月: 2023年1月

What Is Chromium Oxide?

Chromium oxide refers to several compounds of chromium, differing by oxidation states. Commonly, chromium oxide (III) is implied, though chromium oxides (II), (IV), and (VI) also exist. Chromium oxide (III) is the most stable form, recognized under safety regulations for its hazardous nature.

Uses of Chromium Oxide

Chromium (III) oxide, known for its stability against acids, alkalis, and high temperatures, is primarily used in refractories. It colors glass and fabrics green, serves as an abrasive, and forms part of ceramics. In chemical processes, it acts as a catalyst for various reactions and in synthesizing chromium salts.

Properties of Chromium Oxide

Chromium (II) oxide is a black powder, insoluble in water and weak acids but soluble in hydrochloric acid. It is chemically unstable, turning into chromium oxide (III) upon oxidation. Chromium (III) oxide is notably stable, insoluble in acids and alkalis, and soluble in heated alkaline bromic acid solutions. Chromium oxide (IV) is ferromagnetic and insoluble in water, while chromium oxide (VI) is red, deliquescent, highly toxic, and forms chromic and dichromic acids when dissolved in water.

Structure of Chromium Oxide

Chromium oxides vary structurally with oxidation state: CrO for chromium oxide (II), Cr₂O₃ for chromium oxide (III) with a corundum-type structure, CrO₂ for chromium oxide (IV) with a rutile-type structure, and CrO₃ for chromium oxide (VI) with an orthorhombic structure. Chromium oxide (III) features chromium ions in octahedral gaps of a hexagonal close-packed oxide ion arrangement.

Other Information on Chromium Oxide

1. Synthesis of Chromium Oxide

Chromium oxide (II) can be produced by oxidizing chromium amalgam or by reacting chromium oxide (III) with hydrogen or ethanol. Chromium oxide (III) is obtainable from chromite or by decomposing chromium nitrate, while chromium oxide (VI) is synthesized from sodium chromate or dichromate treated with sulfuric acid.

2. Chromium Oxide Reactions

Chromium oxide (III) is amphoteric, dissolving in both acids and concentrated alkalis, and can be reduced to chromium metal. Chromium oxide (VI) serves as a potent oxidizing agent in synthetic chemistry, transforming alcohols into aldehydes or ketones.

What Is Gallium Oxide?

Gallium oxide is a white powder inorganic compound with the chemical formula Ga₂O₃, a molecular weight of 187.44, and a CAS registration number of 12024-21-4. It is recognized for its chemical stability under recommended storage conditions. 

For storage, it is advised to use glass as a safe container and packaging material, keeping the product in a sealed container in a cool, well-ventilated area away from direct sunlight.

Applications of Gallium Oxide

Gallium oxide serves as a key raw material for green phosphors and substrates in LEDs (Light-Emitting Diodes), which are increasingly replacing traditional fluorescent lamps and bulbs in lighting. Furthermore, power semiconductor devices utilizing gallium oxide are anticipated to be more compact and efficient, offering reduced loss due to lower resistance during conduction compared to devices made from silicon carbide.

Properties of Gallium Oxide

This compound is soluble in various acids, including hydrochloric acid, but almost insoluble in water. Gallium (III) oxide exists in five different forms: α, β, γ, δ, and ε, with β-gallium oxide (III) being the most stable and having a melting point of 1740°C.

Structure of Gallium Oxide

The most stable β-gallium (III) oxide form exhibits a distorted cubic close-packed structure, featuring both tetrahedral and octahedral distortions. The Ga-O bond distances measure 1.83 Å and 2.00 Å, contributing to its stability.

Other Information on Gallium Oxide

1. Synthesis of Gallium Oxide

Gallium (III) oxide can be synthesized through various methods, including precipitation from acidic or basic gallium salt solutions, heating gallium metal in air, or pyrolyzing gallium (III) nitrate at 200-250°C. β-Ga₂O₃ is specifically produced by heating certain gallium (III) compounds at 1,000°C.

2. Other Crystal Structures of Gallium Oxide

Transformations between gallium oxide polymorphs can be achieved under specific conditions, such as heating or hydrating, to obtain α, γ, δ, and ε forms, each with unique properties and synthesis methods.

