Strontium oxide properties

Wilson et al. [25] analyzed various brands of commercial cements and specified their possible composition, properties, and microstructure. Wilson et al. report the most representative and comprehensive data on commercial porcelain dental cements. These cements consist of powdered alumina-lime-silica glass mixed with phosphoric acid that formed a hard and translucent product. The starter glass powder consists of 31.5-41.6 wt% silica, 27.2-29.1 wt% alumina, 7.7-9.0wt% calcium oxide, 7.7-11.2 wt% sodium oxide, 13.3-22 wt% fluorine and small amounts of phosphorous and zinc oxides. Often very small amounts of magnesium and strontium oxides are also present. 

Property Strontium fluoride Strontium hydroxide Strontium nitrate Strontium phosphate Strontium oxide... 

The formula for calcium oxide is CaO. What are the formulas for magnesium oxide and strontium oxide A common mineral of barium is barytes, or barium sulfate (BaS04). Because elements in the same periodic group have similar chemical properties, we might expect to find some radium sulfate (RaS04) mixed with barytes since radium is the last member of Group 2A. Flowever, the only source of radium compounds in nature is in uranium minerals. Why ... 

Properties Wh. powd. odorless readily sol. in dil. HCI or HNO3 m.w. 177.66 Toxicology Poisonous if ingested irritating to eyes, skin, respiratory system target organ kidneys TSCA listed Precaution Avoid contact with acid Uses Mfg. of pyrotechnic compositions Manuf/Distrib. ABCR http //www.abcr.de-, Aldrich http //www.sigma-aldrich.com-. Barium Chems. http //www.bariumchemicais.com-, Noah http //www.noahtech.com Strontium oxide... 

The conventional production-type oxide cathode consists of a coating of barium and strontium oxides on a base metal such as nickel. Nickel alloys, in general, are stronger, tougher, and harder than most nonferrous alloys and many steels. The most important property of nickel alloys is their abihty to retain strength and toughness at elevated temperatures. The oxide layer is formed by first coating a nickel structure (a can or disc) with a mixture of barium and strontium carbonates, suspended in a binder material. The mixture is approximately 60% barium carbonate and 40% strontium carbonate. 

We note here that CTV neck and funnel glasses often contain between 20 and 30 wt% PbO. Because of the tendeney for electron browning mentioned in Sec. 6.1.2.2, current panel glasses contain less than 5 percent PbO, and sometimes none. Barium oxide (BaO), strontium oxide (SrO), and zirconium oxide (ZrOj) provide the required magnitude of x-ray absorption. Tables 6.7 and 6.8 show compositions and properties for several commercial TV panel glasses. 

The metal oxide solubilities in the chloride-bromide sequence were shown in our papers to considerably decrease. For example, strontium oxide, which is referred to as moderately soluble in low-acidic chloride melts, becomes slightly soluble in the bromide melt. Calcium and cadmium oxides slightly soluble in chloride melts become practically insoluble in molten bromides. The basic properties of BaO in the bromide melt essentially weaken, and degree of its dissociation, in the saturated solution in molten bromide, considerably diminishes. 

In general, the chemistry of inorganic lead compounds is similar to that of the alkaline-earth elements. Thus the carbonate, nitrate, and sulfate of lead are isomorphous with the corresponding compounds of calcium, barium, and strontium. In addition, many inorganic lead compounds possess two or more crystalline forms having different properties. For example, the oxides and the sulfide of bivalent lead are frequendy colored as a result of their state of crystallisation. Pure, tetragonal a-PbO is red pure, orthorhombic P PbO is yeUow and crystals of lead sulfide, PbS, have a black, metallic luster. 

Strontium [7440-24-6] Sr, is in Group 2 (IIA) of the Periodic Table, between calcium and barium. These three elements are called alkaline-earth metals because the chemical properties of the oxides fall between the hydroxides of alkaU metals, ie, sodium and potassium, and the oxides of earth metals, ie, magnesium, aluminum, and iron. Strontium was identified in the 1790s (1). The metal was first produced in 1808 in the form of a mercury amalgam. A few grams of the metal was produced in 1860—1861 by electrolysis of strontium chloride [10476-85-4]. 

Health and Safety Factors. The strontium ion has a low order of toxicity, and strontium compounds are remarkably free of toxic hazards. Chemically, strontium is similar to calcium, and strontium salts, like calcium salts, are not easily absorbed by the intestinal tract. Strontium carbonate has no commonly recognized hazardous properties. Strontium nitrate is regulated as an oxidizer that promotes rapid burning of combustible materials, and it should not be stored in areas of potential fire hazards. 

