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Superior zinc oxide formula. The World of Modern Materials - Zinc Oxide ZnO




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White zinc

zinc oxide.

Product chemical formula: ZnO

Trade designations of the product:

  • Zinc white
  • White zinc
  • zinc oxide
  • Zinc flowers
  • C.I. pigment white 4
  • Oxozinc
  • Zincite
  • Lassar Paste

Product description:

zinc oxideis an inorganic compound with the formula ZnO. zinc oxide is a white powder that is insoluble in water and is widely used as an additive in many materials and products, including rubbers, plastics, ceramics, glass, cement, lubricants, paints, ointments, adhesives, sealants, pigments, foodstuffs, batteries, ferrites , flame retardants and adhesive tape. Although it occurs naturally as the mineral zincite, most zinc oxide obtained synthetically. White zinc is a wide-gap semiconductor of semiconductor group II-VI. Natural doping of a semiconductor due to oxygen vacancies or n-type zinc interstices. This semiconductor has a number of favorable properties, including good transparency, high electron mobility, a wide band gap, and strong luminescence at room temperature. These properties are valuable in new applications for: transparent electrodes in liquid crystal displays, energy-saving or heat-shielding windows, and electronics in the form of thin-film transistors and light-emitting diodes. zinc oxide(also called white zinc) is an amorphous white or yellowish powder, insoluble in water and alcohol, but soluble in acid and alkalis. Particles zinc oxide may be spherical, needle or globular depending on the manufacturing process. The shape of the particles is important for maximizing the physical properties. zinc oxide absorbs virtually all UV radiation at wavelengths below 360 nm and provides excellent protection for binders. zinc oxide reacts with acid components of coatings and forms zinc soaps. Zinc soaps improve the flexibility and hardness of coatings. It is used as a pigment in rubber formulation, as a white pigment in the ceramic industry, as an opaque base in cosmetics, and has other applications in the paper, paint, and optical glass industries.

zinc oxidecrystallizes in two main forms: hexagonal wurtzite and cubic galvanized blende. The wurtzite structure is the most stable under ambient conditions and hence the most common. The shape of zinc blende can be stabilized by growing zinc oxide on substrates with a cubic lattice structure. In both cases, the zinc and oxide centers are tetrahedral, the most characteristic geometry for Zn(II). zinc oxide is converted at relatively high pressures, about 10 GPa. Hexagonal and galvanized polymorphs do not have inversion symmetry (reflecting a crystal about any given point does not turn it into itself). This and other lattice symmetry properties lead to the piezoelectricity of hexagonal and galvanized zinc oxide and the pyroelectricity of hexagonal zinc oxide. As with most Group II-VI materials, the bonding of atomic structures in zinc oxide is largely ionic (Zn 2 + -O 2 - ) with corresponding radii of 0.074 nm for Zn2+ and 0.140 nm for O 2 - . This property explains the predominant formation of the wurtzite structure, rather than zinc blende, as well as strong piezoelectricity. zinc oxide a. Because of the polar Zn-O bonds, the zinc and oxygen planes are electrically charged. To maintain electrical neutrality, these planes are restored at the atomic level in most relative materials, but not in zinc oxide- its surfaces are atomically flat, stable and have no reconstruction. This anomaly zinc oxide not fully explained.

zinc oxide- relatively soft material with an approximate hardness of 4.5 on the Mohs scale. Its elastic constants are smaller than those of corresponding III-V semiconductors such as GaN. High heat capacity and thermal conductivity, low thermal expansion and high melting point zinc oxide beneficial for ceramics. Of the tetrahedrally bonded semiconductors, it has been claimed that zinc oxide has the highest piezoelectric tensor, or at least comparable to GaN and AlN. This property makes it a technologically important material for many piezoelectric applications that require a large electromechanical connection. zinc oxide has a relatively large direct band gap of ~3.3 eV at room temperature. The benefits associated with a larger range gap include higher breakdown voltages, the ability to withstand large electric fields, lower electronic noise, and operation at high temperatures and high power. Gap zinc oxide can be further tuned to ~3-4 eV by doping it with magnesium oxide or cadmium oxide. Majority zinc oxide has an n-type character, even in the absence of intentional doping. Nonstoichiometry is generally the source of the n-type character, but the subject remains debatable. An alternative explanation has been proposed, based on theoretical calculations, that unintentional replacement hydrogen impurities are the cause. Controlled n-type doping is easily achieved by replacing Zn with Group III elements such as Al, Ga, In, or by replacing oxygen with Group VII elements with chlorine or iodine.

