Silica

Silica
LHcheM · CC BY-SA 3.0 · source
Name	Silica
Other names	Silicon dioxide
Formula	SiO2
Molar mass	60.08 g·mol−1
Appearance	Colorless, white or transparent
Density	2.65 g·cm−3 (quartz)
Melting point	1713 °C (quartz)
Boiling point	2230 °C

Silica Silica, or silicon dioxide, is a ubiquitous inorganic compound composed of silicon and oxygen atoms. It forms a wide range of crystalline and amorphous materials and underpins technologies from Semiconductor fabrication to Glass manufacture, while also shaping geological features such as the Sahara Desert dunes and Mount Everest bedrock. Silica’s properties link it to major figures and institutions in science and industry, including James Hutton, Antoine Lavoisier, IBM, DuPont, and Bell Labs.

Introduction

Silica is central to disciplines influenced by Charles Darwin, Marie Curie, Linus Pauling, Isaac Newton, and Dmitri Mendeleev through its role in mineralogy, chemistry, materials science, and engineering. Its presence in soils ties to regions like the Amazon Basin, Great Barrier Reef, and the Ganges river system, and its industrial lifecycle involves corporations such as General Electric, Siemens, BASF, 3M, and Bayer. Historical developments around silica intersect with events like the Industrial Revolution, innovations at the Massachusetts Institute of Technology, and patents adjudicated by the United States Supreme Court.

Chemical Properties and Structure

Silicon dioxide exhibits covalent bonding networks studied by researchers at institutions including Max Planck Society, Harvard University, Stanford University, California Institute of Technology, and University of Cambridge. Crystalline polymorphs such as Quartz and Cristobalite adopt tetrahedral SiO4 units linked in three-dimensional frameworks; these structures were elucidated by techniques developed by Erwin Schrödinger, Rosalind Franklin, and Ernest Rutherford contemporaries. Amorphous forms including Fumed silica and Glass lack long-range order, a subject of work by Ludwig Boltzmann and Peter Debye. Bond angles and network connectivity influence properties referenced in standards from International Organization for Standardization and measurements by National Institute of Standards and Technology.

Natural Occurrence and Minerals

Silica occurs as major minerals like Quartz, Tridymite, Cristobalite, Coesite, and Stishovite, which are pertinent to geologists at US Geological Survey, Geological Survey of India, and universities such as Oxford University and University of California, Berkeley. Sedimentary forms include Sandstone beds exposed in locales like the Grand Canyon, while biogenic silica is produced by organisms studied by teams at Scripps Institution of Oceanography and Woods Hole Oceanographic Institution, notably in Diatom frustules and Radiolarian skeletons. Hydrothermal systems at sites such as Yellowstone National Park facilitate sinter and geyserite deposition, subjects of research by Smithsonian Institution scientists.

Industrial Production and Uses

Industrial silica production involves mining operations run by companies like Rio Tinto, BHP, Vale, ArcelorMittal, and processing firms such as Saint-Gobain. Applications span Glass (architectural projects like Burj Khalifa), Optical fiber networks deployed by AT&T and Verizon, Semiconductor wafers produced by Intel and TSMC, Abrasive manufacturing used by Bosch, and Construction materials marketed by Cemex and LafargeHolcim. Specialized forms enable catalysts and adsorbents used by Johnson Matthey and ExxonMobil, dental ceramics developed at Nobel Biocare, and coatings for aerospace firms like Boeing and Airbus.

Health and Safety

Occupational exposure to respirable crystalline silica is regulated by agencies including Occupational Safety and Health Administration, National Institute for Occupational Safety and Health, European Medicines Agency, and public health bodies such as World Health Organization. Chronic inhalation links to silicosis and lung cancer, issues litigated in courts including the United States Court of Appeals and addressed by union organizations like the International Labour Organization. Medical imaging and epidemiology studies tracing silica-related disease have been conducted at Mayo Clinic, Johns Hopkins University, and Imperial College London.

Environmental Impact and Biogeochemistry

Silica cycling influences global biogeochemical models from groups at Intergovernmental Panel on Climate Change, NASA, NOAA, European Space Agency, and research by Woods Hole and Scripps. Terrestrial weathering of silicate rocks, studied since the era of James Hutton and John Playfair, controls carbon dioxide drawdown and interacts with carbon cycle legislation reviewed by the United Nations Framework Convention on Climate Change. Marine silica uptake by Diatoms affects fisheries managed by agencies such as FAO and conservation efforts by World Wildlife Fund.

Analytical Methods and Characterization

Characterization techniques for silica utilize instrumentation from vendors like Thermo Fisher Scientific, Bruker, Agilent Technologies, and facilities at CERN and national labs including Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory. Methods include X-ray diffraction pioneered by Max von Laue and William Henry Bragg, electron microscopy developed with contributions by Ernst Ruska, nuclear magnetic resonance techniques advanced by Felix Bloch and Edward Purcell, spectroscopies used by Graham Bell-era laboratories, and surface area analysis following BET theory by Stephen Brunauer, Paul Emmett, and Edward Teller.

Category:Inorganic compounds