3. Gallium Oxide Catalyst

β-Gallium (III) oxide plays a crucial role in catalyst production, notably in the synthesis of Ga₂O₃-Al₂O₃ catalysts, which are created by reacting gallium (III) nitrate with aluminum oxide and undergoing specific thermal treatments.

4. Nanostructure of Gallium Oxide

Gallium (III) oxide nanoribbons and nanosheets can be synthesized under high-temperature conditions, resulting in pure single-crystal structures. These nanostructures are characterized using techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), and energy dispersive X-ray spectrometry (EDS), revealing their unique physical forms and properties.

What Is Indium Oxide?

Indium oxide is an inorganic compound formed by oxidizing indium, primarily used as a semiconductor and in display technologies. It has the chemical formula In₂O₃, a molecular weight of 277.63, and CAS No. 1312-43-2. It is soluble in acids and insoluble in water. Indium oxide is classified as a Hazardous and Noxious Substance under the Safety and Health Law, a Class 1 Designated Chemical Substance (Class 1 No. 44) under the PRTR Law, and a Hazardous Air Pollutant under the Air Pollution Control Law.

Uses of Indium Oxide

Indium oxide is the primary ingredient in indium tin oxide (ITO), a transparent conductive film created by adding tin oxide. ITO films, utilizing indium oxide, are employed in:

1. Transparent Conductive Films

Used in touch panels for smartphones and tablets, and in display technologies such as LCDs and organic EL panels due to their transparency and electrical conductivity.

2. Solar Cells

Applied as electrodes in solar cells to collect electrons generated by light absorption in semiconductor materials like silicon.

3. Electronic Materials

Utilized in manufacturing electronic components, including LCD backlights and LED electrodes, and in semiconductor production.

Properties of Indium Oxide

Indium oxide, a combination of indium and oxygen, exhibits unique properties, such as transparency to visible light, electrical conductivity, heat resistance, chemical stability, and paramagnetism, making it valuable in the semiconductor and display industries.

1. Transparency

Exhibits high transparency in the ultraviolet to near-infrared wavelength range.

2. Conductivity

Conducts electricity while maintaining transparency, ideal for transparent conductive films.

3. Heat Resistance

Remains stable under high temperatures, suitable for high-temperature manufacturing processes.

4. Chemical Stability

Maintains stability in air and against acids and alkalis.

5. Magnetism

Shows paramagnetism without being magnetized by magnetic fields.

Other Information on Indium Oxide

Indium Oxide Production Methods

1. Thermal Oxidation Method: Metallic indium is oxidized at high temperatures, with oxygen or air supplied to enhance the oxidation. Quality and yield are controlled by adjusting the oxygen flow and temperature.

2. Hydrothermal Method: Water and indium salts are reacted under high temperature and pressure, producing oxides with uniform particle sizes and high crystallinity. Shape variations can be achieved by adjusting reaction conditions.

3. Precipitation Method: Raising the pH of an aqueous solution containing indium ions with an alkaline agent causes a reaction. The resulting precipitate is collected and dried to obtain indium oxide, a method favored for its simplicity and consistent product quality.

Sputtering, a vapor deposition technique, is utilized for creating thin, uniform transparent conductive films.

What Is Yttrium Oxide?

Yttrium oxide, also known as yttria, is an inorganic compound composed of yttrium and oxygen with the chemical formula Y₂O₃. It appears as a white powdered solid, exhibiting various applications across industries.

Applications of Yttrium Oxide

1. Luminescent Materials

Yttrium oxide is instrumental in producing luminescent materials such as YVO₄:Eu, Y2O3:Eu, and Y₂O₂S:Eu, which impart red color to color TV CRTs. These materials offer high color purity and narrow line width in emission spectra, making them ideal for high color-rendering fluorescent lamps and other applications requiring faithful color reproduction.

2. Laser Materials

Yttrium oxide is a key component in solid-state lasers, particularly those employing ytterbium as a dopant. These lasers operate efficiently in both continuous wave and pulsed regimes, finding application in various fields.