In production zinc oxide there are three main methods.

  1. indirect method. In indirect or French process metallic zinc melts in a graphite crucible and evaporates at temperatures above 907 °C (usually around 1000 °C). Couples zinc react with oxygen in the air, which leads to the formation of ZnO, accompanied by a drop in its temperature and bright luminescence. Particles zinc oxide are transported to the cooling channel and collected in a bag. This indirect method was popularized by LeClaire (France) in 1844 and is therefore commonly known as the French process. Its product usually consists of agglomerated particles zinc oxide with an average size of 0.1 to several micrometers. Most of the weight zinc oxide in the world is produced according to the French method.
  2. direct process. The direct or American process starts with a variety of contaminated zinc composites such as zinc ores or by-products of the smelter. Precursors zinc are reduced (carbothermal reduction) by heating with a carbon source such as anthracite to produce vapors zinc a, which is then oxidized, as in the case of an indirect process. Due to the lower purity of the starting material, the final product is also of lower quality in the direct process compared to the indirect one.
  3. Wet chemical process . A small amount of industrial production is associated with wet chemical processes that begin with aqueous solutions of zinc salts, from which precipitates zinc carbonate or zinc hydroxide. The solid precipitate is then calcined at temperatures around 800 °C.

There are numerous specialized methods for obtaining zinc oxide for scientific research and application in niche areas. These methods can be classified according to the form of ZnO obtained (bulk, thin film, nanowire), temperature ("low", close to room temperature or "high", i.e. T ~ 1000 °C), type of process (vapor deposition or growth from solution) and other parameters. Large single crystals (many cubic centimeters) can be grown by gas transfer (vapor deposition), hydrothermal synthesis, or melt growth. However, due to the high vapor pressure zinc oxide melt growth is problematic. It is difficult to control the growth of gas transport, leaving preference for the hydrothermal method. Thin films can be produced by chemical vapor deposition, metal-structured vapor phase epitaxy, electrodeposition, pulsed laser deposition, sputtering, sol-gel synthesis, atomic layer deposition, sputter pyrolysis, etc. plain white powder zinc oxide can be obtained in the laboratory by electrolysis of a sodium bicarbonate solution with a zinc anode. Produced zinc hydroxide and hydrogen. Zinc hydroxide when heated, it decomposes to zinc oxide. Zinc oxide nanostructures can be synthesized into various morphologies, including nanowires, nanorods, tetrapods, nanoobjects, nanofibers, nanoparticles, etc. Nanostructures can be obtained using most of the above methods under certain conditions, as well as using the vapor-liquid-solid method. The synthesis is usually carried out at temperatures around 90 °C in an equimolar aqueous solution of nitrate zinc a and hexamine, the latter providing the main medium. Some additives such as polyethylene glycol or polyethyleneimine can improve the size ratio of nanofilaments. zinc oxide. Doping of nanowires zinc oxide was achieved by adding other metal nitrates to the growth solution. The morphology of the resulting nanostructures can be tuned by changing parameters related to the composition of the precursors (such as zinc concentration and pH) or to the thermal treatment (such as temperature and heating rate).

Physical and chemical properties Zinc oxide.

indicators

meaning

Physical condition and appearance zinc oxide

Solid (Powder solid)

Smell zinc oxide

Without smell

Taste zinc oxide

Bitter

Molecular weight zinc oxide

81.38 g/mol

Color zinc oxide

white to yellowish white

Melting temperature zinc oxide

1975°C (3587°F)

Specific gravity zinc oxide

5.607 (water = 1)

Dispersion properties zinc oxide

Not dispersible in cold water, hot water.

Solubility zinc oxide

Does not dissolvein cold water, hot water. Soluble in dilute acetic acid or mineral acids, ammonia, ammonium carbonate, fixed alkali.

