Memorial Tributes: Volume 27
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  • Don Uhlmann
  • Vincent Fratello
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  • KENNETH A. JACKSON (1930-2022)
    KENNETH A. JACKSON

     

    BY VINCENT FRATELLO AND DON UHLMANN

    KENNETH ARTHUR JACKSON, a pioneering research physicist known for his groundbreaking work in crystal growth physics, passed away January 7, 2022, at the age of 91 at his home in Prescott, Arizona.

    Ken’s life was a shining example of great curiosity enhanced by a brilliant scientific mind and remarkable diligence in his continuous quest for excellence in research. His major scientific interests were the shape and form of crystals and how they evolve, kinetic processes of crystal growth, the molecular theory of crystal growth, thin film growth and characterization, ion beam processes, and semiconductor processing.

    His contributions include enhanced understanding and theory of constitutional supercooling, which laid the foundation for the field of shape stability of crystals during growth, the surface roughening transition, defect formation in crystals, and studies of alloy crystallization and molecular dynamics simulations of crystal growth. Ken rationalized the crystallization behavior of inorganic and organic compounds in terms of the dimensionless entropy of melting, ΔSm/R, which is used as a scale for the ease of crystallization.

    Ken was born in Connaught, Ontario, on October 23, 1930, and grew up in Timmins, a modest-sized city in northeastern Ontario. Throughout elementary and high school, he enjoyed skating and playing hockey on ice-covered asphalt surfaces. Given the climate of the region (temperatures of −20°F to −40°F were not uncommon), ice was produced by simply flooding the surfaces with water.

    As an undergraduate at the University of Toronto he was a star pupil of Professor Bruce Chalmers (NAS 1975), who became the first editor of Acta Metallurgica the year Ken received his BS degree in engineering physics (1952). It was Chalmers who inspired Ken’s interest in what was to become his passion, the study of crystal growth in all its ramifications. Chalmers assembled an outstanding group of young scientists at Toronto. Besides Ken, the group included Bill Tiller and John Rutter. Working under Chalmers’ tutelage, this triumvirate of scholars analyzed the mathematics of the diffusion process in the liquid ahead of a crystal growth interface and derived the equation for constitutional supercooling, producing a seminal paper, “The Redistribution of Solute Atoms During the Solidification of Metals,”1 that had an enormous influence on the field and has been cited more than a thousand times.

    Ken received his MS in metallurgy from the University of Toronto in 1953 and then went with Chalmers to Harvard, where he received his PhD in applied physics three years later (1956) and was appointed assistant professor. He then tackled surface roughening and developed what became celebrated as the Jackson a factor, which gives a relatively smooth surface with a few adatoms and a few missing atoms for a large value, and an atomically rough surface for a small value.2 This factor includes the entropy of fusion and the fraction of bonds that an atom makes to neighbors in an interface plane and makes it possible to predict the growth mechanisms of different materials. Ken’s model was conceptually simple (as a single-level Bragg-Williams type of model), but it had outstanding predictive power that was not surpassed by subsequent, more sophisticated models.

    Ken was an inspiring teacher, even in courses dealing with “dry” subjects such as crystallography, and a mentor to many students. He was not content to provide insight into crystal growth only to fellow scientists but took on a responsibility for educating the public about the field. Perhaps the most striking example of this is the ice machine that he developed for the Boston Museum of Science, demonstrating that water can be supercooled well below the melting point of ice because of the necessity of forming crystal nuclei.

    In 1962 Ken joined AT&T Bell Laboratories in Murray Hill, New Jersey, as head of the Materials Physics Research Group. He found a kindred spirit in postdoc John Hunt. They found they could estimate the entropy of fusion of a material from its crystallization morphology,3 and made a movie to illustrate typical growth morphologies for materials with various entropies of fusion (it is available from the AT&T archives on YouTube4). Ken and John went on to study the question of where the nuclei come from to make the equiaxed zone in metal alloy castings. When they presented this work at a TMS meeting, Cyril Stanley Smith (NAS 1957) said that (as Ken quoted him) “he had learned more about castings in the past 30 minutes than he had in the previous 20 years.” Ken and John further studied dendritic growth and experimentally compared the calculated interface shapes, defining the three classes of dendrite microstructures based on the entropies of fusion of the components.5

    Ken also pioneered computer simulation studies of atomic-scale processes during crystal growth, in collaboration with George Gilmer and Harry Leamy. They were able to generate excellent and enlightening images of surfaces below and above the surface roughening transition.6

    In 1989 Ken joined W. David Kingery (NAE 1975) and one of the authors (DRU) at the University of Arizona when he accepted an appointment as professor of materials science and engineering. He developed an active research group of young scientists and engineers and together they contributed important new insight into nonequilibrium segregation during crystal growth, nucleation and growth in an Ising-type system, crystallization of silicon simulated using Monte Carlo modeling,7 discontinuities in growth rate as a function of undercooling, impurity distribution in InSb single crystals, and nonequilibrium phase transformations. He also continued his interest in electronic packaging viewed from a materials perspective.

