omniomni/omni-engineering huggingface dataset:
Hafnium(IV) oxide. Hafnium(IV) oxide is the inorganic compound with the formula . Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. Hafnium dioxide is an intermediate in some processes that give hafnium metal.

Hafnium(IV) oxide is quite inert. It reacts with strong acids such as concentrated sulfuric acid and with strong bases. It dissolves slowly in hydrofluoric acid to give fluorohafnate anions. At elevated temperatures, it reacts with chlorine in the presence of graphite or carbon tetrachloride to give hafnium tetrachloride.

Structure
Hafnia typically adopts the same structure as zirconia (ZrO2). Unlike TiO2, which features six-coordinate Ti in all phases, zirconia and hafnia consist of seven-coordinate metal centres. A variety of other crystalline phases have been experimentally observed, including cubic fluorite (Fmm), tetragonal (P42/nmc), monoclinic (P21/c) and orthorhombic (Pbca and Pnma). It is also known that hafnia may adopt two other orthorhombic metastable phases (space group Pca21 and Pmn21) over a wide range of pressures and temperatures, presumably being the sources of the ferroelectricity observed in thin films of hafnia.

Thin films of hafnium oxides deposited by atomic layer deposition are usually crystalline. Because semiconductor devices benefit from having amorphous films present, researchers have alloyed hafnium oxide with aluminum or silicon (forming hafnium silicates), which have a higher crystallization temperature than hafnium oxide.

Applications
Hafnia is used in optical coatings, and as a high-κ dielectric in DRAM capacitors and in advanced metal–oxide–semiconductor devices. Hafnium-based oxides were introduced by Intel in 2007 as a replacement for silicon oxide as a gate insulator in field-effect transistors. The advantage for transistors is its high dielectric constant: the dielectric constant of HfO2 is 4–6 times higher than that of SiO2. The dielectric constant and other properties depend on the deposition method, composition and microstructure of the material.

Hafnium oxide (as well as doped and oxygen-deficient hafnium oxide) attracts additional interest as a possible candidate for resistive-switching memories and CMOS-compatible ferroelectric field effect transistors (FeFET memory) and memory chips.

Because of its very high melting point, hafnia is also used as a refractory material in the insulation of such devices as thermocouples, where it can operate at temperatures up to 2500 °C.

Multilayered films of hafnium dioxide, silica, and other materials have been developed for use in passive cooling of buildings. The films reflect sunlight and radiate heat at wavelengths that pass through Earth's atmosphere, and can have temperatures several degrees cooler than surrounding materials under the same conditions.

References

Hafnium compounds
High-κ dielectrics
Transition metal oxides
Ferroelectric materials
Stephen Moulton. Stephen Moulton (7 July 1794 – 26 April 1880) was an Englishman who, as an agent of the American rubber pioneer Charles Goodyear, first brought samples of vulcanized rubber to the United Kingdom.

Biography
Moulton, who was born in Whorlton, County Durham, subsequently shared the samples with Thomas Hancock, who then beat Goodyear to a UK patent for the vulcanization process by a matter of a few weeks in 1843.

After various disputes with Hancock and Goodyear over patents and manufacturing rights, Moulton established his own factory in 1848 at Kingston Mill near Bradford-on-Avon, Wiltshire, England.  His company, S.Moulton & Co., specialised in rubber applications for engineering industries and in 1855 acquired the Middle Mill adjacent to the existing factory along with the nearby Staverton woollen mill between 1851 and 1860.  With the increasing importance of the British railway industry he concentrated on providing rubber suspension systems and components for railway carriages. Moulton's home in Bradford was The Hall, a Jacobean mansion on the eastern edge of the town.

In 1891, eleven years after Moulton's death, his company amalgamated with that of George Spencer in London to become George Spencer Moulton & Co. Ltd., which in 1956 became part of Avon Rubber.

Family connection
Moulton's great-grandson Dr Alex Moulton was himself a pioneer of rubber engineering, being responsible for many innovations including the rubber suspension system he designed for the innovative BMC car, the Mini.

