Role of Catalyst on Refractive Index Tunability of Porous Silica Antireflective Coatings by Sol−Gel Technique

Abstract

Porous silica coatings were prepared by acid- and base-catalyzed sol−gel method. Surface morphology studies by atomic force microscopy showed smooth surface for acid-catalyzed coatings while base catalysis resulted in coarse particle morphology. On increasing the tetraethyl orthosilicate to base molar ratio from 1:1 to 1:3, the mean particle size of the coating shifted from 30 to 100 nm while the pore size varied from 4.7 to 14 nm. Infrared spectral analysis exhibited a change in the ratio of integrated peak intensities of Si−O−Si to Si−OH in acid-and base-catalyzed silica coatings. Textural studies showed an increase in particle size and porosity with base concentration. Optical transmission and surface roughness of base-catalyzed samples were found to be higher than that of acid-catalyzed silica coatings.

Fabrication of SiO₂-TiO₂ Double Layers Anti-Reflection Coating by Sol-Gel Method and Study of its Optical Properties

“…In the second step, ethanol was added to the solution so that the molar ratios became TIVBT:EtOH:CH 3 COOH=1:150:0.5, After this, the solution was stirred for 1 h more still at room temperature then the solution came out homogeneous and transparent. [12][13] We prepare thin films from TiO 2 by immersing the cleaned substrate into the Sol and get it up with a controlled withdrawal speed then we put it in the furnace at 100 C for 15 min, annealed it at 500 C for 1 hour then we cooled it to room temperature which we called procedure No.1 [14][15][16] The SiO 2 sol was prepared by tetra ethyl ortho silicate (Si(OC 2 H 5 ) 4 [18][19].…”

“…compounds are coated as a thin film on glass by a variety of techniques [1][2]. SiO 2 coatings, for example, have attracted attention due to their transmittance of glass as a result of their low refractive index and low surface scattering [3][4]. SiO 2 -coated anti-reflective glasses are currently used commercially in TV screens, picture framing, optical lenses and solar panels [5][6].…”

Surface Modification of Sol-Gel Silica Antireflective Coatings by F-PMHS: A Simple Method for Improvement of Amphiphobicity

“…The three peaks around 2964 cm −1 corresponds to the stretching vibration of C-H bonds from -CH3 [18]. The water deformation band appear at about 1630 cm −1 [19]. The absorption bands at around 1090 cm −1 and 800 cm −1 are the characteristic absorption band of Si-O-Si bond due to the asymmetric and symmetric vibration, respectively [20,21].…”

Preparation of mechanically stable triple-layer interference broadband antireflective coatings with self-cleaning property by sol–gel technique

“…As to acid-catalyzed sol, the growth of clusters can be described as a RLCA (Reaction Limited Cluster-cluster Aggregation) model, 53 resulting in a structure of linear chains, and the particle size are very small with many particle-particle bondings, 54 and thus the formed lm tends to be dense and robust. Additionally, the sintering process of the coatings enables the formation of anatase-TiO 2 , which exhibits high hardness.…”