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Highly Oriented Pyrolytic Graphite
Highly oriented pyrolytic graphite (HOPG) is a highly pure and ordered form of synthetic graphite. It is characterised by a low mosaic spread angle, meaning that the individual graphite crystallites are well aligned with each other. The best HOPG samples have mosaic spreads of less than 1 degree. Note that the term "highly ''ordered'' pyrolytic graphite" is sometimes used for this material, but IUPAC favors "highly ''oriented''". Synthesis The method used to produce HOPG is based on the process used to make pyrolytic graphite, but with additional tensile stress in the basal-plane direction. This produces improved alignment of the graphite crystallites and an interplanar spacing close to that observed in natural graphite. The "stress recrystallization" of graphite was first described by L. C. F. Blackman and Alfred Ubbelohde in 1962. The diameters of the individual crystallites in HOPG are typically in the range 1–10 μm. Application HOPG is used in x-ray optics as a monoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graphite
Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large scale (300 kton/year, in 1989) for uses in pencils, lubricants, and electrodes. Under high pressures and temperatures it converts to diamond. It is a weak conductor of heat and electricity. Types and varieties Natural graphite The principal types of natural graphite, each occurring in different types of ore deposits, are * Crystalline small flakes of graphite (or flake graphite) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken. When broken the edges can be irregular or angular; * Amorphous graphite: very fine flake graphite is sometimes called amorphous; * Lump graphite (or vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrolytic Carbon
Pyrolytic carbon is a material similar to graphite, but with some covalent bonding between its graphene sheets as a result of imperfections in its production. Pyrolytic carbon is man-made and is thought not to be found in nature.Ratner, Buddy D. (2004). Pyrolytic carbon. In Biomaterials science: an introduction to materials in medicine'. Academic Press. p. 171-180. . Google Book Search. Retrieved 7 July 2011. Generally it is produced by heating a hydrocarbon nearly to its decomposition temperature, and permitting the graphite to crystalize (pyrolysis). One method is to heat synthetic fibers in a vacuum. It is used in high temperature applications such as missile nose cones, rocket motors, heat shields, laboratory furnaces, in graphite-reinforced plastic, coating nuclear fuel particles, and in biomedical prostheses. Physical properties Pyrolytic graphite samples usually have a single cleavage (crystal), cleavage plane, similar to mica, because the graphene sheets crystallize in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfred Ubbelohde
Alfred René Jean Paul Ubbelohde FRS (14 December 1907 – 7 January 1988) was a Belgian-born English physical chemist. Education, early life and career Ubbelohde was born in Antwerp, Belgium, in 1907. He was educated at St Paul's School, 1920-1926 and at Christ Church, Oxford, 1926-1930. He was senior scholar of Christ Church from 1931-1933. He then became a senior researcher in the Department of Thermodynamics at Oxford, 1933-1935. This was followed by excursions as a Dewar Fellow of the Royal Institution, London, 1936-1940 as Principal Experimental Officer at the Ministry of Supply, 1940-1945 and as Professor of Chemistry at Queen's University, Belfast, 1945-1954. He was elected as a Fellow of the Royal Society in 1951. In 1954, Ubbelohde became a professor of thermodynamics at Imperial College London, a position he held until 1975. In 1961 he was awarded CBE; from 1961 to 1975 he was the head of the Chemical Engineering Department at Imperial College; following this he was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scanning Probe Microscopy
Scan may refer to: Acronyms * Schedules for Clinical Assessment in Neuropsychiatry (SCAN), a psychiatric diagnostic tool developed by WHO * Shared Check Authorization Network (SCAN), a database of bad check writers and collection agency for bad checks * Space Communications and Navigation Program (SCaN) * Social Cognitive and Affective Neuroscience (journal) * Scientific content analysis (SCAN), also known as statement analysis Businesses * Scan Furniture, Washington, D.C., US chain * SCAN Health Plan, not-for-profit health care company based in Long Beach, California * Scan AB or Scan Foods UK Ltd, the Swedish and UK subsidiaries of the Finnish HKScan Oyj * Seattle Community Access Network, Seattle, Washington, US TV channel * Scan (company), a software company based in Provo, Utah, US Electronics or computer related * 3D scanning * Counter-scanning, in physical micro and nanotopography measuring instruments like scanning probe microscope * Elevator algorithm (also SC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