Stability zinc oxide

stable

Storage and transportation of zinc oxide:

Precautionary measures:

Keep closed. Do not swallow. Do not inhale dust. Wear appropriate protective clothing. In case of insufficient ventilation, wear suitable respiratory equipment. If swallowed, seek medical advice immediately and show container or label. Keep away from incompatible substances such as acids.

Storage: Keep container tightly closed. Store container in a cool, well ventilated area. Do not store above 25°C (77°F).

Applications for zinc oxide:

  1. Powder Applications zinc oxide are numerous, and the main ones are listed below. Most applications use the oxide's reactivity as a precursor to other zinc compounds. For applications in materials science zinc oxide has a high refractive index, high thermal conductivity, binding, antibacterial and UV protective properties. Consequently, it is added to materials and products, including plastics, ceramics, glass, cement, rubber, lubricants, paints, ointments, adhesives, sealants, concrete production, pigments, food products, batteries, ferrites.
  2. Rubber production. The rubber industry uses 50% to 60% zinc oxide. zinc oxide together with stearic acid is used for vulcanization of rubber Additive zinc oxide also protects rubber from fungi and UV radiation.
  3. ceramic industry. The ceramic industry consumes a significant amount zinc oxide, in particular in ceramic glazes and frit compositions.The relatively high heat capacity, thermal conductivity and high temperature stability of zinc oxide, combined with a relatively low coefficient of expansion, are desirable properties in the manufacture of ceramics.zinc oxideaffects the melting point and optical properties of glazes, enamels and ceramic compositions.zinc oxidein the form of low expansion, the secondary flow improves the elasticity of glazes, reducing the change in viscosity with temperature and preventing cracking.
  4. The medicine. zinc oxide widely used to treat various skin conditions including dermatitis, itching due to eczema, diaper rash and acne. It is used in products such as baby powder and barrier creams for diaper treatments, calamine creams, anti-dandruff shampoos, and antiseptic ointments. . zinc oxide can be used in ointments, creams and lotions to protect against sunburn and other skin damage caused by ultraviolet light. Many sunscreens use nanoparticles zinc oxide(along with nanoparticles titanium dioxide), because such small particles do not scatter light and therefore do not appear white. Nanoparticles zinc oxide may enhance the antibacterial activity of ciprofloxacin.
  5. tobacco industry. zinc oxide is an integral part of cigarette filters. The filter, which consists of coal impregnated with zinc oxide and iron oxide, removes significant amounts of hydrogen cyanide and hydrogen sulfide from tobacco smoke without affecting its flavor.
  6. Food supplement. zinc oxide added to many foods, including breakfast cereals, as a source of zinc, an essential nutrient. zinc sulfate also used for the same purpose.
  7. Production of pigments. zinc oxide white is used as a pigment in paints and is more opaque than Lithopone but less opaque than titanium dioxide It is also used in paper coatings. Chinese white is a special variety of zinc white that is used in artists' pigments. The use of white zinc (zinc oxide) as a pigment in oil painting began in the mid-18th century. It partially replaced poisonous white lead and was used by artists such as Becklin, Van Gogh, Manet, Munch. It is also the main ingredient in mineral makeup.
  8. Coatings. Paints containing powder zinc oxide, have long been used as anti-corrosion coatings for metals. They are especially effective for galvanized iron. Iron is difficult to protect because its reactivity with organic coatings results in brittleness and lack of adhesion. Based paints zinc oxide retain their flexibility and adhesion on such surfaces for many years. Plastics such as polyethylene naphthalate (PEN) can be protected by zinc oxide coating. The coating reduces oxygen diffusion with PEN. Zinc oxide layers can also be used on polycarbonate (PC) in outdoor applications. The coating protects the PC from solar radiation and reduces the rate of oxidation and photo-yellowing of the PC.
  9. Corrosion Prevention in Nuclear Reactors . zinc oxide, depleted in 64 Zn (an isotope of zinc with an atomic mass of 64), is used to prevent corrosion in nuclear pressurized water reactors. Depletion is necessary because the 64 Zn is converted to radioactive 65 Zn when the reactor is irradiated with neutrons.
  10. Methane reform . zinc oxide used as a pre-treatment step to remove hydrogen sulfide from natural gas after hydrogenation of any sulfur compounds to a methane reformer, which can poison the catalyst.

