We advance and implement X-ray crystallography for probing materials structures. We investigate fine structures on different length scales to obtain standard crystallographic, structural disorder and microstructural information. We study materials under electric, thermal and (in future) mechanical perturbation. We are currently focused on piezoelectrics and ferroelectrics but open for exploring any materials where the relationship between structure and properties are not yet understood.
1. Investigation of multidomain crystals using high-resolution X-ray diffraction
Domain is a finite volume of a crystal, where a physically meaningful order parameter is uniform. Domains and domain walls may mediate new physical properties, such as giant piezoelectricity or shape-memory effect. We advance the methods of investigation of domains using X-ray and neutron scattering inspecting domains from Bragg peaks splitting and track their response to external field.
2. Development of time resolved X-ray single crystal diffractometry
X-ray diffraction is the leading tool for the investigation of materials structures. Understanding the structure-properties relationship relies on the ability of measure how the structure adapts to the external conditions. This adaptation might be e.g. distortion of the chemical bonds, macroscopic strains, variations in the microstructure / domain pattern. For example application of electric field to a piezoelectric material induces macroscopic deformation, which can be to the structural effect or domain wall motion. We develop data aquisition systems for synchronized collection of X-ray diffraction and application of external stimuli to a material (probing a device in action).
3. Crystallography of cleavage
Cleavage describes the tendency of a crystal to break easily along a specific lattice planes.
Acquiring the information about cleavage in a given crystal structure is essential for the investigation of key mechanical properties such as fracture toughness, plasticity and strength.
Although cleavage planes are commonly known for simple crystals (e.g. silicon), such information about arbitrary crystals is not available.
We develop an universal algorithm for automatic inspection of crystal structures, and the prediction of likely cleavage planes in them. The algorithm is being implemented in the form of MATLAB program. The project is carried out in collaboration with Prof Dov Sherman and his brittle fracture laboratory .
15 January 2021
Not really news, but the nice view of the lab! Red light is on, data collection is running. Nobel Prize? Maybe tomorrow!
1 January 2021
Welcome Yair Dror, our new laboratory engineer. He will work half of his time with us and another half with Dr Maxim Sokol (ceramics laboratory). We wish Yair a smooth start, years of succesfull and pleasant work. And of course, the standard wish of staying healthy during this challenging times.
12 December 2020
The wait is over: the multi-channel analyzer for time-resolved X-ray diffraction experiments with a point detector arrives. It was developed by the former colleagues in the University of Siegen. Great to the see the old friend.
30 August 2020
Our measurements of time-resolved X-ray diffraction under external electric field continue. Does this material have a chance to become the new "star" of piezoelectricity? If so, why? We will get the answer soon.
27 July 2020
The next milestone celebration in the lab. Our first laboratory-based experiments on crystals under electric field have started. This time, it is test measurements of the piezoelectric coefficient of single crystal of quartz. Synchronization of PILATUS detector with the applied electric field is realized using this methodoly.
U. Vaknin, D. Sherman, S. Gorfman
Geometrical prediction of cleavage planes in crystal structures
International Union of Crystallography Journal, 8 (5), in press, (2021)
S. Gorfman, D. Spirito, N. Cohen, P. Siffalovic, P. Nadazdy, Y. Li
Multipurpose diffractometer for in situ X-ray crystallography of functional materials
Journal of Applied Crystallography, 54 (3), 914 - 923,(2021)
A. Auslender, G. Levi, V. Ezersky, S. Gorfman, O. Dieguez, A. Kohn
Mean inner potential of graphite measured by electron holography: Probing charge distribution and orbital diamagnetic susceptibility
Carbon, 179, 288 - 298,(2021)
J. Schultheiss, L. Porz, L. K. Venkataraman, M. Hoefling, C. Yildirim, P. Cook, C. Detlefs S. Gorfman, J. Roedel, H. Simons
Quantitative mapping of nanotwin variants in the bulk
Scripta Materialia, 199 (6),113878,(2021)
Israel Science Foundation
Fine structure, polarization rotation and low-symmetry phases in ferroelectric perovskites
October 2018 - October 2022
Funding agency: BSF: US-Israel Billateral Science Foundation
Project title: Local structure mechanisms of electromechanical coupling in oxide ferroelectrics
Project partner: Dr Igor Levin , National Institute of Standards and Technology. Gaithersburg, USA
Project duration: October 2020 - October 2023
Wolfson Building for Mechanical Engineering, George Wise Street, Tel Aviv, ISRAEL