Copper Tin Alloy (Bronze) Nanoparticles are black brown spherical high surface area metal particles. Nanoscale Copper Tin Alloy Particles are typically 10-30 nanometers (nm) with specific surface area (SSA) in the 30 - 70 m2/g range and also available with an average particle size of 70 -100 nm range with a specific surface area of approximately 5 - 10 m2/g.