The role of excess magnesium oxide or lead oxide in determining the microstructure and properties of lead magnesium niobate

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · American Ceramic Society Bulletin; (USA)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb05121.x· OSTI ID:6763386

Wang, H C; Schulze, W A ^[1]

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1. New York State College of Ceramics, Alfred Univ., Alfred, NY (US)

Near-phase pure perovskite lead magnesium niobate (PMN) with MgO or PbO additives was produced by reacting PbO with MgNb{sub 2}O{sub 6} at 800{degrees}C and sintering at 1200{degrees}C. Dense ceramics were characterized by scanning electron microscopy, x-ray diffraction, and dielectric measurements. The microstructural studies showed that excess MgO exists as micrometer spherical particles either in the grain boundary as a discrete particle or in the perovskite grain as an inclusion. The pyrochlore phase exists in large isolated grains in the microstructure. The 10 mol% MgO excess composition had a peak dielectric constant of 19500 at 100 Hz, which suggests very clean or uninhibiting grain boundaries. The excess addition of PbO did not improve the yield of perovskite PMN phase and decreased the dielectric constant. PMN grain boundaries are the dominant path of fracture. This paper explores the chemistry and characteristics of these grain boundaries.

• OSTI ID: 6763386
• Journal Information: American Ceramic Society Bulletin; (USA), Journal Name: American Ceramic Society Bulletin; (USA) Vol. 73:4; ISSN ACSBA; ISSN 0002-7812
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
426001* -- Engineering-- Superconducting Devices & Circuits-- (1990-)
656002 -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTION KINETICS
COHERENT SCATTERING
CRYSTAL DOPING
CRYSTAL STRUCTURE
DIELECTRIC PROPERTIES
DIFFRACTION
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
HIGH TEMPERATURE
KINETICS
LEAD COMPOUNDS
LEAD OXIDES
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MICROSCOPY
MICROSTRUCTURE
MINERALS
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PEROVSKITE
PEROVSKITES
PHASE STUDIES
PHYSICAL PROPERTIES
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
SCANNING ELECTRON MICROSCOPY
SCATTERING
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION