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The earliest determinations of crystal structure

However, the great breakthrough in crystal structure determination came in a paper authored solely by WLB, 'The Structure of Some Crystals as indicated by their Diffraction of X-rays' read to the Royal Society on 26th June 1913 and subsequently published(13). This paper was followed immediately by a joint paper on the Structure of the Diamond(14). The structural analysis confirmed the tetravalency of the carbon atom. The crystal itself, a particularly fine specimen, was supplied surreptitiously (i.e. against the instructions of the Professor) by Arthur Hutchinson, a demonstrator in Mineralogy at Cambridge.

The Professor was Lewis and he had given strict orders that no mineral should ever leave the safe-keeping of the collection at Cambridge. Many years later WLB recalled: "I shall never forget Hutchinson's kindness in organising a black market in minerals to help a callow young student. I got all my first specimens and all my first advice from him and I am afraid that Professor Lewis never discovered the source of my supply".

By the end of 1913 the Braggs submitted three further papers to the Royal Society: Influence of the Constituent of a Crystal on the Form of the Spectrum in the X-ray Spectrometer(15) (WHB, read November 27th) and Analysis of Crystals in the X-ray Spectrometer(16), (WLB read November 27th) which gave the complete analysis of CaF2 (fluorite), FeS2 (iron pyrites) ZnS (zinc blende) and a proposed structure for CaCO3 (calcite) and finally 'The X-ray Spectra given by Crystals of Sulphur and Quartz'17 WHB, received December 1st 1913 read January 29th 1914.

The papers recorded above cover the period of the dated entries in the notebook. However, the Braggs' work with the spectrometer in this last summer of Edwardian peace was soon to be interrupted by the cataclysm of the first world war, which also saw the termination of their association with Leeds. WLB enlisted in the Horse Artillery in August 1914 shortly after the outbreak of war and was billeted in Norfolk before being sent over to France in August 1915.

During this 'phoney war' period he wrote, in collaboration with his father the book, X-rays and Crystal Structure(8), first published by Bell in 1915 and subsequent editions to 1928. Early in 1915 WHB accepted the Quain chair of Physics at University College London but almost immediately was seconded to be Resident Director of Research at a naval research station in the Firth of Forth.

The closing months of 1915 were, for the Bragg family, a time both of tragedy and triumph. In September WLB's younger brother, Bob, was killed in the Gallipoli landings, and in November he and his father were jointly awarded the 1915 Nobel Prize for physics. The news of both reached WLB from his parents whilst on service in France. WLB, at the age of 25, still holds the record as the youngest person ever to have won a Nobel Prize.