Barium Nitrate
Definition
Ba(NO3)2, the oxidiser in conventional primer formulations, decomposing thermally to release molecular oxygen that sustains the combustion of antimony sulphide fuel.
- Formula
- Ba(NO3)2
- Role in GSR
- Oxidiser in conventional primer mixtures
- Function
- Decomposes thermally to release oxygen for combustion
- Fuel it supports
- Antimony sulphide
Common questions
Why does barium matter specifically for GSR detection by SEM-EDX?+
Barium, together with antimony and lead, forms the classic three-component particle signature that SEM-EDX analysis targets. Finding all three elements co-located in a single spherical particle is far more specific to firearm discharge than finding any one element alone, since barium or lead can occur individually from unrelated sources.
Does the presence of barium nitrate rule out lead-free ammunition?+
No. Many modern primer formulations, including lead-free and less-toxic variants, replace barium nitrate and antimony sulphide with other oxidiser-fuel pairs. A particle profile built only around the classic barium-antimony-lead signature will miss residue from these newer formulations, so examiners must know which primer chemistry is in use locally.
Related terms
- Antimony Sulphide
- Sb2S3, the primary fuel in conventional primer formulations, burning rapidly in the presence of oxygen released by barium nitrate during ignition.
- ASTM E1588
- ASTM International standard practice for gunshot residue analysis by scanning electron microscopy with energy-dispersive spectrometry. Defines particle classification (characteristic, consistent-with, indicative), morphology...
- Automated Particle Search (APS)
- A software-driven SEM mode that scans the entire stub surface using backscattered electron contrast, flags particles above an atomic-number threshold, and triggers...
- Characteristic Particle
- ASTM E1588 category: a single particle in which Pb, Sb, and Ba are simultaneously detected by EDS, with morphology consistent with melt-and-quench...
- Consistent Particle
- ASTM E1588 category: a particle containing two of the three primer elements (Pb-Sb, Pb-Ba, or Sb-Ba), or all three elements without spherical...
- ENFSI EWG-GSR
- The European Network of Forensic Science Institutes Expert Working Group on Gunshot Residue. Produces best-practice manuals, proficiency test rounds, and guidance on...
- Lead Styphnate
- Lead trinitroresorcinate (Pb(C6H(NO2)3O2)), the primary explosive in conventional primer compounds. Co-oxidised with barium nitrate and antimony sulfide to produce the Pb-Ba-Sb triad...
- Melt-and-Quench Mechanism
- The physical process by which GSR particles form: primer components are vaporised at firing temperatures, condense into spherical droplets in the expanding...
- Secondary Transfer
- The movement of a glass fragment from a primary surface (which contacted the broken glass) to a secondary surface (which contacted the...