Structural studies of CaAl12O19, SrAl12O19, La2/3+δ Al12–δO19, and CaAl10NiTiO19 with the hibonite structure; indications of an unusual type of ferroelectricity

AbstractVarious oxides with the hibonite structure were synthesized and structurally analyzed using powder neutron diffraction. The structure of CaAl12O19 at 298 and 11 K shows dipoles that are apparently too dilute to order unless subjected to a suitable electric field. Magnetoplumbites, such as BaFe12O19, are isostructural with hibonite. These compounds possess ferromagnetic properties, which combined with the electric dipoles may influence multiferroic behavior. Our SrAl12O19 sample showed two distinct hexagonal phases, a major phase with the normal hibonite structure and a minor phase having a closely related structure. Our sample of the defect hibonite phase La2/3+δAl12–δO19 shows a distinctly higher δ value (0.25) vs. that reported (~0.15) for samples made from the melt. Finally, we used to advantage the negative scattering length of Ti to determine the site occupancies of Ni and Ti in CaAl10NiTiO19.

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Structural Studies of a Carbonate Fluorapatite from Powder Neutron Diffraction Data

Materials Science Forum ◽

10.4028/www.scientific.net/msf.321-324.924 ◽

2000 ◽

Vol 321-324 ◽

pp. 924-931 ◽

Cited By ~ 1

Author(s):

Th. Leventouri ◽

B.C. Chakoumakos ◽

H.Y. Moghaddam ◽

V. Perdikatsis

Keyword(s):

Neutron Diffraction ◽

Diffraction Data ◽

Structural Studies ◽

Neutron Diffraction Data ◽

Powder Neutron Diffraction ◽

Carbonate Fluorapatite ◽

Powder Neutron Diffraction Data

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Effect of Cao from Different Sources on the Nanostructured Cordierite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.364.368 ◽

2011 ◽

Vol 364 ◽

pp. 368-371 ◽

Cited By ~ 2

Author(s):

Ibrahim Norfadhilah ◽

Mohamad Hasmaliza ◽

Zainal Arifin Ahmad ◽

J. Banjuraizah

Keyword(s):

Xrd Analysis ◽

Oxide Material ◽

X Ray Diffraction ◽

Minor Phase ◽

Major Phase ◽

X Ray ◽

Pure Oxide ◽

Crystallite Sizes ◽

A Minor ◽

Different Sources

Cordierite was synthesized via glass-route using mineral and pure oxide material. Kaolin, talc, dolomite, magnesia, alumina, silica, and calcium oxide were mixed and melted. CaO from mineral and pure oxide was added in order to investigate the properties of each material in cordierite system. Sample was characterized using X-ray diffraction (XRD) analysis and dilatometer testing. The result showed that when 5wt% CaO from mineral (C5 Min) was added and sintered at 900°C, α-cordierite exist as major phase and anorthite as a minor phase. While for a sample consists of 5wt% CaO from pure oxide (C5 Ox), α-cordierite was present as major phases, µ-cordierite and anorthite as minor phases. Crystallite sizes of each material were in nanorange and crystallite size of C5 Ox was less than C5 Min.

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Dependence of defect concentration, optical and photocatalytic properties of β-Ni(OH)2/ZnO and NiO/ZnO composite powders on phase transformation

Materials Science-Poland ◽

10.2478/msp-2020-0031 ◽

2020 ◽

Vol 38 (2) ◽

pp. 219-227

Author(s):

Sumetha Suwanboon ◽

Sarunya Klubnuan ◽

Mukdawan Homkaew ◽

Pongsaton Amornpitoksuk

Keyword(s):

Particle Shape ◽

Optical Band Gap ◽

Phase Particle ◽

Minor Phase ◽

Composite Powders ◽

Calcination Process ◽

Major Phase ◽

X Ray ◽

A Minor ◽

Scanning Electron

Abstractβ-Ni(OH)2/ZnO composite powders were successfully synthesized by hydrothermal method at 180 °C for 15 h whereas NiO/ZnO composite powders formed after the as-prepared powders were calcined at 800 °C for 1 h in air. The X-ray diffractometer (XRD), scanning electron microscope (SEM), UV-Vis spectrophotometer were used to characterize the phase, particle shape as well as size and optical properties, respectively. In this system, it was found that ZnO is a major phase while β-Ni(OH)2 and NiO are a minor phases. The altered particle shape of ZnO was influenced by addition of Ni(CH3COO)2·6H2O whereas the particle shape of the minor phase was changed due to the calcination process. The optical band gap decreased when the amount of minor phase increased. For photocatalytic study, it was found that 6 mol% β-Ni(OH)2/ZnO composite powders exhibited the best decolorization of methylene blue aqueous solution.

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Structural Study on Molten (7Li, K)Cl and (7Li, Na, K)Cl of the Eutectic Composition by Pulsed Neutron Diffraction

Zeitschrift für Naturforschung A ◽

10.1515/zna-1988-1108 ◽

1988 ◽

Vol 43 (11) ◽

pp. 961-964 ◽

Cited By ~ 2

Author(s):

Akira Endoh ◽

Toshio Yamaguchi ◽

Yusuke Tamura ◽

Osamu Odawara ◽

Isao Okada ◽

...

Keyword(s):

Neutron Diffraction ◽

Eutectic Composition ◽

Scattering Length ◽

Ternary Mixtures ◽

The Other ◽

Nearest Neighbour ◽

Neighbour Distance ◽

Binary And Ternary Mixtures ◽

Negative Scattering Length ◽

Pulsed Neutron

Abstract Pulsed neutron diffraction Pulsed neutron diffraction measurements have been performed on molten (7Li, K)C1 and (7Li, Na, K)Cl mixtures of the eutectic composition to determine the nearest neighbour distance between Li+ and Cl- ions. Owing to the negative scattering length of the 7Li nucleus, this contribution becomes negative in the radial distribution function and can be separated from the other contributions. The nearest neighbour distance between Li+ ion and Cl- ion is found to be 240 pm in both the binary and ternary mixtures.

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