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GERMANIUM

BETHANY HALFORD, C&EN WASHINGTON

If the elements in the periodic table were pictures in a high school yearbook, germanium would be that geeky, nondescript kid that no one remembers. Part of germanium's problem is its status as the middle child of the main group, sandwiched between elemental overachievers carbon and silicon on one side and tin and lead on the other.

When Mendeleyev conceived the periodic table, germanium hadn't even been discovered. I imagine him as a father with an overwhelming brood, leaving a place for an errant child, knowing that it has to be around somewhere. It doesn't even get respect from spellcheck, which insists on renaming it as a flower.

But as elements go, germanium is a late bloomer. It took the inventions of the transistor and crystal diode in the 1940s to transform it from chemical curiosity to important industrial material. Before 1945, only a few hundred pounds of the element were produced each year. But by the end of the 1950s, annual worldwide production had reached 40 metric tons.

Finding steady work in solid-state electronics, germanium held onto its high-tech reputation through the 1970s. And when sister silicon edged in on its territory, germanium moved on to more intriguing applications: polymerization catalysts, fiber-optic communication networks, and infrared night-vision systems.

The U.S. government even designated germanium as a strategic and critical material, calling for a 146,000-kg supply in the national defense stockpile for 1987. Like the brainy, adolescent wallflower who grows up to make a fortune as president of a high-tech company, germanium had made a metamorphosis.

Its cachet has come at a cost, though. In 1998, the price of 1 lb of germanium was almost $800; 1 lb each of silicon, tin, and lead could be bought for less than $5.

My own personal experience with germanium, and its high cost, came the summer before I started graduate school when I worked with noted main-group organic chemist Peter P. Gaspar at Washington University in St. Louis. I was to make several hundred grams of (CH3)2GeCl2 using Gaspar's clever synthetic protocol [Synth. React. Inorg. Met.-Org. Chem., 20, 77 (1990)]. Perhaps because he was reluctant to let an inexperienced student like me work with pricey germanium powder--I had given him a purchase order for several thousand dollars' worth of the stuff--Gaspar suggested I call some chemical suppliers and see if any would be willing to discount their older stock. A little bit cocky, I was hurt at his lack of faith in my synthetic skills.

One supplier gave me a bargain price on some decade-old "five nines" pure material that had been taking up space on his shelves. Gaspar had said that less pure material tended to work better in the reaction, so I agreed. I figured the stoichiometry in my notebook for the germanium I needed if it was only 5/9 pure. I told Gaspar of the deal.

"I thought I told you that less pure material worked better," he said.

"Yeah, it's only five nines pure," I countered.

He stared at me, unmistakably annoyed. Irritated at his lack of enthusiasm, I skulked away. Only when the dusty old bottle arrived did I learn that "five nines" pure means 99.999%.

Gaspar once showed me a half-kilo ingot of germanium metal that a company had given him in the halcyon days before the government began stockpiling the stuff. I can still remember the sleek, cool feel of the dark metal. By the way Gaspar cradled the bread-loaf-shaped object in his hand, I could tell it was one of his treasures. I was paralyzed by the thought that he might actually ask me to grind the material up and use it.

For this essay, I called Gaspar to ask if he still had the ingot or if some unlucky student had to grind it up in the six years that had passed. "I keep it as a curiosity," he said, but conscious of its value, would not elaborate. "It's in a safe place."

When I asked Gaspar what he thinks about my theory of germanium as the main group's middle child, he said he could see the parallel, but added--in his wise professorial tone of voice--that germanium has never had plain-Jane status in chemistry. On the contrary, "the most important thing about germanium was the fact that it started as a twinkle in Mendeleyev's eye," he said. "It might have been found much later than it was if it weren't for the fact that it had to be there if the periodic table was correct."

MONSTER MACHINE Gammasphere, a -ray spectrometer, uses 110 Ge semiconductor detectors. Although harmless, it was used as the model for the monster-making machine in the 2003 film "The Hulk."
COURTESY OF LAWRENCE BERKELEY NATIONAL LABORATORY


Bethany Halford is an assistant editor at C&EN. Five nines of the time spent on this essay went into writing this sentence.


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GERMANIUM AT A GLANCE
Name: From the Latin Germania, Germany.
Atomic mass: 72.64
History: In 1871, Mendeleyev used his periodic table to predict the existence of a silicon-like element. German chemist Clemens Winkler discovered it 15 years later.
Occurrence: are. Found in coal and compounds such as argyrodite.
Appearance: Gray, solid metalloid.
Behavior: Germanium is a semiconductor but exhibits poor conductivity.
Uses: Doped germanium materials are used to make transistors for miniature electronics.

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