Gadolinium oxide is an inorganic compound with the formula Gd2O3. It is one of the most commonly forms of the rare earth element gadolinium. The cubic, No. 206) structure is similar to that of manganese oxide, the cubic structure features two types of gadolinium sites, each with a coordination number of 6 but with different coordination geometries. At room temperature, the structure is more stable. The phase change to the structure takes place at 1200 °C. Above 2100 °C to the point at 2420 °C, a hexagonal phase dominates. Gadolinium oxide can be formed by decomposition of the hydroxide, carbonate. Gadolinium oxide forms on the surface of gadolinium metal, gadolinium oxide is a rather basic oxide, indicated by its ready reaction with carbon dioxide to give carbonates. The nanoparticles are coated with a protective material to avoid the formation of larger polycrystalline aggregates. Nanoparticles of gadolinium oxide is a potential contrast agent for magnetic resonance imaging, a dextran-coated preparation of 20–40 nm sized gadolinium oxide particles had a relaxivity of 4.8 s−1mM−1 per gadolinium ion at 7.05 T.
Smaller particles, between 2 and 7 nm, were tested as a MRI agent in
Holmium oxide, or holmium oxide is a chemical compound of a rare-earth element holmium and oxygen with the formula Ho2O3. Together with dysprosium oxide holmium oxide is one of the most powerfully paramagnetic substances known, the oxide, called holmia, occurs as a component of the related erbium oxide mineral called erbia. Typically the oxides of the trivalent lanthanides coexist in nature and separation of these components requires specialized methods, holmium oxide is used in making specialty colored glasses. Glass containing holmium oxide and holmium oxide solutions have a series of optical absorption peaks in the visible spectral range. They are therefore used as a convenient calibration standard for optical spectrophotometers. Holmium oxide has some fairly dramatic color changes depending on the lighting conditions, in daylight, it is a tannish yellow color. Under trichromatic light, it is an orange red, almost indistinguishable from the way erbium oxide looks under this same lighting.
This is related to the emission bands of the phosphors. Holmium oxide has a band gap of 5.3 eV. The yellow color originates from abundant lattice defects and is related to internal transitions at the Ho3+ ions, holmium oxide has a cubic, yet rather complex structure, with many atoms per unit cell and a large lattice constant of 1.06 nm. This structure is characteristic of oxides of heavy elements, such as Tb2O3, Dy2O3, Er2O3, Tm2O3, Yb2O3 and Lu2O3. The thermal expansion coefficient of Ho2O3 is large at 7.4 ×10−6/°C. Later in 1878, Per Teodor Cleve independently discovered the element while he was working on erbia earth, using the method developed by Carl Gustaf Mosander, Cleve first removed all of the known contaminants from erbia. The result of effort was two new materials, one brown and one green. He named the brown substance holmia and the green one thulia, holmia was found to be the holmium oxide and thulia was thulium oxide. Holmium oxide occurs in trace amounts in the minerals gadolinite, holmium metal readily oxidizes in air, therefore presence of holmium in nature is synonymous with that of holmia.
