DETERMINATION OF BISMUTH(III) IN K-BA-BI-O HIGH-T-C SUPERCONDUCTING MATERIALS BY POTENTIOSTATIC COULOMETRY AND SLOW POTENTIAL SWEEP COULOMETRY

It is demonstrated that a Pt netting electrode with a large surface ar ea can be used for the determination of bismuth by potentiostatic coul ometry and slow potential sweep coulometry. For samples of high-T-c, s uperconductors containing Ba(II) and K(I), a procedure is developed fo r the potentiostatic coulometric determination of 1-5 mu g of bismuth in 0.5-3.5 M HClO4 with RSD 0.2%. It is demonstrated that in the deter mination of bismuth by slow potential sweep coulometry, the degree of reduction of Bi(III) to Bi(O) at v = 1-2 mV/s is as high as 98% with R SD 0.8%.