This paper has some density of YBaCuO reported - 5.38-5.43 g/cm3. The authors were measuring the mass attenuation coefficient of X-rays.
http://www.iop.org/EJ/abstract/0953-2048/18/1/016
Measurement of mass attenuation coefficients for YBaCuO superconductor at different energies
U Çevik1, H Baltas2, S Çelik2, I Karaca3 and I Kopya1
1 Karadeniz Technical University, Faculty of Arts and Sciences, Department of Physics, 61080 Trabzon, Turkey
2 Karadeniz Technical University, Rize Faculty of Arts and Sciences, Department of Physics, 53100 Rize, Turkey
3 Nigde University, Faculty of Arts and Sciences, Department of Physics, 51200 Nigde, Turkey
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I would recommend completing the calculation of density which would be the theoretical value.