Silicon and phosphorus alkoxide mixture: Sol-gel study by spectroscopic technics

Influence of calcium precursors on the morphology and crystallinity of sol–gel-derived hydroxyapatite nanoparticles

“…The chemical reaction analysis using liquid state NMR is especially helpful for the analysis of sol to gel conversion [19]. P 31 NMR spectra of samples aged for different periods are shown in Fig.…”

Structural characterization of some sol–gel derived phosphosilicate glasses

“…3a), due to the PAO symmetric stretch [30], seems alike for the Gel_TEP and liquid TEP, its reduced intensity for the Gel_TEPI (Fig. 3b) Lack of the P@O bonds, Raman band located at 1261 cm À1 [7], is identified for the Gel_(TEPI/H 3 PO 4 ) (see Fig. 3b and c).…”

“…Due to the lack of the TEP reactivity probed by 31 P NMR, Fernando-Lorenzo et al [6] used H 3 PO 4 as phosphorous source and the obtained materials by heat treatment of the gels at 300, 500 and 800°C were highly non-homogeneous. Among the three phosphorous alkoxides used by Scrotter et al [7], OP(OC 2 H 5 ) 3 (TEP), P(OC 2 H 5 ) 3 (TEPI) and (OC 2 H 5 ) 2 -O-P(OC 2 H 5 ) 2 , TEP was little reacted in sol after ten months while system with TEPI gave PAOAP and PAOASi in the corresponding gel. Hydrolysis of TEOS was proven to be faster then the phosphorous alkoxides.…”

“…Extensive NMR investigations [4,[10][11][12][13] of the phosphosilicate gels and corresponding glasses were carried out while Raman approach of their structure draws less attention [14,15]. Both Raman and NMR spectroscopies are versatile tools to monitor various stages of the whole sol-gel to glass preparation process [7,16,17]. Analogous to gels, the final glass structure is highly dependent on the synthesis parameters [18].…”

Improvement of Hydroxyapatite Sol–Gel Coating on Titanium with Ammonium Hydroxide Addition

“…22 Different from the single component gelation, in the HA sol-gel process, along with the hydration of P to P-OH, the introduction of Ca source and a further formation of [-Ca-O-P-] are necessary to mature the HA structure. Since the P-OH hydration is known to occur nearly completely after 24 h of stirring, 21,24 the [-Ca-O-P-] chain formation can be a rate-determining step. Therefore, the NH 4 OH, which was added to the Ca-P mixture solution, not to the P solution, played a role in increasing the [-Ca-O-P-] chain reaction rather than the P-OH hydration.…”