Tungsten

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Differences Between Ammonium Metatungstate and Ammonium Heptamolybdate 38

Although both ammonium metatungstate (AMT) and ammonium heptamolybdate (AHM) are important transition metal compounds with wide applications in the chemical industry, they differ in terms of chemical composition, molecular structure, physical and chemical properties, production technologies, and specific applications. 1. Molecular Structure Differences Ammonium Metatungstate (H???N?O??W??) is a white powder belonging to the class of tungstates, while Ammonium Heptamolybdate ((NH?)?Mo?O??·4H?O) is a molybdate compound that appears as a colorless or slightly greenish rhombic crystal. The two compounds differ significantly in…

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What Are the Differences Between Ammonium Metatungstate and Ammonium Paratungstate? 41

Ammonium metatungstate (AMT) and ammonium paratungstate (APT) are both important tungsten compounds, classified as ammonium salts of tungsten. They contain tungsten (W), nitrogen (N), hydrogen (H), and oxygen (O), and are commonly used in the preparation of downstream products such as tungsten trioxide and tungsten powder. However, they differ in chemical composition, physicochemical properties, production processes, and applications. 1. Differences in Chemical Composition and Molecular Structure The molecular formula of AMT is H??N?O??W??. In its molecular structure, tungsten atoms coordinate…

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What Are the Purification Methods of Ammonium Metatungstate? 22

The purity of Ammonium Metatungstate is typically categorized based on the application scenario: Industrial Grade: Approximately 98% to 99%, allowing trace amounts of sodium, iron, and other metal ions, and moisture. Suitable for general catalysts or ceramic raw materials. Reagent Grade: Purity greater than 99.5%, with lower impurity content, ideal for laboratory synthesis and analysis. Electronic Grade: Over 99.9%, with strict control over alkali metals like sodium and potassium, as well as heavy metals. Meets the high-end demands of semiconductor…

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What Is the Chemical Activity of Ammonium Metatungstate? 21

Chemical activity refers to the ease with which a substance undergoes a chemical reaction. Ammonium metatungstate (AMT) exhibits chemical activity primarily through its decomposition and transformation behavior under acidic conditions and thermal treatment. As a precursor to tungsten compounds, AMT plays a vital role in industrial applications and chemical synthesis. AMT is moderately soluble in water, but under acidic or high-temperature conditions, it decomposes to release tungstic acid (H?WO?) or forms other poly-tungstate salts, indicating higher chemical reactivity in acidic…

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What Is the Thermal Stability of Ammonium Metatungstate? 36

Ammonium Metatungstate (AMT) is a white crystalline powder that is easily soluble in water but insoluble in alcohol. It serves as a key precursor in the preparation of tungsten powder, tungstates, and catalysts, and is widely used in electronics, catalysis, and functional materials. The thermal stability of ammonium metatungstate refers to its ability to maintain chemical structure and properties under heat. Its decomposition occurs in stages: at lower temperatures, it loses crystal water; at medium to high temperatures, it decomposes…

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What Is the Specific Surface Area of Ammonium Metatungstate? 19

Specific surface area refers to the total surface area per unit mass of a substance, typically measured in m2/g or m2/kg. For ammonium metatungstate (AMT) powder, this includes not only the external surface area of the particles but also the surface area of internal pores, cracks, and other microstructural features. This parameter directly reflects the degree of dispersion and surface activity of the material—finer particles or greater porosity result in a larger specific surface area. As a key intermediate in…

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What Is the Bulk Density of Ammonium Metatungstate? 16

The bulk density of ammonium metatungstate (AMT) refers to the mass per unit volume of AMT powder in its naturally piled state, typically measured in g/cm3 or kg/m3. The term “natural piling” emphasizes that the powder is not compacted by external force but settles freely into a container under gravity, reflecting microstructural features such as porosity between particles, particle shape, particle size distribution, and surface roughness. From a physical perspective, bulk density is a key indicator of the flowability and…

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What Is the Density of Ammonium Metatungstate? 20

Ammonium metatungstate (AMT), a typical transition metal compound, appears as a white crystalline powder or slightly yellowish powder, with the molecular formula H28N6O41W12 and a density of 2.3-2.8 g/cm3. It has a wide range of applications. In the field of catalysis, AMT excels as a catalyst and support for reactions like hydrogenation and dehydrogenation in petrochemical processes. In functional materials, it is used to prepare tungsten-based energy storage materials and electrochromic materials. AMT is also utilized in producing ultrafine tungsten…

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Factors Affecting the Thermal Shock Resistance of Barium Tungsten Electrodes 86

The thermal shock resistance of barium tungsten electrodes is affected by many factors. The following is an analysis of the main influencing factors: 1. Material Composition and Purity 1.1 Barium Content: As a low work function material, barium can improve the electron emission performance of the electrode, but excessive or uneven barium distribution may cause internal stress concentration in the material and reduce thermal shock resistance. 1.2 Tungsten Matrix Characteristics: The grain size, purity and microstructure (such as grain boundary…

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Factors Affecting the Thermal Conductivity of Barium Tungsten Electrode 84

The thermal conductivity of barium tungsten electrode is affected by the combined effect of multiple factors, involving multiple aspects such as material science, thermodynamics and preparation process. 1. Material Composition and Microstructure 1.1 Barium Content and Distribution The Role of Barium: The addition of barium can significantly reduce the work function of tungsten and improve the electron emission performance, but excessive barium will lead to uneven distribution, forming a second phase (such as barium oxide) or pores, increasing phonon scattering,…

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