On the search for a stable BiPbSrCaCuO 2223 polytype

A new crystallographic form of the 2223 polymorph has been identified by means of convergent beam electron diffraction, with a c-axis of 36.8 Å and with the space group F2dd. In contrast to the well-known 2223 polymorph of the compound PbBiSrCaCuO with the c-axis of 37.1 Å and a space group of A2aa/Amaa, which has a limited shelf life, the new form is stable at room temperature and in normal atmospheric conditions, but with a slightly lower T c of 102.2 K, with an onset temperature of 103.3 K.