References

1794 births
1880 deaths
People from County Durham (district)
English railway mechanical engineers
Indium(III) telluride. Indium(III) telluride (In2Te3) is an inorganic compound. A black solid, it is sometimes described as an intermetallic compound, because it has properties that are metal-like and salt like. It is a semiconductor that has attracted occasional interest for its thermoelectric and photovoltaic applications.  No applications have been implemented commercially however.

Preparation and reactions
A conventional route entails heating the elements in a seal-tube:

Indium(III) telluride reacts with strong acids to produce hydrogen telluride.

Further reading

References

Tellurides
Indium compounds
Semiconductor materials
Lead(II) fluoride. Lead(II) fluoride is the inorganic compound with the formula PbF2.  It is a white solid.  The compound is polymorphic, at ambient temperatures it exists in orthorhombic (PbCl2 type) form, while at high temperatures it is cubic (Fluorite type).

Preparation
Lead(II) fluoride can be prepared by treating lead(II) hydroxide or lead(II) carbonate with hydrofluoric acid:
 Pb(OH)2 + 2 HF → PbF2 + 2 H2O

Alternatively, it is precipitated by adding hydrofluoric acid to a lead(II) salt solution, or by adding a fluoride salt to a lead salt, such as potassium fluoride to a lead(II) nitrate solution,
 2 KF + Pb(NO3)2 → PbF2 + 2 KNO3
or sodium fluoride to a lead(II) acetate solution.
 2 NaF + Pb(CH3COO)2 → PbF2 + 2 NaCH3COO

It appears as the very rare mineral fluorocronite.

Uses

Lead(II) fluoride is used in low melting glasses, in glass coatings to reflect infrared rays, in phosphors for television-tube screens, and as a catalyst for the manufacture of picoline. The Muon g−2 experiment uses  scintillators in conjunction with silicon photomultipliers.

It also serves as a oxygen scavenger in high-temperature fluorine chemistry, as plumbous oxide is relatively volatile.

References

Fluorides
Lead(II) compounds
Metal halides
Phosphors and scintillators
Reagents for organic chemistry
Glass compositions
Fluorite crystal structure
Lithium molybdate. Lithium molybdate (Li2MoO4) is a chemical compound.  It is mainly used as an inhibitor in some types of industrial air conditioning.

Uses
Lithium molybdate is used as corrosion inhibitor in LiBr (Lithium bromide) absorption chiller for industrial central air conditioning.  It is manufactured and shipped as either a colorless, transparent fluid or a white crystal powder.  In either state it not classified as a hazardous material.

Li2MoO4 crystals have been found applicable for cryogenic phonon-scintillation detectors, which are used to investigate some rare nuclear processes. The use of Li2MoO4 ceramics for antennas has been studied due to their low loss dielectric properties and the possibility to fabricate them by a room-temperature densification method instead of conventional sintering.
Li2MoO4 (LMO) have also been used with hollow glass microspheres (HGMS) to make low permittivity composite which has been used to make lenses for lens antennas.

References

Molybdates
Lithium compounds
Phosphors and scintillators
Corrosion inhibitors
Lithium oxide. Lithium oxide (O) or lithia is an inorganic chemical compound. It is a white solid. Although not specifically important, many materials are assessed on the basis of their Li2O content. For example, the Li2O content of the principal lithium mineral spodumene (LiAlSi2O6) is 8.03%.

Production

Lithium oxide forms along with small amounts of lithium peroxide when lithium metal is burned in the air and combines with oxygen at temperatures above 100 °C:
4Li +  → 2.
Pure  can be produced by the thermal decomposition of lithium peroxide, , at 450 °C
2 → 2 +

Structure
Solid lithium oxide adopts an antifluorite structure with four-coordinated Li+ centers and eight-coordinated oxides.