With the abundance of 1.4 mg/kg, holmium is the 56th most abundant element, the main mining areas are China, United States, India, Sri Lanka and Australia with reserves of holmium oxide estimated as 400,000 tonnes. A typical extraction process of oxide can be simplified as follows, The mineral mixtures are crushed
Neodymium oxide or neodymium sesquioxide is the chemical compound composed of neodymium and oxygen with the formula Nd2O3. It forms very light grayish-blue hexagonal crystals, the rare earth mixture didymium, previously believed to be an element, partially consists of neodymium oxide. Neodymium oxide is used to dope glass, including sunglasses, to make solid-state lasers, neodymium-doped glass turns purple due to the absorbance of yellow and green light, and is used in welding goggles. Some neodymium-doped glass is dichroic, that is, it changes depending on the lighting. One kind of glass named for the mineral alexandrite appears blue in sunlight, about 7000 tonnes of neodymium oxide are produced worldwide each year. Neodymium oxide is used as a polymerization catalyst. Neodymium oxide is formed when neodymium nitride or neodymium hydroxide is burned in air
Curium oxide is a compound composed of curium and oxygen with the chemical formula Cm2O3. It is a solid with a unit cell that contains two curium atoms and three oxygen atoms. The simplest synthesis equation involves the reaction of metal with O2−,2 Cm3+ +3 O2− ---> Cm2O3. Curium trioxide can exist as five polymorphic forms, two of the forms exist at extremely high temperatures, making it difficult for experimental studies to be done on the formation of their structures. The three other forms which curium sesquioxide can take are the body-centered cubic form, the monoclinic form. Curium oxide is white or light tan in color and, while insoluble in water, is soluble in inorganic. Its synthesis was first recognized in 1955, Curium sesquioxide can be prepared in a variety of ways. Ignition with O2, Curium oxalate is precipitated through a capillary tube, the precipitate is ignited by gaseous oxygen at 400 °C, and the resulting product is thermally decomposed via 600 °C and 10−4 mm of pressure. Aerosolized Curium Sesquioxide, The aerosolization process of Cm2O3 can be done through multiple experimental processes, typically, Cm2O3 is aerosolized for experimental procedures which set out to discover the effects of curium metal within a biological system.
Route 1, The traditional aerosolization reaction utilizes curium metal as the starting material, while curium metal has been discovered to naturally exist as a mixture of 87. 4% 244Cm,8. 4% 243Cm,3. 9% other curium isotopes, and ~0. NH3OH is added to the purified curium nitrate, and the precipitate is collected and rinsed with deionized water. The precipitate is resuspended in solvent and aerosolized with some sort of high output aerosol generator, route 2, In other aerosolizations, instead of the addition of NH3OH to the purified curium nitrate, ammonium hydroxide is utilized to adjust the pH value of the solution to 9. The increased basicity of the solution creates a curium hydroxide precipitate and this precipitate is collected through filtration and resuspended in deionized water, and a nebulizer is used to aerosolize the product. Reduction by Hydrogen Gas, A solution of curium trichloride is evaporated to dryness with pure nitric acid to produce curium nitrate, the curium nitrate is ignited in air, producing curium oxide, believed to be an intermediate structure between CmO2 and the formation of Cm2O3.
The intermediate is scraped into capillary tubes attached to a vacuum system, obtaining Curium-244, For many of the reactions described above, curium metal is provided by an outside retailer. However, 244curium is one of the more unstable curium isotopes and it has been experimentally determined that, within one day, 244CmO2s lattice parameter increases by a factor of 0. 2%. This has been hypothesized to be a result of the weakening interatomic interactions between curium and the neighboring oxide groups as a result of alpha-decay and this affects the thermal conductivity of curium oxides, causing it to exponentially decrease over time as the effects of alpha-decay strengthen. The body-centered cubic and monoclinic forms are the most common forms of curium trioxide
Iron oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the two being iron oxide, which is rare, and iron oxide, which occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the source of iron for the steel industry. Fe2O3 is ferromagnetic, dark red, and readily attacked by acids, Iron oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition. To a chemist, rust is considered a material, described as hydrated ferric oxide. Fe2O3 can be obtained in various polymorphs, in the main ones, α and γ, iron adopts octahedral coordination geometry. That is, each Fe center is bound to six oxygen ligands, α-Fe2O3 has the rhombohedral, corundum structure and is the most common form. It occurs naturally as the mineral hematite which is mined as the ore of iron. It is antiferromagnetic below ~260 K, and exhibits weak ferromagnetism between 260 K and the Néel temperature,950 K and it is easy to prepare using both thermal decomposition and precipitation in the liquid phase.