3. Dental Ceramics

In dentistry, yttrium oxide stabilizes zirconia to create yttria-stabilized zirconia (YSZ), a hard ceramic material used for dental restorations.

4. Microwave Filters

Yttrium oxide contributes to the production of yttrium iron garnet (YIG), a highly effective microwave filter utilized in microwave, acoustic, optical, and magneto-optical applications.

5. Other Applications

Yttrium oxide finds further use in superconducting materials, fine ceramics, optical lenses, materials for nickel-hydrogen batteries, and various other industrial applications.

Properties of Yttrium Oxide

Yttrium oxide has a melting/solidification point of 2,420°C and a boiling point of approximately 4,300°C. It possesses a density of 5.01 g/cm³ and a thermal conductivity of 27 W/(m-K). Chemically, it is almost insoluble in water but soluble in dilute nitric acid. It adopts a fluorite-type cubic crystal structure with octahedral coordination.

Other Information on Yttrium Oxide

1. Production and Discovery

Yttrium oxide was first isolated in 1789 by Johan Gadolin from a rare earth mineral found in the Ytterby mine near Stockholm, Sweden. It also occurs naturally as yttriaite, a mineral species discovered in 2010.

2. Legal Considerations

Relevant laws and regulations include labeling and notification requirements under the Safety and Health Law. Yttrium oxide does not fall under major regulations such as the Fire Service Law.

3. Handling and Storage Precautions

When handling yttrium oxide, it is important to keep the container tightly closed and store it in a cool, dark place. Outdoor or well-ventilated areas should be chosen for usage, with precautions taken against dust dispersion and electrostatic discharge. Protective gloves and glasses are recommended, and thorough hand washing is advised after handling. In case of skin or eye contact, appropriate rinsing and medical attention should be sought if necessary.

What Is Aluminum Oxide?

Aluminum oxide, commonly known as alumina, is an oxide of aluminum. It encompasses various forms including γ-alumina and the stable α-alumina, along with several intermediate types.

Naturally occurring as corundum or bauxite, aluminum oxide is abundantly found in mineral deposits. Bauxite, in particular, serves as the primary source for industrial extraction of alumina and aluminum.

Uses of Aluminum Oxide

Renowned for its exceptional physical and chemical properties, aluminum oxide finds versatile applications as an oxide-based ceramic material. Its notable attributes include a high melting point and superior heat resistance.

These properties make it indispensable in the production of refractory materials such as bricks and aggregates, offering excellent resistance to heat and corrosion. It is also employed in chemical-resistant porcelain and piping for handling corrosive liquids.

With remarkable mechanical strength and wear resistance, aluminum oxide is extensively utilized in precision equipment components requiring durability and precision. Additionally, its biocompatibility renders it valuable in medical applications for artificial joints and implants.

Properties of Aluminum Oxide

Aluminum oxide has a melting point of 2,072°C and a boiling point of 2,977°C. It exists as a white powder and remains insoluble in water, diethyl ether, and ethanol, displaying robust chemical stability.

Its strong bond between oxygen and aluminum makes it challenging to separate individual aluminum pieces. However, the Hall-Héroult process offers a practical method for aluminum smelting through electrolysis.

Structure of Aluminum Oxide

Aluminum oxide, represented by the chemical formula Al₂O₃, exhibits a molar mass of 101.96 g/mol and a density ranging from 3.95 to 4.1 g/cm³.

The pure form, known as α-alumina, undergoes dehydration to form γ-alumina, which typically contains a small amount of water. α-alumina features a triangular crystal structure, while γ-alumina adopts a cubic crystal structure. Notably, γ-alumina is valued for its high specific surface area, making it useful as a catalyst.

Other Information on Aluminum Oxide

1. Production and Synthesis

Aluminum oxide occurs naturally as sapphire, ruby, and corundum. Synthetic production methods involve thermal decomposition of salts like aluminum sulfate or reaction of aluminum chloride vapor with oxygen or water vapor.

