COMPRES Multi-Anvil Cell Assembly Development Project
(By Kurt Leinenweber. Last updated February 24, 2009)
This material is based upon work supported by the National Science Foundation under a subcontract to COMPRES, the Consortium for Mineral Physics Research in Earth Sciences. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
The COMPRES Multi-Anvil Cell Assembly Development project is a community-wide project to develop, test and use cell assemblies for multi-anvil high pressure research. The project is run by Kurt Leinenweber and James Tyburczy, at Arizona State University. It is funded by the National Science Foundation, as a subcontract of COMPRES (Consortium for Mineral Physics Research in Earth Sciences).
New assemblies are under development, using both existing and new designs, materials and processes. Any laboratory that is a member of COMPRES is invited to participate in the design, testing, and use of the COMPRES cell assemblies.
How to Participate
Join COMPRES first, the details are at the COMPRES website. Contribute your designs, ideas, and information about your high-pressure techniques, that could be incorporated into the COMPRES designs or the pool of information. Get in touch with Kurt Leinenweber and request a batch of assemblies of some size, or partial assemblies, for testing and use (see below for some of the details of assembies currently under development). Unfortunately, we do not currently have carbide to supply, but we intend to supply all the other necessary parts, partly for purposes of direct comparison, and partly so that all laboratories can participate. Testing can be done both at conventional laboratories and at synchrotrons. The results of the testing will be assembled into a useful form that will help all of the laboratories to better understand the assemblies. The goals are to reduce costs and increase the ease and precision of high-pressure work at all of the laboratories.
San Francisco meeting summary
A group of high pressure researchers met in San Francisco, at the AGU meeting, to plan the first stages of the COMPRES cell assembly development effort. A consensus was reached to start with an 8/3 assembly, because for many people this would be a new capability for their laboratory, extending the pressure and temperature range to over 20 GPa and 2000 degrees C. Also, it is easier to settle on an interlaboratory design when each laboratory has not already invested in its own design and calibration.
Summary of high pressure assemblies
Several different assemblies are under simultaneous development, and some overall conceptual development is also underway. The specifics of assemblies are shown on the links below, while the conceptual advances (ceramics, thermocouples, etc) are listed later.
14/8 Assembly Progress Summary
10/5 Assembly Progress Summary
Synchrotron Assemblies and "Hybrid Assemblies"
Certain new developments in synchrotron assemblies are also a target of this project. Syncrotron work requires capable assemblies made of low-atomic number materials. This is particularly challenging because some of the best ceramic thermal insulators (zirconia) and heaters (lanthanum chromite, rhenium) are highly opaque to x-rays. Even with the most intense synchrotron sources, the quality of x-ray data from the sample is greatly diminished when these materials are used.
The synchrotron assembly part of this effort will be pursued in collaboration with synchrotron laboratories. We are testing such things as machinable silicon carbide and TiN/BN composite furnaces, along with low-thermal conductivity, low atomic number pressure media with spinel (MgAl2O4), and a porous mullite ceramic, as materials for new assemblies. In addition to new assemblies, improved techniques for fabricating cell assemblies will reduce the load on beamline scientists and users.
"Hybrid assemblies," which combine the advantages of synchrotron readiness with suitability for conventional work, are under development. The primary advantage of this will be better characterization of the conventional cell assemblies if they are also used for synchrotron work. This is a difficult problem, however, because the requirements for synchrotron work and conventional work are very different. This is discussed more on the "hybrid assembly" link below.
Also, some of the specific synchrotron and hybrid assembly developments are listed in the individual pages for the assembly sizes (8/3, 14/8, 10/5 above).
Other sizes and types of assemblies
There is no doubt that a need for other sizes, both larger and smaller than those listed above, and more specific purposes (controlled fugacities, in-situ property measurements, special types of containment, etc.) will arise. The selection of these will be made through the community's input during the course of the project.
Ceramics for octahedra
(Back to Multi-Anvil Cell Assemblies: An Overview (Multianvil Web))