William Houlder Zachariasen

William Houlder Zachariasen (5 February 1906 – 24 December 1979), more often known as W. H. Zachariasen, was a Norwegian-American physicist, specializing in X-ray crystallography and famous for his work on the structure of glass.^[1]

Background

Zachariasen was born in

Career

In 1930 Zachariasen, at the age of 24, became a member of the faculty of physics at the

In 1930, before leaving Norway, Zachariasen married Ragni Durban-Hansen, granddaughter of the geologist W. C. Brøgger. The Zachariasens had two children, Fredrik and Ellen. As a couple, the Zachariasens were close friends with four other couples consisting of four male physicists and their wives. The four physicists were: Samuel Allison, Elmer Dershem (1881–1965), Marcel Schein, and John Harry Williams (1908–1966). Allison, Williams, and Zachariasen took a number of canoeing vacations together, sometimes accompanied by Rudolph "Buddy" Thorness (1909–1969)^[11] and perhaps one or two other men. In 1974, Zachariasen retired from the University of Chicago and moved with his wife to Santa Fe, New Mexico, where they purchased the first house they ever owned. He continued to write scientific papers, often working with his friends Finley H. Ellinger and Robert A. Penneman, both from Los Alamos National Laboratory. Zachariasen also worked with Bernd Matthias, a professor at the University of California, San Diego. Zachariasen's son, Fredrik "Zach" Zachariasen (1931–1999), was a theoretical physicist, specializing in the interactions of elementary particles at high energies. Fredrik Zachariasen was a physics professor at Caltech and coauthored two books on high energy physics and another book related to the acoustics of antisubmarine warfare.^[12]

Influence on the science of glass

In 1932 W. H. Zachariasen published "The Atomic Arrangement in Glass",^[13] a classic article that greatly influenced material scientists of that era. This article perhaps had more influence than any other published work on the science of glass. A glass has an amorphous structure, whereas a crystal has a long-range ordered structure; however, both glasses and crystals have the same building blocks, i.e. polyhedra consisting of cations and anions bound together. The crystallographer Zachariasen is generally credited as the greatest pioneer of the understanding of the structure of glass for his 1932 random network theory of glass. In this theory, the nature of bonding in the glass is the same as in the crystal, but the basic structural units in a glass are connected in a random manner in contrast to the periodic arrangement in a crystalline material. The work of Zachariasen provided a foundation for the development of the understanding of the structure of glass and the structure's relation with its chemical composition. According to Professor Richard L. Lehman of Rutgers University, "Zachariasen considered the relative glass-forming ability of oxides and concluded that the ultimate condition for glass formation is that a substance can form extended three-dimensional networks lacking periodicity but with energy comparable with that of the corresponding crystal networks. From this condition he derived four rules for oxide structure that allow selection of those oxides that tend to form glasses. ... Overall, in spite of Zachariasen's mediocre prediction record, he has received great recognition as being the first to systematically address the relationship between atomic structure and glass forming ability."^[14]

Assume that ${\displaystyle A}$ represents a metal atom, i.e. a cation. The four rules for the formation of a glass from an oxide ${\displaystyle A_{m}O_{n}}$ are:

• An oxygen atom is linked to no more than two glass-forming atoms A.
• The number of oxygen atoms around each glass-forming atom A is small, perhaps 3 or 4.
• Among the oxygen-containing polyhedra, a polyhedron cation A shares corners, but no sides or faces.
• For three-dimensional networks of oxygen-containing polyhedra, at least three corners must be shared.

Work on 5f elements

According to Robert Penneman of Los Alamos National Laboratory, "No other crystallographer has done so much to expand our knowledge of heavy element chemistry, or had a such a central role in the development of atomic energy." During the early stages of the Manhattan Project, only microgram quantities of the transuranium elements were produced. The chemists who did microchemistry on these samples of transuranium elements sent the samples in capillaries to Zachariasen to find out what the samples consisted of. Zachariasen's X-ray diffraction analysis was an essential basis for experimental evidence that the transuranium elements formed a 5f series analogous to the 4f series of the rare-earth elements. His X-ray studies of the transuranium elements were essential for the development of the metallurgy of the transuranium elements, particularly plutonium. In 1948 he published a paper on new structure types for compounds of the 5f series of elements.^[15]

Physics Department at University of Chicago

According to

The changes that Willie made were momentous and lasting. He immediately ended the domination of the department by Michelson's grating ruling engines by giving them away, one to Bausch and Lomb, and one to the Massachusetts Institute of Technology. He immediately turned the department from autocratic to democratic. The then tenured faculty met for the first time in many years to consider departmental affairs.

Zachariasen, with the support of the physics department faculty, brought

• Crystal chemistry
• Pauling's rules
• Structure of liquids and glasses
• X-ray crystallography

References