Mr. Arad Lang PhD candidate
David Wang Auditorium, 3rd floor Dalia Meidan Bldg.
Biominerals possess improved mechanical properties compared to their synthetic counterparts. One reason for such improvement is the incorporation of organic biomacromolecules into the crystal lattice of the inorganic mineral, which act as barriers for cracks propagation. Similar mechanical enhancement is achieved in calcite single crystals, when individual amino acids are synthetically incorporated into their lattice. Recently, the concept of amino acids incorporation was also demonstrated on inorganic semiconductors. Such incorporation was accompanied by an increase in the band gap of the semiconducting hosts, which allowed to introduce a novel bioinspired route of band gap tuning.
Here, we aimed to expand this bioinspired strategy to more complex materials systems. First, the incorporation of lysine into the hybrid perovskite MAPbBr3, and the mechanism by which it induces a shrinkage of its unit cell, will be discussed. The lysine-incorporated crystals demonstrate modified physical properties such as an enlarged band gap, a reduced thermal expansion coefficient and different crystal morphologies. Most importantly, we observed that amino acid incorporation improves the otherwise poor stability of the perovskite under humid conditions. Further, the incorporation of amino acids into MnCO3 will be discussed wherein aspartic acid induces anisotropic lattice expansion. The changes in the inter-atomic distances reduce magnetic interactions in the crystal, hence induce changes in the magnetic properties of the host, measured both above and below the Néel temperature of the host.
Arad obtained a double B.Sc. degree in materials science and engineering and chemistry at Technion in 2017. He started his M.Sc. in the Pokroy group in 2017, and moved to a direct Ph.D. track one year later.
Supervisor: Prof. Boaz Pokroy