| 摘要 |
<p>A PZT ferroelectric ceramic contains, as a partial substituent for one of the principal constituents, an element which (a) has a valency lower by one than that of one of the principal constituents; (b) has a position in a lower group in the Periodic Table than this constituent; and (c) has an ionic radius within /sB 7% of that of the constituent. The basic compositions fall into three categories: (a) lead titanate-zirconates; (b) lead titanate-stannates; and (c) lead titanate-zirconate-stannates, a preferred binary composition being Pb(Ti.47Zr.53)O3. Binary and ternary stannate compositions preferably have a mol. ratio PbTiO3: PbSnO3 in the range 40: 60 to 50: 50. Three examples of substituents are: 2 atom per cent scandium; 2 atom per cent indium; and 1 atom per cent potassium, all applied to the lead titanate-zirconate composition given above, the starting materials being, respectively, scandium oxide, indium oxide and potassium carbonate. The compositions are fired twice, first at 870 DEG C. then at 1350 DEG C. One or more of the alkaline earth metals strontium, calcium or barium may be present as substituents for up to 30 atom per cent of the lead.</p> |
