Part III: lithium metasilicate (Li2SiO3)—mild condition hydrothermal synthesis, characterization and optical properties

Excitonic effects in the optical spectra of Li2SiO3 compound

Li2SiO3 compound exhibits unique electronic and optical properties. The state-of-the-art analyses, which based on first-principle calculations, have successfully confirmed the concise physical/chemical picture and the orbital bonding in Li-O and Si-O bonds. Especially, the unusual optical response behavior includes a large red shift of the onset frequency due to the extremely strong excitonic effect, the polarization of optical properties along three-directions, various optical excitations structures and the most prominent plasmon mode in terms of the dielectric functions, energy loss functions, absorption coefficients and reflectance spectra. The close connections of electronic and optical properties can identify a specific orbital hybridization for each distinct excitation channel. The presented theoretical framework will be fully comprehending the diverse phenomena and widen the potential application of other emerging materials.

First-principles studies of electronic properties in lithium metasilicate (Li2SiO3)

Lithium metasilicate (Li2SiO3), which could serve as the electrolyte material in Li+-based batteries, exhibits unique lattice symmetry (an orthorhombic crystal), valence and conduction bands, charge density distribution, and van Hove singularities. Delicate analyses, based on reliable first-principles calculations, are utilized to identify the critical multi-orbital hybridizations in Li-O and Si-O bonds, 2s-(2s, 2p x , 2p y , 2p z ) and (3s, 3p x , 3p y , 3p z )-(2s, 2p x , 2p y , 2p z ), respectively. This system shows a huge indirect gap of 5.077 eV. Therefore, there exist many strong covalent bonds, with obvious anisotropy and non-uniformity. On the other hand, the spin-dependent magnetic configurations are thoroughly absent. The theoretical framework could be generalized to explore the essential properties of cathode and anode materials of oxide compounds.

Study of Surface Structure Changes for Selected Ceramics Used in the CAD/CAM System on the Degree of Microbial Colonization, In Vitro Tests

In the article has been presented an analysis of susceptibility of selected dental materials, made in the CAD/CAM technology. The morphology and structural properties of selected dental materials and their composites were determined by using XRPD (X-ray powder diffraction) techniques, as well as the IR (infrared) spectroscopy. Moreover, an adhesion as well as development of biofilm by oral microorganisms has been studied. It has been shown that a degree of the biofilm development on the tested dental materials depended on microorganism genus and species. Streptococcus mutans has demonstrated the best adhesion to the tested materials in comparison with Candida albicans and Lactobacillus rhamnosus. However, the sintered materials such as IPS e.max® and the polished IPS e.max® have showed the best "anti-adhesive properties" in relation to S. mutans and L. rhamnosus that have not formed the biofilm on the polished IPS e.max® sample. Furthermore, S. mutans have not formed the biofilm on both surfaces. On the contrary to S. mutans and L. rhamnosus, C. albicans has demonstrated the adhesive properties in relation to the above-mentioned surfaces. Moreover, in contrast to S. mutans and C. albicans, L. rhamnosus has not formed the biofilm on the polished IPS Empress material.