Its magnetic properties are dependent on many factors, e. g. pressure, particle size and it is metastable and converted from the alpha phase at high temperatures. It occurs naturally as the mineral maghemite and it is ferromagnetic and finds application in recording tapes, although ultrafine particles smaller than 10 nanometers are superparamagnetic. It can be prepared by thermal dehydratation of gamma iron oxide-hydroxide, another method involves the careful oxidation of Fe3O4. The ultrafine particles can be prepared by decomposition of iron oxalate. Several other phases have been identified or claimed, the β-phase is cubic body centered, and at temperatures above 500 °C converts to alpha phase. It can be prepared by reduction of hematite by carbon, pyrolysis of iron chloride solution, the epsilon phase is rhombic, and shows properties intermediate between alpha and gamma, and may have useful magnetic properties. Preparation of the pure epsilon phase has proven challenging due to contamination with alpha.
Material with a proportion of epsilon phase can be prepared by thermal transformation of the gamma phase. This phase is metastable, transforming to the alpha phase at between 500 and 750 °C
Erbium oxide, is synthesized from the lanthanide metal erbium. It was partially isolated by Carl Gustaf Mosander in 1843, and first obtained in pure form in 1905 by Georges Urbain and it has a pink color with a cubic crystal structure. Under certain conditions erbium oxide can have a hexagonal form, Erbium oxide is toxic when inhaled, taken orally, or injected into the blood stream in massive amounts. The effect of erbium oxides in low concentrations on humans over long periods of time has not been determined, Erbium metal tarnishes slowly in air. Erbium burns readily to form erbium oxide, Formation of erbium oxide,4 Er +3 O2 →2 Er2O3 Erbium oxide is insoluble in water, Er2O3 readily absorb moisture and carbon dioxide from the atmosphere. It can react with acids to form the corresponding erbium salts, reaction with hydrochloric acid, Er2O3 +6 HCl →2 ErCl3 +3 H2O One interesting property of erbium oxides is their ability to up convert energy. Erbium oxide nanoparticles possess photoluminescence properties, Erbium oxide nanoparticles can be formed by applying ultrasound in the presence of multiwall carbon nanotubes.
The erbium oxide nanoparticles that have successfully made by employing ultrasound are erbium carboxioxide. Each ultrasonically formed erbium oxide is photoluminescence in the region of the electromagnetic spectrum under excitation of 379 nm in water. Hexagonal erbium oxide photoluminescence is long lived and allows higher energy transitions, spherical erbium oxide does not experience 4S3/2 - 4I15/2 energy transitions. The applications of Er2O3 are varied due to their electrical, nanoscale materials doped with Er+3 are of much interest because they have special particle-size-dependent optical and electrical properties. Erbium oxide doped nanoparticle materials can be dispersed in glass or plastic for display purposes, Erbium oxide is among the most important rare earth metals used in biomedicine. The photoluminescence property of erbium oxide nanoparticles on carbon nanotubes makes them useful in biomedical applications, for example, erbium oxide nanoparticles can be surface modified for distribution into aqueous and non-aqueous media for bioimaging.
Erbium oxides are used as gate dielectrics in semi conductor devices since it has a high dielectric constant. Erbium is sometimes used as a coloring for glasses and erbium oxide can be used as a neutron poison for nuclear fuel
Arsenic trioxide is an inorganic compound with the formula As 2O3. This commercially important oxide of arsenic is the precursor to other arsenic compounds. Approximately 50,000 tonnes are produced annually, many applications are controversial given the high toxicity of arsenic compounds. Arsenic trioxide can be generated via processing of arsenic compounds including the oxidation of arsenic. Illustrative is the roasting of orpiment, an arsenic sulfide ore. 2 As 2S3 +9 O2 →2 As 2O3 +6 SO2 Most arsenic oxide is, for example, arsenopyrite, a common impurity in gold- and copper-containing ores, liberates arsenic trioxide upon heating in air. The processing of minerals has led to numerous cases of poisonings. Only in China are arsenic ores intentionally mined, in the laboratory, it is prepared by hydrolysis of arsenic trichloride,2 AsCl3 +3 H2O → As2O3 +6 HCl As 2O3 occurs naturally as two minerals and claudetite. Both are relatively rare secondary minerals found in zones of As-rich ore deposits. Sheets of As2O3 stand for part of structures of the recently discovered minerals lucabindiite, As4O6, Arsenic trioxide is an amphoteric oxide, and its aqueous solutions are weakly acidic.