The ground state gas phase  molecule is linear with a bond length consistent with strong ionic bonding. VSEPR theory would predict a bent shape similar to .

Uses
Lithium oxide is used as a flux in ceramic glazes; and creates blues with copper and pinks with cobalt. Lithium oxide reacts with water and steam, forming lithium hydroxide and should be isolated from them.

Its usage is also being investigated for non-destructive emission spectroscopy evaluation and degradation monitoring within thermal barrier coating systems. It can be added as a co-dopant with yttria in the zirconia ceramic top coat, without a large decrease in expected service life of the coating. At high heat, lithium oxide emits a very detectable spectral pattern, which increases in intensity along with degradation of the coating. Implementation would allow in situ monitoring of such systems, enabling an efficient means to predict lifetime until failure or necessary maintenance.

Lithium metal might be obtained from lithium oxide by electrolysis, releasing oxygen as by-product.

Reactions
Lithium oxide absorbs carbon dioxide forming lithium carbonate:
 +  → 

The oxide reacts slowly with water, forming lithium hydroxide:
 +  → 2

See also
 Lithium monoxide anion
 Lithium peroxide
 Lithium cobalt oxide
 Lithium-oxide memristor

References

External links
 CeramicMaterials.Info entry

Oxides
Lithium compounds
Fluorite crystal structure
Lithium peroxide. Lithium peroxide is the inorganic compound with the formula Li2O2. Lithium peroxide is a white solid, and unlike most other alkali metal peroxides, it is nonhygroscopic. Because of its high oxygen:mass and oxygen:volume ratios, the solid has been used to remove CO2 from and release O2 to the atmosphere in spacecraft.

Preparation
It is prepared by the reaction of hydrogen peroxide and lithium hydroxide. This reaction initially produces lithium hydroperoxide:
LiOH + H2O2 → LiOOH + H2O
This lithium hydroperoxide may exist as lithium peroxide monoperoxohydrate trihydrate (Li2O2·H2O2·3H2O).
Dehydration of this material gives the anhydrous peroxide salt:
2 LiOOH → Li2O2 + H2O2 

Li2O2 decomposes at about 450 °C to give lithium oxide:
2 Li2O2 → 2 Li2O + O2

The structure of solid Li2O2 has been determined by X-ray crystallography and density functional theory. The solid features eclipsed "ethane-like" Li6O2 subunits with an O-O distance of around 1.5 Å.

Uses

Air Purification
It is used in air purifiers where weight is important, e.g., spacecraft or other sealed spaces and apparatuses to absorb carbon dioxide and release oxygen in the reaction:

Li2O2 + CO2 → Li2CO3 +  O2

Similar to the reaction of lithium hydroxide with carbon dioxide to release 1 Li2CO3 and 1 H2O, lithium peroxide has high absorption capacity and absorbs more CO2 than does the same weight of lithium hydroxide and offers the bonus of releasing oxygen instead of water.

Polymerization of Styrene
Lithium peroxide can also act as a catalyst for polymerization of styrene to polystyrene. The polymerization of styrene to polystyrene typically involves the use of radical initiators via the free radical chain mechanism but lithium peroxide can also initiate radical polymerization reactions under certain conditions, although not as widely used.

Lithium-air Battery
The reversible lithium peroxide reaction is the basis for a prototype lithium–air battery. Using oxygen from the atmosphere allows the battery to eliminate storage of oxygen for its reaction, saving battery weight and size.

See also
 Lithium oxide

References

External links
 WebElements entry

Peroxides
Lithium compounds
Oxidizing agents
Methyl vinyl ketone. Methyl vinyl ketone (MVK, IUPAC name: butenone) is the organic compound with the formula CH3C(O)CH=CH2. It is a reactive compound classified as an enone, in fact the simplest example thereof.  It is a colorless, flammable, highly toxic liquid with a pungent odor.  It is soluble in water and polar organic solvents.  It is a useful intermediate in the synthesis of other compounds.

