Conductivity Breakthrough Has Promise: Practical Uses
Researchers have discovered a new family of ceramics that promise to carry much greater electrical currents than existing “high-temperature” superconductors, experts said Monday.
The new materials, discussed publicly for the first time here at a meeting of the American Assn. for the Advancement of Science, promise to bring practical applications of superconductors much nearer to reality.
The inability of the high-temperature superconductors to carry large amounts of current has been the chief problem dogging the new materials since their discovery was reported 16 months ago.
Unless superconductors can carry large amounts of current, they cannot be used for such promising applications as long-distance electric power transmission, high-speed, magnetically levitated trains and ultrafast computers.
‘Very Good News’
The latest discovery, first announced in Japan and the first breakthrough in superconductor research in nearly a year, “is very good news for all of us,” said physicist K. Alex Muller of IBM. Muller shared the 1987 Nobel Prize for physics for the discovery of the high-temperature superconductors.
Superconductors carry electricity with no losses due to resistance. But until 16 months ago, the only materials that could do this had to be cooled to temperatures near absolute zero (minus 459 degrees Fahrenheit) to achieve superconductivity. That is a very expensive proposition.
In 1986, Muller and J. Georg Bednorz of IBM reported that a ceramic composed of barium, strontium, copper and oxygen was superconducting at minus 396 degrees, well above existing superconductor temperatures.
That discovery touched off a race that culminated last February when Paul C. W. Chu of the University of Houston announced that a ceramic made of barium, yttrium, copper and oxygen was superconducting at minus 297 degrees. Chu’s finding was crucial because it meant that the new superconductors could be cooled with inexpensive liquid nitrogen, which boils at minus 321 degrees. Cheap cooling is necessary for most potential applications of superconductivity.
Intensive Research
Despite intensive research at laboratories around the world, scientists had been unable to find superconductors that worked at still higher temperatures.
But on Jan. 22, a Japanese financial newspaper reported that Hiroshi Maeda and his colleagues at the National Research Institute of Metals in Tsukuba had discovered a different ceramic--composed of bismuth, strontium, calcium, copper and oxygen--that is superconducting at minus 243 degrees, nearly 50 degrees higher than the existing materials.
That discovery has since been confirmed by at least half a dozen large laboratories in the United States and Europe, said physicist Praveen Chaudhari of IBM.
No one has actually measured the current-carrying capacity of the new material, said physicist John M. Rowell of Bell Communications Research in Red Bank, N.J. But researchers are confident that it will have a high capacity, he said.
The key is that the current-carrying capacity of all superconductors increases sharply as they are cooled below the temperature at which they become superconducting--the so-called critical temperature. The critical temperatures of the existing superconducting ceramics are so close to the boiling point of liquid nitrogen that researchers haven’t been able to take advantage of this characteristic.
Critical Temperature
But because the bismuth compound’s critical temperature is nearly 50 degrees higher, it should be able to carry a much higher current. “It would be staggering if it didn’t behave this way,” Rowell said.
Some evidence also suggests that the new material can be more easily fabricated into wires and other shapes than the previous ceramics, Rowell added. This would also simplify the production of practical superconducting devices.
In other developments at the meeting:
- A Massachusetts Institute of Technology researcher theorized that a storm of acid rain as poisonous as battery acid killed off the dinosaurs and other creatures 64 million years ago.
Animals deep in their burrows and creatures living in lakes with limestone bottoms might have been among the few survivors, said Ronald G. Prinn of MIT.
The new theory is a variation on a hotly debated hypothesis that an asteroid doomed the dinosaurs.
Prinn suggests that a large comet--one that makes Halley’s comet look like “a little speck of sand”--struck the Earth with 1 million times more force than the world’s entire nuclear arsenal.
Prinn theorizes that when the comet hit, it blasted out a crater, spewing water and rock into the air at supersonic speeds, suddenly heating the atmosphere to enormous temperatures. The heat made oxygen and nitrogen in the air combine to form nitric acid, which rained on Earth for a year.
The idea that an asteroid wiped out the dinosaurs was first proposed in 1980 by physicist Luis Alvarez and his son, Walter, a geologist. They said that dust and soot thrown into the air would have blocked out the sunlight. Temperatures would have plummeted, and many animals, including the dinosaurs, would have frozen to death.
Prinn noted that while there was a large extinction, not all animals fared equally badly. The great land reptiles and many kinds of sea life were decimated, but many mammals and plants survived reasonably well. He said his acid rain theory may explain “the peculiar selectivity of the extinctions.”
Hibernating Animals
Because limestone would neutralize the acid, fish in limestone lakes might have lived. Hibernating animals deep in burrows might also have waited out the worst of the acid rain storm, and eggs laid in the ground could also have survived.
Plants would have been killed, but their seeds would have remained to sprout after the acid storm cleared. However, plant-eating animals, such as large dinosaurs, would have starved or been asphyxiated.
Many scientists doubt that something from space caused the massive destruction of species. They note that dinosaurs and other long-gone creatures died out over many centuries, not all at once, so a single catastrophe cannot be the culprit.
- Research in Scandinavia suggests that schoolyard bullies are apparently much more likely than other children to be headed for a life of crime, according to Dan Olweus, a professor of psychology at the University of Bergen in Norway.
He said large Scandinavian studies indicate the common phenomenon of bullying in the schools can also damage the emotional health of victims.
The research showed that 60% of boys who were considered to be bullies in grades 6 through 9 had at least one court conviction by age 24, and 40% of the bullies had three or more court convictions by the same age. In comparison, only 10% of children who were not bullies got into trouble with the law at that age.
