Origin and structure of polar domains in doped molecular crystals.
Doping is a primary tool for the modification of the properties of materials. Occlusion of guest molecules in crystals generally reduces their symmetry by the creation of polar domains, which engender polarization and pyroelectricity in the doped crystals. Here we describe a molecular-level determination of the structure of such polar domains, as created by low dopant concentrations (<0.5%). The approach comprises crystal engineering and pyroelectric measurements, together with dispersion-corrected density functional theory and classical molecular dynamics calculations of the doped crystals, using neutron diffraction data of the host at different temperatures. This approach is illustrated using centrosymmetric α-glycine crystals doped with minute amounts of different L-amino acids. The experimentally determined pyroelectric coefficients are explained by the structure and polarization calculations, thus providing strong support for the local and global understanding of how different dopants influence the properties of molecular crystals.
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
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Meirzadeh
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
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Azuri
The Makineni Theoretical Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
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Y
Qi
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
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Ehre
The Makineni Theoretical Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
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Rappe
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
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Lahav
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
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Kronik
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
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Lubomirsky