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Ruthenium Tribromide
Ruthenium(III) bromide is a chemical compound of ruthenium and bromine with the formula RuBr3. It is a dark brown solid that decomposes above 400 °C. Preparation Ruthenium(III) bromide can be prepared by the reaction of ruthenium metal with bromine at high temperature and pressure (720 K and 20 bar): :2 Ru + 3 Br2 → 2 RuBr3 Structure The crystal structures of ruthenium(III) bromide contain parallel (RuBr3)∞ columns. The compound undergoes a phase transition around 384 K (111 °C) from an ordered orthorhombic structure in space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ... ''Pnmm'' with alternating long and short Ru-Ru distances to a disordered hexagonal TiI3-like structure in space group ''P63/mcm'' with (on average) equal Ru-Ru distances. In the disordered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthorhombic
In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular Prism (geometry), prism with a rectangular Base (geometry), base (''a'' by ''b'') and height (''c''), such that ''a'', ''b'', and ''c'' are distinct. All three bases intersect at 90° angles, so the three lattice vectors remain mutually orthogonal. Bravais lattices There are four orthorhombic Bravais lattices: primitive orthorhombic, base-centered orthorhombic, body-centered orthorhombic, and face-centered orthorhombic. For the base-centered orthorhombic lattice, the primitive cell has the shape of a right rhombic prism;See , row oC, column Primitive, where the cell parameters are given as a1 = a2, α = β = 90° it can be constructed because the two-dimensional centered rectangular base layer can also be descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Transition
In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic State of matter, states of matter: solid, liquid, and gas, and in rare cases, plasma (physics), plasma. A phase of a thermodynamic system and the states of matter have uniform physical property, physical properties. During a phase transition of a given medium, certain properties of the medium change as a result of the change of external conditions, such as temperature or pressure. This can be a discontinuous change; for example, a liquid may become gas upon heating to its boiling point, resulting in an abrupt change in volume. The identification of the external conditions at which a transformation occurs defines the phase transition point. Types of phase transition States of matter Phase transitions commonly refer to when a substance tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruthenium(III) Compounds
Ruthenium is a chemical element; it has symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is unreactive to most chemicals. Karl Ernst Claus, a Russian scientist of Baltic-German ancestry, discovered the element in 1844 at Kazan State University and named it in honor of Russia. (He used the Latin name ''Ruthenia'', which can have other meanings, but specifically stated that the element was named in honor of his "motherland".) Ruthenium is usually found as a minor component of platinum ores; the annual production has risen from about 19 tonnes in 2009 to some 35.5 tonnes in 2017. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors. A minor application for ruthenium is in platinum alloys and as a chemical catalyst. A new application of ruthenium is as the capping layer for extreme ultraviolet photomasks. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry Of Materials
Chemistry of Materials is a peer-reviewed scientific journal, published since 1989 by the American Chemical Society. It was founded by Leonard V. Interrante, who was the Editor-in-Chief until 2013. Jillian M. Buriak took over as Editor-in-Chief in January 2014. She was followed by Sara E. Skrabalak, who assumed the position of Editor-in-Chief in November 2020. Abstracting, indexing, and impact factor According to the ''Journal Citation Reports'', ''Chemistry of Materials'' has a 2022 impact factor of 8.6. It is indexed in the following bibliographic databases: *Scopus *Web of Science *British Library The British Library is the national library of the United Kingdom. Based in London, it is one of the largest libraries in the world, with an estimated collection of between 170 and 200 million items from multiple countries. As a legal deposit li ... *CAS Source Index See also * ACS Materials Letters References External links * Chemistry journals Materials science j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexagonal Close Packing
In geometry, close-packing of equal spheres is a dense arrangement of congruent spheres in an infinite, regular arrangement (or lattice). Carl Friedrich Gauss proved that the highest average density – that is, the greatest fraction of space occupied by spheres – that can be achieved by a lattice packing is :\frac \approx 0.74048. The same packing density can also be achieved by alternate stackings of the same close-packed planes of spheres, including structures that are aperiodic in the stacking direction. The Kepler conjecture states that this is the highest density that can be achieved by any arrangement of spheres, either regular or irregular. This conjecture was proven by Thomas Hales. The highest density is so far known only for 1, 2, 3, 8, and 24 dimensions. Many crystal structures are based on a close-packing of a single kind of atom, or a close-packing of large ions with smaller ions filling the spaces between them. The cubic and hexagonal arrangements are very clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (materials Science)
