Clara Brink Shoemaker (1921-2009)

[Clara Brink Shoemaker]

Clara Brink Shoemaker, professor emeritus at Oregon State U., died September 30, 2009. Clara was born in Rolde, Netherlands, in 1921. She received her doctorate in chemical crystallography from Utrecht U. in 1950, having studied crystallography with Caroline MacGillavry in Amsterdam, with whom she published the crystal structures of K2AgI3 and K2CuCl3. Clara worked with Dorothy Hodgkin on Vitamin B12 in Oxford and was encouraged, both by MacGillavry and Hodgkin, to consider further postdoctoral experience. Possibly influenced by a niece living in Boston who was married to Nicholaas Bloembergen, a faculty member in Harvard's Physics Department and subsequent Nobel Prize winner, she went to MIT, where she was warmly welcomed by Martin Buerger and Bertram Warren.

Her collaboration with David Shoemaker led to their first joint study published in Acta Cryst. in 1955. They established the σ-phase materials as typifying a promising new field. In August of that year, Clara and David were married in MIT's chapel. They were the first to recognize that interstices in tetrahedrally close-packed metal crystals are exclusively tetrahedral, with coordination types restricted to a set of four with coordination numbers 16, 15, 14 and 12. They also noted that half the hexagonal holes present in σ-phase materials become distorted pentagons in the P-phase, resulting in a coordination number reduction from 14 to 12 in half the atoms of the subsidiary layers.

Many contributions to this new field of intermetallic structure followed, including a major paper by Linus Pauling in 1988 on icosahedral cluster P-phase packing that acknowledged their early work. Among these are numerous X-ray and neutron diffraction and modeling studies by others. The σ and P phases, now among the most intensively studied intermetallics due to their tendency to precipitate from stainless steels in the form of austenitic, ferritic or austenitic-ferritic phases, have given rise to a large literature in which the pioneering work of Clara and David is often referenced.

Clara's breadth of interest is exemplified by her publications, including an insulin analysis with Barbara Low, the nature of the S-O bond with Klass Eriks, a coding system applicable to a wide range of layered tetrahedrally close-packed structures, a hypothetical tetrahedrally close-packed σ-phase proposed by Erwin Parthé, and demonstration of the existence of the pentagon-σ structure with composition FeSiW with Bill Pearson, NRC Canada.

In 1970, David accepted both the chairmanship of the Chemistry Department at Oregon State U. and the presidency of the American Crystallographic Association. State regulations prohibited close family members from holding faculty positions at the same time. The potential impediment to Clara's appointment was examined by the president of the university, Robert MacVicar, who discovered that the law prohibited joint family appointments 'except under exceptional circumstances'. He announced that any husband and wife scientific team qualified as an exceptional circumstance and Clara's appointment, as well as that of Lise Hedberg, wife of one of the present authors, went forward. It was determined that each husband would take responsibility for the scientific effort of the other's wife. This arrangement required that each husband assure the other that his wife was doing a good job. The process was certainly easy to carry out, but seems a bit comical in retrospect. Clara and David attended all IUCr Congresses from the 4th (Montreal, 1957) to the 13th (Hamburg, 1984).

Clara maintained her departmental contacts after David's death, joining a luncheon discussion group each Friday and participating in morning coffee-break sessions. She enjoyed both chamber and orchestral music and regularly attended the Oregon Shakespeare Festival.

Erudite and cultured, Clara was also kind, gentle and characteristically reserved. She loved her family and was proud of her son Robert, Professor of 18th-Century British History and Co-Director, Old Bailey Online, Plebeian Lives and the Making of Modern London, at the U. of Sheffield in the UK. She was delighted that her grandson Roland is presently a third-generation Shoemaker undergraduate at Reed College. Clara Brink Shoemaker was a fine person in every respect, and her friends and colleagues will miss her greatly.

We gratefully acknowledge the biographical notes on Clara compiled by Mary F. Singleton, available at:

Sidney C. Abrahams and Kenneth Hedberg