Crystalline colorless powder, turning yellow with gradual heating and subliming at 1800 degrees. Insoluble in water. zinc in this compound - 2. Chemical formula ZnO. This substance is important for humanity. It has a multifaceted effect on the human body.

Zinc oxide: physical properties

  1. Thermal conductivity is 54 W/(m*K).
  2. It is a semiconductor with a band width of 3.3 eV.

Chemical properties of zinc oxide

  1. Reacts with acids. This forms salts.
  2. Reacts with alkalis to form tetra-, tri- and hexahydroxyzincates.
  3. This substance is soluble in ammonia water solution. In this case, complex ammonia is formed.
  4. When fused with oxides and alkalis, zinc oxide forms zincates.
  5. When fused with and boron, zinc oxide forms silicates and vitreous beads.

How is zinc oxide (ZnO) obtained?

Zinc oxide can be obtained in several ways:

  • from the natural mineral zincite;
  • by burning zinc vapor (Zn) in oxygen (O) - this is the so-called "French process";
  • by thermal decomposition of the following compounds: hydroxide Zn(OH)2, zinc acetate Zn(CH3COO)2, nitrate Zn(NO3), carbonate ZnCO3;
  • in oxidative roasting ZnS (zinc sulfide);
  • in hydrothermal synthesis;
  • by extraction from sludge and dust of metallurgical plants. Of particular importance are those plants that specialize in scrap metal, which contains a significant proportion of

Application of zinc oxide

Zinc oxide is used in the production of rubber, paper, some plastics, rubber products, artificial leather, electrical cables, glass, ceramics, cosmetics (sun creams, various beauty treatments) and perfumes. It is used as a vulcanization activator of various rubbers, a catalyst for the synthesis of organic matter - methanol, a vulcanizing agent for chloroprene rubbers, a pigment and a filler in the production. Previously, zinc oxide was needed as a white pigment in the production of enamels and paints, but now it has been completely replaced by TiO2 (titanium dioxide is non-toxic). Zinc oxide is also widely used in the paint and varnish, tire and oil refining industries.

Zinc oxide has become widespread in medicine and pharmaceuticals (drugs "Zinc ointment", "Sudokrem", "Pasta Lassara"). It is used in the form of powders. In practice, it is used to create bactericidal ceilings and coatings in hospitals, self-cleaning surfaces. Zinc oxide is used to produce toothpastes and cements. It was previously used on an industrial scale for photocatalytic water purification.

Also, the substance we are considering is used in the production of paints and glasses based on liquid glass, as one of the components of a rust remover and as an additive to animal feed. In addition, the powder of this substance is a promising material as a working medium for powder lasers. Based on zinc oxide, a blue LED was created. And some nanostructures (for example, thin films) based on this substance can be used as biological or gas sensitive sensors.

What effect does zinc oxide have on humans?

This chemical compound has low toxicity. In the air of working premises, MPC should be no more than 6 milligrams per cubic meter. Zinc oxide dust can form when brass items are fired. When working with zinc oxide, it is necessary to prevent the substance from getting into the eyes. Medicines with zinc oxide are recommended to be used only as directed by a doctor.

Ministry of Education and Science of the Russian Federation

federal state budgetary educational institution

higher professional education

PETROZAVODSK STATE UNIVERSITY

Faculty of Medicine

Abstract on the discipline "Pharmaceutical chemistry"

Topic: Zinc oxide. zinc sulfate.

The work was done by a 4th year student

Specialty: Pharmacy

Correspondence department

Group: 73Z42

Rigoeva Anna Sergeevna

Work checked

Teacher:

Ermakova Galina Vladimirovna

Petrozavodsk 2012

Zinc is an element of a side subgroup of the second group, the fourth period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 30.

It is designated by the symbol Zn (lat. Zincum).

A simple substance zinc under normal conditions is a brittle transition metal of a bluish-white color (it tarnishes in air, becoming covered with a thin layer of zinc oxide).

A typical example of a metal that forms amphoteric compounds. Zinc compounds ZnO and Zn(OH)2 are amphoteric. The standard electrode potential is −0.76 V, in the series of standard potentials it is located before iron.

