Glass Ceramic Derivatives Research Articles

Design and Properties of Novel Substituted Borosilicate Bioactive Glasses and Their Glass-Ceramic Derivatives

Three novel borosilicate bioactive glasses (BBGs) of general formula of 0.05Na2O·0.35x·0.20B2O3·0.40SiO2 (molar ratio, where x = MgO or CaO or SrO) were prepared and used to investigate the effect of crystallization on their properties including cytotoxicity. The three postmelt compositions were determined using X-ray fluorescence spectroscopy, and crystallization events were studied using differential thermal analysis and X-ray diffraction. This information was used to determine heat treatments to prepare glass-ceramics by controlled crystallization. X-ray diffraction analysis and Fourier transform infrared spectroscopy showed that, after higher heat treatment temperatures (800–900 °C), borosilicate bioactive glass-ceramics (BBGCs) contained mainly borate and silicate crystalline phases. Specifically, BBG-Mg, BBG-Ca, and BBG-Sr glass-ceramics detected the presence of magnesium silicate-Mg2(SiO3)2 and magnesium borate-Mg2B2O5; wollastonite-2M-CaSiO3 and calcium borate-Ca(BO2)2; and strontium silicate-SrSi...

Optical and crystallization studies of titanium dioxide doped sodium and potassium silicate glasses

Combined optical and FTIR spectral analysis were used to investigate prepared invert two alkali silicate glasses (Na2O·SiO2K2O·SiO2) containing high titanium oxide content. Glass ceramic derivatives were prepared through thermal two step regime of the parent glasses and they were characterized by FTIR and X-ray diffraction measurements. Experimental optical spectra indicate the appearance of an additional UV band due to absorption of tetravalent titanium ions beside the UV bands due to trace ferric ions impurities. FT infrared absorption spectra reveal composite vibrational bands due to vibrational modes of both silicate groups and TiO4 or SiOTi units. Such tetravalent groupings of titanium ions confirm the stability of such invert glasses containing as such two main glass forming oxides. FTIR spectra of the glass – ceramic derivatives show nearly the same IR vibrational modes as their parent glasses. X-ray diffraction analysis show the separation of crystalline sodium or potassium titanate phases beside a minor form of silica and the results confirm that TiO2 acts mainly as network forming units leading to the formation of crystalline titanate phases.

Comparative studies on the bioactivity of some borate glasses and glass–ceramics from the two systems: Na2O–CaO–B2O3 and NaF–CaF2–B2O3

Combined FTIR spectroscopy and X-ray diffraction analysis have been employed to investigate the bone-bonding ability or bioactivity of some prepared borate glasses and their glass–ceramic derivatives from the two systems (Na2O–CaO–B2O3) and (NaF–CaF2–B2O3). The present study includes the mentioned FTIR spectral and X-ray analytical techniques before and after immersion of the glasses and glass–ceramics for 2 weeks in 0.025 M sodium phosphate (Na2HPO4) solution. Also, the work extends to evaluate the corrosion behavior for specified grains of the studied samples (0.3–0.6 mm) after immersion in phosphate solution for 2 weeks at 37°C. The FTIR spectra of the two glass systems after immersion show some changes in the vibrational bands than before immersion. The generation of the characteristic peaks at about 580 and 680cm−1 after immersion confirms the bone bonding ability by the formation of hydroxyapatite phase. The X-ray diffraction studies show the separation of (CaF2) which is known to be an efficient nucleator. Weight loss data show a difference in solubility in the sodium phosphate solution between fluoride and oxide glass systems due to the strong action of the leaching solution and ease of solubility of fluoride glasses than corresponding oxide glasses in this solution. SEM data indicate the formation of small rounded or nodular shape crystals which are characteristics for the formation of hydroxyapatite layer and complete agreement with X-ray data.

Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives

Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass–ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550–680cm−1 after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content.

