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Influence of heating temperature on structural properties of sol-gel materials

Bauer J., Ulatowska-Jarża A., Podbielska H., Lechna-Marczyńska M., Bindig U., Muller G., Beuthan J.

Optica Applicata

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2005

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Vol. 35, nr 4

791-797

EN

In this paper, the influence of heating temperature on the properties of sol-gel materials was investigated . The aim of the study was to examine the production repeatability. All samples were made with factor R = 15, denoting the ratio of the number of precursor (TEOS) moles to solvent (water) moles. The samples were prepared in acid hydrolysis route on water, whereas two groups were considered: in one group the hydrolysis was terminated by addition of NH3źH2O and in the other there was no addition of base. The samples were stored for 1 month at room temperature and then exposed to high temperatures: 1000, 1200 and 1350°C. They were examined by means of scanning electron microscopy (SEM). The electron microphotographs were recorded, digitized and analyzed. The Fisher linear discriminant analysis for evaluation of the microscopic images was exploited. It was shown that the repeatability varied between 83.24% and 95.48%. The analysis demonstrated that the best results were achieved for neutralized samples made at 1000°C.

2

Mutual correlation of sol-gel optical properties and repeatability of production process examined by statistical pattern recognition methods

Kobel J., Podbielska H., Lechna-Marczyńska M., Ulatowska-Jarża A.

Optica Applicata

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2003

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Vol. 33, nr 1

97-105

EN

The methods based on the statistical pattern recognition are used for the evaluation of microscopic images of sol-gel matrices. The applied classification is a two steps scheme: dimensionality reduction of the data and cluster analysis. The obtained results have demonstrated that the molar ratio R (the number of solvent moles to the number of substrate moles) influences the stability of sol-gel materials, thus enabling us to reach the higher repeatability of the production process. It has been shown that the repeatability varies between 96.67% (for molar ratio R = 5) and 98.33% (for R = 15, 32, 50). This corresponds with the results of light scattering and transmission measurements.

3

Influence of the temperature of preparation process on refractive index of sol-gel matrices.

Lechna-Marczyńska M., Podbielska H.

Optica Applicata

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2001

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Vol. 31, nr 1

257-261

EN

The preparation of sol-gel materials in the form of bulks and thin films at different temperatures is described The procedure involves running the reaction at 50 degrees C and 90 degrees C in an open vessel. Such an approach enables acceleration of hydrolysis and condensation reactions. This procedure yields crack-free sol-gel glasses. The changes in refractive index of sol-gel materials were studied by using a Pulfrich refractometer. The experimental data indicates significant differences in the optical properties of sol-gel glasses, depending on the temperature during the preparation. The samples show normal dispersion, whereas a higher refractive index was stated for films prepared at a higher temperature.

4

Biomedyczne zastosowania porowatych materiałów zol-żelowych a rozpraszanie światła w biomateriałach wykonanych w technologii zol-żel

Lechna-Marczyńska M., Podbielska H., Ulatowska-Jarża A., Andrzejewski D.

Elektronizacja : podzespoły i zastosowania elektroniki

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2001

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nr 5

30-34

5

Computer-aided microscopic examination of the structure of sol-gel glasses prepared in the form of thin films.

Ulatowska-Jarża A, Lechna-Marczyńska M., Podbielska H.

Optica Applicata

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2000

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Vol. 30, nr 4

537-542

EN

For the studies described, the sol-gel matrices were prepared by way of acid hydrolysis. Thin films were produced in the form of thin layers covering the microscopic glasses. The optical microscope was used for examination of the sol-gel glass surfaces. The sol-gel materials produced from TEOS with various molar ratios R (ratio of the number of solvent moles to the number of TEOS moles) have been examined. The microscopic images were acquired by a computer and their Sobel transforms were calculated. The analysis of the experimental data showed that the sol-gel prepared with the molar ratio equal to 32 (R=32) are stable, do not crack and have smooth surface.