An accurate method of iodometric titration to measure copper valence of high-T-c superconductors

The double iodometric titration is the method widely used to determine copper valence of high-T-c superconductors. There are some problems that remain to be solved, and certain procedures are used: adding KSCN to release adsorbed iodine, adding HN4HF2 to eliminate the interference of some dopants, and using a new calculating equation to accurately calculate experiment results. Al- and Fe-doped samples were prepared and their copper valence, 2+p, was determined by the improved double iodometric titration method. With these samples, how to use the above procedures to improve experiment results is discussed. We find that the iodometric titration method described here can be used to determine copper valence and oxygen content for doped and undoped samples with high accuracy.