Lanthanide doped fluorosilicate glass-ceramics:A review on experimental and theoretical progresses

Significant developments have been made in the past few decades for lanthanide(Ln)ions doped fluorosilicate glass-ceramics(Flusi-GCs).As novel generation of luminescence materials with a wide range of applications,Flusi-GCs as a single host combine the advantages of glass and ceramics/crystals as well as fluorides and silicates.In this review,the chemical design principles and experimental procedures of Flusi-GCs are summarized in detail.Flusi-GCs are categorized as those containing PbxCd_(1-x)F_(2),RF_(3)(R=Y,La,Gd),MF_(2)(M=Ca,Sr,Ba),xMF_(2)-yRF_(3)(R=Y,La-Lu),mAF-nRF_(3)(A=Li,Na,K),KTF_(3)(T=Zn,Mn)and K2 SiF6 nanocrystals(NCs).Theoretical breakthroughs mainly by molecular dynamic(MD)simulation have been recapitulated as efficient routes for composition-design,nano-crystallization-prediction,and performance-optimization of Flusi-GCs containing target fluoride NCs.Essential research progresses pertaining photonic applications have been made in random lasers,communication amplifiers,optical fibers,spectral converters,white light-emitting-diodes(WLEDs),and thermal sensors.In the end,we propose three future research directions for Flusi-GCs.

Bioactive glass coatings on metallic implants for biomedical applications

Metallic implant materials possess adequate mechanical properties such as strength,elastic modulus,and ductility for long term support and stability in vivo.Traditional metallic biomaterials,including stainless steels,cobalt-chromium alloys,and titanium and its alloys,have been the gold standards for load-bearing implant materials in hard tissue applications in the past decades.Biodegradable metals including iron,magnesium,and zinc have also emerged as novel biodegradable implant materials with different in vivo degradation rates.However,they do not possess good bioactivity and other biological functions.Bioactive glasses have been widely used as coating materials on the metallic implants to improve their integration with the host tissue and overall biological performances.The present review provides a detailed overview of the benefits and issues of metal alloys when used as biomedical implants and how they are improved by bioactive glass-based coatings for biomedical applications.

Effect of solution condition on hydroxyapatite formation in evaluating bioactivity of B2O3 containing 45S5 bioactive glasses

The effects of testing solutions and conditions on hydroxyapatite(HAp)formation as a means of in vitro bioactivity evaluation of B2O3 containing 45S5 bioactive glasses were systematically investigated.Four glass samples prepared by the traditional melt and quench process,where SiO2 in 45S5 was gradually replaced by B2O3(up to 30%),were studied.Two solutions:the simulated body fluid(SBF)and K2HPO4 solutions were used as the medium for evaluating in vitro bioactivity through the formation of HAp on glass surface as a function of time.It was found that addition of boron oxide delayed the HAp formation in both SBF and K2HPO4 solutions,while the reaction between glass and the K2HPO4 solution is much faster as compared to SBF.In addition to the composition and medium effects,we also studied whether the solution treatments(e.g.,adjusting to maintain a pH of 7.4,refreshing solution at certain time interval,and no disturbance during immersion)affect HAp formation.Fourier transform infrared spectrometer(FTIR)equipped with an attenuated total reflection(ATR)sampling technique and scanning electron microscopy(SEM)were conducted to identify HAp formation on glass powder surfaces and to observe HAp morphologies,respectively.The results show that refreshing solution every 24 h produced the fastest HAp formation for low boron-containing samples when SBF was used as testing solution,while no significant differences were observed when K2HPO4 solution was used.This study thus suggests the testing solutions and conditions play an important role on the in vitro bioactivity testing results and should be carefully considered when study materials with varying bioactivities.