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Zone melting (or zone refining, or floating-zone method, or floating-zone technique) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved along the crystal. The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind ...
William Gardner Pfann (October 27, 1917 – October 22, 1982) was an inventor and materials scientist with Bell Labs.Pfann is known for his development of zone melting which is essential to the semiconductor industry.
The molten zone carries the impurities away with it and hence reduces impurity concentration (most impurities are more soluble in the melt than the crystal). Specialized doping techniques like core doping, pill doping, gas doping and neutron transmutation doping are used to incorporate a uniform concentration of desirable impurity.
Fractional freezing is a process used in process engineering and chemistry to separate substances with different melting points. It can be done by partial melting of a solid, for example in zone refining of silicon or metals, or by partial crystallization of a liquid, as in freeze distillation, also called normal freezing or progressive freezing.
Refining is easily the least glamorous aspect of the oil and gas business. And yet, this is where the next smart play is for energy investors. An increase in energy production in North America ...
The methods involve heating polycrystalline material above its melting point and slowly cooling it from one end of its container, where a seed crystal is located. A single crystal of the same crystallographic orientation as the seed material is grown on the seed and is progressively formed along the length of the container.
Zone refining techniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 10 10, [37] making it one of the purest materials ever obtained. [38]
Oil company Phillips 66 announced Wednesday that it plans to shut down a Los Angeles-area refinery by the end of 2025, citing market concerns. The company said it will remain operating in the state.