Alkaline-Earth Titanates. Some physical properties of representative alkaline-earth titanates ate Hsted in Table 15. The most important apphcations of these titanates are in the manufacture of electronic components (109). The most important member of the class is barium titanate, BaTi03, which owes its significance to its exceptionally high dielectric constant and its piezoelectric and ferroelectric properties. Further, because barium titanate easily forms solid solutions with strontium titanate, lead titanate, zirconium oxide, and tin oxide, the electrical properties can be modified within wide limits. Barium titanate may be made by, eg, cocalcination of barium carbonate and titanium dioxide at ca 1200°C. With the exception of Ba2Ti04, barium orthotitanate, titanates do not contain discrete TiO ions but ate mixed oxides. Ba2Ti04 has the P-K SO stmcture in which distorted tetrahedral TiO ions occur. 

To be effective, there must be a certain minimum concentration of inhibitor at the interface to be protected. Therefore, there must be sufficient inhibitor in the primer, and these inhibitors need to be soluble enough in water to enable transport of inhibitor to the oxide surface as water permeates the adhesive joint. However, too high of a solubility will rapidly deplete the primer layer of inhibitor resulting in a loss of protection. One of the fortuitous properties of zinc and strontium chromates is the limited solubility of these compounds in water (about 1.2 g/1 at 15°C [33]). 

Resoles are usually those phenolics made under alkaline conditions with an excess of aldehyde. The name denotes a phenol alcohol, which is the dominant species in most resoles. The most common catalyst is sodium hydroxide, though lithium, potassium, magnesium, calcium, strontium, and barium hydroxides or oxides are also frequently used. Amine catalysis is also common. Occasionally, a Lewis acid salt, such as zinc acetate or tin chloride will be used to achieve some special property. Due to inclusion of excess aldehyde, resoles are capable of curing without addition of methylene donors. Although cure accelerators are available, it is common to cure resoles by application of heat alone. 

Highly pure lanthanum oxide is used to make optical glass of high refractive index for camera lenses. It also is used to make glass fibers. The oxide also is used to improve thermal and electrical properties of barium and strontium titanates. Other applications are in glass polishes carbon arc electrodes fluorescent type phosphors and as a diluent for nuclear fuels. In such apph-cations, lanthinum oxide is usually combined with other rare earth oxides. 

For some applications, such as the cathode materials in solid oxide fuel cells (see Section 5.4.4), a material is needed that can conduct both ions and electrons. The strontium-doped perovskites LaMn03 (LSM), and LaCr03 (LSC) have both these properties. 

This discovery was soon followed by the isolation of barium, strontium, and calcium. By analogy, it was further inferred that all amorphous powders—alumina, magnesia, etc.—possessing similar properties, were metallic oxides. As a result, when a new earth is now discovered, chemists believe, by faith, that it is the oxide of a metal even in cases where the supposed metal has never been isolated. 

How can the oxides, peroxides, and hydroxides of the alkaline-earth metals be prepared What are the commercial names of calcium and barium hydroxide solutions How do the solubility, basic properties, and thermal stability of the hydroxides change in the series calcium-strontium-barium ... 

Barium Arsenide, Ba3As2.—By passing arsine over barium oxide at red heat Soubeiran 4 obtained a mixture of arsenide and arsenite. Lebeau 6 prepared the pure arsenide by reduction of barium arsenate with carbon in an electric furnace. Barium arsenide is very similar in properties to the arsenides of calcium and strontium it is slightly darker in colour, more readily fusible and more reactive chemically. Its density at 15° C. is 4-1. It burns spontaneously in fluorine, chlorine or bromine vapour. In oxygen it burns at about 300° C. and in sulphur vapour at dull red heat. 

Research chemists found that they could modify the conducting properties of solids by doping them, a process commonly used to control the properties of semiconductors (see Section 3.13). In 1986, a record-high Ts of 35 K was observed, surprisingly not for a metal, but for a ceramic material (Section 14.24), a lanthanum-copper oxide doped with barium. Then early in 1987, a new record T, of 93 K was set with yttrium-barium-copper and a series of related oxides. In 1988, two more oxide series of bismuth-strontium-calcium-copper and thallium-barium-calcium-copper exhibited transition temperatures of 110 and 125 K, respectively. These temperatures can be reached by cooling the materials with liquid nitrogen, which costs only about 0.20 per liter. Suddenly, superconducting devices became economically viable. 

---