Extraction-Spectrophotometric Determination of Average Valence of Copper in Superconductor Y–Ba–Cu–O

Abstract

Abstract The determination method of the average valence of copper in a Y–Ba–Cu–O superconductor has been investigated. Spectrophotometry was introduced to the iodometry considered to be a conventional method in order to decrease the amount of sample used. The iodine liberated by the reaction between Cu2+ and/or Cu3+ and I− ions was extracted into chloroform with Zephiramine (Zeph+Cl−) as a Zeph+I3− ion pair complex. The extraction of I3− enhanced the reproducibility. The effect of the HCl concentration was significant. The sample was dissolved with 5 ml of a 0.1 M (M = mol dm−3) HCl solution by means of ultrasonic irradiation. The employed method decreased the amount of consumed sample down to 4 mg. The modified method, using cuproine, decreased the amount down to 2 mg.