Authors: Iain Massie, J.M.S. Skakle, Iain R. Gibson
Abstract: Silicate-substituted calcium phosphates have been shown to result in enhanced biological
performance compared to the corresponding, silicate-free, calcium phosphates. We have produced a
range of silicate-substituted alpha-TCP compositions using two different synthesis methods and two
different substitution mechanisms. Single phase compositions were only observed for a silicate
substitution of 1.3 wt% by both solid state synthesis and aqueous precipitation synthesis, although
the latter was the result of a design composition with a higher silicate substitution (3 wt%). The
silicate substitution resulted in small changes in the unit cell parameters of the alpha-TCP. More
importantly, this small level of silicate substitution had a strong effect on the thermal stability of the
alpha-TCP phase, with the silicate substitution stabilising the alpha-polymorph to lower
temperatures. This has an immediate advantage in that the quenching conditions are not as critical
for the production of silicate-substituted alpha-TCP compositions compared to silicate-free alpha-
TCP.
67
Authors: Guo Jian Jiang, Jia Yue Xu, Hui Shen, Yan Zhang, Lin He Xu, Han Rui Zhuang, Wen Lan Li
Abstract: Zinc silicate-based (Zn2SiO4:Eu3+) long afterglow phosphors were fabricated by combustion synthesis and annealing method. The effects of different Zn sources, annealing temperature, Eu3+ additive on the properties of the combustion products have been studied. The results show that, the product is white with ZnO as zinc source while that from Zn(NO3)26H2O is slightly yellow. At higher annealing temperature, the sample is purer. Small amount of Eu2O3 additive did not change the phase composition. The fluorescence spectroscopy shows that, the emission peak of the sample with Eu3+ additive located at 620nm.
304
Authors: Yang Ouyang, Na Yin, Shi Yan Chen, Lian Tang, Hua Ping Wang
Abstract: A novel composites material consisting of calcium silicate deposited in bacterial cellulose membrane was synthesized by immersing BC membrane in the calcium and silicate solutions by turns with different cycle times and characterized. The results indicated that the CaSiO3 particles were homogeneously dispersed on the surface of nanofibers with the effect of BC template when two cycles of soaking proceed, during which the fabrication of most CaSiO3 particles took place. The FT-IR reveals the strong interaction between the two parts of the BC/CaSiO3 composite. The XRD pattern demonstrated a crystal structure disruption of the cellulose aroused by CaSiO3 particle. BC/ CaSiO3 is considered to have a potential application in bone tissue field.
863
Authors: F.J. Harden, Iain R. Gibson, J.M.S. Skakle
Abstract: The addition of silicon ions to hydroxyapatite (HA) provides a more inorganic bone-like chemical composition compared to stoichiometric HA. It is known to aid the bioactivity of the material and to improve the rates of osseointegration, osteoconduction and bone mineralisation. The literature, however, lacks detailed information regarding each step of the aqueous precipitation procedure to produce silicon-substituted HA (Si-HA). The current work utilised Raman spectroscopy at each stage of the aqueous precipitation method to determine how the silicate is incorporated into the HA structure when producing Si-HA. Raman spectra indicated that at the initial stages of the reaction the disilicate ion (Si2O76-) formed with the orthosilicate (SiO44-) ion becoming more dominant after sintering. The results demonstrated that the form of silicate in the Si-HA aqueous precipitation method can be tracked using Raman spectroscopy.
94
Authors: Liu Shun Wu, Yun Zhou, Yuan Chi Dong
Abstract: In order to concentrate vanadium in converter slag bearing vanadium, the effect of SiO2 on behavior of vanadium in the process of enriching was studied. Experimental results show that, during cooling, dicalcium silicate containing vanadium and phosphorus precipitate first from original slag. For original with 7% SiO2, most of vanadium dissolves in calcium silicate phase. However, the proportion of dicalcium silicate is big. For slag modified by 12% SiO2, during cooling, two vanadium-rich minerals precipitate firstly, i.e. Ca3(V,P)2O8(30-33%V2O5) and Ca3(V,P)2O8•nCa2SiO4 (14-31%V2O5), then 3CaO•2SiO2 (2-4%V2O5) generates. With addition amount of SiO2 increasing, the proportion of 3CaO•2SiO2 decreases gradually, and the content of vanadium in vanadium-rich phase increases gradually. So appropriate SiO2 addition can suppress the precipitation of Ca2SiO4 and Ca3•Si2O7, and promote the generation of vanadium-rich phase.
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