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 .
31 May 2020
We are happy to announce that our first article on the topic of "Crystallography of Cleavage in functional materials" is now published in the latest issue of Acta Materialia. This results from the internal collaboration with Prof Dov Sherman and his brittle fracture laboratory
10 April 2020
These times of COVID-19 outbreak are dominated by self-isolation, Zoom meetings and online teaching. The laboratory is closed, the experiments are suspended. This time might be useful for analitycal research, analyzing the data, unpacking the old and yet unpublished algorithms.
15 October 2020
The "reality" of the reciprocal space. X-ray diffraction experiment is "reflected" from the surface of the X-ray detector. Nothing special, just a pretty image.
19 September 2019
A few colorful photos of our laboratory are now available via the link here. Special thanks to Limor Ben Moshe for such an amazing photography.
18 August 2019
On our way to Vienna to ECM32 (European Crystallographic Meeting). At this conference we are present with the talk of Dr S Gorfman and poster of U. Vakhnin. Looking forward!
7 August 2019
Sometimes, it is necessary to work until late. Especially when another important conference is coming. But at least the night views on the Tel Aviv University campus are relaxing and beautiful.
5 July 2019
The installation is now complete! The intense weeks with amazing Youli Li from Forvis Technologies are over and our X-ray diffractometer is almost ready for research challenges.
Y. Hirsh, S. Gorfman, D. Sherman
Cleavage and surface energies of LiNbO3
Acta Materialia, 192, 338-349, (2020)
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: Octoer 2019 - October 2022
Wolfson Building for Mechanical Engineering, George Wise Street, Tel Aviv, ISRAEL