Marie Colmont
University of Lille
Title: Towards the synthesis of novel selenium based geoinspired materials
Biography
Biography: Marie Colmont
Abstract
The search for new non-centrosymmetric materials is still attractive do to their various related properties such as piezoelectricity, ferroelectricity or pyroelectricity... Particularly, Se4+ cations are fascinating because of its stereo active lone pair usually related to asymmetric environments. The crystallochemistry of selenium is particularly favorable because, in case of association with a transition metal and another lone paire cation such as Pb2+ or Bi3+, the chances to obtain asymetric units and as a consequence non-centrosymmetric crystal structures are enhanced. From an experimental point of view, two synthesis routes are prefered: (1) CVT: chemical vapor transport and (2) hydrothermal synthesis. Particularly, they allow the simulation of natural conditions growth of minerals.
In this talk, after a brief sum up of advantages of each method, several chemical systems will be presented among those with nickel1, lead2, copper3 and bismuth4. Each time, experimental details will be presented along with isolated crystal structures.
As an example, the results obtained with copper are presented figure 1. Crystals of K[Cu5O2](SeO3)2Cl3 were isolated from the warmest zone of the sealed tube. This structure is related to those of a mineral called illinskite. They will be discussed during the presentation.