boron-oxide and potassium-oxide

Divalent Mn2+ ions containing 20ZnO+xLi2O+(30-x)K2O+50B2O3(5≤x≤25) mol% glasses are prepared by using melt quench technique and are characterized by several spectroscopic techniques. Various physical parameters are evaluated from the measured values of density and refractive index for the observation of mixed alkali effect. Structural changes of Mn2+ doped ZLKB glasses are investigated by Powder XRD, UV-VIS absorption, Electron Paramagnetic Resonance and FT-IR spectroscopic studies. The XRD pattern indicates the amorphous nature of prepared glasses. FT-IR measurements of all glasses revealed that the network structure of glass system are mainly based on BO3 and BO4 units placed in different structural groups in which the BO3 units being dominant. The EPR spectra of Mn2+ ions doped glasses exhibited a characteristic hyperfine sextet around g=2.0. The spectroscopic analyses of the obtained results confirmed near octahedral site symmetry for the Mn2+ impurity ions. Crystal field and Racah parameters are evaluated from optical absorption spectra. The optical band gap and Urbach energies are determined which exhibited the mixed alkali effect.

Topics: Alkalies; Boron Compounds; Electron Spin Resonance Spectroscopy; Glass; Lithium Compounds; Magnesium; Oxides; Potassium Compounds; Powder Diffraction; Spectrophotometry; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction; Zinc Oxide

Herein, we report the results of the in vitro dissolution tests, which were carried out by immersing the selected glass-ceramic samples in artificial saliva (AS) for various time periods of up to 42 days. In our experiments, the SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass ceramics with different crystal morphology and crystal content were used and a comparison is also made with the baseline glass samples (without any crystals). The bioactivity of the samples was probed by measuring the changes in pH, ionic conductivity and ionic concentration of AS following in vitro dissolution experiments. High resistance of the selected glass-ceramic samples against in vitro leaching has been demonstrated by minimal weight loss (<1%) and insignificant density change, even after 6 weeks of dissolution in artificial saliva. While XRD analysis reveals the change in surface texture of the crystalline phase, FT-IR analysis weakly indicated the Ca-P compound formation on the leached surface. The experimental measurements further indicate that the leaching of F(-), Mg(2+) ions from the sample surface commonly causes the change in the surface chemistry. Furthermore, the presence of (Ca, P, O)-rich mineralized deposits on the leached glass-ceramic surface as well as the decrease in Ca(2+) ion concentrations in the leaching solutions (compared to that in the initial AS solution) provide evidences of the moderate bioactive or mild biomineralisation behaviour of investigated glass-ceramics.

Topics: Aluminum Oxide; Boron Compounds; Ceramics; Crystallography, X-Ray; Fluorine; Glass; Hydrogen-Ion Concentration; In Vitro Techniques; Ions; Magnesium Oxide; Oxides; Potassium Compounds; Saliva, Artificial; Silicon Dioxide; Spectrophotometry, Infrared; X-Ray Diffraction

The bioactivity, i.e., bone-bonding ability, of 26 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2 was studied in vivo. This investigation of bioactivity was performed to establish the compositional dependence of bioactivity, and enabled a model to be developed that describes the relation between reactions in vivo and glass composition. Reactions in vivo were investigated by inserting glass implants into rabbit tibia for 8 weeks. The glasses and the surrounding tissue were examined using scanning electron microscopy (SEM), light microscopy, and energy-dispersive X-ray analysis (EDXA). For most of the glasses containing < 59 mol % SiO2, SEM and EDXA showed two distinct layers at the glass surface after implantation, one silica-rich and another containing calcium phosphate. The build-up of these layers in vivo was taken as a sign of bioactivity. The in vivo experiments showed that glasses in the investigated system are bioactive when they contain 14-30 mol % alkali oxides, 14-30 mol % alkaline earth oxides, and < 59 mol % SiO2. Glasses containing potassium and magnesium bonded to bone in a similar way as bioactive glasses developed so far.

Topics: Animals; Biocompatible Materials; Bone Cements; Boron Compounds; Calcium Compounds; Electron Probe Microanalysis; Female; Glass; Implants, Experimental; Magnesium Oxide; Male; Materials Testing; Microscopy, Electron, Scanning; Osseointegration; Oxides; Phosphorus Compounds; Potassium Compounds; Rabbits; Silicon Dioxide; Sodium Compounds; Tibia