Pressure-Induced polymerization of LiN(CN)2

Derek W. Keefer, Huiyang Gou, Andrew P. Purdy, Albert Epshteyn, Duck Young Kim, John V. Badding, Timothy A. Strobel

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The high-pressure behavior of lithium dicyanamide (LiN-(CN)2) was studied with in situ Raman and infrared (IR) spectroscopies, and synchrotron angle-dispersive powder X-ray diffraction (PXRD) in a diamond anvil cell (DAC) to 22 GPa. The fundamental vibrational modes associated with molecular units were assigned using a combination of experimental data and density functional perturbation theory. Some low-frequency modes were observed for the first time. On the basis of spectroscopic and diffraction data, we suggest a polymorphic phase transformation at ∼8 GPa, wherein dicyanamide ions remain as discrete molecular species. Above ca. 18 GPa, dicyanamide units polymerize, forming a largely disordered network, and the extent of polymerization May be increased by annealing at elevated temperature. The polymerized product consists of tricyanomelaminate-like groups containing sp2-hybidized carbon−nitrogen bonds and exhibits a visible absorption edge near 540 nm. The product is recoverable to ambient conditions but is not stable in air/ moisture.

Original languageEnglish (US)
Pages (from-to)9370-9377
Number of pages8
JournalJournal of Physical Chemistry A
Volume120
Issue number47
DOIs
StatePublished - Jan 1 2016

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

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