In air, zinc is covered with a thin film of ZnO oxide. When heated strongly, it burns out with the formation of amphoteric white oxide ZnO:

Zinc oxide reacts both with acid solutions:

and alkalis:

Zinc of ordinary purity actively reacts with acid solutions:

and alkali solutions: forming hydroxo-zincates. Very pure zinc does not react with solutions of acids and alkalis. The interaction begins with the addition of a few drops of a solution of copper sulfate CuSO4.

When heated, zinc reacts with halogens to form ZnHal2 halides. With phosphorus, zinc forms phosphides Zn3P2 and ZnP2. With sulfur and its analogues - selenium and tellurium - various chalcogenides, ZnS, ZnSe, ZnSe2 and ZnTe.

Zinc does not directly react with hydrogen, nitrogen, carbon, silicon and boron. Nitride Zn3N2 is obtained by the reaction of zinc with ammonia at 550-600 °C.

In aqueous solutions, zinc ions Zn2+ form aquacomplexes 2+ and 2+.

zinc sulfate

ZnSO4, colorless crystals. Dissolves in water. ZnSO4 7H2O crystallizes from solutions - zinc vitriol. It is used in the production of viscose, glazes, to protect wood from decay.

ZINC SULFATE

ZINC SULPHATE (zinc sulfate) Zinci sulfas, ZnSO4. ZnSO4 · 7H2O - zinc vitriol - crystallizes from solutions. It is used in the production of viscose, glazes, to protect wood from decay.

Characteristic:

Colorless transparent crystals or fine crystalline powder, astringent taste, odorless. It vanishes in the air. Very easily soluble in water, practically insoluble in ethanol, slowly soluble in glycerin (1:10). Aqueous solutions are acidic.

Zinc sulfate has an antimicrobial, astringent, drying and local anti-inflammatory effect.

Application:

Conjunctivitis, laryngitis, urethritis, vaginitis - locally; the need to induce vomiting - inside in high doses; zinc deficiency in the body with violations of anabolic, immunological and other processes (prevention and treatment) - inside; hypogonadism, alopecia areata, cerebral palsy, liver disease, diabetes mellitus, diffuse connective tissue diseases, etc. (as part of complex therapy) - inside.

Contraindications:

Hypersensitivity.

Side effects:

Nausea, vomiting, diarrhea (when taking high doses orally).

Zinc sulfate, zinc sulfate, ZnSO4 - zinc salt of sulfuric acid.

Colorless crystals, density 3.74 g/cm³. Solubility in water (%): 29.4 (0°C), 37.7 (99°C). ZnSO4 7H2O (zinc vitriol) crystallizes from solutions at a temperature below 38.8 °C, ZnSO4 6H2O crystallizes from 38.8 °C to 70 °C, and ZnSO4 H2O monohydrate forms above 70 °C. The latter is dehydrated at 238°C. Zinc sulfate in the range of 600-900 °C decomposes into ZnO and SO3. Weak solutions of zinc sulfate become cloudy during hydrolysis due to the precipitation of 3Zn(OH)2 ZnSO4 4H2O.

Receipt

Zinc vitriol is obtained by evaporation and crystallization from solutions (along with the production of zinc). Zn+H2SO4=ZnSO4+H2

Application

It is used in the production of viscose, mineral paints, glazes, in metallurgy (flotation agent) and in medicine.

Active-active substance / beginning: zinc (zinc sulfate, picolinate, asparaginate)

Bio-zinc; Solgar zinc picolinate; zinc sulfate; Zinc aspartate; Zinc picolinate; zinc sulfate; Zincite; Zincteral.

It is used for liver diseases (cirrhosis), enteritis, enteropathic dermatitis, psoriasis, collagenosis (rheumatoid arthritis, lupus erythematosus), cerebral palsy, frequent colds. Topically used for conjunctivitis, laryngitis, urethritis, vaginitis.

Zinc (zinc sulfate, picolinate, aspartate).

Dosage forms:

Effervescent tablets.

Eye drops.

Solution for external use.