    In 2004, when he entered his 74th year, Ken decided to retire from the university, becoming professor emeritus, and to direct his effort full time to completing his book, Kinetic Processes: Crystal Growth, Diffusion and Phase Transitions in Materials (Wiley, 2004). This volume, now in its second edition, provides his unique and insightful perspective on kinetic processes in materials.

    An important facet of Ken’s role at Bell Labs was the leadership and support he displayed for the materials science community as a whole. He was part of the organizing committee of the first International Conference on Crystal Growth (ICCG) in Boston in 1966. In 1974 he was founding copresident, with Robert A. Laudise (NAE 1980, NAS 1991), of the American Association for Crystal Growth (AACG), which was critical in developing crystal growth as an independent discipline. In Ken’s words, “One of the prime motivations for starting the AACG, in addition to establishing a forum where we could assemble to interchange our news and views on the subject, was to promote crystal growth and to provide an identity for our field.”

    In 1978 Ken also served as the third president of the Materials Research Society (MRS), which was then in its formative years. He pushed to hold the first Laser Annealing symposium at the 1978 meeting, a great success in attracting the electronic materials community. Ken realized that this represented new, very fast regimes of crystal growth.

    Of the more than 145 articles he published, notable review papers include “On the Nature of Crystal Growth from the Melt”8 and “The Interface Kinetics of Crystal Growth Processes.”9 He also edited ten books and held four patents. In addition to his published work, Ken leaves a rich legacy in his scientific family tree as a teacher and mentor.

    Among Ken’s honors, he won the Frank Prize of the International Organization for Crystal Growth (IOCG) at ICCG-XII in Jerusalem in 1998. Five years later he was selected for the Bruce Chalmers Award (2003) from the Materials Processing & Manufacturing Division of the Minerals, Metals & Materials Society “For outstanding contributions to the science of solidification with physically realistic interpretations and analyses of diverse kinetic phenomena at crystal-liquid interfaces.” He was made a lifetime member of the AACG executive committee, and he was elected to the NAE in 2005.

    Ken lived life to the fullest. He was a connoisseur of food and wine, and loved living in Arizona because he could eat dinner outdoors almost every day of the year. His manifold passions also included photography, woodworking, painting, ice hockey (having been born with skates on his feet like the Ontario native he was), and skiing. He canoed (with the Murray Hill Canoe Club), tested his endurance on long climbing hikes and bicycle rallies, and square danced. He traveled widely, became an accomplished folk and classical guitarist, and hosted memorable blind wine tastings. He also enjoyed kayaking, sailing, and other outdoor activities with his wife, Gina Kritchevsky. After his retirement they moved to Prescott.

    Ken is survived by Gina, daughters Stacy Jackson Pendell and Meredith Jackson Voboril, and four grandchildren.

    We join his family and all his friends worldwide in celebrating a life well lived and remembering our friend and colleague Ken. The scientific community and the world are better for his generous spirit and contributions.

    _________________________
    1 Tiller WA, Jackson KA, Rutter JW, Chalmers B. 1953. Acta Metallurgica 1(4):428–37.
    2Jackson KA. 1958. Liquid Metals and Solidification (p. 174). Cleveland: ASM.
    3Jackson KA, Hunt JD. 1965. Transparent compounds that freeze like metals. Acta Metallurgica 13(11):1212–15.
    4 https://www.youtube.com/watch?v=Y3GwvN5W1dE
    5 Jackson KA, Hunt JD. 1966. Lamellar and rod eutectic growth. Transactions of the Metallurgical Society of AIME 236(8):1129.
    6 Leamy HJ, Gilmer GH, Jackson KA. 1975. Statistical dynamics of clean surfaces. In: Surface Physics on Materials, Vol. 1 (p. 121), ed. JM Blakely. New York: Academic Press.
    7 Beatty KM, Jackson KA. 2000. Monte Carlo modeling of silicon crystal growth. Journal of Crystal Growth 211(1):13–17.
    8 Jackson KA, Uhlmann DR, Hunt JD. 1967. Journal of Crystal Growth 1(1):1–36.
    9 Jackson KA. 2002. Interface Science 10(2-3):159–69.