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Curie, Pierre

radioactivity effect temperature electric

(1859–1906) French physicist: discovered piezoelectric effect; pioneer in study of radioactivity.

The son of a physician, Pierre Curie was educated at the Sorbonne where he became an assistant teacher in 1878. He was appointed laboratory chief at the School of Industrial Physics and Chemistry in 1882 and in 1904 was appointed to a new chair of physics at the Sorbonne. He and his brother Jacques (1855–1941) first observed the phenomenon they named piezoelectricity; this occurs when certain crystals (eg quartz) are mechanically deformed; they develop opposite charges on opposite faces and, conversely, when an electric charge is applied to a crystal a deformation is produced. If a rapidly changing electric potential is applied, the faces of the crystal vibrate rapidly. This effect can be used to produce beams of ultrasound. Crystals with piezoelectric properties are used in microphones, pickups, pressure gauges and quartz oscillators for timepieces. Jacques and Pierre Curie used the effect to construct an electrometer to measure small electric charges; this was later used by his wife in her investigation into radioactivity. For his doctorate (1895), Pierre Curie studied the effect of heat on ferromagnetism and showed that at a certain temperature, specific to a substance, it will lose its ferromagnetic properties and become paramagnetic; this is now known as the Curie point (eg 1043 K for iron) He had already shown that magnetic susceptibility for diamagnetic materials is generally independent of temperature, but for paramagnetic materials the susceptibility is inversely proportional to absolute temperature (Curie’s Law).

He married Manya Sklodowska and thereafter followed her into research on radioactivity. Together with they were awarded the Nobel Prize for physics in 1903 for this work. Pierre Curie showed that 1 g of radium gave out about 500 J h –1 , the first indication of the energy available within the atom and the dangers of radioactivity.

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