M.A. Azooz

Bio: M.A. Azooz is an academic researcher from Shaqra University. The author has contributed to research in topics: Materials science & Infrared spectroscopy. The author has an hindex of 18, co-authored 47 publications receiving 1199 citations.

UV-vis absorption of the transition metal-doped SiO2–B2O3–Na2O glasses

Abstract: Ultravoilet (UV)–vis absorption spectra of undoped and transition metal (TM)-doped borosilicate glasses before and after successive gamma rays irradiation are reported. Before irradiation, the undoped glass reveals UV absorption due to trace iron impurities and no visible bands whereas the TM-doped glasses show the absorption bands which are characteristic for each TM ion in the UV and visible regions. The induced absorption bands are examined and related to either intrinsic radiation-induced defects from the host base borosilicate glass or extrinsic induced defects generated from TMs. The response of the glasses to gamma irradiation is related to the creation of defect color centers, the approach of a saturation condition and/or the possible photochemical effect on TM.

Physicochemical studies of phosphate based P2O5–Na2O–CaO–TiO2 glasses for biomedical applications

Abstract: Glasses P2O5–Na2O–CaO–TiO2 with different TiO2 contents and fixed P2O5 (45 wt%) and CaO (24 wt%) have been prepared employing the normal melting and annealing technique. Measurements such as ultrasonic velocity, attenuation, solubility and pH have been carried out in all the compositions of the glasses. It is interesting to note that the above measured ultrasonic parameters exhibit an abnormal behavior (minimum) at 0.5 wt% of TiO2 content, beyond which an increase in these parameters with increasing TiO2 content is observed. The maximum pH values and Ca2+ ion release have been observed for the TiO2 free glass those compositions with and the low TiO2(⩽1.0 wt%) content. As the content of the TiO2 increases, the solubility of the glasses decreases. The observed weight loss reveals two stages of phosphate dissolution kinetics i.e. the first stage, in which the weight loss is proportional to t1/2, and a second stage in which a linear behavior is observed.

Elastic Properties and Short-to Medium-Range Order in Glasses

Abstract: Very different materials are named “Glass,” with Young's modulus (E) and Poisson's ratio (ν) extending from 5 to 180 GPa and from 0.1 to 0.4, respectively, in the case of bulk inorganic glasses. Although glasses have in common the lack of long-range order in the atomic organization, they offer a wide range of structural features at the nanoscale and we show in this analysis that beside the essential role of elastic properties for materials selection in mechanical design, the elastic characteristics (E, ν) at the continuum scale allow to get insight into the short- and medium-range orders existing in glasses. In particular, ν, the atomic packing density (Cg) and the glass network dimensionality appear to be strongly correlated. Maximum values for ν and Cg are observed for metallic glasses (ν∼0.4 and Cg>0.7), which are based on cluster-like structural units. Atomic networks consisting primarily of chains and layers units (chalcogenides, low Si-content silicate, and phosphate glasses) correspond to ν>0.25 and Cg>0.56. On the contrary, ν<0.25 is associated with a highly cross-linked network, such as in a-SiO2, with a tri-dimensional organization resulting in a low packing density. Moreover, the temperature dependence of the elastic moduli brings a new light on the structural changes occurring above the glass transition temperature and on the depolymerization rate in the supercooled liquid. The softening rate depends on the level of cooperativity of atomic movements at the source of the deformation process, with an obvious correlation with the “fragility” of the liquid.

A Review on Infrared Spectroscopy of Borate Glasses with Effects of Different Additives

Abstract: Borate glasses are the technologically important class of glasses and play a significant role in various applications. Borate glasses contain planar BO3 groups as structural units, rather than tetrahedral SiO4 groups. The oxygen atoms are, as in SiO2, again connected to two network-forming atoms, in case of boron. The radial distribution analysis describes the B2O3 glass structure as consisting of boroxol rings, that is, planar rings containing three boron atoms and three oxygen atoms. The network forming of the B2O3 and the SiO4 is affected with the addition of some metal cation additives Pb, Zn, Cd, and so forth. These additives also work as a network modifier and a nucleating agent for crystallization of glass. Therefore, the optical properties of the borate glasses have been changed significantly.

Performance of Dental Ceramics Challenges for Improvements

Abstract: The clinical success of modern dental ceramics depends on an array of factors, ranging from initial physical properties of the material itself, to the fabrication and clinical procedures that inevitably damage these brittle materials, and the oral environment. Understanding the influence of these factors on clinical performance has engaged the dental, ceramics, and engineering communities alike. The objective of this review is to first summarize clinical, experimental, and analytic results reported in the recent literature. Additionally, it seeks to address how this new information adds insight into predictive test procedures and reveals challenges for future improvements.