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Americium(III) Oxide
Americium(III) oxide or americium sesquioxide is an oxide of the element americium. It has the empirical formula Am2O3. Since all isotopes of americium are only artificially produced, americium (III) oxide has no natural occurrence. The colour depends on the crystal structure, of which there are more than one. It is soluble in acids. Formation Americium(III) oxide can be made by heating americium dioxide in hydrogen at 600°C. : Forms The hexagonal form is coloured tan, and the cubic form is coloured red-brown the same as persimmon The persimmon () is the edible fruit of a number of species of trees in the genus '' Diospyros''. The most widely cultivated of these is the Chinese and Japanese kaki persimmon, ''Diospyros kaki''. In 2022, China produced 77% of the world's p .... The cubic form converts to the hexagonal form on heating to 800°C. The cubic form is non-stoichimetric with variable oxygen composition. It darkens with increasing oxygen. References {{Oxides Am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pearson Symbol
The Pearson symbol, or Pearson notation, is used in crystallography as a means of describing a crystal structure. It was originated by William Burton Pearson and is used extensively in Pearson's handbook of crystallographic data for intermetallic phases. The symbol is made up of two letters followed by a number. For example: * Diamond structure, cF8 * Rutile structure, tP6 Construction The two letters in the Pearson symbol specify the Bravais lattice, and more specifically, the lower-case letter specifies the Crystal system, crystal family, while the upper-case letter the Lattice (group), lattice type. The number at the end of the Pearson symbol gives the number of the atoms in the conventional unit cell (atoms which satisfy 1 > x,y,z \geq 0 for the atom's position (x,y,z) in the unit cell). [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium Dioxide
Americium dioxide (AmO2) is a black compound of americium. In the solid state, AmO2 adopts a fluorite structure (like CaF2). It is used as a source of alpha particles. Historical context The demand for americium dioxide stems from the difficulty of storing the element americium as a solution of americium(III) chloride because the alpha radiation and hydrochloric acid decomposes storage containers over time. To solve the liquid storage problem, scientists at Oak Ridge National Laboratory devised a synthesis to turn liquid americium–acid solution into a precipitated form of americium for safer handling and more efficient storage. Synthesis Synthesis of americium dioxide, as described by the Oak Ridge National Laboratory in 1960, starts by dissolving americium in hydrochloric acid, and then neutralizing the excess acid with ammonium hydroxide (). Then, saturated oxalic acid solution () is added to the now neutralized solution to precipitate dull pink americium(III) oxalate crystal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium(II) Oxide
Americium is a synthetic chemical element; it has symbol Am and atomic number 95. It is radioactive and a transuranic member of the actinide series in the periodic table, located under the lanthanide element europium and was thus named after the Americas by analogy. Americium was first produced in 1944 by the group of Glenn T. Seaborg from Berkeley, California, at the Metallurgical Laboratory of the University of Chicago, as part of the Manhattan Project. Although it is the third element in the transuranic series, it was discovered fourth, after the heavier curium. The discovery was kept secret and only released to the public in November 1945. Most americium is produced by uranium or plutonium being bombarded with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium. It is widely used in commercial ionization chamber smoke detectors, as well as in neutron sources and industrial gauges. Several unusual applications, such as nucle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curium(III) Oxide
Curium is a synthetic chemical element; it has symbol Cm and atomic number 96. This transuranic actinide element was named after eminent scientists Marie and Pierre Curie, both known for their research on radioactivity. Curium was first intentionally made by the team of Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso in 1944, using the cyclotron at Berkeley. They bombarded the newly discovered element plutonium (the isotope 239Pu) with alpha particles. This was then sent to the Metallurgical Laboratory at University of Chicago where a tiny sample of curium was eventually separated and identified. The discovery was kept secret until after the end of World War II. The news was released to the public in November 1947. Most curium is produced by bombarding uranium or plutonium with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains ~20 grams of curium. Curium is a hard, dense, silvery metal with a high melting and boiling point for an actinide. It is p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxide
An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of (called a passivation layer) that protects the foil from further oxidation.Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. . Stoichiometry Oxides are extraordinarily diverse in terms of stoichiometries (the measurable relationship between reactants and chemical equations of an equation or reaction) and in terms of the structures of each stoichiometry. Most elements form oxides of more than one stoichiometry. A well known example is carbon monoxide and carbon dioxide.Greenwood, N. N.; & Earnsh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium
