|
Arsenide Minerals
In chemistry, an arsenide is a compound of arsenic with a less electronegative element or elements. Many metals form binary compounds containing arsenic, and these are called arsenides. They exist with many stoichiometries, and in this respect arsenides are similar to phosphides. Alkali metal and alkaline earth arsenides The group 1 alkali metals and the group 2, alkaline earth metals, form arsenides with isolated arsenic atoms. They form upon heating arsenic powder with excess sodium gives sodium arsenide (Na3As). The structure of Na3As is complex with unusually short Na–Na distances of 328–330 pm which are shorter than in sodium metal. This short distance indicates the complex bonding in these simple phases, i.e. they are not simply salts of As3− anion, for example. The compound LiAs, has a metallic lustre and electrical conductivity indicating some metallic bonding. These compounds are mainly of academic interest. For example, "sodium arsenide" is a structural mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphide
In chemistry, a phosphide is a compound containing the ion or its equivalent. Many different phosphides are known, with widely differing structures. Most commonly encountered on the binary phosphides, i.e. those materials consisting only of phosphorus and a less electronegative element. Numerous are polyphosphides, which are solids consisting of anionic chains or clusters of phosphorus. Phosphides are known with the majority of less electronegative elements with the exception of Hg, Pb, Sb, Bi, Te, and Po.Von Schnering, H.G. and Hönle , W. (1994) "Phosphides - Solid-state Chemistry" in ''Encyclopedia of Inorganic Chemistry''. R. Bruce King (ed.). John Wiley & Sons Finally, some phosphides are molecular. Binary phosphides Binary phosphides include phosphorus and one other element. An example of a group 1 phosphide is sodium phosphide (). Other notable examples include aluminium phosphide () and calcium phosphide (), which are used as pesticides, exploiting their tendenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group 12 Elements
Group 12, by modern Group (periodic table)#CAS and old IUPAC numbering (A/B), IUPAC numbering, is a Periodic table group, group of chemical elements in the periodic table group, periodic table. It includes zinc (Zn), cadmium (Cd), Mercury (element), mercury (Hg), and copernicium (Cn). Formerly this group was named ''IIB'' (pronounced as "group two B", as the "II" is a Roman numeral) by Group (periodic table)#CAS and old IUPAC numbering (A/B), CAS and old IUPAC system. The three group 12 elements that occur naturally are zinc, cadmium and mercury. They are all widely used in electric and electronic applications, as well as in various alloys. The first two members of the group share similar properties as they are solid metals under standard conditions. Mercury is the only metal that is a liquid at room temperature. While zinc is very important in the biochemistry of living organisms, cadmium and mercury are both highly toxic. As copernicium does not occur in nature, it has to be synt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zintl Phase
In chemistry, a Zintl phase is a product of a reaction between a group 1 (alkali metal) or group 2 (alkaline earth metal) and main group metal or metalloid (from groups 13, 14, 15, or 16). It is characterized by intermediate metallic/ ionic bonding. Zintl phases are a subgroup of brittle, high-melting intermetallic compounds that are diamagnetic or exhibit temperature-independent paramagnetism and are poor conductors or semiconductors.Sevov, S.C., Zintl Phases in Intermetallic Compounds, Principles and Practice: Progress, Westbrook, J.H.; *Freisher, R.L.: Eds.; John Wiley & Sons. Ltd., Chichester, England, 2002, pp. 113-13Slavi Chapter/ref> This type of solid is named after German chemist Eduard Zintl who investigated them in the 1930s. The term "Zintl Phases" was first used by Laves in 1941. In his early studies, Zintl noted that there was an atomic volume contraction upon the formation of these products and realized that this could indicate cation formation. He suggested tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
423080Asonly
4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures. In mathematics Four is the smallest composite number, its proper divisors being and . Four is the sum and product of two with itself: 2 + 2 = 4 = 2 x 2, the only number b such that a + a = b = a x a, which also makes four the smallest squared prime number p^. In Knuth's up-arrow notation, , and so forth, for any number of up arrows. By consequence, four is the only square one more than a prime number, specifically three. The sum of the first four prime numbers two + three + five + seven is the only sum of four consecutive prime numbers that yields an odd prime number, seventeen, which is the fourth super-prime. Four lies between the first proper pair of twin primes, three and five, which are the first two Fermat primes, like seventeen, which is the third. On the other hand, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sperrylite
Sperrylite is a platinum arsenide mineral with the chemical formula and is an opaque metallic tin white mineral which crystallizes in the isometric system with the pyrite group structure. It forms cubic, octahedral or pyritohedral crystals in addition to massive and reniform habits. It has a Mohs hardness of 6 - 7 and a very high specific gravity of 10.6. It was discovered by Francis Louis Sperry, an American chemist, in 1889 at Sudbury. The most important occurrence of sperrylite is in the nickel ore deposit of Sudbury Basin in Ontario, Canada. It also occurs in the layered igneous complex of the Bushveld region of South Africa and the Oktyabr'skoye copper-nickel deposit of the Eastern-Siberian Region, Russia. Geologic occurrence Sperrylite is the most common platinum mineral, it generally occurs with a wide array of other unusual minerals, including cooperite [], laurite [], kotulskite [], merenskyite [], iridium-osmium (Ir-Os) alloys, sudburyite [], omeiite [], testibio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band Theory
