Sample Environment Research & Development
Fig. 1. Cryogenic sample changer (FERNS) developed for the SNS powder diffractometer POWGEN, now available as a commercial product through Materials Development Inc.
Small business collaborations are providing a huge boost to the Sample Environment Program, particularly in the area of laboratory automation. The “FERNS” cryogenic sample changer (Fig. 1) [1] was delivered to the SNS in 2006, and has since undergone rigorous testing and upgrades to make it a user-ready system which is now available as a commercial product [2]. While FERNS handles sample cans, the SNS Liquids Reflectometer needs to handle sample plates designed for horizontal scattering geometry. A system featuring an articulating robot arm and environmentally controlled storage racks was designed and fabricated for the Liquids Reflectometer [3]. At the other end of the spectrum, the SNS Single Crystal Diffractometer “TOPAZ” will be cooling and remotely manipulating salt-grain-sized samples using a special system under development by a small business. [4]
Other R&D collaborations have led to the development of gas pressure cells, controlled atmosphere furnaces, and a controlled humidity cell. The humidity cell (Fig. 2) was tested and commissioned on the SNS Liquids Reflectometer during the summer [5]. Other new environments are more extreme. A 1700 Celsius controlled atmosphere reaction (CAR) furnace was tested off-line in October [6]. The CAR furnace will be commissioned on the HFIR WAND instrument, and will be available for use on other HFIR and SNS instruments. Additional furnace designs are under development. New gas pressure cells were also designed, including a sapphire cell optimized for inelastic measurements on the SNS BASIS instrument [7].
Fig. 3. Displex™ Closed Cycle Refrigerator customized for the Magnetism Reflectometer
A Swiss-led project to develop a 16-Tesla actively shielded split-coil vertical field magnet for neutron scattering [8] is progressing on schedule. The analysis phase was completed in April 2007 and the design phase is underway and will be completed by April 2008. The Swiss magnet will be delivered to the SNS in 2009. In the meantime, smaller systems have been ordered, such as a 5- Tesla actively shielded vertical magnet (ordered in 2006, delivery in late 2007) and a 2-Tesla electromagnet and integrated Displex system was installed on the SNS Magnetism Reflectometer. (Fig. 3)
ORNL scientists [9] performed the first in-situ study of phase transformation under simultaneous high magnetic field and high temperature. This proof of principle experiment began with building a high-temperature sample insert to fit inside the magnet on the WAND instrument of HFIR. (Fig. 4) A similar insert will be made for the SNS 16-Tesla magnet due to arrive in 2009. The success of this new technique opens the door to greater understanding of the role of magnetic field on structure changes at high temperatures.
Fig. 4. Special environment developed by ORNL scientists to study thermal-magnetic materials processing. For the first time ever, in-situ, time-resolved measurements of the shift in the equilibrium phase transformation temperatures by the application of a high magnetic field at elevated temperatures have been accomplished using neutron diffraction methods at the HFIR on Fe-C binary alloys.
References:
[1] J. E. Rix et. al., Rev. Sci. Inst., 78, 013907 (2007)
[2] Materials Development, Inc.
[3] Robert J. Viola, STTR Project: An Automated Sample Handling Workcell for the SNS Liquids Reflectometer, U.S. Department of Energy Small Business Technology Transfer Program, FY 2006 Phase II – Abstract #64 http://www.science.doe.gov/sbir/awards_abstracts/sbirsttr/cycle23/phase2/contents.htm
[4] Robert J. Viola, A Compact Crystal Positioning System for Neutron Diffraction, U.S. Department of Energy Small Business Technology Transfer Program, FY 2006 Phase II – Abstract #68
[5] William Heller, Infrastructure Development for Neutron Scattering for Biomembranes and Biomimetic Membranes, ORNL Laboratory Directed Research and Development Award # D06-015
[6] Initial design by A. Payzant, ORNL Laboratory Directed Research and Development Award; Final design by Sample Environment Group and Diffraction and Thermal Physical Properties Group, C. Hubbard
[7] E. Mamontov, "High-Temperature, High-Pressure Studies of Dynamics of Fluids in Nanopores using the Spallation Neutron Source Backscattering Spectrometer," ORNL Laboratory Directed Research and Development Award # D07-019
[8] Raffaele Gilardi, New high-field actively shielded split-coil magnet for neutron scattering, Proceeding of 3rd Workshop on Inelastic Neutron Spectrometers (WINS), Berlin, 29.-30.9.2006
[9] G. M. Ludtka and J. Fernandez-Baca, Neutron Sciences Progress at Oak Ridge National Laboratory, July 2007
