Superlattice reflections in hot-pressed Pb(Mg1/3Nb2/3)O3 ceramics

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2004-05, Vol.372 (1-2), p.56-65
• Main Authors: TSAI, Tsung-Fu, LIN, Ming-Hong, YANG, Ru-Yuan, LU, Hong-Yang
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Materials synthesis; materials processing; Methods of materials synthesis and materials processing; Physics; Treatment of materials and its effects on microstructure and properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2003.09.091

Pb(Mg1/3Nb2/3)O3 (PMN) ceramics have been hot-pressed and post-hot-pressing annealed at 1000DGC in a conventional tube furnace under 1 atm of oxygen and argon, respectively; their microstructures investigated via transmission electron microscopy (TEM) and crystalline phases analyzed via X-ray diffractometry (XRD). Three types of the superlattice reflections from the fundamental spots of the perovskite structure were detected in both the as-hot-pressed and annealed samples by selected-area electron diffraction (SADP). The {1/2 1/2 1/2}-type of the superlattice F-spots is observed in as-hot-pressed samples. The nanoscale ordered domains of approximately 5 nm size giving rise to F-spots are observed by dark field imaging. *a-Spots of the {1/2 1/2 0}-type have appeared in post-hot-pressing-annealed samples after heat-treatment at 1000 C in an oxygen as well as argon atmosphere. Superlattice reflections of the {1/2 1/2 1}-type, termed *a'-spots, are also observed from hot-pressed samples annealed at the same temperature for 500 h in an oxygen atmosphere. The occurrence of *a-spots associated with lead vacancies (V''Pb) is discussed by considering that Pb(Mg1/3Nb2/3)O3 grains is consisted of the acceptor-type nanoscale ordered domains in a donor-type disordered matrix.