Piezoelectric ceramic materials based on lead zirconate titanate (PZT) having the crystal structure perovskite
The invention relates to piezoelectric ceramic materials based on the system Pb(Zr,Ti)O 3 , i.e. solid solutions of lead zirconate PbTO 3 , characterized by having very good dielectric and electromechanical properties that can be adopted for different uses by modifying the composition. The piezoelectric ceramic materials based on the system Pb(Zr,Ti)O 3 are modified in order to obtain a high level of piezoelectric activity. The invention provides piezoelectric ceramic materials based on lead zirconate titanate (PZT) having the crystal structure of perovskite with formula A 2+ B 4+ O 3 2− , which are characterized by a substitution of heterovalent acceptor and donator ions at Zr/Ti sites.
1. A piezoelectric ceramic material comprising lead zirconate titanate (PZT) having the formula Pb 2+ (Zr 4+ ,Ti 4+ )O 3 2− and the crystal structure of perovskite having the formula A 2+ B 4+ O 3 2− , characterized by substitution of partially valence compensating acceptor and donor ion pairs B 3+ y /B 5+ z for the formation of only partially valence compensated compositions of the system
Pb 2+ 1−w Sr 2+ z [B 3+ y (Zr x Ti 1−x ) 4+ 1−y−z Nb 5+ z ]O 2− 3
wherein w=0.00 to 0.005, x=0.50 to 0.55, y<z, and z=0.00 to 0.05,
wherein a coupled substitution of heterovalent acceptor and donor ions at Zr/Ti sites is present in the material and the B 4+ site is occupied by Al 3+ or Fe 3+ ions.
2. A piezoelectric ceramic material having the formula [Pb 0.995 Sr 0.02 ][Al 0.005 (Zr x Ti 1−x ) 0.975 Nb 0.02 ]O 3 , where x=0.50 to 0.55.
3. A piezoelectric ceramic material having the formula [Pb 0.995 Sr 0.02 ][Fe 0.005 (Zr x Ti 1−x ) 0.975 Nb 0.02 ]O 3 , where x=0.50 to 0.55.
4. A piezoelectric ceramic material as claimed in claim 1 , wherein the material is produced by a mixed oxide technique.
5. A piezoelectric ceramic material as claimed in claim 1 , wherein the material is sintered at temperatures in the range of 1100° C. to 1200° C.