A series of single-phase 0953-2048/9/10/011/img9 0953-2048/9/10/011/img10 compounds with tetragonal triple-perovskite structure is studied by Rietveld analysis. For 0953-2048/9/10/011/img11, all of the 0953-2048/9/10/011/img12 ions enter the centre site: the 0953-2048/9/10/011/img13 site of the tetragonal 0953-2048/9/10/011/img14 phase. For 0953-2048/9/10/011/img15, a maximum of about 1/2 of the 0953-2048/9/10/011/img13 sites are occupied by 0953-2048/9/10/011/img12 ions and the extra 0953-2048/9/10/011/img12 ions enter the 0953-2048/9/10/011/img19 site. Double plateaux are found between 0953-2048/9/10/011/img20 and 0953-2048/9/10/011/img21 (the difference between the occupancy factor of 0953-2048/9/10/011/img12 ions at the 0953-2048/9/10/011/img13 site and that of 0953-2048/9/10/011/img24 ions at the 0953-2048/9/10/011/img19 site). It is suggested that 0953-2048/9/10/011/img20 of the La - Ca - Ba - Cu - O compounds containing 50 mol% copper atoms with tetragonal triple-perovskite structure can be predicted from the correlation of 0953-2048/9/10/011/img20 versus 0953-2048/9/10/011/img21.
Superconductor Science and Technology 9(10), pp.893-897