Meet the Crystallography and Mineral Physics group.

Photo 1: Photographs of Left) the cold stage and, Right)high-temperature furnace used during the neutron powder diffraction experiment of the thermal expansion and magnetostriction in fayalite (June 2020) of Prof. Ian Wood and Eve Tripoliti. 

What makes up planetary interiors? This is the question the Crystallography and Mineral Physics (CMP) group is trying to answer by combining computational techniques with high-pressure and temperature experiments. CMP in house facilities, located in the Kathleen Lonsdale Building, UCL, consist of 4 laboratories managed by Dr. Andrew Thomson, Prof. Ian Wood, and Prof. David Dobson(Haskel Multi-Anvil, Diamond Anvil Cell, X-ray Diffraction, and Mantle Rheology) where they, with their Postdoc staff Dr. Fang Xu, Dr. Rong Huang and Dr. Longjian Xie, and PhD students Eve Tripoliti and Nick Backhouse, study materials’ response to extreme pressures and temperatures so as to understand planetary evolution, dynamics, and elasticity. 

Photo 2: Left) X-ray powder diffractometer loaded with the cold stage that allows measurements between 40 and 310 K, Middle) multi-anvil press during synthesis of high-pressure mantle phases and, Right) DT-cup deformation apparatus that allows measurements of the relative strength of materials.

In the Haskel Multi-Anvil laboratory we synthesise high-pressure material phases (at the moment, wadsleyite, ringwoodite, pyroxene, garnet, and perovskite) and develop new cell assemblies for high-pressure synchrotron experiments (e.g., Dr. L. Xie at beamline PSICHÉ SOLEIL, 2022). In our labs we can measure the thermal expansion of materials with a X’Pert PRO PANalytical X-ray diffractometer equipped with two environmental stages allowing measurements from 40 K to 1453 K (e.g., Wood et al., 2018; MSc Thesis Poster 3  by Eve Tripoliti). The stress and strain of materials can be measured in the Rheology laboratory, with a DT-cup apparatus (e.g., Hunt & Dobson, 2017; Hunt et al., 2014; Xu et al., 2022) that performs sample deformation at high-pressures. Finally, in the newly developed Diamond Anvil Cell laboratory, fitted with X-ray tomography and pulse-echo ultrasonic equipment, we can measure the seismic velocities of materials under extreme pressures and temperatures (e.g., Poster 2 by Nick Backhouse).

Photo 3:  Photographs from the experiments of Dr. Andrew Thomson and Dr . Rong Huang on the seismic velocities of garnets and olivine’s high-pressure polymorphs at the European Synchrotron (November 2022). Left) Large Volume Press (LVP) of beamline ID06, ESRF, Middle) Sample loaded into the  LVP and Right) Waveform measured by Pulse-Echo Ultrasonic Interferometry .
 

Additional experiments are regularly performed at national and international synchrotron radiation facilities including the European Synchrotron (e.g., Thomson et al., 2019; see photo 3 from the most recent experiments of Dr. A. Thomson and Dr. R. Huang, 2022), Diamond and the Photon Factory (in Tsukuba, Japan) and at HRPD of the ISIS Neutron and Muon Source laboratory (e.g., Wood et al., 2004; Poster 1 by Eve Tripoliti and photo 1 of the most recent neutron diffraction experiment of Prof. I. Wood and E. Tripoliti, 2020).

Photo 4:  Left) Paper and cover of nature geosciences by  Dr. Yunguo Li, Prof. Lidunka Vočadlo, Dr. Tao Sun & Prof. John Brodholt (2020) (read more about this project  here). Right) new research project of Dr.  Haiyang Luo, Prof. Lidunka Vočadlo, Prof. John Brodholt, and Dr. John Ballentine (2022). 

Our group has access to high-performance computing via the UK Mineral Physics Consortium managed by Prof. John Brodholt with Prof. Lidunka Voc ̆adlo, Prof. Dario Alfe, and Dr. Monica Pozzo, and Postdoc research staff Dr. Jac van Driel and Dr. Haiyang Luo, and PhD student Isaac Taschimowitz.

Photo 5: The composition of the Martian Core, a molecular dynamics study of Dr. Jac van Driel

Their research focuses primarily on the composition and evolution of planetary cores by investigating iron alloys (e.g., photo 5 from the work of Dr. Jack van Driel), water content (e.g., Li et al., 2020; see photo 4, nature geoscience cover by Dr. Yunguo Li, Prof. Lidunka Vočadlo and Prof. John Brodholt), Highly Siderophile Elements (HSEs) (e.g., photo 4 by Dr. Haiyang Luo with Prof. Lidunka Vočadlo, Prof. John Brodholt, and Dr. Chris Ballentine) as well as develop new Equations-of-State for various melt systems (e.g., Poster 4 by Isaac Taschimowitz). They use ab initio methods to investigate material properties at extreme conditions, often beyond those achieved by experimental techniques. 

Don’t forget to follow UCL WiES, founded by Prof. Lidunka Vočadlo, as well as the One-Minute Geology website and YouTube channel of Prof. David Dobson for some exciting geology! 

Article written by Eve Tripoliti.

References:

• Hunt, S. A., et al. (2014) ‘Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa.’ Review of Scientific Instruments 85.8.
• Hunt, S. A., and David P. Dobson. (2017) ‘Note: Modified anvil design for improved reliability in DT-Cup experiments.’ Review of Scientific Instruments 88.12.
• Li, Y., et al. (2020) ‘The Earth’s core as a reservoir of water.’ Nature Geoscience 13.6: 453-458.
• Thomson, A. R., et al. (2019) ‘Seismic velocities of CaSiO3 perovskite can explain LLSVPs in Earth’s lower mantle’, Nature, 572(7771), pp. 643–647. 
• Wood, I. G., et al. (2004) ‘Thermal expansion and crystal structure of cementite, Fe3C, between 4 and 600 K determined by time-of-flight neutron powder diffraction’, Journal of Applied Crystallography, 37(1), pp. 82–90. 
• Wood, I. G., et al. (2018) ‘Investigation of high-pressure planetary ices by cryo-recovery. I. an apparatus for X-ray powder diffraction from 40 to 315 k, allowing “cold loading” of samples’, Journal of Applied Crystallography, 51, pp. 685–691..
• Xu, F., et al. (2022) ‘Deformation of Post‐Spinel Under the Lower Mantle Conditions.’ Journal of Geophysical Research: Solid Earth 127.3.

Links:

• Crystallography and Mineral Physics (CMP) research group.
• Haskel Multi-Anvil
• Diamond Anvil Cell
• X-ray Diffraction
• Mantle Rheology