Past and present crystallographic work at the NBS/NIST reactor

Abstract

Neutron diffraction at NBS/NIST started soon after the NBS reactor became operational in the summer of 1969. Since that time, literally hundreds of crystal structures have been determined and refined using single crystal and powder neutron diffraction data, collected with a variety of instruments. This work has been usually done in collaboration with other NBS/NIST divisions and/or universities and industrial laboratories. In parallel with the technical developments and the experimental work, also theoretical aspects of crystal geometry have been clarified, and significant improvements in the techniques of profile refinements have been made. It is therefore understandable that a comprehensive description of all the crystallographic studies carried out up to the present is impossible under the constraints of space and time imposed by a review of this type, and, in the following sections, we will limit ourselves to give, only a brief account of the topics which, in our opinion, represent the highlights of the work carried out at the reactor.

Magnetic phase diagram of the solid solution LaMn2(Ge1-xSix)2 (0 ≤ x ≤ 1) unraveled by powder neutron diffraction

“…At the CNBC, diffraction patterns for the LaMn 2 (Ge 1−x Si x ) 2 samples with x = 0.18, 0.58, 0.78 and 1 were collected on the High Resolution Powder Diffractometer C2 in the angular range 2θ between 18.9° to 99° with a neutron wavelength of λ = 2.3722(17) Å in a He-cryostat (3 K to 290 K) and a dedicated furnace (320 K to 380 K). At NCNR, the measurements with the compositions x = 0, 0.05, 0.33 and 0.47 took place at the High Resolution Neutron Powder Diffractometer BT-1 [51] equipped with 32 3 He detectors covering an angular range of 3° ≤ 2θ ≤ 166° with a step size of 0.050°. The data were collected using a Ge (311) monochromator wavelength of λ = 2.0787(2) Å and in pile collimation of 60 min per arc.…”

Magnetic phase diagram of the solid solution LaMn2(Ge1−xSix)2 (0 ≤ x ≤ 1) unraveled by powder neutron diffraction

“…At the CNBC, diffraction patterns for the LaMn 2 (Ge 1− x Si x ) 2 samples with x = 0.18, 0.58, 0.78 and 1 were collected on the High Resolution Powder Diffractometer C2 in the angular range 2 θ between 18.9° to 99° with a neutron wavelength of λ = 2.3722(17) Å in a He-cryostat (3 K to 290 K) and a dedicated furnace (320 K to 380 K). At NCNR, the measurements with the compositions x = 0, 0.05, 0.33 and 0.47 took place at the High Resolution Neutron Powder Diffractometer BT-1 56 equipped with 32 3 He detectors covering an angular range of 3° ≤ 2 θ ≤ 166° with a step size of 0.050°. The data were collected using a Ge (311) monochromator wavelength of λ = 2.0787(2) Å and in pile collimation of 60 min per arc.…”

Compact Thermal Actuation by Water and Flexible Hydrophobic Nanopore

“…The instrument is described elsewhere. 35 One gram of sample was loaded into an aluminum pressure cell connected to a syringe-pump system through a 1.6 mm stainless steel thin-wall tube. The temperature was controlled by a glycol−water circulating bath and was stable within 1 °C.…”

“…Data were collected over the range 1.3–166.3° 2-theta with a step size of 0.05°. The instrument is described elsewhere . One gram of sample was loaded into an aluminum pressure cell connected to a syringe-pump system through a 1.6 mm stainless steel thin-wall tube.…”