Characterization of YBa2Cu4O8 Superconductor Prepared by Using YBa2Cu3O7-x and CuO Via Solid State Reaction Technique with Heating under Ordinary Oxygen Pressure

The aim and objective of this study is to investigate the material synthesis and superconducting properties of YBa2Cu4O8 (Y-124) synthesized from YBa2Cu3O7-x (Y-123) and CuO powders. A commercial Y-123 and CuO powders were used to synthesize polycrystalline Y-124 employing the conventional solid state reaction method with heating at 1 atm oxygen pressure. Sodium nitrate was used as catalytic enhancer during the chemical reaction. The samples were subjected to twice sintering at 815 °C for 24 h with intermittent grinding. Analysis of the x-ray diffraction (XRD) data showed that Y-124 phase is dominance (81.1 wt%) in the samples with the presence of Y-123, and CuO as secondary phases. The thermogravimetric curve shows a small oxygen loss at ∼ 400 °C and rapid oxygen loss above ∼ 850 °C. Scanning electron microscope (SEM) images revealed that the samples had irregular grain shapes ranging in size from a few micrometers to fractions of a micrometer. The four-point-probe method was used to measure superconducting transition temperature (Tc). The samples exhibited a dual superconducting transition with the onset Tc of around 77 K and 87 K, respectively. This is consistent with the co-existence of superconducting phase Y-124 and Y-123. This two-level Tc characteristic of the sample gave potential application in multiples industries, including electronics, transportation, and data storage and processing. This study demonstrates how efficient and optimal conditions can be used to produce the Y-124 phase.