Technology: Plastic magnets that turn in the cold

 作者:钟离巯隗     |      日期:2019-03-04 09:16:01
A JAPANESE laboratory has produced a plastic that exhibits magnetic properties at low temperatures. This breakthrough could greatly affect technologies such as magnetic sensors. Previous attempts to make magnetic plastics could not produce a uniform material of consistent quality, but the group at the University of Hokkaido in northern Japan is using a process that avoids many of these difficulties. The team, led by Masaaki Tabata, made the material by dissolving a derivative of acetylene in ethanol and reacting it in the presence of a rhodium catalyst for 24 hours. A yellow precipitate was produced which, when heated to 200 Degree C, transformed into a plastic material of uniform characteristics. The material is nonmagnetic at room temperature, but at temperatures lower than -180 Degree C it shows magnetic properties. This is just above the temperature of liquid nitrogen. Many companies, including IBM and Du Pont, are working on magnetic plastics, but the processes developed so far have been unreliable. The reason for their interest in the plastics is that they can be pressed into very thin films to make new types of magnetic sensors. Other applications, for example replacing metal magnets in loudspeakers,