In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called ''band gaps'' or ''forbidden bands''). Band theory derives these bands and band gaps by examining the allowed quantum mechanical wave functions for an electron in a large, periodic lattice of atoms or molecules. Band theory has been successfully used to explain many physical properties of solids, such as electrical resistivity and optical absorption, and forms the foundation of the understanding of all solid-state devices (transistors, solar cells, etc.). Why bands and band gaps occur The electrons of a single, isolated atom occupy atomic orbitals each of which has a discrete energy level. When two or more atoms join together to form a molecule, their atomic orbitals overlap and hybridize. Similarly, if a large number ''N'' of identical atoms come ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidation Numbers
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state may be positive, negative or zero. While fully ionic bonds are not found in nature, many bonds exhibit strong ionicity, making oxidation state a useful predictor of charge. The oxidation state of an atom does not represent the "real" formal charge on that atom, or any other actual atomic property. This is particularly true of high oxidation states, where the ionization energy required to produce a multiply positive ion is far greater than the energies available in chemical reactions. Additionally, the oxidation states of atoms in a given compound may vary depending on the choice of electronegativity scale used in their calculation. Thus, the oxidation state of an atom in a compound is purely a formalism. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skutterudite
Named after Skuterudåsen, a hill in Modum, Norway, skutterudite is a cobalt arsenide mineral containing variable amounts of nickel and iron substituting for cobalt with the ideal formula CoAs3. Some references give the arsenic a variable formula subscript of 2–3. High nickel varieties are referred to as nickel-skutterudite, previously chloanthite. It is a hydrothermal ore mineral found in moderate to high temperature veins with other Ni-Co minerals. Associated minerals are arsenopyrite, native silver, erythrite, annabergite, nickeline, cobaltite, silver sulfosalts, native bismuth, calcite, siderite, barite and quartz. It is mined as an ore of cobalt and nickel with a by-product of arsenic. The crystal structure of this mineral has been found to be exhibited by several compounds with important technological uses. The mineral has a bright metallic luster, and is tin white or light steel gray in color with a black streak. The specific gravity is 6.5 and the hardness is 5.5–6. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorite Structure
In solid state chemistry, the fluorite structure refers to a common motif for compounds with the formula MX2. The X ions occupy the eight tetrahedral interstitial sites whereas M ions occupy the regular sites of a face-centered cubic (FCC) structure. Many compounds, notably the common mineral fluorite (CaF2), adopt this structure. Many compounds with formula M2X have an antifluorite structure. In these the locations of the anions and cations are reversed relative to fluorite (an anti-structure); the anions occupy the FCC regular sites whereas the cations occupy the tetrahedral interstitial sites. For example, Magnesium silicide, Mg2Si, has a lattice parameter of 6.338 Å with magnesium cations occupying the tetrahedral interstitial sites, in which each silicide anion is surrounded by eight magnesium cations and each magnesium cation is surrounded by four silicide anions in a tetrahedral fashion. File:Fluorite Structure.jpg, The fluorite structure of calcium fluoride CaF2. File:Anti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Cadmium Phosphide Arsenide
Zinc cadmium phosphide arsenide ( Zn- Cd- P- As) is a quaternary system of group II (IUPAC group 12) and group V (IUPAC group 15) elements. Many of the inorganic compounds in the system are II-V semiconductor materials. The quaternary system of II3V2 compounds, (Zn1−xCdx)3(P1−yAsy)2, has been shown to allow solid solution continuously over the whole compositional range. This material system and its subsets have applications in electronics, optoelectronics, including photovoltaics, and thermoelectrics. List of all binary compounds This system of elements contains numerous binary compounds and their solid solutions. Stable at atmospheric pressure The binary compounds thermodynamically stable at atmospheric pressure are listed in the following table: Metastable or unstable at atmospheric pressure Compounds metastable or unstable at atmospheric pressure are the following: Quaternary compounds The compounds of the form II3V2 have similar crystalline structures and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc Arsenide
Zinc arsenide (Zn3As2) is a binary compound of zinc with arsenic which forms gray tetragonal crystals. It is an inorganic semiconductor with a band gap of 1.0 eV. Synthesis and reactions Zinc arsenide can be prepared by the reaction of zinc with arsenic :3 Zn + 2 As → Zn3As2 Structure Zn3As2 has a room-temperature tetragonal form that converts to a different tetragonal phase at 190 °C and to a third phase at 651 °C. In the room-temperature form, the zinc atoms are tetrahedrally coordinated and the arsenic atoms are surrounded by six zinc atoms at the vertices of a distorted cube. The crystalline structure of zinc arsenide is very similar to that of cadmium arsenide (Cd3As2), zinc phosphide (Zn3P2) and cadmium phosphide (Cd3P2). These compounds of the Zn-Cd-P-As quaternary system exhibit full continuous solid-solution. Electronic structure Its lowest direct and indirect bandgaps are within 30 meV or each other. References arsenide zinc Zinc i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
