Growing Crystals in the Lab

Hafnium Carbide Crystals, Grown at the University of New Mexico, in Dr. Milewski's Lab.
Hafneium Carbide

Grown in an Advanced Materials lab at the University of New Mexico.

Silicon Carbide Whisker Crystals Whiskers Crystals:   are high purity single crystals grown in or on one axis so they form a fiber material. We grow these using a method known as the V.L.S. process; which stands for Vapor, Liquid, Solid. When frost forms on your windows, it is a vapor–solid crystal growth process. When ice forms in a pond, it is a liquid solid crystal growth process. Our process is different than these two.

Silicon Carbide Whisker Crystal In our process the vapor is the feed material in gaseous form, the liquid is the catalyst, and the final crystal being grown, is of course a solid. For example, when we are growing silicon carbide the vapor feed contains a carbon bearing gas methane (basically natural gas) and a silicon bearing gas, silicon monoxide. The catalyst is a metal material like iron alloys or stainless steel in fine powder form. At high temperature e.g. 1400° C. (2561° F.), the metal catalyst melts and dissolves some of the carbon and silicon from the gas stream. Soon the metal reaches saturation of Silicon & Carbon in solution and begins to precipitate out the SiC crystals against the substrate. As the crystal grows, it lifts the liquid catalyst up and a fiber crystal is formed. Longer time in the furnace produces longer fiber. The diameter of the catalyst control the diameter of the fiber. Fine metal catalyst powders produces fine fibers and larger diameter catalyst produces larger diameter fiber or rod like crystals.{3}

Control unit and furnace for growing V.L.S. Whisker Crystals. By changing the chemistry of the feed gas and catalyst, Fiber Crystals, of almost any kind of material, can be grown. Metals such as iron, gold, silver, cadmium and ceramics such as SiC, Si3N4, Sapphire, boron carbide, graphite have been grown. The literature gives over 60 different elements or compounds.

Furnace inlet - for growing V.L.S. Whisker Crystals. Currently, I am working on a DOE (Department of Energy) contract to produce Hafnium Carbide Filaments for the development of a new, more efficient light bulb, that will last longer, give a more natural spectrum of light and be more energy efficient.

—   John V. Milewski PhD   —

Hafnium Carbide Crystals, Grown at the University of New Mexico, in Dr. Milewski's Lab.

The Wonderful World of Advanced Materials
Dr. John V. Milewski

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