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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

SEM images of the edge of a HfO2 nanosheet. (a) Wide view showing differences between smooth top side and cluster-filled bottom side. (b) Close-up of edge. Edge thickness is 200 nm.
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Figure 3: SEM images of the edge of a HfO2 nanosheet. (a) Wide view showing differences between smooth top side and cluster-filled bottom side. (b) Close-up of edge. Edge thickness is 200 nm.

Mentions: The HfO2 sheets were so thin that, in the SEM, it was often possible to see through them and measure the pores of the carbon tape to which they were attached. Also, the larger clusters bound to the brighter side were often detectable as cloudy features (Figure 2c) seen when the darker side of the sheet faced the electron beam. It was possible to directly measure the thickness of a few of the larger sheets as they were bound to the carbon tape in a perpendicular fashion. The sheet shown in Figure 3 originally had side lengths that exceeded 1 mm, and after some fortuitous breakage became bound to the carbon tape by its edge. The differences between the bright (bottom) and dark (top) sides are readily apparent in the wide area view shown in Figure 3a, even though differences in relative intensity are muted when the sample is viewed at this angle. The dark side originally facing the quartz is almost featureless while the bright side is covered with clusters of various sizes. A higher magnification image of the edge is shown in Figure 3b. The thickness of the sheet itself, ignoring particulate or other clusters, was measured to be about 200 nm. Given that this was one of the thicker sheets, this implies that these HfO2 nanosheets are highly two-dimensional structures with dimensions similar to those used in thin film device applications.


Synthesis of freestanding HfO2 nanostructures.

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

SEM images of the edge of a HfO2 nanosheet. (a) Wide view showing differences between smooth top side and cluster-filled bottom side. (b) Close-up of edge. Edge thickness is 200 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: SEM images of the edge of a HfO2 nanosheet. (a) Wide view showing differences between smooth top side and cluster-filled bottom side. (b) Close-up of edge. Edge thickness is 200 nm.
Mentions: The HfO2 sheets were so thin that, in the SEM, it was often possible to see through them and measure the pores of the carbon tape to which they were attached. Also, the larger clusters bound to the brighter side were often detectable as cloudy features (Figure 2c) seen when the darker side of the sheet faced the electron beam. It was possible to directly measure the thickness of a few of the larger sheets as they were bound to the carbon tape in a perpendicular fashion. The sheet shown in Figure 3 originally had side lengths that exceeded 1 mm, and after some fortuitous breakage became bound to the carbon tape by its edge. The differences between the bright (bottom) and dark (top) sides are readily apparent in the wide area view shown in Figure 3a, even though differences in relative intensity are muted when the sample is viewed at this angle. The dark side originally facing the quartz is almost featureless while the bright side is covered with clusters of various sizes. A higher magnification image of the edge is shown in Figure 3b. The thickness of the sheet itself, ignoring particulate or other clusters, was measured to be about 200 nm. Given that this was one of the thicker sheets, this implies that these HfO2 nanosheets are highly two-dimensional structures with dimensions similar to those used in thin film device applications.

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