Can you tell me what copper powder PMU 99.999% purity is used for?
Also, what does PMU stand for?

Answer:
Superfine ultradispersed Copper Powder:
Chemical purity: 99.993%-99.997%, Cu63 69.09+-0.05 , Cu65 30.91+-0.03
A mixture of the two non-radioactive copper isotopes Cu63 and Cu65 in the above ratios and hence extremely expensive.
The sum of controlled dopes is not more than 0.007%
Particle-size: less than 7.7 μm
The form of particles is spherical.
Up to 1000 kg per month
150-200 dollars per gram

I do not know the applications for this material.

Country of Origin PMU, Russian Federation
PMU is the Russian abbreviation for Superfine ultradispersed Powder