Production
MVK has been prepared industrially by the condensation of acetone and formaldehyde, followed by dehydration.  Similarly it is prepared by the Mannich reaction involving diethylammonium chloride and acetone, which produces the Mannich adduct:
CH3C(O)CH3 + CH2O + [H2NEt2]Cl → [CH3C(O)CH2CH2N(H)Et2]Cl + H2O

Heating this ammonium salt releases the ammonium chloride and the MVK:
[CH3C(O)CH2CH2N(H)Et2]Cl   →   CH3C(O)CH=CH2  +  [H2NEt2]Cl

Reactivity and applications
MVK can act as an alkylating agent because it is an effective Michael acceptor.  It gained early attention for its use in the Robinson annulation, a method useful in the preparation of steroids:

Its alkylating ability is both the source of its high toxicity and the feature that makes it a useful intermediate in organic synthesis.  MVK will polymerize spontaneously.  The compound is typically stored with hydroquinone, which inhibits polymerization.  

As an electrophilic alkene, it forms an adduct with cyclopentadiene.  The resulting norbornene derivative is an intermediate in the synthesis of the anticholinergic drug biperiden.  Via its cyanohydrin is also a precursor to vinclozolin.  It is also a precursor to synthetic vitamin A.

MVK is an intermediate in the synthesis of some pharmaceutical drugs including etorphine, buprenorphine, tolquinzole, butaclamol, and etretinate.

MVK is used in the synthesis of Wieland–Miescher ketone.

Safety
MVK is extremely hazardous upon inhalation causing coughing, wheezing and shortness of breath even at low concentrations.  It will also readily cause irritation of the skin, eyes, and mucous membranes.

References

External links
 NJ Hazardous Substance Factsheet for methyl vinyl ketone
 MSDS for methyl vinyl ketone 
 Compilation of Henry's law constants for inorganic and organic species of potential importance in environmental chemistry. Sander, R. 1999-04-08.

Alkylating agents
Vinyl compounds
Enones
Pulmonary agents
Bundesautobahn 281. is an autobahn in Bremen in northwestern Germany. The first part was opened in 1995, parts near the Bremen Airport are currently under construction. A second Weser tunnel will be part of the project, presumably being financed as a toll road and built by a private contractor.

Exit list 

|-
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|-
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External links 

281
A281
Proposed roads in Germany
Dan Rahmel. Dan Rahmel (born 1969) is an American author best known for his work relating to Visual Basic and database servers. Rahmel first began work as a writer for various magazines including DBMS, American Programmer, and Internet Advisor. He co-authored his first book Interfacing to the PowerPC Microprocessor in 1995 and began writing steadily about the programming and database development fields.

In 2002, he began working in Hollywood film production and gained experience as a gaffer, property master, production designer, and lighting technician. He has written a number of articles about his Hollywood experience and in 2004 publisher Focal Press released his book Nuts and Bolts Filmmaking that describes guerrilla filmmaking techniques.

His books have been translated into various languages including Chinese, Japanese, Spanish, French, and Portuguese. In 2006, Focal Press issued a special edition of Nuts and Bolts Filmmaking for release in India.

Bibliography
 Advanced Joomla! (APress)
 Beginning Joomla!: From Novice to Professional, 2nd Edition (APress)
 Professional Joomla! (Wrox)
 Beginning Joomla!: From Novice to Professional (APress)
 Nuts and Bolts Filmmaking (Focal Press)
 Visual Basic .NET Reference Book, 3rd Edition (Osborne)
 Building Web Database Applications with Visual Studio (Osborne)
 Visual Basic/VBA/VB Script Reference Book, 2nd Edition (Osborne)
 Teach Yourself Visual Basic Database Design in 24 hours (SAMS)
 Three-D Business Data Analysis with VRML (Prentice Hall)
 Server-side solutions with Visual JavaScript (McGraw-Hill)
 Visual Basic/VBA/VB Script Reference Book (Osborne)
 Active Platform Sourcebook (John Wiley & Sons)
 Visual Basic for Applications 5, “Techniques from the Experts” chapters (QUE)
 Teach Yourself Visual Basic 5 (MIS Press)
 Using Microsoft Outlook, chapter 28 and chapter 29 (QUE)
 Developing Client/Server Applications with Visual Basic 4.0 (SAMS)
 Interfacing to the PowerPC Microprocessor (SAMS)