Zinc (zinc sulfate, picolinate, aspartate)

Properties / Action:

Zinc is an essential trace element. It is an integral part of more than 90 different enzymes that synthesize DNA and participate in metabolic processes. Zinc stimulates the synthesis of nucleic acids, proteins, tissue regeneration, promotes weight gain. Zinc is necessary for the functioning of insulin, hormones of the gonads, maintains the stability of cell membranes, limiting the release of histamine from mast cells. It limits free radical reactions, prevents damage to cell membranes. Zinc is necessary for the normal activity of lymphoid tissue, alkaline phosphatase, carboxypeptidases, alcohol dehydrogenase.

Zinc increases resistance to infectious diseases, promotes wound healing, accelerates growth, increases efficiency, improves memory, and prevents hair loss.

Certain populations, such as pregnant women, breastfeeding mothers, teenagers, athletes, and consistent vegetarians, have an increased need for zinc. Zinc deficiency can be caused by insufficient intake or malnutrition, unbalanced diets, impaired absorption of zinc (for example, with intestinal diseases), or increased excretion of zinc, for example, with alcoholism, taking laxatives or other medications.

Indications:

Elimination of hypozincemia, incl. with violations of anabolic, immunological and other processes, which can occur with liver diseases (especially with cirrhosis), steatorrhea, enteritis, helminthic invasion, enteropathic acrodermatitis, psoriasis, with kidney diseases, hypovitaminosis D, with burns.

Prophylactically in the following conditions: diabetes mellitus, collagenosis (rheumatoid arthritis, lupus erythematosus), hypogonadism, alopecia areata, cerebral palsy, frequent colds, glucocorticoids, pregnancy and lactation.

Locally (zinc sulfate):

Conjunctivitis, laryngitis, urethritis, vaginitis.

Dosage and administration:

On an empty stomach, in dragee or effervescent tablets. For the prevention of hypozincemia 10 mg of zinc 1-2 times a day. For therapeutic purposes - 20-50 mg 2-3 times a day.

Locally (zinc sulfate):

With conjunctivitis - eye drops of 0.1-0.5%, with laryngitis - lubrication or spraying with a 0.25-0.5% solution, with urethritis and vaginitis - douching with a 0.1-0.5% solution.

Overdose:

Possible when taken orally: fever, impaired lung function, dehydration, plasma electrolyte imbalance, lethargy, muscle movement disorders, renal failure.

Contraindications:

active autoimmune processes, especially immune encephalitis;

acute renal failure, severe parenchymal lesions of the kidneys.

Use during pregnancy and lactation:

Application is possible only with a proven deficiency of zinc in the body.

Side effect:

Appears when taking large doses. At the same time, dyspeptic disorders (nausea, vomiting, diarrhea), dehydration, imbalance of electrolytes in blood plasma, lethargy, and renal failure are observed.

When used in therapeutic doses, complications are extremely rare.

Storage conditions:

At room temperature no higher than 25C.

Keep out of the reach of children.

Expiration dates are indicated on the packaging. The drug cannot be used after the expiration date.

Vacation from the pharmacy: without a doctor's prescription.

zinc oxide (Zincioxidum)

White or white with a yellowish tint amorphous powder, odorless. Absorbs carbon dioxide from the air .

Practically insoluble in water and alcohol, soluble in alkali solutions, diluted mineral acids, and also in acetic acid.

When heated, the substance changes color: white at room temperature, zinc oxide becomes yellow. This is explained by a decrease in the band gap and a shift of the edge in the absorption spectrum from the UV region to blue.

Zinc oxide amphoterene - reacts with acids to form salts, when interacting with alkali solutions, it forms complex tri-tetra- and hexahydroxy zincates (Na2, Ba2):

OH-2-

Zinc oxide dissolves in an aqueous solution of ammonia, forming complex ammonia:

ZnO + 4NH3 + H20 - (OH)2

When fused with alkalis and metal oxides, zinc oxide forms zincates:

ZnO + 2NaOH Na2ZnO2 + H2O

ZnO + CoO CoZnO2

When fused with oxides of boron and silicon, zinc oxide forms vitreous borates and silicates:

