Tel Aviv University, Israel
We develop and implement advanced crystallography for probing materials structures by single crystal X-ray diffraction. We investigate fine structures on different length scales to obtain standard crystallographic , structural disorder and microstructural information. Our studies are performed during the application of electric, thermal and (in future) mechanical perturbation. We are currently focused on piezoelectric and ferroelectric crystals but open for exploring new materials where the relationship between structure and properties are not yet understood.
1. Investigation of multidomain crystals using high-resolution X-ray diffraction
The presence of domains and mobility of domain walls may greatly affect technologically important physical properties. Domain is a finite volume of a crystal, where some physically meaningful order parameters are uniform. Domain patterns appear after the phase transitions, which remove certain symmetry elements from the symmetry group of atomic structure. External influences may affect domains patterns and trigger new physical properties, mediated by domain-wall motion. Most importantly, domains may be switched between one another. We advance experimental methods for the investigation of domains using high-resolution X-ray diffraction where domains can be inspected from the ultra-fine splitting between Bragg peaks. This splitting can be used to identify domains / domain walls and track their response to external field.
2. Development of time-resolved X-ray single crystal diffractometry
X-ray diffraction is the leading experimental tool for the investigation of atomic structures and microstructures of materials. Understanding the structure-properties relationship relies on the ability of measure how the structure adapts to the change of external conditions. This adaptation might be e.g. distortion of the chemical bond, 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 .
19 Septemper 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.
12 Septemper 2019
From now on we are able to use CrysAlisPro software to hunt for and index reflections in single crystal diffraction data. The reconstruction of the reciprocal space from Na0.5Bi0.5TiO3 crystal shows that even diffuse X-ray scattering is detectable.
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 stay at work a bit longer. Especially when another important conference is coming. But at least the night views on the Tel Aviv University campus are relaxing and beautiful.
15 July 2019
Summer conference time! International Meeting on Application of Ferroelectrics in Lausanne, Switzerland. Invited and contributed talks of Dr Gorfman, alongside with the poster presentation of Dr Spirito.
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.
3 July 2019
Positive response from the US-Isral binational Science foundation. For the next three years, starting from October 2022 our collaborative research with Dr Igor Levin from National Institute of Standards and Technology is supported by this funding agency. The work will be devoted to the elucidation of the local structure and disorder in functional ferroelectric oxides.
29 June 2019
And this is the first test diffraction pattern! Simply put a piece of Al foil in the beam and got these wonderful Debye-Scherrer rings. Congratulations!
28 June 2019
The real crystallography begins when the X-ray detector is allowed to be at high scattering angle to the X-ray beam. Our custom-built instrument is surely able to do that.
Works with Prof Nava Setter
M. Angst, S. Adiga, S. Gorfman, M. Ziolkowski, J. Strempfer, C. Grams, M. Pietsch, J. Hemberger.
Intrinsic Ferroelectricity in Charge-Ordered Magnetite
Crystals, 9(11), 546, (2019)
G.D.L. Flor, S. Gorfman, B. Michailova.
Local-scale structural response of (1-x)Na0.5Bi0.5TiO3-xBaTiO3 to external electric fields
Applied Physics Letters, 114(4), 042901, (2019)
N. Zhang, S. Gorfman, H. Choe, T. Vergentev, V. Dyadkin, H. Yokota, D. Chernyshov, B. Wang, A. M. Glazer, W. Ren, Z.-G. Ye.
Probing the intrinsic and extrinsic origins of piezoelectricity in lead zirconate titanate single crystals
Journal of Applied Crystallography, 51(5), 1396-1403, (2018)
S. Gorfman, A. A. Bokov, A. Davtyan, M. Reiser, Y. Xie, Z.-G. Ye, A.V. Zozulya, M. Sprung, U. Pietsch, C. Gutt
Ferroelectric domain wall dynamics characterized with X-ray photon correlation spectroscopy
Proceedings of National Academy of Sciences, 115(29), E6680 - E6689, (2018)
H. Choe, J. Bieker, N. Zhang, A.M.Glazer, P.A.Thomas, S.Gorfman
Monoclinic distortion, polarization rotation and piezoelectricity in the ferroelectric Na0.5Bi0.5TiO3
International Union of Crystallography Journal, 5, 417 - 427, (2018)
C. Richter, M. Zschornak, D. Novikov, E. Mehner, M. Nentwich, J. Hanzig, S. Gorfman, D.C.Meyer
Picometer polar atomic displacements in strontium titanate determined by resonant X-ray diffraction
Nature Communications, 9(1), 178, (2018)
N. Zhang, H.Yokota, A.M. Glazer, D.A. Keen, S. Gorfman, P.A. Thomas, W.Ren, Z.-G. Ye
Local-scale structures across the morphotropic phase boundary in PbZr1-xTixO3
International Union of Crystallography Journal, 5(1), 73-81, (2018)
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