Structural Characterization of Gel-Derived Calcium Silicate Systems

Abstract

The main aim of this study is to synthesize calcium silicate ceramics that exhibit suitable properties to be used for biomedical applications. In the present work, attention was paid to the understanding of processing-structure relationships. A particular effort was made to clarify the identification of Ca-O-Si bonds by means of spectroscopy. The calcium silicate systems were prepared via a sol-gel route, varying the chemical compositions, the catalyst concentration, and the temperature and time of aging and heat treatment. The processes and the phases evolved during the sol-gel procedure were determined. The bond systems were investigated by Fourier transform infrared (FTIR) and (29)Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and the aggregate structures by scanning electron microscopy (SEM), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and X-ray diffraction (XRD) measurements.

Characterization of Calcium-doped Silica Gel Prepared in an Aqueous Solution

“…3b). This band is corresponding to Si-O-Ca bonds in wollastonite 6,7 . This result suggests that the Si-O-Ca bonds have been formed by the modification of silica gel with the Ca(OH) 2 solution.…”

“…Calcium ions can react with soluble silica formed under basic conditions and with silanol groups located on the silica gel surface to produce various calcium silicate species depending on the molar ratio of Ca 2+ ions to silica 6,24 . Different species may yield different performance in applications due to their properties.…”

“…Through these silanol groups, the surface of silica gel can be easily modified with either organic functional groups or inorganic cations [2][3][4] . Calcium ions have been widely used to synthesize both calcium-doped silica and calcium silicate composites [5][6][7][8][9] . Calcium-doped silica (CS) was synthesized and its functionality as a catalyst, drug carrier, and anticorrosion pigment was investigated 5,[10][11][12] .…”

Phosphate Removal from Aqueous Solutions Using Calcium Silicate Hydrate Prepared from Blast Furnace Slag

“…CSH is known to transform into various crystalline calcium silicate phases (such as tobermolite (Ca 5 Si 6 O 16 (OH) 2 ·4H 2 O), wollastonite (CaSiO 3 ) and belite (Ca 2 SiO 4 )) by thermal treatment. 25) Considering the crystalline structures and diffraction intensity of the solid, the product is considered to be a low-crystalline amorphous CSH. Minor peaks seen at 11.2 and 60.8° can be indexed to Mg-Al hydrotalcite, a layered double hydroxide compound (LDH) consisting of Mg(OH) 6 and Al(OH) 6 octahedra, which might be formed in the early stage of precipitation due to their lower equilibrium product constants than that of Ca.…”

Peculiarities of the Composition and Regularity of Dissolving Materials Based on Hydroxyapatite Obtained in Water Systems With Varied Content of Silicate Ions

“…Помимо полос поглощения груп-пировок, входящих в структуру ГА, в спектрах твердых фаз, осажденных в системах Ca(NO 3 ) 2 -(NH 4 ) 2 HPO 4 -Na 2 SiO 3 -NH 4 ОН -H 2 O при у ≥ 0.3, фиксируются пики, отвечающие самостоятельной силикатной фазе. При 790 -800 см -1 в спектрах образцов регистрируется мода валентных колебаний силоксановых мостиков (Si-О-Si) в составе оксида кремния [1,4] и гидросиликата кальция (ГСК, rСаО·mSiO 2 ·nН 2 О) [5]. Плечо в области 1200 см -1 обусловлено валентными колебаниями связей Si-О в SiO 2 [4] и ГСК, для которого молярное соотно-шение Ca/Si ≤ 0.7 [6].…”