Electron paramagnetic resonance investigation of acceptor centers in Pb(Zr,Ti)O{sub 3} ceramics
- Sandia National Labs., Albuquerque, NM (United States)
- Army Research Lab., Fort Monmouth, NJ (United States)
Ferroelectric Pb(Zr,Ti)O{sub 3} (PZT) thin-film dielectrics are an emerging technology for semiconductor nonvolatile memories. Ferroelectric thin-film capacitors appear to have significant advantages with respect to endurance, write speed, and nonvolatility over polysilicon-nitride-oxide-silicon devices. The nature of extrinsic point defects in lead zirconate titanate (PZT) ceramics of various compositions prepared by solution chemistry has been explored. Using electron paramagnetic resonance (EPR), several impurity sites have been identified in the as-received materials, which include Fe{sup 3+}--oxygen vacancy (V{sub o}) complex and isolated Cu{sup 2+} ions; both of these ions are incorporated into the lattice by replacing the Ti (Zr) ion. A Fe{sup 3+}--V{sub o} complex serves as a sensitive probe of the local crystalline field environment of the ceramic; the symmetry of this defect is roughly correlated with its phase diagram as the composition is varied from PbTiO{sub 3} to PbZrO{sub 3}. The Fe{sup 3+}--V{sub o} complex experiences tetragonal, rhombic, or orthorhombic symmetry as the composition is varied from PbTiO{sub 3} to PbZrO{sub 3}. As the composition of the Cu{sup 2+} ion is varied, it appears as though the addition of Zr, and not necessarily a change in phase, is largely responsible in determining the local environment of this acceptor impurity. Also, the Cu{sup 2+} resonance parameters weakly reflect the relative Ti-O (Zr-O) bond covalency in the perovskite lattice.
- Research Organization:
- Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
- Sponsoring Organization:
- Defense Advanced Research Projects Agency, Arlington, VA (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 474148
- Journal Information:
- Journal of the American Ceramic Society, Vol. 80, Issue 3; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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