External links 

 
 Nuts and Bolts Filmmaking book page on the publisher's (Elsevier Publications) web site
 Joomla Jumpstart  is the support web site for Joomla! books

1972 births
Living people
American technology writers
Filmmakers from Wisconsin
SMSS. SMSS may refer to:

Session Manager Subsystem (smss.exe), a component of the Microsoft Windows NT operating system
Switching and Management Subsystem, in wireless communication technology
Squad Mission Support System, military robotic system developed by Western company Lockheed Martin
St. Margaret's Secondary School, a government-aided autonomous girls' secondary school in Bukit Timah, Singapore
Sailor Moon SuperS, the fourth season of the anime series Sailor Moon
 SkyMapper Sky Survey
Antichlor. An antichlor is a substance used to decompose residual hypochlorite or chlorine after chlorine-based bleaching, in order to prevent ongoing reactions with, and therefore damage to, the material that has been bleached. Antichlors include sodium bisulfite, potassium bisulfite, sodium metabisulfite, sodium thiosulfate, and hydrogen peroxide.

In the textile industry, the antichlor is usually added right before the end of the bleaching process. Antichlors are used mainly on fiber, textiles, and paper pulp. Rinsing with water should follow the antichlor treatment in order to flush out by-products of the procedure. For household use, rinsing both before and after use is recommended.

Hydrogen peroxide is by itself a strong bleaching agent and should be used only in diluted form, such as a 3% solution in water. Hypochlorite plus peroxide releases triplet oxygen, which is itself a bleaching agent, but is short-lived in water solution. Reacting large amounts of peroxide can release enough oxygen to create a fire or explosion hazard.

Antichlors are sometimes added to shampoos for treating hair after swimming in chlorinated water.

References

Antichlor
Palladium(II) oxide. Palladium(II) oxide is the inorganic compound of formula PdO. It is the only well characterised oxide of palladium. It is prepared by treating the metal with oxygen. Above about 900 °C, the oxide reverts to palladium metal and oxygen gas. It is not attacked by acids.

Structure
The structure of PdO is tetragonal (P42/mmc) a = 3.044, c = 5.328 Å. The Pd atoms are square planar as expected for a d8 metal ion and the oxygen atoms are approximately tetrahedral. The closest Pd–Pd distance is 3.044 Å and is almost within the range which can be considered a bonding distance.

Preparation
PdO is often obtained as a poorly defined material that is generated for applications as a catalyst. Palladium oxide is prepared by heating palladium sponge metal in oxygen at 350 °C.

The oxide is obtained as a black powder. The oxide also may be prepared specially for catalytic use by heating variously a mixture of palladium(II) chloride and potassium nitrate,

 (possible reaction)

or the product of dissolving palladium in aqua regia, followed by the addition of sodium nitrate at 600 °C.  A hydrated form of the oxide (which dissolves in acid) can be prepared by precipitation from solution, for example, by hydrolysis of palladium nitrate or reaction of a soluble palladium compound with a strong base. The brown hydrated oxide converts to black anhydrous oxide on heating. Its susceptibility to attack by acids decreases at lower water content.

The hydrated oxide, PdO.nH2O can be produced as a dark-yellow precipitate by adding alkali to a solution of palladium nitrate, Pd(NO3)2.

Applications
Materials called palladium oxide are useful catalysts for catalytic hydrogenation in organic synthesis.

References

Palladium compounds
Transition metal oxides
Platinum(IV) chloride. Platinum(IV) chloride is the inorganic compound of platinum and chlorine with the empirical formula PtCl4. This brown solid features platinum in the 4+ oxidation state.

