Piero Giorgio Bordoni

Piero Giorgio Bordoni (Rome, 18 July 1915 – 19 September 2009) was an Italian physicist, who first measured the anelastic relaxation effect (dissipation of elastic energy and softening of the elastic modulus), named after him, due to the stress induced motion of dislocations in metals. That experiment, together with a similar one by T.S. Kê, opened the way to the study of the dynamics of dislocations in solids. Those were also the first experiments of anelasticity in solids, a branch of physics studying defects, excitations and phase transitions in condensed matter, first systematised by Clarence Zener.

He received the Degree in Electrotechnical Engineering at the Sapienza University of Rome in 1937, following the steps of his father, Ugo Bordoni, Engineering Professor in the same Faculty (after whom the Fondazione Ugo Bordoni was named in Italy, established in 1952 for supporting research and applications of telecommunications).

His interest in acoustics was first aroused, still a student in 1936, by the invitation to join the newly founded Institute of Ultracoustics (later of Electroacoustics and then of Acoustics) of Consiglio Nazionale delle Ricerche (CNR), then directed by Orso Mario Corbino.

During the Second World War, he was initially in the Aeronautics and head of the Laboratory of Electroacoustics in Guidonia, where he worked at acoustically triggered torpedoes for the Navy.

In 1944 he became researcher of the Institute of Ultracoustics.

In 1947/8 he obtained a fellowship from CNR to stay 8 months at the Massachusetts Institute of Technology of Boston for studying the acoustic properties of lead down to liquid helium temperatures in the laboratory of John C. Slater, and discovered the anelastic effect due to dislocations, later named "Bordoni relaxation" or "Bordoni peak".

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