In vitro bioactivity of soda lime borate glasses with substituted SrO in sodium phosphate solution

Borate glasses with the basic composition 0.6B2O3?0.2Na2O?0.2CaO and SrO progressively substituting CaO were prepared and characterized for their bone-bonding ability. The obtained glasses were thermally treated and converted to their glass-ceramic derivatives. In this study, FTIR spectral analyses were done for the prepared glasses and glass-ceramics before and after immersion in a sodium phosphate solution for extended times. The appearance of two IR bands within the spectral range 550-680 cm-1 after immersion confirms the formation of hydroxyapatite. X-ray diffraction studies and scanning electron microscope analysis supported the obtained infrared spectroscopy results. The solubility test (measurements of the weight loss in aqueous sodium phosphate solution) was conducted for measuring the dissolution of both glassy and crystalline derivatives to find out the role of SrO. The corrosion behaviour of the glasses and glass-ceramics indicate the increase of weight loss with the increase of SrO content. Different suggested proposals were introduced to explain this abnormal behaviour.

Investigations on In Vitro and Degradation Properties of ZnO‐Added Phosphate‐Based Glasses and Glass Ceramics

A series of phosphate based glasses of composition 45P2O5–(40−x)CaO–15Na2O–xZnO (x = 0, 3, 6, 8 10, and 12 mol%) were prepared employing melt‐quenching techniques. Based on the thermal analysis data of glasses, the schedule of thermal treatments have been designed and employed to obtain their glass ceramic derivatives. The increase in thermal stability and decrease in crystallization tendency was observed from differential thermal analysis traces. The durability of phosphate glasses were improved as a result of the addition of ZnO content. The increasing ZnO content alters the phosphate glass structure and enhances the cross‐link formation between different network chains. A broad‐based characterization approach combining different techniques was used to investigate the in vitro properties of glasses and their glass‐ceramic equivalents against the addition of ZnO content into the glass composition. The in vitro results revealed the decreasing nature of apatite forming ability of phosphate glasses with increase in ZnO content before and after thermal treatments. Both the glass and glass‐ceramics containing ZnO content above 10 mol% exhibited poor in vitro performance mainly because of their dissolution nature. The weight loss analysis revealed that the decreasing solubility of glass and glass‐ceramics was observed as increasing of ZnO content.

Thermal, structure and morphological properties of lithium disilicate glasses doped with copper oxide and their glass–ceramic derivatives

This research aims to investigate and compare the structural and the morphological properties of both lithium disilicate glasses doped with copper oxide and their glass–ceramic derivatives. Density measurements were measured for all samples by Archimedes method at room temperature. Differential scanning calorimetric analysis was used to determine the glass transition temperature (Tg) and crystallization temperature (Tc) for all glasses. The glass transition temperature was observed to decrease with increasing CuO concentration indicating the formation of non-bridging oxygen bonds in the glass network. X-ray analysis patterns reveal the appearance of crystalline lithium metasilicate phase as the main phase within the glass–ceramic derivatives, and their crystallite sizes were observed to decrease as the CuO increased. Experimental infrared absorption data indicate the existence of characteristic vibrational bands due to structural building SiO4 units in resemblance to the same vibrations observed from traditional crystalline silicates. Scanning electron microscopic investigations show the vitreous nature for lithium disilicate glasses and the distinct crystalline morphological features for the corresponding glass–ceramic derivatives.

Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

Ternary borate glasses from the system Na2O?CaO?B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crys?talline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution for extended times were characterized by the grain method (adopted by several authors and recommended by ASTM) and Fourier-transform infrared spectra to justify the formation of hydroxyapatite as an indication of the bone bonding ability. The influence of glass composition on bioactivity potential was discussed too.

