IEC 61788-23 Ed. 3.0 B:2024

This part of IEC 61788 addresses a test method for the determination of the residual resistance
ratio (RRR), rRRR, of cavity-grade niobium. This method is intended for high-purity niobium
grades with 150 < rRRR < 600. The test method is valid for specimens with rectangular or round
cross-section, cross-sectional area greater than 1 mm2 but less than 20 mm2, and a length not
less than 10 nor more than 25 times the width or diameter.