ZnO + B2O3 Zn(BO2)2

ZnO + SiO2 ZnSiO3

Receipt

natural mineral zincite

combustion of zinc vapor in oxygen ("French process")

thermal decomposition of compounds:

acetate Zn(CH3COO)2

hydroxide Zn(OH)2

carbonate ZnCO3

nitrate Zn(NO3)2

oxidative roasting of ZnS sulfide

hydrothermal synthesis

extraction from dust and sludge from metallurgical plants, especially those that work on scrap metal as a raw material (it contains a significant proportion of galvanized iron).

extraction from the ternary phase equilibrium system "zinc nitrate-amine nitrate-water" (with pyridine and quinoline nitrate, the particle size is about 5-10 nm up to 75%)

Application

vulcanization activator of some rubbers

vulcanizing agent for chloroprene rubbers

methanol synthesis catalyst

white pigment in the production of paints and enamels (currently (2007) replaced by non-toxic titanium dioxide TiO2)

filler and pigment in production:

plastics

perfumery and cosmetics

In medicine, in the form of powders and as part of ointments as an antiseptic.

animal feed additive

in the production of glass and paints based on liquid glass

as one of the rust converter components

It is also known that zinc oxide has photocatalytic activity, which is used in practice to create self-cleaning surfaces, bactericidal coatings for walls and ceilings in hospitals, etc. Zinc oxide is not currently used for industrial-scale photocatalytic water purification.

In addition, zinc oxide powder is a promising material as a working medium for powder lasers. Based on zinc oxide, a blue LED was created. Thin films and other nanostructures based on zinc oxide can be used as sensitive gas and biological sensors.

The properties of zinc oxide make it widely used in the pharmaceutical industry. Zinc oxide has found wide application in the creation of abrasive toothpastes and cements in therapeutic dentistry, in sunscreens and cosmetic procedures, in the production of electrical cables, artificial leather and rubber products. In addition, the application is widespread in the tire, paint and varnish, oil refining industries. Zinc oxide is involved in the production of glass and ceramics.

Zinc oxide preparations are anti-inflammatory dermatotropic agents with a drying effect for external use. Zinc oxide also has an adsorbing, astringent and antiseptic effect; forms albuminates and denatures proteins. Reduces the phenomena of exudation, inflammation and irritation of tissues, forms a protective barrier against the action of irritating factors. Softens irritated skin. It is used as a remedy with a protective effect in eczema (in the acute stage), dermatitis (diaper dermatitis, contact dermatitis), diaper rash, prickly heat, bedsores, superficial wounds, cuts, scratches, burns, ulcerative skin lesions, herpes simplex, streptoderma, trophic ulcers.

Active active substance:

Zinc oxide / Zinc oxide.

Dosage forms:

Liniment.

zinc oxide

Properties / Action:

Zinc oxide exhibits a weak astringent effect and is used as a protective agent for eczema and skin flaking.

Indications:

intertrigo;

dermatitis, incl. diaper dermatitis (diaper rash in infants), contact dermatitis;

bedsores;

superficial wounds, cuts, scratches;

burns (thermal, solar);

ulcerative skin lesions;

eczema in the acute stage;

simple herpes;

streptoderma;

trophic ulcers.

Dosage and administration:

Zinc oxide preparations are used externally, in the form of an ointment, paste, liniment.

Wash and dry the affected area. Apply to cleansed and dried skin.

Zinc oxide preparations are applied in a thin layer to the affected areas of the skin 4-6 times a day.

The course of treatment is up to 1 month.

The amount of the drug applied depends on the extent of the lesion.

Minor thermal and sunburns, cuts, scratches, wounds - apply a thin layer on the affected surface, if necessary, apply a gauze bandage.

Diaper rash in children - if the first signs of hyperemia, diaper rash or minor skin irritation appear, the ointment is applied 3 or more times a day, if necessary, during each diaper change; prophylactically treat areas of the body that are in prolonged contact with wet linen.

Contraindications:

individual intolerance (including history of hypersensitivity) to zinc oxide.

Side effects:

Allergic reactions (skin itching, hyperemia, skin rash).

Special instructions and precautions:

For external use only. Avoid contact with eyes.

The ointment is applied only to superficial and non-infected lesions and is not used to treat pustular skin lesions. Not intended for prescribing treatment without the participation of a doctor.

