Affiliation:
1. School of Chemistry and Physics and Centre for Materials Science Queensland University of Technology Brisbane Queensland 4000 Australia
2. Key Laboratory of Polar Materials and Devices Ministry of Education and Department of Electronic Engineering East China Normal University 500 Dongchuan Road Shanghai 200241 China
3. Central Analytical Research Facility Institute for Future Environments Queensland University of Technology Brisbane Queensland 4000 Australia
4. Clinical Translational Research Center of Aggregation‐Induced Emission School of Medicine The Second Affiliated Hospital School of Science and Engineering The Chinese University of Hong Kong Shenzhen (CUHK‐Shenzhen) Shenzhen 518172 China
Abstract
AbstractHerein, a low‐temperature sublimation‐based vapor deposition (SVD) method is developed to synthesize hexagonal crystal plates of cyanuric acid‐melamine (CAM) with outstanding crystallinity. Through meticulous design of the reaction apparatus and careful selection of source materials, substrate‐confined SVD in a tube furnace is explored to grow single crystals of CAM in hexagonal shapes. Additionally, the orientation preference of the (202) facet is revealed, corresponding to the 2D arrangement of the H‐bonded network, of single‐crystalline plates on surfaces using selected area electron diffraction and X‐ray diffraction techniques. By employing atomic force microscopy and scanning electron microscopy for topography characterization, a mechanism of three‐stage step‐growth crystallization is proposed, including nucleation, in‐plane expansion, and out‐of‐plane growth. Furthermore, it is found that the interactions among melamine molecules in CAM synthesized via SVD are more intense compared to those in CAM synthesized via water‐based methods, as evidenced by infrared and photoluminescent spectra studies. Subsequent nanoindentation tests on the (202) facet of CAM single‐crystalline plates reveals a reduced modulus and hardness of 12.8 and 0.82 GPa, respectively. This methodology addresses the longstanding challenge of synthesizing hexagonal CAM single crystals and provides valuable insights for the fabrication of functional organic crystalline materials.
Funder
Basic and Applied Basic Research Foundation of Guangdong Province
Shenzhen Science and Technology Innovation Program
China Postdoctoral Science Foundation
Australian Research Council