Crystal structure: Trigonal, hR30, space group= R3c, No. 167
Lattice constant: a = 478.5 pm, c = 1299.1 pm
Coordination geometry: octahedral
|Molar mass||101.96 g·mol−1|
|Melting point||2,072 °C (3,762 °F; 2,345 K)|
|Boiling point||2,977 °C (5,391 °F; 3,250 K)|
|Solubility in water||insoluble|
insoluble in diethyl ether
-low permeability and elasticity
-considerable strength, hardness, toughness, whiteness, translucency, resonance
-high resistance to chemical attack and thermal shock
Common name: glass
Chemical formula SiO2
Molar mass 60.08 g/mol
Appearance Transparent solid
Density 2.648 (α-quartz), 2.196 (amorphous) g·cm−3
Melting point 1,713 °C (3,115 °F; 1,986 K) (amorphous)
Boiling point 2,950 °C (5,340 °F; 3,220 K)
Thermal conductivity 12 (|| c-axis), 6.8 (⊥ c-axis), 1.4 (am.) W/(m⋅K)
Refractive index 1.544 (o), 1.553 (e)
Most glass is a mixture of silica obtained from beds of fine sand or from pulverized sandstone; an alkali to lower the melting point, usually a form of soda or, for finer glass, potash; lime as a stabilizer; and cullet (waste glass) to assist in melting the mixture.
The properties of glass are varied by adding other substances, commonly in the form of oxides, e.g., lead, for brilliance and weight; boron, for thermal and electrical resistance; barium, to increase the refractive index, as in optical glass; cerium, to absorb infrared rays; metallic oxides, to impart color; and manganese, for decolorizing.
The term "crystal glass," derived from rock crystal, was at first applied to clear, highly refractive glass; it has come to denote in the trade a high-grade, colorless glass and is sometimes applied to any fine hand-blown glass.
Scientists at the University of Southampton are using nanostrucutured glass to develop the recording and retrieval processes of five dimensional (5D) digital data by femtosecond laser writing, which may be capable of surviving for billions of years. More information can be found here.
From Chemical & Engineering News: Opening and Closing Nano Venetian Blinds
Researchers led by Soroush Shabahang and Ayman F. Abouraddy at the University of Central Florida are making nanoparticles with their bare hands––and some crafty materials science. To create uniform micro- and nanoscale structures, the team is simply stretching fibers and sheets made from a ductile polymer composite containing either a brittle core or coating (Nature 2016, DOI: 10.1038/nature17980).
Chemical formula TiO2
Molar mass 79.866 g/mol
Appearance White solid
Density 4.23 g/cm3 (Rutile), 3.78 g/cm3 (Anatase)
Melting point 1,843 °C (3,349 °F; 2,116 K)
Boiling point 2,972 °C (5,382 °F; 3,245 K)
Solubility in water insoluble
Band gap 3.05 eV (rutile)
Refractive index 2.488 (anatase), 2.583 (brookite), 2.609 (rutile)