2. Additional Forms

Besides aluminum oxide (III) (Al₂O₃), other forms such as aluminum oxide (II) (AlO) and aluminum oxide (I) (Al₂O) also exist. These forms have been observed in specific conditions, including high-altitude explosions and astronomical observations.

Aluminum oxide (I) is typically gaseous and exists within a specific temperature range, typically from 1,050°C to 1,600°C.

What Is Methyl Acetate?

Methyl acetate, with the chemical formula CH₃COOCH₃ and a molecular weight of 74.08, is an organic compound belonging to the family of acetic acid esters. It is the simplest ester with the lowest carbon number in this group and exhibits high solubility in water.

This clear, colorless, and flammable liquid has a distinctive odor. It is highly soluble in ethanol and can dissolve various metal salts.

Under regulatory frameworks like the Industrial Safety and Health Law, methyl acetate is categorized as a hazardous substance requiring labeling. Similarly, under the Fire Service Law, it falls under Class 4 Inflammable Liquid and Class 1 Petroleum Non-Water Soluble Liquid.

Uses of Methyl Acetate

Due to its lipophilic (hydrophobic) nature, methyl acetate serves as a versatile solvent in both industrial and laboratory settings. Common applications include its use as a solvent for adhesives, paints, resins, and printing inks.

It finds further application as a solvent in nail polish removers, lacquers, and as a flavoring agent in fruits and other food products. However, it is worth noting that methyl acetate is not employed in food applications due to its higher toxicity compared to ethyl acetate.

What Is Butyl Acetate?

Butyl acetate, the ester of acetic acid and butanol with the molecular formula C₆H₁₂O₂, is commonly known as butyl acetate. It is a clear, colorless liquid with a distinctive sweet, fruity odor. Its molecular weight is 116.16 g/mol, and it has the CAS number 123-86-4.

Butyl acetate is highly soluble in ethanol but insoluble in water. It exists in four structural isomers: n-butyl acetate, isobutyl acetate, sec-butyl acetate, and tert-butyl acetate, each with its own unique properties.

Uses of Butyl Acetate

Butyl acetate finds extensive use as a solvent across various applications. It is commonly employed in paints, inks, resins, cosmetics, pharmaceuticals, adhesives, fragrances, leather, enamel, shoe polish, and rubber.

In the paint and ink industry, butyl acetate serves as a heavy solvent with a relatively high boiling point, contributing to better flow and brush resistance. It is often blended with other solvents of lower volatility to adjust drying characteristics. For instance, it is commonly combined with ethyl acetate in nail polish formulations.

Additionally, butyl acetate is favored as a solvent in lacquers due to its excellent flowability and brush resistance on resin-coated surfaces, offering compatibility with materials like cellulose nitrate, ethyl cellulose, polystyrene, and methyl methacrylate resin.

Its pleasant aroma also makes it a valuable ingredient in the food industry for flavoring agents, fruit essences, and spices, enhancing the taste of various products such as candy, ice cream, and cheese.

Properties of Butyl Acetate

Butyl acetate has a melting point of -74°C and a boiling point of 124°C. Despite its relatively high boiling point, its vapor pressure at room temperature is sufficient for it to emit its characteristic aroma.

The different structural isomers of butyl acetate exhibit distinct odors, with n-butyl acetate and isobutyl acetate presenting apple or banana-like scents, while tert-butyl acetate has a blueberry-like aroma. These variations allow for specific applications in fragrance compositions.

Naturally, butyl acetate is present as a volatile aroma component in fruits like grapes, strawberries, and apples.

Other Information on Butyl Acetate

1. Safety and Regulations

While butyl acetate is generally considered safe for humans and the environment, it may cause irritation to the eyes and respiratory tract. Inhalation of high concentrations can lead to symptoms such as headache, nausea, dizziness, and difficulty breathing.

Due to its flammability, butyl acetate is classified as a hazardous substance and should be handled with caution. Storage and use are subject to regulations to prevent fire hazards and ensure safe handling practices.

2. Manufacturing Process

Industrial production of butyl acetate involves an esterification reaction between acetic acid and butanol, typically using an acid catalyst such as sulfuric acid. The crude product undergoes distillation to remove impurities, yielding purified butyl acetate suitable for various applications.