Thus, it dissolves readily in alkaline solutions to give arsenites and it is less soluble in acids, although it will dissolve in hydrochloric acid. Reduction gives elemental arsenic or arsine depending on conditions, As2O3 +6 Zn +12 HNO3 →2 AsH3 +6 Zn2 +3 H2O This reaction is used in the Marsh test. In the liquid and gas phase below 800 °C, arsenic trioxide has the formula As 4O6 and is isostructural with P 4O6, above 800 °C As 4O6 significantly dissociates into molecular As 2O3, which adopts the same structure as N 2O3. Three forms are known in the state, a high temperature cubic As 4O6, containing molecular As 4O6. The polymers, which both crystallize as monoclinic crystals, feature sheets of pyramidal AsO3 units that share O atoms, large scale applications include its use as a precursor to forestry products, in colorless glass production, and in electronics. Being the main compound of arsenic, the trioxide is the precursor to elemental arsenic, arsenic alloys, organoarsenic compounds, e. g. feed additives and pharmaceuticals, are derived from arsenic trioxide.
Bulk arsenic-based compounds sodium arsenite and sodium cacodylate are derived from the trioxide, a variety of applications exploit arsenics toxicity, including the use of the oxide as a wood preservative. Copper arsenates, which are derived from arsenic trioxide, are used on a scale as a wood preservative in the US and Malaysia
Bismuth oxide is perhaps the most industrially important compound of bismuth. It is a starting point for bismuth chemistry. It is found naturally as the mineral bismite and sphaerobismoite, but it is obtained as a by-product of the smelting of copper. Bismuth trioxide is used to produce the Dragons eggs effect in fireworks. The structures adopted by Bi2O3 differ substantially from those of oxide, As2O3. Bismuth oxide, Bi2O3 has five crystallographic polymorphs, the room temperature phase, α-Bi2O3 has a monoclinic crystal structure. There are three high temperature phases, a tetragonal β-phase, a body-centred cubic γ-phase, a cubic δ-Bi2O3 phase, the room temperature α-phase has a complex structure with layers of oxygen atoms with layers of bismuth atoms between them. The bismuth atoms are in two different environments which can be described as distorted 6 and 5 coordinate respectively, β-Bi2O3 has a structure related to fluorite. γ-Bi2O3 has a related to that of Bi12SiO20, where a fraction of the Bi atoms occupy the position occupied by SiIV.
δ- Bi2O3 has a defective fluorite-type crystal structure in two of the eight oxygen sites in the unit cell are vacant. ε- Bi2O3 has a related to the α- and β- phases. It can be prepared by means and transforms to the α- phase at 400 °C. The monoclinic α-phase transforms to the cubic δ-Bi2O3 when heated above 729 °C, the behaviour of Bi2O3 on cooling from the δ-phase is more complex, with the possible formation of two intermediate metastable phases, the tetragonal β-phase or the body-centred cubic γ-phase. The γ-phase can exist at room temperature with very slow cooling rates, the α-phase exhibits p-type electronic conductivity at room temperature which transforms to n-type conductivity between 550 °C and 650 °C, depending on the oxygen partial pressure. The conductivity in the β, γ and δ-phases is predominantly ionic with oxide ions being the charge carrier. Of these δ- Bi2O3 has the highest reported conductivity, at 750 °C the conductivity of δ- Bi2O3 is typically about 1 Scm−1, about three orders of magnitude greater than the intermediate phases and four orders greater than the monoclinic phase.
The conductivity in the β, γ and δ-phases is predominantly ionic with oxide ions being the charge carrier. δ- Bi2O3 has a defective fluorite-type crystal structure in two of the eight oxygen sites in the unit cell are vacant