J. Appl. Cryst. (1996). 29, 746.
Melvin H. Mueller died of heart disease Friday 28 June 1996. Mel, as he was known to all his friends, was born 22 February 1918 in Spencer, Iowa and graduated PhD in Chemistry from the University of Illinois in 1949. After several years at Deere & Company, the US Rubber Company and the University of Illinois, he joined the Argonne National Laboratory in 1960; he was a Senior Scientist at Argonne when he retired. Mel was very active in actinide structural research and published numerous papers in that field. He continued a successful collaboration with his Argonne colleagues after retirement. He made many significant contributions to powder diffraction methods. Among them, his 1960 least-squares program for lattice-parameter determination written with LeRoy Heaton and K. T. Miller is still highly regarded and widely used. He collected the first set of single-crystal neutron diffraction data on the CP-5 reactor, in collaboration with Sid Sidhu and Stan Simonsen. His knowledge of the numerous uranium phases, including anisotropic grain growth in bulk uranium (later used as a target material at the IPNS spallation neutron source at Argonne), led to phase characterization of the uranium silicides. Mel also made numerous major contributions to a variety of scientific organizations. In all of them, his was a voice of reason and compassion in difficult situations. He served most effectively as Secretary of the American Crystallographic Association from 1973 to 1975, undertaking any task that would advance the ACA regardless of the time and effort required. He was later appointed to the American Institute of Physics Governing Board from 1981 to 1987, serving as a Member of the Executive Committee from 1985 to 1986, and is remembered as a very thoughtful and supportive member of both AIP governance bodies. He also served on the International Centre for Diffraction Data (ICDD) Board of Directors from 1991 to 1995. His association with the ICDD goes back to its predecessor, the Joint Committee on Powder Diffraction Standards. He served on a number of ICDD committees after retiring from Argonne. His work on the Metals and Alloys Subcommittee resulted in the recently produced Metals & Alloys Search Manual being always current and available in a form that was most useful both for newcomers and those more experienced in the field. Mel chaired the Grants-in-Aid Committee from 1989 to 1993, a period over which the number of grant recipients, especially from overseas, increased significantly; much of this increase is directly attributable to Mel's efforts. Ancillary to his own studies, many first-rate powder diffraction patterns were developed that he then contributed to the Powder Diffraction File. His positive attitude toward life and its challenges earned him a host of lasting friends. He will long be remembered by them as a fine scientist, an enthusiastic collaborator, and a compassionate human being who will be sadly missed.
R. A. YOUNG
Index to Crystallographers
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