit...

Optical properties of composites with nanodimensional oxide coatings versus the properties of film-forming sols. I. The influence of sol’s oxide composition

“…It was found [8] that the deposit consists largely of a copper containing component: X ray phase analysis data for powders obtained by drying a sol having been aged for 2 days show that the amount of TiO 2 is 73 and that of CuCl 2 ⋅2H 2 O is 33 arb. units.…”