Chemistry: Matter and ChangeChapter 7: The ElementsIn the NewsDiamonds Are for ChemistsDecember 2004Chemists see the world a little differently than other folks. When people lean into a jewelry store window to start *ooo*-ing and *aahh*-ing the diamonds, only the chemist is thinking: *now that would make an excellent insulator.* Actually, diamonds are terrific insulators. In fact, they have a whole range of properties that make them of interest to scientists. Diamond, for example, is the hardest material known in nature. When a geologist does a quick scratch test to figure out what various samples are, diamond is always at the top of the list: it scratches everything but nothing scratches it. Diamond has the highest thermal conductivity of any material. It's transparent to UV and infrared light. Its also chemically inert--in a big way! Nearly all acids and bases can be splashed across a diamond without harming it. Diamonds just don't react. With properties like that, it isn't hard to come up with ideas for things you could build in which a little diamond might be useful. Computer chips that can take more heat than today's silicon ones can handle? A new kind of semiconductor? How about something nutty--like a window that won't ever crack? The hard part hasn't been coming up with ideas . . . just coming up with diamonds. Coming Up with Diamonds Well, how does nature come up with diamonds? Maybe, you might be thinking, if we could replicate the conditions under which diamonds naturally form, we could make some of our own. That's just what research scientists have done. Diamonds form in the Earth when carbon--say, in a lump of coal-- is subjected to enormous temperature and pressure for long periods of time. As far back as the early 1950's a team of researchers at the *Allmanna Svenska Elektriska Aktiebolaget* Laboratory in Stockholm, Sweden, recreated these conditions in the lab, and produced the first make-it-yourself diamonds. The diamonds were tiny and low-quality, but nonetheless, the process worked. Scientists working for General Electric soon did the same, and synthesized diamonds became part of industry--serving, say, as the unbreakable tips of industrial drills. The problem, though, was in making them big. High-power saw blades can be studded with little synthetic diamonds to help them cut through other things without chipping, but in order really to tap the potential of diamonds as a building material, it would have to be possible to “home grow” large, high-quality samples. Enter the chemists. Enter the Chemists *Chemical & Engineering News,* the newsmagazine of the American Chemical Society, reported in February that modern companies such as Gemesis in Florida and Apollo Diamond in Boston are now capable of producing large, gem-quality diamonds in the lab. These are “chemically true diamonds,” all but indistinguishable from the kind mother nature makes (and for which people pay so much). Some of the techniques being used to build these diamonds don't need to replicate the high pressure conditions under which natural diamonds form, either. CVD, or “Chemical Vapor Deposition,” is a method by which chemists can carefully apply new layers to a lattice of carbon, building up a diamond bit by bit. Curse of the Hope Diamond Color in diamonds is the result of impurities, as are such properties as conductivity. Chemists at Apollo have found a way to grow colored diamonds as well, “injecting” chemical elements into the diamond as it is forming. Adding some nitrogen gives the diamond a yellow color. Have you ever seen the Hope diamond? It has a lovely blue tint. Diamonds turn blue, it turns out, when they have extra boron, which also happens to make them excellent semiconductors. Who Can Tell? The easier it becomes to synthesize diamonds, the cheaper they will become. Of course, that means there will be more danger of someone trying to pass them off as natural diamonds in order to make a huge profit. Law enforcement officials will have to figure out ways to keep that from happening. But on the scientific side of things, it seems likely that the next generation of computers, industrial tools, and all sorts of devices will be not just as good as gold--they'll be as good as diamonds. Activity: If one of your parents or someone you know owns a diamond, ask them to let you examine it. What do you notice? Try to look at it as a scientist would. Don't examine the “setting”--that is, the pretty way it is held by a ring or a chain--but at the stone itself. Would the person who owns the diamond feel it were less precious if the exact same stone could be created in a lab, do you think? Why, or why not? Chemical & Engineering News: Apollo Diamond: Gemesis: |  |