For high-purity applications, additional distillation steps may be employed to remove specific impurities, ensuring the quality required for food-grade or electronic applications.

What Is Vinyl Acetate?

Vinyl acetate, the ester of vinyl alcohol and acetic acid, is a clear, colorless, flammable liquid with a sweet aroma and faint pungent odor. It serves as a raw material for organic synthesis, polyvinyl acetate (PVA), polyvinyl alcohol, and paints.

The production of vinyl acetate initially utilized the acetylene process, discovered in 1912, followed by the ethylene process and the ethylidene diacetate process. Major production bases are located in the United States, China, Japan, and Taiwan.

Uses of Vinyl Acetate

Vinyl acetate is primarily employed in the production of polyvinyl acetate and polyvinyl alcohol, which find applications in various industrial and consumer products.

Polyvinyl acetate is widely used in paints, adhesives, artificial turf, denture stabilizers, gum paste, wire, plastic fuel tanks for automobiles, and food packaging containers.

Polyvinyl alcohol serves as a raw material for polarizers in liquid crystal displays, fiber and paper processing agents, emulsion dispersants, and ceramic binders.

Properties of Vinyl Acetate

Vinyl acetate has a melting point of -100.2°C and a boiling point of 72-73°C. It readily polymerizes under light or heat to form polyvinyl acetate, necessitating the inclusion of polymerization inhibitors like hydroquinone.

Hydrolysis of vinyl acetate with dilute acid or alkali yields acetic acid and acetaldehyde. Under ultraviolet light, vinyl acetate decomposes to produce ketones, aldehydes, and alcohols.

It has a molecular formula of C₄H₆O₂, molecular weight of 86.09, and specific gravity of 0.9312. Vinyl acetate is classified as a suspected human carcinogen by the International Agency for Research on Cancer, although there is no evidence of carcinogenicity in humans.

Other Information on Vinyl Acetate

1. Synthetic Methods of Vinyl Acetate

Vinyl acetate is industrially synthesized via the Wacker oxidation reaction, involving the reaction of ethylene and acetic acid with oxygen in the presence of a palladium catalyst. Alternatively, it can be produced by the addition of acetic acid to acetylene using a metal catalyst, with zinc acetate being the current preferred catalyst.

Another method involves the thermal decomposition of ethylidene diacetate to produce vinyl acetate.

2. Synthesis of Polyvinyl Acetate

Radical polymerization of vinyl acetate yields polyvinyl acetate, a colorless, transparent thermoplastic resin. Ethylene-vinyl acetate copolymer can also be synthesized by copolymerizing ethylene and vinyl acetate monomers.

Hydrolysis of the ester acetate bonds of polyvinyl acetate yields polyvinyl alcohol, a highly hydrophilic synthetic resin, as vinyl alcohol cannot be polymerized directly due to its unstable molecular structure.

What Is Tantalum Oxide?

Tantalum oxide, a white to almost white inorganic compound, is recognized by its chemical formula Ta₂O₅, with a molecular weight of 441.89, and a CAS registration number of 1314-61-0. Notable for its high decomposition temperature of 1,470℃, it is almost insoluble in water.

It is regulated under the Safety and Health Law, specifically designated in the Hazardous and Noxious Substances to be labeled.

Uses of Tantalum Oxide

Due to its high refractive index and superior film stability in ion-assisted deposition (IAD) processes, tantalum oxide is a key material in optical lens manufacturing. It also serves as a raw material for antireflective coatings and interference filters in various applications, including computer displays and automobile windshields. Additionally, its high dielectric constant makes it vital in the production of electronic ceramics, such as dielectrics for electrolytic capacitors.

Properties of Tantalum Oxide

This oxide is an inert material characterized by its high refractive index and low absorption, insoluble in all solvents but corrosive to strong bases and hydrofluoric acid. While it shows resistance to reactions with HCl or HBr, it dissolves in hydrofluoric acid and reacts with potassium hydrofluoride and HF.