The drug is not contraindicated during pregnancy and lactation.

Drug interaction:

Not described.

Storage conditions:

At temperatures up to 30°C, away from heat sources and direct sunlight.

The shelf life is indicated on the packaging.

Vacation from a pharmacy - without a doctor's prescription.

Zinc oxide ZnO - semiconductor connection. Zinc oxide is a white compound that sublimates at 2000 K, melts at 2250 K, exhibits both basic and acidic properties, dissolves in acids and alkalis.

The most common crystalline modification is the hexagonal wurtzite type. A rarer cubic sphalerite type is also known.

Zinc oxide can be obtained by burning or oxidizing zinc, by roasting zinc sulfide in air, by calcining
salts, precipitation with ammonia from a boiling aqueous solution of zinc nitrate.

Compact samples of zinc oxide (zincite) are obtained by pressing blanks from a powdered compound and their subsequent sintering. Preliminary sintering is carried out at 1100 K. Final sintering is carried out at 1700...1800 K. Heating is carried out either in special high-temperature furnaces or by direct current passing through the samples after they have been preheated to a temperature at which sufficient electrical conductivity occurs. At a final sintering temperature of 1700...1800 K, coarse-grained samples with crystals up to 2 mm are formed. To obtain a finer-grained structure, the sintering temperature is reduced to 1300...1400 K. Zinc oxide single crystals are grown by the hydrothermal method and from the gas phase.

Thin films of zinc oxide ZnO can be obtained by evaporation and condensation of zinc on a substrate in a vacuum, followed by oxidation of the metal film when heated in an oxygen atmosphere or reactive two-electrode ion sputtering Zn in an Ar + O 2 atmosphere.

ZnO thin films exhibit the piezoelectric effect.

Main properties of zinc oxide

Molecular weight 81.38

Crystal structure G

Crystal lattice constants, nm:

A 0.3250

C 0.5206

Density, Mg / m 3 5.67

Temperature, K:

melting point 2250

boiling 2000

Specific heat capacity, J/(kg× K) 495

Temperature coefficient of linear expansion for
single crystal, α× I 0 6 , K -1 5.7 || a

5.2 || With

Resistivity, Ohm× cm 10 8 …10 9

Thermal conductivity coefficient, W/(m× K) 15…30

Mohs hardness 4.0…5.0

Refractive index 1.96

Dielectric constant 8.5

The use of zinc oxide.

Zinc oxide is used in radio electronics for the manufacture of self-activated phosphor ZnO:Zn. This phosphor is obtained by calcination ZnO in a weakly reducing atmosphere of carbon monoxide at 1270 K - The color of the glow of the phosphor is blue-green, the radiation is characterized by two maxima, falling at wavelengths of 0.385 microns (ultraviolet region) and 0.505 microns (blue-green region of the spectrum). This phosphor has a very short afterglow, about 2 μs.

Zinc oxide has found its main application in the production of varistors, devices whose electrical resistance is highly dependent on the applied voltage. On the basis of varistors, surge arresters (SPDs) are created that suppress surges in power networks.

This is due to a special property of varistors - the nonlinearity of the current-voltage characteristic. The non-linearity of the current-voltage characteristic also has silicon carbide, but the coefficient of nonlinearity of varistors based on zinc oxide is 1-1.5 orders of magnitude higher.

For the manufacture of varistors, submicron ZnO powder, oxides of other metals ~5% (bismuth, cobalt, antimony, manganese, chromium) and inorganic binders are mixed, molded under a pressure of ~10 4 ... 10 6 MPa and fired for several hours at temperatures from 1200 to 1600 °C. During the reaction interaction, the material is transferred through the liquid phase from zinc oxide grains with a high surface energy to grains with a lower surface energy. The material is compacted during sintering, and as a result a new polycrystalline structure is obtained.

A zinc oxide varistor is a polycrystalline semiconductor material whose individual grains are in electrical contact with each other. At the contact points of zinc oxide grains, there are thin insulating regions, which cause the nonlinearity of the current-voltage characteristic. The mechanism of non-linearity of varistors is not well understood. Most likely, the nonlinearity is due to the phenomena at grain boundaries, and additional additives in the composition of varistors also have a decisive influence.