Development of micro-coulometry for measuring oxygen content in copper oxides

A micro-coulometry system was newly developed and employed for measuring the oxygen content in copper oxides using a reduced amount of material. To achieve this reduction in sample size, Ar flow rate, and coulometric current were optimized. When using 5.0 mg of YBa2Cu3O6.71, which is about 1/10 the amount used in conventional coulometry, the oxygen content was successfully determined to be 6.68 ± 0.03, Ar flow rate, and coulometric current were 0.1 l/min, and 1.0 mA, respectively. It was found to be necessary to continue to pass Ar through the solution before coulometry more than ten minutes and during the coulometric measurement. This method will be useful for measuring the oxygen content of oxide samples smaller than 10 mg, i.e. oxide materials produced in small quantities for electronic applications.