X-ray diffractometric determination of crystalline phase content in bioactive glasses

Abstract

A rapid routine determination of the content of crystalline CaF(2) and Al(2)O(3) inclusions in bioactive glass ceramics is performed using X-ray diffractometry with a standard addition technique. Multiple ratio analysis, even using peaks with different broadenings, indicates that differences in crystallite properties (e.g., crystal imperfection, particle size and morphology, preferred orientation) between the unknown sample and standard do not bias the result. In this respect, an exact match between their crystallographic integrities does not seem to be required for a reliable estimation of the crystalline content with a relative standard deviation of 7%.

Phosphorous pentoxide-free bioactive glass exhibits dose-dependent angiogenic and osteogenic capacities which are retained in glass polymeric composite scaffolds

“…This might be related to the presence of trace elements within the glass that could be responsible for inducing the crystallization of some silicate phases. 22,37 Thermal analysis performed by TG-DTA showed a total mass loss of <1% upon heating (Fig. 1B), which can be explained by water loss at 82 °C (α) and -OH group breakage at 174 °C (β).…”

Calcium phosphate cements modified with pore expanded SBA-15 materials

“…Peak areas were used for the calculation of R in order to reduce effects of particle size, stacking disorder or degree of crystallinity. 28 The area of the selected peaks was calculated by fitting the peaks using a leastsquares curve-fitting program based on the Levenberg-Marquardt non-linear minimization algorithm. The peaks were fitted most accurately using asymmetric double sigmoid profiles.…”

Apatite formation in composites of α-TCP and degradable polyesters

“…These peaks are representative for the corresponding calcium phosphates with an acceptable relative intensity and minimal overlap with neighboring peaks in the diffractograms of the composites. Peak areas were used for the calculation of R in order to reduce effects of particle size, stacking disorder or degree of crystallinity [31]. The integrated intensity ratio R enables a reproducible quantitative determination of crystalline phases in a mixture without the use of standard materials or the knowledge of the mass absorption coefficients of the different phases [31].…”

“…Peak areas were used for the calculation of R in order to reduce effects of particle size, stacking disorder or degree of crystallinity [31]. The integrated intensity ratio R enables a reproducible quantitative determination of crystalline phases in a mixture without the use of standard materials or the knowledge of the mass absorption coefficients of the different phases [31]. Moreover, the latter are not known for the experimental polymer matrices and most probably change during the polyester degradation.…”