Samarium is a chemical element; it has symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of samarium(II) are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II) iodide.
In crystallography, the cubiccrystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.
Heusler compounds are magnetic intermetallics with face-centered cubic crystal structure and a composition of XYZ (half-Heuslers) or X2YZ (full-Heuslers), where X and Y are transition metals and Z is in the p-block. The term derives from the name of German mining engineer and chemist Friedrich Heusler, who studied such a compound (Cu2MnAl) in 1903. Many of these compounds exhibit properties relevant to spintronics, such as magnetoresistance, variations of the Hall effect, ferro-, antiferro-, and ferrimagnetism, half- and semimetallicity, semiconductivity with spin filter ability, superconductivity, topological band structure and are actively studied as Thermoelectric materials. Their magnetism results from a double-exchange mechanism between neighboring magnetic ions. Manganese, which sits at the body centers of the cubic structure, was the magnetic ion in the first Heusler compound discovered. (See the Bethe–Slater curve for details of why this happens.)
In chemistry, hypomanganate, also called manganate(V) or tetraoxidomanganate(3−), is a trivalent anion (negative ion) composed of manganese and oxygen, with formula MnO3−
4.
Helimagnetism is a form of magnetic ordering where spins of neighbouring magnetic moments arrange themselves in a spiral or helical pattern, with a characteristic turn angle of somewhere between 0 and 180 degrees. It results from the competition between ferromagnetic and antiferromagnetic exchange interactions. It is possible to view ferromagnetism and antiferromagnetism as helimagnetic structures with characteristic turn angles of 0 and 180 degrees respectively. Helimagnetic order breaks spatial inversion symmetry, as it can be either left-handed or right-handed in nature.
Chromium hydrides are compounds of chromium and hydrogen, and possibly other elements. Intermetallic compounds with not-quite-stoichometric quantities of hydrogen exist, as well as highly reactive molecules. When present at low concentrations, hydrogen and certain other elements alloyed with chromium act as softening agents that enables the movement of dislocations that otherwise not occur in the crystal lattices of chromium atoms.
Chromium(III) boride, also known as chromium monoboride (CrB), is an inorganic compound with the chemical formula CrB. It is one of the six stable binary borides of chromium, which also include Cr2B, Cr5B3, Cr3B4, CrB2, and CrB4. Like many other transition metal borides, it is extremely hard (21-23 GPa), has high strength (690 MPa bending strength), conducts heat and electricity as well as many metallic alloys, and has a high melting point (~2100 °C). Unlike pure chromium, CrB is known to be a paramagnetic, with a magnetic susceptibility that is only weakly dependent on temperature. Due to these properties, among others, CrB has been considered as a candidate material for wear resistant coatings and high-temperature diffusion barriers.
In chemistry, molybdenum bronze is a generic name for certain mixed oxides of molybdenum with the generic formula A
xMo
yO
z where A may be hydrogen, an alkali metal cation (such as Li+, Na+, K+), and Tl+. These compounds form deeply coloured plate-like crystals with a metallic sheen, hence their name. These bronzes derive their metallic character from partially occupied 4d bands. The oxidation states in K0.28MoO3 are K+1, O2−, and Mo+5.72. MoO3 is an insulator, with an unfilled 4d band.
Lithium molybdenum purple bronze is a chemical compound with formula Li
0.9Mo
6O
17, that is, a mixed oxide of molybdenum and lithium. It can be obtained as flat crystals with a purple-red color and metallic sheen.
Langbeinites are a family of crystalline substances based on the structure of langbeinite with general formula M2M'2(SO4)3, where M is a large univalent cation, and M' is a small divalent cation. The sulfate group, SO2−4, can be substituted by other tetrahedral anions with a double negative charge such as tetrafluoroberyllate, selenate, chromate, molybdate, or tungstates. Although monofluorophosphates are predicted, they have not been described. By redistributing charges other anions with the same shape such as phosphate also form langbeinite structures. In these the M' atom must have a greater charge to balance the extra three negative charges.
Cerium nitrate refers to a family of nitrates of cerium in the +3 or +4 oxidation state. Often these compounds contain water, hydroxide, or hydronium ions in addition to cerium and nitrate. Double nitrates of cerium also exist.
Nickel forms a series of mixed oxide compounds which are commonly called nickelates. A nickelate is an anion containing nickel or a salt containing a nickelate anion, or a double compound containing nickel bound to oxygen and other elements. Nickel can be in different or even mixed oxidation states, ranging from +1, +2, +3 to +4. The anions can contain a single nickel ion, or multiple to form a cluster ion. The solid mixed oxide compounds are often ceramics, but can also be metallic. They have a variety of electrical and magnetic properties. Rare-earth elements form a range of perovskite nickelates, in which the properties vary systematically as the rare-earth element changes. Fine tuning of properties is achievable with mixtures of elements, applying stress or pressure, or varying the physical form.
Iron germanide (FeGe) is an intermetallic compound, a germanide of iron. At ambient conditions it crystallizes in three polymorphs with monoclinic, hexagonal and cubic structures. The cubic polymorph has no inversion center, it is therefore helical, with right-hand and left-handed chiralities.
Cobalt germanide (CoGe) is an intermetallic compound, a germanide of cobalt.
Manganese disilicide (MnSi2) is an intermetallic compound, a silicide of manganese. It is a non-stoichiometric compound, with a silicon deficiency expressed as MnSi2–x. Crystal structures of many MnSi2–x compounds resemble a chimney ladder and are called Nowotny phases. They include MnSi2 (x=0), Mn4Si7 (x=0.250), Mn11Si19 (x=0.273), Mn15Si26 (x=0.267) and Mn27Si47 (x=0.259). These phases have very similar unit cells whose length varies from 1.75 nm for MnSi2 or Mn4Si7, which have almost the same structures, to 11.8 nm for Mn27Si47.
Manganese monosilicide (MnSi) is an intermetallic compound, a silicide of manganese. It occurs in cosmic dust as the mineral brownleeite. MnSi has a cubic crystal lattice with no inversion center; therefore its crystal structure is helical, with right-hand and left-hand chiralities.
The borophosphates are mixed anion compounds containing borate and phosphate anions, which may be joined together by a common oxygen atom. Compounds that contain water or hydroxy groups can also be included in the class of compounds.
Mavlyanovite is a manganese-silicon mineral with formula Mn5Si3. It was named after Gani Mavlyanov, an Uzbek geologist who lived from 1910 to 1988.
Silicide carbides or carbide silicides are compounds containing anions composed of silicide (Si4−) and carbide (C4−) or clusters therof. They can be considered as mixed anion compounds or intermetallic compounds, as silicon could be considered as a semimetal.
Samarium compounds are compounds formed by the lanthanide metal samarium (Sm). In these compounds, samarium generally exhibits the +3 oxidation state, such as SmCl3, Sm(NO3)3 and Sm(C2O4)3. Compounds with samarium in the +2 oxidation state are also known, for example SmI2.
