We present results of Raman and infrared spectroscopic studies of the composite system of superconducting YBa2Cu3O7-δ and metallic BaPbO3, with the BaPbO3 fraction ranging from 5 to 30 in weight. The Raman spectra of the YBa2Cu3O7-δ grains in the composite system are typical of well-oxygenated YBa2Cu3O7-δ bulk single crystals, even up to the grain boundaries, independent of the BaPbO3 fraction. We have also performed infrared reflectivity measurements and have identified the major c-axis transverse-optical phonons of YBa2Cu3O7-δ, consistent with the single-crystal data, confirming that the constituent YBa2Cu3O7-δ crystallites are fully oxygenated. The absence of mode splitting suggests that the crystal symmetry of YBa2Cu3O7-δ grains remains the same as that of bulk single crystals. No phonons indicative of other YBa2Cu3O7- or BaPbO3-related impurity phases, such as YBa2Cu3O6, Y2BaCuO5, and Ba2PbO4, have been detected in our Raman and infrared spectra. All these optical features clearly indicate that YBa2Cu3O7-δ is well separated from BaPbO3 and that BaPbO3 is an excellent additive material for the synthesis of YBa2Cu3O7-δ bulk materials.
Bibliographical noteFunding Information:
Part of this work was supported by the National Creative Research Initiative Center for Superconductivity, Pohang University of Science and Technology, Korea. ISY appreciates the support of Korea Science Engineering Foundation through grant No. 961-0207-044-2. SSY was supported in part by the Korea Science Engineering Foundation through the Reseach Center for Dielectric and Advanced Matter Physics at Pusan National University. JHK acknowledges the financial support of Korea Science Engineering Foundation through Grant No. 961-0208-047-2.
- Infrared spectroscopy
- Intergranular material
- Raman spectroscopy