Discipline: Chemistry and Chemical Sciences
Subcategory: Materials Science
Francisco Guzman - Cal State San Bernardino
Co-Author(s): Judy Tran, Kimberley Cousins, Paul K. Dixon, Douglas Smith, Timothy D. Usher, and Renwu Zhang, California State University, San Bernardino
Croconic acid is the first single ferroelectric organic molecule material that exhibits a very high spontaneous polarization (~ 20 C/cm 2 ). This high polarization is due to the intermolecular shifting of H-bonds under an external electric field. This uniform alignment of H-bonds is critical to the spontaneous polarization and therefore, the use of a high quality single crystal of croconic acid is crucial in order to achieve a higher polarization, which is exhibited through the ferroelectric properties of croconic acid. The quality of such a crystal is regulated by several factors, which one includes the void defects upon crystallization. Void formation is highly dependent upon the individual crystallization process that was utilized. The conventional method used to remove these defects from the single crystal is through the use of thermal annealing treatment. In this experiment, the void defects in a single crystal of croconic acid are characterized using positron annihilation lifetime spectroscopy (PALS). Both the defect void size and intensity are measured, as well as the dependence of time relative to the thermal treatment is studied. In addition, the relationship between void defects and the ferroelectric properties of croconic acid are established.
Funder Acknowledgement(s): CREST
Faculty Advisor: Renwu Zhang, firstname.lastname@example.org
Role: I did the annealing treatment of the single crystal. This included baking the single crystal under vacuum using an oil bath with electric stirrer. The temperature was monitored using a thermocouple. I then tested the void defects of the sample after each heat treatment using PALS (Positron Annihilation Lifetime Spectroscopy). Finally, tested the hysteresis loop of the croconic acid single crystal to confirm that it retained its ferroelectric property.