A Few Quarternary Systems of Perovskite Type A²⁺B⁴⁺O₃ Solid Solutions

The properties of the quarternary systems (Sr–Pb)(Ti–Zr)O 3 and (Ba–Pb)(Ti–Sn)O 3 are studied. The shift of transition points with composition is measured by the temperature variation of the dielectric constant of the ceramic sample, and the phase diagrams at room temperature are determined with help of X-ray measurement. The phase diagram of (Sr–Pb)(Ti–Zr)O 3 includes two ferroelectric phases F α (rhombohedral) and F β (tetragonal), two antiferroelectric ones A α (pseudotetragonal) and A β (tetragonal) and a paraelectric one P . A β occupies larger area than expected. The diagram of (Ba–Pb)(Ti–Sn)O 3 resembles that of (Ba–Pb)(Ti–Zr)O 3 previously reported by the author and consists of F 1 , F 2 (the same as the low temperature phases in BaTiO 3 ), F α , F β and P , although the immiscible region is found in the composition containing smaller amounts of Ba and Ti. Roth early classified graphically the perovskite ABO 3 compounds on the basis of electronic polarizability of A ion and ionic radius of B ion. The present author advances this line experimentally by taking up a factor of A ion and one of B ion, using many data already published as well as the present results. The arrangement of A ions nearly agrees with that in terms of the electronic polarizability. Concerning the disposition of B ions, however, the ordering of Ti–Zr–Hf–Sn is adopted, and in addition, Sn and Hf ions are arranged near Zr ion. This diagram may be rather successfully applied to the classification of perovskite A 2+ B 4+ O 3 solid solutions. Furthermore, the possibilities for dielectric and piezoelectric use of the ceramic materials belonging to these systems are examined. Larger dielectric constants are found with certain compositions in (Ba–Pb)(Ti–Sn)O 3 , but a striking improvement for PZT ceramics may be rather questionable in both systems.