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Synthesis of freestanding HfO2 nanostructures.

Kidd T, O'Shea A, Boyle K, Wallace J, Strauss L - Nanoscale Res Lett (2011)

Bottom Line: This simple process resulted in the formation of nanometer scale crystallites of HfO2.The thinnest sheets appeared transparent when viewed in a scanning electron microscope.These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

View Article: PubMed Central - HTML - PubMed

Affiliation: Physics Department, University of Northern Iowa, Cedar Falls, IA 50614, USA. tim.kidd@uni.edu.

ABSTRACT
Two new methods for synthesizing nanostructured HfO2 have been developed. The first method entails exposing HfTe2 powders to air. This simple process resulted in the formation of nanometer scale crystallites of HfO2. The second method involved a two-step heating process by which macroscopic, freestanding nanosheets of HfO2 were formed as a byproduct during the synthesis of HfTe2. These highly two-dimensional sheets had side lengths measuring up to several millimeters and were stable enough to be manipulated with tweezers and other instruments. The thickness of the sheets ranged from a few to a few hundred nanometers. The thinnest sheets appeared transparent when viewed in a scanning electron microscope. It was found that the presence of Mn enhanced the formation of HfO2 by exposure to ambient conditions and was necessary for the formation of the large scale nanosheets. These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

No MeSH data available.


Related in: MedlinePlus

XRD patterns from fresh powder and a relatively large HfO2 nanosheet. Significant peaks related to the different phases are indicated by symbols.
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Figure 5: XRD patterns from fresh powder and a relatively large HfO2 nanosheet. Significant peaks related to the different phases are indicated by symbols.

Mentions: A comparison of the XRD patterns taken from fresh powder and a relatively large HfO2 sheet are shown in Figure 5. The fresh powder was exposed to air for only a few hours while the sheet had been exposed to air for many days during sample handling and measurements. This powder and the sheets came from the same growth ampoule. The pattern from the fresh powder could be matched to peaks derived from HfTe2 [14], HfO2 [15], and MnTe [16] while the sheet pattern was essentially that of HfO2. The HfO2 sheet showed some enhancement of the peak at 28.3° but not enough to definitively imply that the sheet was made up of a single, oriented crystal. The intensity of this peak was also enhanced in the powder sample, but this is likely due to an overlap with a MnTe peak located at 28.2°. The HfTe2 peaks showed significant (001) orientation from the intensity of the (002) peak at 13.4°, which should nominally be only 1.5% of the intensity of the main (011) peak found at 29.3°. This orientation is common for layered dichalcogenides in powder form as they are typically made up of small, thin platelets that are difficult to force into a random configuration.


Synthesis of freestanding HfO2 nanostructures.

Kidd T, O'Shea A, Boyle K, Wallace J, Strauss L - Nanoscale Res Lett (2011)

XRD patterns from fresh powder and a relatively large HfO2 nanosheet. Significant peaks related to the different phases are indicated by symbols.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211360&req=5

Figure 5: XRD patterns from fresh powder and a relatively large HfO2 nanosheet. Significant peaks related to the different phases are indicated by symbols.
Mentions: A comparison of the XRD patterns taken from fresh powder and a relatively large HfO2 sheet are shown in Figure 5. The fresh powder was exposed to air for only a few hours while the sheet had been exposed to air for many days during sample handling and measurements. This powder and the sheets came from the same growth ampoule. The pattern from the fresh powder could be matched to peaks derived from HfTe2 [14], HfO2 [15], and MnTe [16] while the sheet pattern was essentially that of HfO2. The HfO2 sheet showed some enhancement of the peak at 28.3° but not enough to definitively imply that the sheet was made up of a single, oriented crystal. The intensity of this peak was also enhanced in the powder sample, but this is likely due to an overlap with a MnTe peak located at 28.2°. The HfTe2 peaks showed significant (001) orientation from the intensity of the (002) peak at 13.4°, which should nominally be only 1.5% of the intensity of the main (011) peak found at 29.3°. This orientation is common for layered dichalcogenides in powder form as they are typically made up of small, thin platelets that are difficult to force into a random configuration.

Bottom Line: This simple process resulted in the formation of nanometer scale crystallites of HfO2.The thinnest sheets appeared transparent when viewed in a scanning electron microscope.These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

View Article: PubMed Central - HTML - PubMed

Affiliation: Physics Department, University of Northern Iowa, Cedar Falls, IA 50614, USA. tim.kidd@uni.edu.

ABSTRACT
Two new methods for synthesizing nanostructured HfO2 have been developed. The first method entails exposing HfTe2 powders to air. This simple process resulted in the formation of nanometer scale crystallites of HfO2. The second method involved a two-step heating process by which macroscopic, freestanding nanosheets of HfO2 were formed as a byproduct during the synthesis of HfTe2. These highly two-dimensional sheets had side lengths measuring up to several millimeters and were stable enough to be manipulated with tweezers and other instruments. The thickness of the sheets ranged from a few to a few hundred nanometers. The thinnest sheets appeared transparent when viewed in a scanning electron microscope. It was found that the presence of Mn enhanced the formation of HfO2 by exposure to ambient conditions and was necessary for the formation of the large scale nanosheets. These results present new routes to create freestanding nanostructured hafnium dioxide.PACS: 81.07.-b, 61.46.Hk, 68.37.Hk.

No MeSH data available.


Related in: MedlinePlus