Zone melting is a process used in metallurgy to purify metals by melting and solidifying them in a zone. The spelling of "zone melting" is straightforward and corresponds to the phonetic transcription: /zəʊn ˈmɛltɪŋ/. The "z" sound at the beginning of "zone" represents the voiced alveolar fricative, the "o" is pronounced as the long "o" vowel /əʊ/, and "ne" is pronounced as "ni" /ni/. The stress is placed on the first syllable. The word "melting" is spelled as it sounds: /ˈmɛltɪŋ/.
Zone melting is a technique used in materials science and metallurgy to purify or refine solid-state materials. It involves the controlled movement of a high-temperature molten zone along a crystalline or polycrystalline material, leading to the redistribution of impurities and the segregation of desired constituents. By selectively melting and resolidifying a material, the technique can effectively remove impurities or separate different chemical components, resulting in a higher level of purity or desired composition.
The process of zone melting begins by locally heating a small region or "zone" of the material, typically using a high-energy heat source such as a laser or electron beam. As the zone passes through the material, it causes localized melting and solidification, leading to the migration of impurities or desired components towards the moving zone. This movement, driven by the gradient in chemical potential, allows impurities to be concentrated in a region of the material that is then removed or discarded.
Zone melting finds wide applications in the fabrication of semiconductor materials, where precise control over impurity levels and dopant distribution is critical for device performance. It is also employed in the purification of metals and alloys, enhancing their mechanical and electrical properties. The technique's ability to achieve high levels of homogeneity and purity makes it an essential tool in the production of advanced materials for various industries, including electronics, aerospace, and energy.
The word "zone melting" is composed of two parts: "zone" and "melting".
The term "zone" refers to a specific region or area. In the context of zone melting, it typically refers to a particular section of a solid material.
The word "melting" is the present participle of the verb "melt", which means to change a substance from a solid state to a liquid state through the application of heat.
When combined, "zone melting" refers to a process in which a specific section or zone of a solid material is selectively melted or refined. This technique is commonly used in material science and metallurgy to purify and enhance the quality of materials by removing impurities or redistributing solutes.