Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction
The phase transformation behavior of TiO 2 sol-gel synthesized nanopowder heated in a sealed quartz capillary from room temperature to 800°C was studied using in-situ synchrotron radiation diffraction (SRD). Sealing of the capillary resulted in an increase in capillary gas pressure with temperature...
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| Format: | Journal Article |
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Wiley-Blackwell Publishing, Inc.
2017
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| Online Access: | http://hdl.handle.net/20.500.11937/55424 |
| _version_ | 1848759617333493760 |
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| author | Albetran, H. O'Connor, Brian Low, It Meng |
| author_facet | Albetran, H. O'Connor, Brian Low, It Meng |
| author_sort | Albetran, H. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The phase transformation behavior of TiO 2 sol-gel synthesized nanopowder heated in a sealed quartz capillary from room temperature to 800°C was studied using in-situ synchrotron radiation diffraction (SRD). Sealing of the capillary resulted in an increase in capillary gas pressure with temperature. The pressures inside the sealed capillary were calculated using Gay-Lussac's Law, and they reached 0.36 MPa at 800°C. The as-synthesized material was entirely amorphous at room temperature, with crystalline anatase first appearing by 200°C (24 wt% absolute), then increasing rapidly in concentration to 89 wt% by 300°C and then increasing more slowly to 97 wt% by 800°C, with there being no indication of the anatase-to-rutile transformation up to 800°C. The best estimate of activation energy for the amorphous-to-anatase transformation from the SRD data was 10(2) kJ/mol, which is much lower than that observed when heating the material under atmospheric pressure in a laboratory XRD experiment, 38(5) kJ/mol. For the experiment under atmospheric pressure, the anatase crystallization temperature was delayed by ~200°C, first appearing after heating the sample to 400°C, after which crystalline rutile was first observed after heating to 600°C. The estimated activation energy for the anatase-to-rutile transformation was 120(18) kJ/mol, which agrees with estimates for titania nanofibers heated under atmospheric pressure. Thus, heating the nanopowders material under pressure promoted the amorphous-to-anatase transformation, but retarded the anatase-to-rutile transformation. This behavior is believed to occur in an oxygen-rich environment and interstitial titanium is also expected to form when the material is heated under high gas pressure. This suggests that atmospheric oxygen appears to accelerate the amorphous-to-anatase transformation, whereas interstitial titanium inhibits TiO 2 structure relaxation, which is required for the anatase-to-rutile transformation. |
| first_indexed | 2025-11-14T10:02:44Z |
| format | Journal Article |
| id | curtin-20.500.11937-55424 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:02:44Z |
| publishDate | 2017 |
| publisher | Wiley-Blackwell Publishing, Inc. |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-554242017-11-03T07:11:02Z Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction Albetran, H. O'Connor, Brian Low, It Meng The phase transformation behavior of TiO 2 sol-gel synthesized nanopowder heated in a sealed quartz capillary from room temperature to 800°C was studied using in-situ synchrotron radiation diffraction (SRD). Sealing of the capillary resulted in an increase in capillary gas pressure with temperature. The pressures inside the sealed capillary were calculated using Gay-Lussac's Law, and they reached 0.36 MPa at 800°C. The as-synthesized material was entirely amorphous at room temperature, with crystalline anatase first appearing by 200°C (24 wt% absolute), then increasing rapidly in concentration to 89 wt% by 300°C and then increasing more slowly to 97 wt% by 800°C, with there being no indication of the anatase-to-rutile transformation up to 800°C. The best estimate of activation energy for the amorphous-to-anatase transformation from the SRD data was 10(2) kJ/mol, which is much lower than that observed when heating the material under atmospheric pressure in a laboratory XRD experiment, 38(5) kJ/mol. For the experiment under atmospheric pressure, the anatase crystallization temperature was delayed by ~200°C, first appearing after heating the sample to 400°C, after which crystalline rutile was first observed after heating to 600°C. The estimated activation energy for the anatase-to-rutile transformation was 120(18) kJ/mol, which agrees with estimates for titania nanofibers heated under atmospheric pressure. Thus, heating the nanopowders material under pressure promoted the amorphous-to-anatase transformation, but retarded the anatase-to-rutile transformation. This behavior is believed to occur in an oxygen-rich environment and interstitial titanium is also expected to form when the material is heated under high gas pressure. This suggests that atmospheric oxygen appears to accelerate the amorphous-to-anatase transformation, whereas interstitial titanium inhibits TiO 2 structure relaxation, which is required for the anatase-to-rutile transformation. 2017 Journal Article http://hdl.handle.net/20.500.11937/55424 10.1111/jace.14798 Wiley-Blackwell Publishing, Inc. restricted |
| spellingShingle | Albetran, H. O'Connor, Brian Low, It Meng Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| title | Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| title_full | Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| title_fullStr | Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| title_full_unstemmed | Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| title_short | Effect of pressure on TiO2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| title_sort | effect of pressure on tio2 crystallization kinetics using in-situ high-temperature synchrotron radiation diffraction |
| url | http://hdl.handle.net/20.500.11937/55424 |