Textural evolution and phase transformation in titania membranes: Part 2. Supported membranes

Krishnankutty-Nair P. Kumar, Klaas Keizer, Anthonie J. Burggraaf, Tatsuya Okubo, Hidetoshi Nagamoto

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Abstract

Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more than 97% density at 600 °C, whereas the supported membranes had a density of only ca. 70–75% even at 700 °C when calcined for 8 h. At 700 °C the average crystallite size of supported and unsupported membranes was ca. 20 and 70 nm, respectively. This behaviour is primarily attributed to the decrease in the driving force for sintering due to the stress developed during the constrained sintering of a film attached to a rigid support and to the inhibition of the reorganization process within the film, resulting in lower coordination numbers in supported membranes. Supported membranes showed a higher transformation temperature (slower rate of transformation) than did the unsupported. Supported and unsupported membranes, calcined for 8 h, transformed to ca. 90% rutile (calculated from Raman spectrum) after calcination at 850 and 650 °C, respectively. This difference in phase transformation behaviour is attributed primarily to the large stress which is developed in a constrained environment owing to the negative volume change during the anatase–rutile transformation.
Original languageEnglish
Pages (from-to)1151-1159
Number of pages9
JournalJournal of materials chemistry
Volume3
Issue number11
DOIs
Publication statusPublished - 1993

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Titanium
Phase transitions
Membranes
Sintering
Crystallite size
titanium dioxide
Densification
Field emission
Calcination
Raman spectroscopy
Raman scattering
X ray diffraction
Scanning electron microscopy
Temperature

Cite this

Kumar, Krishnankutty-Nair P. ; Keizer, Klaas ; Burggraaf, Anthonie J. ; Okubo, Tatsuya ; Nagamoto, Hidetoshi. / Textural evolution and phase transformation in titania membranes : Part 2. Supported membranes. In: Journal of materials chemistry. 1993 ; Vol. 3, No. 11. pp. 1151-1159.
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title = "Textural evolution and phase transformation in titania membranes: Part 2. Supported membranes",
abstract = "Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more than 97{\%} density at 600 °C, whereas the supported membranes had a density of only ca. 70–75{\%} even at 700 °C when calcined for 8 h. At 700 °C the average crystallite size of supported and unsupported membranes was ca. 20 and 70 nm, respectively. This behaviour is primarily attributed to the decrease in the driving force for sintering due to the stress developed during the constrained sintering of a film attached to a rigid support and to the inhibition of the reorganization process within the film, resulting in lower coordination numbers in supported membranes. Supported membranes showed a higher transformation temperature (slower rate of transformation) than did the unsupported. Supported and unsupported membranes, calcined for 8 h, transformed to ca. 90{\%} rutile (calculated from Raman spectrum) after calcination at 850 and 650 °C, respectively. This difference in phase transformation behaviour is attributed primarily to the large stress which is developed in a constrained environment owing to the negative volume change during the anatase–rutile transformation.",
author = "Kumar, {Krishnankutty-Nair P.} and Klaas Keizer and Burggraaf, {Anthonie J.} and Tatsuya Okubo and Hidetoshi Nagamoto",
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Textural evolution and phase transformation in titania membranes : Part 2. Supported membranes. / Kumar, Krishnankutty-Nair P.; Keizer, Klaas; Burggraaf, Anthonie J.; Okubo, Tatsuya; Nagamoto, Hidetoshi.

In: Journal of materials chemistry, Vol. 3, No. 11, 1993, p. 1151-1159.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - Textural evolution and phase transformation in titania membranes

T2 - Part 2. Supported membranes

AU - Kumar, Krishnankutty-Nair P.

AU - Keizer, Klaas

AU - Burggraaf, Anthonie J.

AU - Okubo, Tatsuya

AU - Nagamoto, Hidetoshi

PY - 1993

Y1 - 1993

N2 - Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more than 97% density at 600 °C, whereas the supported membranes had a density of only ca. 70–75% even at 700 °C when calcined for 8 h. At 700 °C the average crystallite size of supported and unsupported membranes was ca. 20 and 70 nm, respectively. This behaviour is primarily attributed to the decrease in the driving force for sintering due to the stress developed during the constrained sintering of a film attached to a rigid support and to the inhibition of the reorganization process within the film, resulting in lower coordination numbers in supported membranes. Supported membranes showed a higher transformation temperature (slower rate of transformation) than did the unsupported. Supported and unsupported membranes, calcined for 8 h, transformed to ca. 90% rutile (calculated from Raman spectrum) after calcination at 850 and 650 °C, respectively. This difference in phase transformation behaviour is attributed primarily to the large stress which is developed in a constrained environment owing to the negative volume change during the anatase–rutile transformation.

AB - Nanostructural evolution and phase transformation in supported and unsupported titania membranes have been studied using Raman spectroscopy, X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Densification of unsupported membranes started at ca. 450 °C and reached more than 97% density at 600 °C, whereas the supported membranes had a density of only ca. 70–75% even at 700 °C when calcined for 8 h. At 700 °C the average crystallite size of supported and unsupported membranes was ca. 20 and 70 nm, respectively. This behaviour is primarily attributed to the decrease in the driving force for sintering due to the stress developed during the constrained sintering of a film attached to a rigid support and to the inhibition of the reorganization process within the film, resulting in lower coordination numbers in supported membranes. Supported membranes showed a higher transformation temperature (slower rate of transformation) than did the unsupported. Supported and unsupported membranes, calcined for 8 h, transformed to ca. 90% rutile (calculated from Raman spectrum) after calcination at 850 and 650 °C, respectively. This difference in phase transformation behaviour is attributed primarily to the large stress which is developed in a constrained environment owing to the negative volume change during the anatase–rutile transformation.

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