Americium is a synthetic element, synthetic chemical element; it has Chemical symbol, symbol Am and atomic number 95. It is radioactive and a transuranic member of the actinide series in the periodic table, located under the lanthanide element europium and was thus named after the Americas by analogy. Americium was first produced in 1944 by the group of Glenn T. Seaborg from Berkeley, California, at the Metallurgical Laboratory of the University of Chicago, as part of the Manhattan Project. Although it is the third element in the transuranic series, it was discovered fourth, after the heavier curium. The discovery was kept secret and only released to the public in November 1945. Most americium is produced by uranium or plutonium being bombarded with neutrons in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium. It is widely used in commercial ionization chamber smoke detectors, as well as in neutron sources and industrial gauges. Several u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopes Of Americium
Americium (95Am) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no known stable isotopes. The first isotope to be synthesized was 241Am in 1944. The artificial element decays by ejecting alpha particles. Americium has an atomic number of 95 (the number of protons in the nucleus of the americium atom). Despite being an order of magnitude longer lived than , the former is harder to obtain than the latter as more of it is present in spent nuclear fuel. Eighteen radioisotopes of americium, ranging from 229Am to 247Am with the exception of 231Am, have been characterized; another isotope, 223Am, has also been reported but is unconfirmed. The most stable isotopes are 243Am with a half-life of 7,370 years and 241Am with a half-life of 432.2 years. All of the remaining radioactive decay, radioactive isotopes have half-lives that are less than seven days, the majority of which are shorter than two hours. This element also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium Dioxide
Americium dioxide (AmO2) is a black compound of americium. In the solid state, AmO2 adopts a fluorite structure (like CaF2). It is used as a source of alpha particles. Historical context The demand for americium dioxide stems from the difficulty of storing the element americium as a solution of americium(III) chloride because the alpha radiation and hydrochloric acid decomposes storage containers over time. To solve the liquid storage problem, scientists at Oak Ridge National Laboratory devised a synthesis to turn liquid americium–acid solution into a precipitated form of americium for safer handling and more efficient storage. Synthesis Synthesis of americium dioxide, as described by the Oak Ridge National Laboratory in 1960, starts by dissolving americium in hydrochloric acid, and then neutralizing the excess acid with ammonium hydroxide (). Then, saturated oxalic acid solution () is added to the now neutralized solution to precipitate dull pink americium(III) oxalate crystal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persimmon
The persimmon () is the edible fruit of a number of species of trees in the genus '' Diospyros''. The most widely cultivated of these is the Chinese and Japanese kaki persimmon, ''Diospyros kaki''. In 2022, China produced 77% of the world's persimmons. Description Like the tomato, the persimmon is not a berry in the general culinary sense, but its morphology as a single fleshy fruit derived from the ovary of a single flower means it is a berry in the botanical sense. The tree ''Diospyros kaki'' is the most widely cultivated species of persimmon. Typically the tree reaches in height and is round-topped. It usually stands erect, but sometimes can be crooked or have a willowy appearance. The leaves are long, and are oblong in shape with brown-hairy petioles in length. They are leathery and glossy on the upper surface, brown and silky underneath. The leaves are deciduous and bluish-green in color. In autumn, they turn to yellow, orange, or red. Persimmon trees are typica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Americium Compounds
Americium compounds are compounds containing the element americium (Am). These compounds can form in the +2, +3, and +4, although the +3 oxidation state is the most common. The +5, +6 and +7 oxidation states have also been reported. Oxides Three americium oxides are known, with the oxidation states +2 (AmO), +3 (), and +4 (). Americium(II) oxide was prepared in minute amounts and has not been characterized in detail. Americium(III) oxide is a red-brown solid with a melting point of 2205 °C.Wiberg, p. 1972 Americium dioxide, Americium(IV) oxide is the main form of solid americium which is used in nearly all its applications. Like most other actinide dioxides, it is a black solid with a cubic (fluorite) crystal structure.Greenwood, p. 1267 The oxalate of americium(III), vacuum dried at room temperature, has the chemical formula . Upon heating in vacuum, it loses water at 240 °C and starts decomposing into at 300 °C, the decomposition completes at about 470 °C. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