In crystallography, polymorphism is the phenomenon where a compound or element can crystallize into more than one crystal structure. The preceding definition has evolved over many years and is still under discussion today. Discussion of the defining characteristics of polymorphism involves distinguishing among types of transitions and structural changes occurring in polymorphism versus those in other phenomena. Overview Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure." Additionally, Walter McCrone described the phases in polymorphic matter as "different in crystal structure but identical in the liquid or vapor states." McCrone also def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium(III) Iodide
Titanium(III) iodide is an inorganic compound with the formula TiI3. It is a dark violet solid that is insoluble in solvents, except upon decomposition. Preparation and structure Titanium(III) iodide can be prepared by reaction of titanium with iodine:F. Hein, S. Herzog "Molybdenum(III) Bromide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1407. :\mathrm It can also be obtained by reduction of TiI4, e.g., with aluminium. In terms of its structure, the compound exists as a polymer of face-sharing octahedra. Above 323 K, the Ti---Ti spacing are equal, but below that temperature, the material undergoes a phase transition In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic Sta .... In the low temperature phase, the Ti-- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallographic Disorder
In X-ray crystallography, crystallographic disorder describes the cocrystallization of more than one rotamer, conformer, or isomer where the center of mass of each form is identical or unresolvable. Due to disorder, the crystallographic solution is the sum of the various forms. In many cases, the components of the disorder are equally abundant, and, in other cases, the weighting coefficients for each component differ. Disorder can entail a pair or several components, and usually arises when the forms are nearly equal in energy and the crystal lattice is sufficiently spacious to accommodate the various components. File:DOSBIW.png, Structure of pentamethylmolybdenum, , showing 4-fold disorder of one methyl group In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated a .... File:DOSBIWoneRot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Group
In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that leave it unchanged. In three dimensions, space groups are classified into 219 distinct types, or 230 types if chiral copies are considered distinct. Space groups are discrete cocompact groups of isometries of an oriented Euclidean space in any number of dimensions. In dimensions other than 3, they are sometimes called Bieberbach groups. In crystallography, space groups are also called the crystallographic or Fedorov groups, and represent a description of the symmetry of the crystal. A definitive source regarding 3-dimensional space groups is the ''International Tables for Crystallography'' . History Space groups in 2 dimensions are the 17 wallpaper groups which have been known for several centuries, though the proof that the list ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Structure
In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter. The smallest group of particles in a material that constitutes this repeating pattern is the unit cell of the structure. The unit cell completely reflects the symmetry and structure of the entire crystal, which is built up by repetitive translation of the unit cell along its principal axes. The translation vectors define the nodes of the Bravais lattice. The lengths of principal axes/edges, of the unit cell and angles between them are lattice constants, also called ''lattice parameters'' or ''cell parameters''. The symmetry properties of a crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruthenium(III) Chloride
Ruthenium(III) chloride is the chemical compound with the formula RuCl3. "Ruthenium(III) chloride" more commonly refers to the hydrate RuCl3·''x''H2O. Both the anhydrous and hydrated species are dark brown or black solids. The hydrate, with a varying proportion of water of crystallization, often approximating to a trihydrate, is a commonly used starting material in ruthenium chemistry. Preparation and properties Anhydrous ruthenium(III) chloride is usually prepared by heating powdered ruthenium metal with chlorine. In the original synthesis, the chlorination was conducted in the presence of carbon monoxide, the product being carried by the gas stream and crystallising upon cooling. Two polymorphs of RuCl3 are known. The black α-form adopts the CrCl3-type structure with long Ru-Ru contacts of 346 pm. This polymorph has honeycomb layers of Ru3+ which are surrounded with an octahedral cage of Cl− anions. The ruthenium cations are magnetic residing in a low-spin J~1/2 ground stat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Decomposition
Thermal decomposition, or thermolysis, is a chemical decomposition of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reaction. Decomposition temperature definition A simple substance (like water) may exist in equilibrium with its thermal decomposition products, effectively halting the decomposition. The equilibrium fraction of decomposed molecules increases with the temperature. Since thermal decomposition is a kinetic process, the observed temperature of its beginning in most instances will be a function of the experimental conditions and sensitivity of the experimental setup. For a rigorous depiction of the process, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