Structure
Typical of Pt(IV), the metal centers adopt an octahedral coordination geometry, {PtCl6}. This geometry is achieved by forming a polymer wherein half of the chloride ligands bridge between the platinum centers. Because of its polymeric structure, PtCl4 dissolves only upon breaking the chloride bridging ligands. Thus, addition of HCl give H2PtCl6. Lewis base adducts of Pt(IV) of the type cis-PtCl4L2 are known, but most are prepared by oxidation of the Pt(II) derivatives.

Formation and reactions
PtCl4 is mainly encountered in the handling of chloroplatinic acid, obtained by dissolving of Pt metal in aqua regia. Heating H2PtCl6 to 220 °C gives impure PtCl4:
H2PtCl6 → PtCl4 + 2 HCl
A purer product can be produced by heating under chlorine gas at 250 °C.

If excess acids are removed, PtCl4 crystallizes from aqueous solutions in large red crystals of pentahydrate PtCl4·5(H2O), which can be dehydrated by heating to about 300 °C in a current of dry chlorine. The pentahydrate is stable and is used as the commercial form of PtCl4.

Treatment of PtCl4 with aqueous base gives the [Pt(OH)6]2− ion. With methyl Grignard reagents followed by partial hydrolysis, PtCl4 converts to the cuboidal cluster [Pt(CH3)3(OH)]4. Upon heating PtCl4 evolves chlorine to give PtCl2:
PtCl4 → PtCl2 + Cl2

The heavier halides, PtBr4 and PtI4, are also known.

References
 Cotton, S. A. Chemistry of Precious Metals, Chapman and Hall (London): 1997. .

Chlorides
Chlorides,4
Platinum group halides
Praseodymium(III) sulfide. Praseodymium(III) sulfide is an inorganic chemical compound with chemical formula Pr2S3.

Preparation
Praseodymium(III) sulfide can be obtained by reacting praseodymium(III) oxide and hydrogen sulfide at 1320 °C:
Pr2O3 + 3H2S → Pr2S3 + 3H2O

It could also be obtained by directly reacting sulfur with metallic praseodymium:
2Pr + 3S → Pr2S3

References

Sesquisulfides
Praseodymium(III) compounds
Rhenium(VII) oxide. Rhenium(VII) oxide is the inorganic compound with the formula Re2O7.  This yellowish solid is the anhydride of HOReO3. Perrhenic acid, Re2O7·2H2O, is closely related to Re2O7.  Re2O7 is the raw material for all rhenium compounds, being the volatile fraction obtained upon roasting the host ore.

Structure
Solid Re2O7 consists of alternating octahedral and tetrahedral Re centres.  Upon heating, the polymer cracks to give molecular (nonpolymeric) Re2O7.  This molecular species closely resembles manganese heptoxide, consisting of a pair of ReO4 tetrahedra that share a vertex, i.e., O3Re–O–ReO3.

Synthesis and reactions
Rhenium(VII) oxide is formed when metallic rhenium or its oxides or sulfides are oxidized at  in air.

Re2O7 dissolves in water to give perrhenic acid.  

Heating Re2O7 gives rhenium dioxide, a reaction signalled by the appearance of the dark blue coloration:
2Re2O7  →  4ReO2  +  3O2

Using tetramethyltin, it converts to methylrhenium trioxide ("MTO"), a catalyst for oxidations:
Re2O7  +  2Sn(CH3)4  → CH3ReO3  +  (CH3)3SnOReO3

In a related reaction, it reacts with hexamethyldisiloxane to give the siloxide:
Re2O7  +  2O(Si(CH3)3)2  → 2(CH3)3SiOReO3

Uses

Hydrogenation catalyst
Rhenium(VII) oxide finds some use in organic synthesis as a catalyst for ethenolysis, carbonyl reduction and amide reduction.

References

Rhenium compounds
Acidic oxides
Hydrogenation catalysts