Speciation of nitrogen - [N(3-)] and [N(2)(2-)] - in binary compounds

Area of Science:

• Materials Science
• Inorganic Chemistry
• Analytical Chemistry

Background:

• Binary compounds of alkaline earth metals with nitrogen are challenging to synthesize and analyze.
• Previous studies suggested complex nitrogen species within these compounds, requiring advanced analytical techniques for confirmation.

Purpose of the Study:

• To accurately determine the nitrogen content in SrN, Sr[N2], and Ba[N2] synthesized under high pressure.
• To develop and validate analytical methods for handling air- and moisture-sensitive nitrogen-rich compounds.
• To quantify different nitrogen species ([N3-] and [N2(2-)]) and confirm structural findings.

Main Methods:

• High-pressure synthesis for preparing binary strontium and barium nitrogen compounds.
• Carrier gas hot extraction method for precise nitrogen content determination.
• Development of a specialized transfer chamber for handling air- and moisture-sensitive samples.
• Implementation of a controlled-heating electrode furnace with a specific temperature program for accurate analysis.

Main Results:

• Successful determination of nitrogen content in SrN, Sr[N2], and Ba[N2].
• Quantification of two distinct nitrogen species: azide ([N3-]) and peroxide ([N2(2-)]).
• Confirmation of the existence and proportions of these nitrogen species, aligning with neutron diffraction data.

Conclusions:

• The developed analytical methodology is effective for quantifying nitrogen in sensitive binary compounds.
• The study confirms the presence of both azide and peroxide anions in the high-pressure synthesized SrN, Sr[N2], and Ba[N2].
• Analytical results corroborate findings from recent neutron diffraction studies on these materials.