Porosity and composition effects in sol-gel derived interference filters

B. D. Fabes, Dunbar P Birnie, B. J J Zelinski

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The effects of porosity and composition on the optical thickness of sol-gel films is analyzed using the Clausius-Mossotti relationship. The optical thickness is predicted to decrease with shrinkage approximately linearly. For high density films the predictions agree with experimental data from SiO2 and SiO2-TiO2-Al2O3 coatings. At low densities, however, the optical thicknesses are much higher than predicted by the Clausius-Mossotti analysis. This difference is attributed to residual species in the unfired films. Using an empirical value for the ratio of the electronic polarizability αr to the molecular weight Wr of the residual species ( αr Wr = 1.65 × 10-25cm3 mol g-1) the difference between experiment and theory is accounted for quantitatively for both the single-component (SiO2) and multicomponent (SiO2-TiO2-Al2O3) coatings. Approaches to fabricating multicolor dichroic filters, which require large changes in optical thickness on heating, are presented.

Original languageEnglish
Pages (from-to)175-180
Number of pages6
JournalThin Solid Films
Volume254
Issue number1-2
DOIs
Publication statusPublished - Jan 1 1995

Fingerprint

Composition effects
optical thickness
Sol-gels
Porosity
gels
porosity
interference
filters
Coatings
coatings
Molecular weight
shrinkage
Heating
molecular weight
Chemical analysis
heating
predictions
Experiments
electronics
TiO2-SiO2

Keywords

  • Ceramics
  • Coatings
  • Ellipsometry
  • Optical coatings

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Metals and Alloys
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces
  • Condensed Matter Physics

Cite this

Porosity and composition effects in sol-gel derived interference filters. / Fabes, B. D.; Birnie, Dunbar P; Zelinski, B. J J.

In: Thin Solid Films, Vol. 254, No. 1-2, 01.01.1995, p. 175-180.

Research output: Contribution to journalArticle

Fabes, B. D. ; Birnie, Dunbar P ; Zelinski, B. J J. / Porosity and composition effects in sol-gel derived interference filters. In: Thin Solid Films. 1995 ; Vol. 254, No. 1-2. pp. 175-180.
@article{3c06c2993e4a47ada403fc127ee64dd9,
title = "Porosity and composition effects in sol-gel derived interference filters",
abstract = "The effects of porosity and composition on the optical thickness of sol-gel films is analyzed using the Clausius-Mossotti relationship. The optical thickness is predicted to decrease with shrinkage approximately linearly. For high density films the predictions agree with experimental data from SiO2 and SiO2-TiO2-Al2O3 coatings. At low densities, however, the optical thicknesses are much higher than predicted by the Clausius-Mossotti analysis. This difference is attributed to residual species in the unfired films. Using an empirical value for the ratio of the electronic polarizability αr to the molecular weight Wr of the residual species ( αr Wr = 1.65 × 10-25cm3 mol g-1) the difference between experiment and theory is accounted for quantitatively for both the single-component (SiO2) and multicomponent (SiO2-TiO2-Al2O3) coatings. Approaches to fabricating multicolor dichroic filters, which require large changes in optical thickness on heating, are presented.",
keywords = "Ceramics, Coatings, Ellipsometry, Optical coatings",
author = "Fabes, {B. D.} and Birnie, {Dunbar P} and Zelinski, {B. J J}",
year = "1995",
month = "1",
day = "1",
doi = "10.1016/0040-6090(94)06244-F",
language = "English",
volume = "254",
pages = "175--180",
journal = "Thin Solid Films",
issn = "0040-6090",
publisher = "Elsevier",
number = "1-2",

}

TY - JOUR

T1 - Porosity and composition effects in sol-gel derived interference filters

AU - Fabes, B. D.

AU - Birnie, Dunbar P

AU - Zelinski, B. J J

PY - 1995/1/1

Y1 - 1995/1/1

N2 - The effects of porosity and composition on the optical thickness of sol-gel films is analyzed using the Clausius-Mossotti relationship. The optical thickness is predicted to decrease with shrinkage approximately linearly. For high density films the predictions agree with experimental data from SiO2 and SiO2-TiO2-Al2O3 coatings. At low densities, however, the optical thicknesses are much higher than predicted by the Clausius-Mossotti analysis. This difference is attributed to residual species in the unfired films. Using an empirical value for the ratio of the electronic polarizability αr to the molecular weight Wr of the residual species ( αr Wr = 1.65 × 10-25cm3 mol g-1) the difference between experiment and theory is accounted for quantitatively for both the single-component (SiO2) and multicomponent (SiO2-TiO2-Al2O3) coatings. Approaches to fabricating multicolor dichroic filters, which require large changes in optical thickness on heating, are presented.

AB - The effects of porosity and composition on the optical thickness of sol-gel films is analyzed using the Clausius-Mossotti relationship. The optical thickness is predicted to decrease with shrinkage approximately linearly. For high density films the predictions agree with experimental data from SiO2 and SiO2-TiO2-Al2O3 coatings. At low densities, however, the optical thicknesses are much higher than predicted by the Clausius-Mossotti analysis. This difference is attributed to residual species in the unfired films. Using an empirical value for the ratio of the electronic polarizability αr to the molecular weight Wr of the residual species ( αr Wr = 1.65 × 10-25cm3 mol g-1) the difference between experiment and theory is accounted for quantitatively for both the single-component (SiO2) and multicomponent (SiO2-TiO2-Al2O3) coatings. Approaches to fabricating multicolor dichroic filters, which require large changes in optical thickness on heating, are presented.

KW - Ceramics

KW - Coatings

KW - Ellipsometry

KW - Optical coatings

UR - http://www.scopus.com/inward/record.url?scp=0029219226&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029219226&partnerID=8YFLogxK

U2 - 10.1016/0040-6090(94)06244-F

DO - 10.1016/0040-6090(94)06244-F

M3 - Article

AN - SCOPUS:0029219226

VL - 254

SP - 175

EP - 180

JO - Thin Solid Films

JF - Thin Solid Films

SN - 0040-6090

IS - 1-2

ER -