Obituary: Professor Bela Szigeti

Bela Szigeti was one of the remarkably large number of Hungarians to achieve distinction in a career in physics. Like many of these he spent most of his working life outside Hungary. His own contribution was to the extremely successful and important post-war effort to develop the basic ideas necessary for understanding the physical properties of solids. A significant part of this effort was directed towards understanding in detail the effects of steady electric fields and of light on transparent crystals such as rock-salt. This was the subject of much of his work at the universities of Bristol, Liverpool and Reading.

He was born in Budapest in 1912, the second son of landowners, and the grandson of a judge. Although he spoke only rarely of his early life, it was clear that he placed great value on the rich cultural background he had enjoyed and on his broad general education, extending from science to Latin and Greek. This was the basis of the breadth of knowledge and wide range of intellectual interests which enriched his life.

He went to Switzerland for his higher education and obtained his PhD in physical chemistry at the University of Zurich shortly before the Second World War. He came to England early in 1939 and until 1941 worked on the application of spectroscopic methods to medical problems, first at St Bartholomew's Hospital, in London, and then in Cambridge. From 1941 to 1945 he did war work in an industrial laboratory.

Szigeti then switched to theoretical physics and from 1945 to 1948 carried out theoretical research in the H.H. Wills Physics Laboratory at Bristol University. His work there on the properties of ionic crystalline solid materials led to his deriving two key relations between dielectric, elastic and vibrational properties. These relations, known universally as the Szigeti relations, already marked him as a theoretical physicist of importance.

From 1948 to 1962 he was on the staff of the Theoretical Physics Department of Liverpool University, where he devoted considerable attention to the torsional (twisting) vibrations of long chain molecules, as well as extending his work on ionic crystals. His ideas on polarisation processes in crystals, in particular his clear perception of the role of the deformations of ions by forces from their near neighbours, were vital for the advances which he, and others influenced by him, subsequently made in the understanding of the motion of atoms in crystals. His important contributions to this field included studies of the effects of impurities on the properties of crystals, a line of investigation which he pursued much further in the Physics Department of Reading University, where from 1962 to his retirement in 1977 he was successively Lecturer, Reader and Professor.

At Reading his own work and work in collaboration, particularly with his colleague Roy Leigh, was very fruitful. Much of this work was prompted by experimental studies in progress there on vibrational properties of impurities in diamond and semi-conducting crystals. The critical examination of the theories then used in the interpretation of such experiments led to important new insights. He demonstrated the limitations of information about vibrations in perfect crystals obtainable from the neutron scattering experiments being conducted in laboratories across the world.

Even a much fuller account of the results of his work would be incomplete if it did not comment on the style of his investigations. Szigeti's aim was always deep understanding of the problem in hand and he was little concerned about how long it took to achieve that understanding. As a result his publications were clear and rigorous and invariably of substantial significance.

Until her early death in 1965, he shared his keen interest in art, music and the theatre with his wife, Lois. His other recreations included chess and bridge, but conversation was his main pleasure. He was an attached member of one of the University Halls at Reading and up to very recently was a regular attender at guest nights. He also enjoyed conversation with friends over coffee. A typical evening would start with conversation, but this would be followed by viewing a film from his collection of videos. His preference was for musicals, comedies and histories. It is perhaps not impertinent to speculate that he enjoyed these mainly as relaxation but also as bringing him from time to time, in a light-hearted way, echoes of his early years in Hungary.

Bela Szigeti, physicist: born Budapest 2 August 1912; married 1946 Lois Yearsley (deceased); died Reading 17 March 1996.