Publications by authors named "Dane Tomasino"
Article Synopsis
- Researchers have discovered a new nitrogen phase using laser-heated diamond anvil cells at extremely high pressures (120-180 GPa), which is beyond the stability of previously known cubic gauche (cg)-N.
- This new nitrogen phase features a singly bonded, layered polymeric (LP) structure, resembling the predicted Pba2 configuration, and exhibits two significant Raman bands at approximately 1000 and 1300 cm^{-1} at 150 GPa, indicating the presence of highly polarized nitrogen atoms.
- The findings enhance our understanding of the nitrogen phase diagram, revealing a unique transition from a 3D cg-N structure to a 2D LP-N structure, with implications on the electrostatic stabilization of the dense LP-N phase (density
Article Synopsis
- Dense nitrogen shows unique molecular structures and a confusing solid-liquid transition at high temperatures, but understanding its phase boundaries is challenging.
- Raman spectroscopy studies were conducted to explore the melting curve and solid-solid transitions in nitrogen from 25 to 103 GPa and temperatures between 300 and 2000 K.
- Findings revealed a melting maximum at 73 GPa and 1690 K, with phase transitions indicating the complexity of nitrogen phases under varying pressures, and no evidence of the ι-phase was observed.
We have studied the pressure-induced physical and chemical transformations of tetracyanoethylene (TCNE or C6N4) in diamond anvil cells using micro-Raman spectroscopy, laser-heating, emission spectroscopy, and synchrotron x-ray diffraction. The results indicate that TCNE in a quasi-hydrostatic condition undergoes a shear-induced phase transition at 10 GPa and then a chemical change to two-dimensional (2D) C=N polymers above 14 GPa. These phase and chemical transformations depend strongly on the state of stress in the sample and occur sluggishly in non-hydrostatic conditions over a large pressure range between 7 and 14 GPa.
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