A neutron diffraction program was initiated recently at the Puerto Rico Nuclear Center. The two double crystal spectrometers in use were assembled with the aid of staff members of the Brookhaven National Laboratory. The first research problem to be completed was a single crystal structure analysis of CaWO4. Choosing the origin at the 4(a) tungsten site in the tetragonal I41/a cell. the 16(f) oxygen parameters were found to be as follows: x=0.2413 ± 0.0005, y=0.1511 ± 0.0006, z=0.0861 ± 0.0001. Anisotropic temperature parameters were also determined for all atoms in the least squares analysis of the structure. The magnetic structure …
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Brookhaven National Laboratory Report BNL-7290
Description
A neutron diffraction program was initiated recently at the Puerto Rico Nuclear Center. The two double crystal spectrometers in use were assembled with the aid of staff members of the Brookhaven National Laboratory. The first research problem to be completed was a single crystal structure analysis of CaWO4. Choosing the origin at the 4(a) tungsten site in the tetragonal I41/a cell. the 16(f) oxygen parameters were found to be as follows: x=0.2413 ± 0.0005, y=0.1511 ± 0.0006, z=0.0861 ± 0.0001. Anisotropic temperature parameters were also determined for all atoms in the least squares analysis of the structure. The magnetic structure of CuSO4 has been determined in a continuation of a study started at Brookhaven in collaboration with Dr. P.J. Brown. Using the Wollan-Koehler-Bertaut notation, the antiferromagnetic spin ordering mode in the orthorhombic Pbnm cell is Ax, with the spin axis parallel to a. A moment of approximately 1 μB was found for the Cu2_ ion. The crystal structure of BaNiO2 was re-examined in a neutron powder diffraction study, and it was found that the earlier x-ray study of Lander is essentially correct. An alternative oxygen arrangement, for which x-rays would not have been very sensitive, had been suspected. BaNiO2 was also investigated for magnetic order at 4.2°K but conclusive results have not been obtained. A magnetic transition has been found in Fe2SiO4 in the neighborhood of 30°K. This compound has an olivine type structure with eight Fe2+ ions in the 4(a) and 4(c) positions of the Pbnm space group. Analysis of the magnetic structure is still in progress, but some preliminary results are discussed.
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Almodovar, I; Bielen, H. J. & Frazer, B. C.Neutron Diffraction Studies at the Puerto Rico Nuclear Center,
report,
October 15, 1963;
Washington D.C..
(https://digital.library.unt.edu/ark:/67531/metadc1255880/:
accessed July 18, 2025),
University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.