Nanometric copper formulations

A formulation comprising particulate matter including nanometric metallic copper particles, at least 10% of said particulate matter being single-crystal metallic copper particles, said particulate matter having an average secondary particle size (d50) within a range of 20 to 200 nanometers (nm), said nanometric metallic copper particles being at least partially covered by at least one dispersant;

• wherein a concentration ratio of crystalline cuprous oxide to said nanometric metallic copper particles, within said particulate matter, is at most 0.4;
• wherein a weight ratio of said dispersant to said particulate matter is at most 0.08;
• the formulation further comprising at least a first solvent, said particulate matter and said solvent forming a dispersion;
• wherein at least 2% of said particulate matter are single-crystal metallic copper particles having a triangular morphology, as determined by manual counting of particles in a High Resolution Scanning Electron Microscope (HRSEM) field having at least 50 particles.