Characterization of phases in the Zr–Nb–Fe ternary system at the Zr–Nb rich side of the phase diagram

Mullite (3Al2O3•2SiO2) exists in a solid solution field (∼57-63 mol% Al2O3) as the only stable compound in the Al2O3•SiO2 phase diagram at ambient pressures. Equilibrium 3:2 mullite has an orthorhombic structure with b>a (o-mullite). However, when initially crystallized from molecularly mixed, 3:2 precursors at temperatures < 1200°C, the first phase that forms has lattice parameters with a ≈b. This structure is often termed pseudotetragonal mullite (pt-mullite), since even when the ‘a’ and ‘b’ lattice parameters are identical, they are symmetrically independent. Pseudotetragonal mullite has been shown to contain approx. 70 mol% Al2O3. with increasing time and temperature, the structure gradually assimilates the residual SiO2, and the lattice parameters change, such that by 1400°C, the material has attained its equilibrium structure and composition.TEM was used to determine the spatial relationship between the crystalline phase and the residual, amorphous, SiO2-rich phase in pt-mullite. The starting materials were quenched, 3:2 mullite beads and fibers (made by containerless processing).

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Morphological Phase Diagram for a Ternary System of Block Copolymer PS310-b-PAA52/Dioxane/H2O

The Journal of Physical Chemistry B ◽

10.1021/jp991365c ◽

1999 ◽

Vol 103 (44) ◽

pp. 9473-9487 ◽

Cited By ~ 241

Author(s):

Hongwei Shen ◽

Adi Eisenberg

Keyword(s):

Phase Diagram ◽

Block Copolymer ◽

Ternary System

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The UCoAl ternary system: Phases formation and isothermal section of the phase diagram at 900 °C

Solid State Sciences ◽

10.1016/j.solidstatesciences.2004.11.025 ◽

2005 ◽

Vol 7 (6) ◽

pp. 780-783 ◽

Cited By ~ 11

Author(s):

Henri Noël ◽

Olivier Tougait ◽

Robert Troc ◽

Vasyl Zaremba

Keyword(s):

Phase Diagram ◽

Isothermal Section ◽

Ternary System

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Phase Evolution and Dielectric Characterization of Lead Nickel Niobate–lead Zirconate Ceramics Prepared from the Hydrothermally Derived Precursors

Journal of Materials Research ◽

10.1557/jmr.1999.0186 ◽

1999 ◽

Vol 14 (4) ◽

pp. 1364-1370 ◽

Cited By ~ 6

Author(s):

Chung-Hsin Lu ◽

Wen-Jeng Hwang

Keyword(s):

Dielectric Response ◽

Pyrochlore Phase ◽

Phase Evolution ◽

Intermediate Compound ◽

Lead Zirconate ◽

Relaxor Ferroelectrics ◽

Dielectric Characterization ◽

Lead Nickel ◽

Rich Side

The perovskite compounds with the composition of (1 – x) Pb(Ni1/3Nb2/3)O3 –xPbZrO3 have been successfully prepared from hydrothermally treated precursors. During calcination, the primary intermediate compound is pyrochlore phase in the Pb(Ni1/3Nb2/3)O3-rich composition, while it is PbZrO3 on the PbZrO3-rich side. On calcination at 800 °C, all precursors convert into perovskite phases. In the formed solid solutions, increasing PbZrO3 content results in a rise in the apparent Curie temperature as well as the maximum dielectric permittivity. The Pb(Ni1/3Nb2/3)O3-rich perovskites (x < 0.8) possess the characteristics of relaxor ferroelectrics. With increasing PbZrO3 content, the dielectric response gradually becomes less diffuse and dispersive, reflecting a reduction in the relaxor characteristics of the formed perovskites.

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