Structure of Tantalum Oxide

Also known as tantalum (V) oxide or tantalum pentoxide, its structure is predominantly disordered, being either amorphous or polycrystalline. Due to the challenges in growing single crystals, structural information is mainly derived from powder X-ray diffraction techniques. The densities for β-Ta₂O₅ and α-Ta₂O₅ are 8.18 g/cm³ and 8.37 g/cm³, respectively.

Other Information on Tantalum Oxide

1. Occurrence of Tantalum Oxide

Tantalum is primarily found in the minerals columbite and tantalite within igneous pegmatites, with notable occurrences in Sweden and Finland. While pure tantalum oxide is rare in nature, these minerals contain significant amounts of tantalum, making them key sources of the metal.

2. Purification of Tantalum Oxide

The purification process involves leaching, extraction, and firing stages. Initially, tantalum ores are treated with hydrofluoric and sulfuric acids, producing water-soluble hydrogen fluoride. Following liquid-liquid extraction using organic solvents, tantalum and niobium are separated, and the pure tantalum fluoride solution is neutralized and calcined to produce tantalum oxide.

3. Synthesis of Tantalum Oxide

For electronics applications, tantalum oxide is synthesized through methods like metalorganic vapor deposition (MOCVD), leveraging the hydrolysis of volatile halides and alkoxides to create thin films essential for various electronic devices.

What Is Amyl Acetate?

Amyl acetate is an organic compound, the ester of amyl acetate and amyl alcohol.

It has the chemical formula C7H14O2 and molecular formula CH3COO(CH2)4CH3. Other names include pentyl acetate, n-amyl acetate, and n-amyl acetate ester.

It has a molecular weight of 130.18, a melting point of -71°C, and a boiling point of 149°C. Its density is 0.876 g/cm³. It is insoluble in water (solubility 1.7×10-3 mg/L (20°C)), but miscible in organic solvents such as alcohol and ether.

The ester produced from one of the isomers of 1-pentanol or a mixture of these isomers can also be referred to as amyl acetate.

Uses of Amyl Acetate

Amyl acetate is mainly used as solvents and lacquers. These include solvents for perfumes and textile dyes, adhesive manufacturing, oil paints, lacquers, and nitrocellulose solvents.

Other applications include film preparations, such as photographic film and celluloid, a synthetic plastic material.

It is used industrially in various applications.

Pearl essence is a liquid that is sprayed on a round glass bead from the outer layer or hollow interior when making imitation pearls, and amyl acetate is sometimes used in this type of paint solution. It may also be included as an ingredient in stain removers.

Chemistry and Synthesis of Amyl Acetate

1. Synthesis of Amyl Acetate

Amyl acetate can be synthesized by the usual ester synthesis reaction using a carboxylic acid (acetic acid), an alcohol (1-pentanol (n-amyl alcohol)), and an acid catalyst such as concentrated sulfuric acid.

As with other esters in general, it is also possible to synthesize amyl acetate using acid anhydrides or acid halides.

2. Chemical Properties of Amyl Acetate

Amyl acetate undergoes hydrolysis in the presence of an acid or base and is decomposed into acetic acid and 1-pentanol. In reactions using reducing agents such as lithium aluminum hydride (LiAlH4), sodium borohydride (NaBH4), and borane (BH3), alcohols (ethanol and 1-pentanol) are formed.

They are relatively stable to heat and light. However, mixing with nitrates, strong oxidizing agents, strong bases, and strong acids should be avoided. Mixing with these substances may cause fire or an explosion hazard.

The flash point is low at 25°C and the substance should be handled as a flammable liquid or vapor. Combustion produces carbon monoxide and carbon dioxide. There is a risk of mild skin irritation, eye irritation, and respiratory tract irritation in humans, and is slightly toxic.

Types of Amyl Acetate

There are several types of amyl acetate supplied to the market, including common chemical reagent products and industrial chemicals. As a chemical reagent, the most common volumes are 25mL and 500mL, which are easy to handle in the laboratory. It is usually served in a glass bottle. This reagent can be transported and stored at room temperature.

As an industrial chemical, it is traded as a type of solvent and is often handled in large packages such as 15kg oil cans, 180kg drums, and 1,000L containers.