Phases of Matter III - Amorphous Solids
Written by Translator on June 22, 2008 – 7:49 pm -Getting down to basics, “amorphous” just means that the solid in question can not be isolated to a unit that repeats, like salt or diamond. The units making up amorphous solids are irregular, and not well defined. Let us take charcoal as an example, and it is a complex one, but it serves to make the point.
By definition, charcoal is the residue from the destructive distillation of wood. Wood is a very complex material, and some of its components are somewhat crystalline. But take that wood, and subject it to high heat without any oxygen, and things change.
The structural elements that hold it in an organized structure disappear, and, because they expand, disrupt the cellular structure of the wood. Finally, only carbon, and whatever nonvolatile trace mineral salts are left. There is still some organization in that the basic structure is often left as a cast, but there is nothing that resembles a crystalline structure. The bonds in charcoal are essentially random.
Another, very popular topic, is glass. There are many myths about glass, and I will touch on a couple of them later. Glass, by definition, is a substance that is more or less transparent to one or more wavelengths of light. The composition of glass is extremely variable, however.
Common glass (your cheap drinking vessels, light bulb enclosures, car windows) is composed of mostly high silica sand and sodium and calcium salts that meld with the silica, lowering the melting point and making the material more easy to work at ambient temperatures.
I used to torment the wonder scientific glassblower at The University of Arkansas, Richard, because my research needed pure quartz to allow UV to pass. Unfortunately for Richard, quartz freezes at a single point, but most glass does not.
Impurities in any substance generally lowers the melting point, and that is very true for glass. The main ingredient, quartz, melts hundreds of degrees about that of glass. But when mixed with calcium oxide, some sodium salts, and with a plethora of trace additives, we have modern glass.
Glass is amorphous, but it in NOT a supercooled liquid, except that some liquids also share the noncrystalline structure of glass. I will cover liquid crystal another time.
As always, I encourage comments, questions, flames, and other. Warmest regards, Doc.
Tags: Amorphous, Matter, Solids, Teaching
Posted in Diaries |
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Hev you thought about doing an e-book or teaching through one of the online schools? I found one a couple of years ago (an online school, that is) that might be right up your alley. Probably wouldn’t pay much, but could open some doors for you.
I definitely think you should be working on an e-book or trying to figure out some way to publish articles on chemistry and science, say, in local newspapers - maybe those monthly ones for starters.
These are nice articles and perfectly dumbed down without being condescending to us non-chemists.
I do not alter the facts, just report the science. I choose not to use esoteric mathematics because neither this site nor Kos is formula friendly, and I am not trying to influence professional scientists.
I NEVER try to “dumb down” anything. The facts are as they are. I just choose words, rather than equations, to describe the ideas.
I understand what you are saying, but please know that, even if not using complex mathematics, I am NOT “dumbing down” anything. The concepts are really pretty simple. It is just our deficient understanding that makes it seem difficult.
Warmest regards, Doc.
Oh, I didn’t mean it in any negative way - quite the contrary. The language is clear and crisp, which is a bit unusual. So much science is written at such a high level that only practitioners can understand it.
But I understand what you’re saying.
No negative thoughts taken. Only positive ones. Warmest regards, Doc.