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Influence of Gelation Temperature on the Properties of Sol-Gel-Derived Calcium Hydroxyapatite Ceramics

Bogdanoviciene I., Tonsuaadu K., Kareiva A.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 1

47-55

EN

An aqueous sol-gel chemistry synthesis route has been developed to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHA) samples at different gelation temperatures. In the sol-gel processes, an aqueous solution of tartaric acid as complexing agent was used. The phase transformations, composition and micro-structural properties of the polycrystalline samples were studied by thermogravimetric analysis (TG), differential thermal analysis (DTA), energy-dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM). It was clearly demonstrated that temperature of initial stage of the preparation of CHA is a crucial parameter to obtain monophasic calcium hydroxy apatite powders with desired morphological properties.

2

Sol-Gel Synthesis and Super conducting Properties of Bi-2212 High-TC Super conductors

Zalga A., Beganskiene A., Kareiva A.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 9

1547-1553

EN

A novel aqueous sol-gel synthesis technique has been refined to prepare heterometallic (Bi1.75Pb0.25)Sr2CaCu2Ox and (Bi1.8Pb0.33)Sr1.87CaCu2Ox (Bi-2212) oxides. The formation of Bi-2212 phase depending on synthesis conditions (duration of annealing, stoichiometry of metals) has been estimated. The synthesized products were characterized by powder X-ray diffraction analysis (XRD) and resistivity measurements. It was demonstrated, that the investigated synthesis conditions only slightly influence on the phase purity and super conducting properties of Bi-2212 phase.

3

Sol-gel preparation and characterization of perovskite gadolinium aluminates

Cizauskaite S., Reichlova V., Nenartaviciene G., Beganskiene A., Pinkas J., Kareiva A.

Materials Science Poland

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2007

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Vol. 25, No. 3

755--765

EN

The paper reports on the results concerning the sol-gel preparation of the nanocrystalline nonsubstituted and Sr-substituted gadolinium aluminate (GdAlO3, GAP) ceramics at slightly varying conditions of synthesis. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain precursors for the non-substituted and Sr-substituted GAP. In the sol-gel processing different starting gadolinium materials such as gadolinium nitrate or gadolinium oxide were employed. The influence of the temperature and the amount of substituent on the phase purity of GAP was also investigated. Phase transformations, composition and micro-structural features in the gels and polycrystalline samples were studied by thermal analysis, powder X-ray diffraction analysis, infrared spectroscopy and scanning electron microscopy.

4

Sol-gel derived antireflective coating with controlled thickness and reflective index

Beganskiene A., Sakirzanovas S., Kazadojev I., Melninkaitis A., Sirutkaitis V., Kareiva A.

Materials Science Poland

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2007

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Vol. 25, No. 3

817--824

EN

Optical properties and structure of antireflective coatings (AR) deposited from hydrolysed TEOS sol have been characterized in detail. The influence of various parameters on the formation of colloidal silica antireflective coatings by the dip-coating technique has been investigated. For the characterization of colloidal silica films, the UV-visible spectroscopy, laser ellipsometry, and atomic force microscopy were used. Using optimal sol-gel processing conditions (dipping rate - 40 mm/min, coating time - 20 s, and temperature - 20 oC), the colloidal silica coatings were obtained and characterized in comparison with non-coated glass substrate. The reflectance of AR coatings increased with increasing the temperature of sol-gel processing. The laser damage threshold of as deposited films was measured at 1064 nm (1H) and 335 nm (3H) wavelength using a Nd:YAG lasers. The laser damage threshold of AR coating exceeded 15.22 J/cm2 at 1064 nm and 26.82 J/cm2 at 355nm.

5

Destructive Effects of Paper Conservation Procedure on the Writing Iron Gall Ink-Evidence from Transmetalation Reaction

Senvaitiene J., Pakutinskiene I., Beganskiene A., Tautkus S., Kazlauskas R., Kareiva A.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 10

1575-1583

EN

The influence of carboxylate-alumoxane protective coatings on the condition of writing paper inked with iron and copper gall inks has been investigated. All paper samples used in this study were coated with hexanato-alumoxane at room temperature changing the soaking time from 1 to 8 h. The influence of deconservation parameters (duration and temperature) on the stability of inks was also studied. Paper samples (untreated, coated and after deconservation) were examined by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Analytical characterization of paper samples showed no degradation of its cellulosic substrate during conservation. However, the destructive effect of alumoxane on the writing iron gall inks was determined.