Effect of ZnO on the Bioactivity of Hench’s Derived Glasses and Corresponding Glass-Ceramic Derivatives

Some glasses based on Hench’s patented bioglass have been prepared with ZnO replacing Na2O or CaO in order to investigate their bioactivity in the glassy state or after conversion to their glass-ceramic derivatives. In-vitro investigations of bioactivity of the prepared glass and their glass-ceramics derivatives were carried out by Infrared absorption spectra (IR) of the samples before and after immersion in simulated body fluid (SBF) for different time periods at 37 °C. An X-ray Diffraction (XRD) analysis technique was performed on the glass-ceramic samples to identify the crystalline phases formed during the controlled thermal treatment. Chemical corrosion experiments were also performed to evaluate the chemical behaviour of both glassy and the glass-ceramic derivatives towards SBF. The IR results showed that the amount of the apatite layer formed on the surface of the sample containing ZnO depends on the wt% of ZnO content. The X-ray results indicate that there are two phases formed: sodium calcium silicate and kilchoanite. Weight loss data were observed to change depending on the percent of ZnO and the role of housing of Zn2+ in the glass structure. Corrosion behaviour of glass-ceramic derivatives indicates higher durability than in the corresponding parent glasses as expected.

Electrical conductivity of gamma-irradiated V 2O 5 doped lithium disilicate glasses doped and their glass–ceramics derivatives

Some physical properties of the lithium disilicate (Li 2Si 2O 5) glasses doped with different ratios of V 2O 5 were investigated before and after gamma-rays irradiation. Increasing V 2O 5 ratio causes remarkable changes in the properties studied. The observed variations in the properties may be correlated with the changes in internal glass network with changes in the chemical composition. Vanadium ions are believed to be present in three possible valence states V 3+, V 4+ and V 5+, and the ratios of these states depend on glass composition. Observed increase in electrical conductivity is assumed to be related to several parameters including the creation of localized state, which increase the charges carrier to conduction band, increase of the number of nonbridging oxygen’s and/ or electron hopping between vanadate ions in different valence states. However, the results indicate that the heat-treatment of amorphous samples accelerate the sequence of formation of lithium metasilicate crystals, causing a decrease in the electrical conductivity. The changes obtained due to gamma-irradiation are correlated to several factors, such as polarization and field strength of the respective cations and to the amount of induced defect centers created upon gamma-irradiation.

Preparation and characterization of some multicomponent silicate glasses and their glass–ceramics derivatives for dental applications

The chemical corrosion and UV–vis absorption and infrared absorption spectra of binary and multicomponent lithium silicate glasses and corresponding glass–ceramics were investigated. The chemical durability of the glasses and derived glass–ceramics was found to be excellent to all leaching media. The IR absorption spectra of the glass and glass–ceramic samples reveal absorption bands of characteristic groups mainly due to major silicate network besides the possible sharing of network units due to some involving oxide constituents. X-ray analysis of glass–ceramics indicates the separation of lithium disilicate phase as the main constituent beside other phases according to the specimen chemical constituents. The obvious promising investigated chemical and physical properties are correlated with the presence of multioxides such as Al 2O 3, TiO 2, MgO and ZrO 2. Transmission and reflectivity properties reveal acceptable data. The prepared glass–ceramics are recommended for dental applications.

Corrosion Behaviour of Bismuth-Silicate Glasses and their Glass-Ceramic Derivatives and the Effect of Ionizing Gamma-Irradiation

The corrosion weight losses by aqueous acidic or alkaline solutions have been studied for binary bismuth oxide-silica glasses and their corresponding glass-ceramic derivatives with the Bi2O3: SiO2 molar per cent varying from 90:10 to 50:50. The corrosive action on these glasses and glass-ceramics by acid solutions has been found to depend on the pH and the type of anion present in solution, and the attack by NaOH solution has been seen to be slightly lower than that by the acidic solutions. Generally, the corrosion decreases with the increase in the SiO2 content in the samples as expected due to the strong structural role of silica in the glass network. Also, the corrosion has been found to increase with the microcrystalline compact glass-ceramic derivatives. Gamma-irradiation slightly changes the corrosion behaviour. Morphology of the glass surface changes has been studied by scanning electron microscopic (SEM) measurements. Various features of islands and surface cracks have been observed to be formed after subjecting the glass to the action of corroding solutions. In general, the bismuth silicate glasses and glass-ceramic derivatives are found to be of acceptable chemical durability and possess marked resistance to gamma-irradiation.