Limits...
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 a bundled nanotube structure sandwiched between two HfO2 nanosheets. The bundle can be easily seen through the transparent upper sheet.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211360&req=5

Figure 4: SEM images of a bundled nanotube structure sandwiched between two HfO2 nanosheets. The bundle can be easily seen through the transparent upper sheet.

Mentions: It was apparent that different sheets had different thicknesses. Measurement of each was very difficult as mounting the sheets on edge was not a stable configuration and the sheets would often wobble or shift when high magnification measurements were attempted. However, one qualitative measure of sheet thickness that can be obtained in the SEM is their degree of transparency. In one area of the sample shown in Figure 4, a bundle composed of either nanotubes or nanorods was found trapped between two small HfO2 sheets. This was one of only a few bundles found in the sample, making it unclear whether this one-dimensional structure was an extremely rare growth product or if it was a contaminant from some bundled TaS2 nanotubes mounted on a different area of the sample stage in the SEM. Regardless of the bundle's origin, the image demonstrates just how transparent, and therefore thin, these sheets can be. The appearance of the bundle as seen through the upper sheet is smeared out, but not significantly dimmer compared to viewing it directly. This degree of transparency is similar to that of single-molecule thick materials [9].


Synthesis of freestanding HfO2 nanostructures.

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

SEM images of a bundled nanotube structure sandwiched between two HfO2 nanosheets. The bundle can be easily seen through the transparent upper sheet.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: SEM images of a bundled nanotube structure sandwiched between two HfO2 nanosheets. The bundle can be easily seen through the transparent upper sheet.
Mentions: It was apparent that different sheets had different thicknesses. Measurement of each was very difficult as mounting the sheets on edge was not a stable configuration and the sheets would often wobble or shift when high magnification measurements were attempted. However, one qualitative measure of sheet thickness that can be obtained in the SEM is their degree of transparency. In one area of the sample shown in Figure 4, a bundle composed of either nanotubes or nanorods was found trapped between two small HfO2 sheets. This was one of only a few bundles found in the sample, making it unclear whether this one-dimensional structure was an extremely rare growth product or if it was a contaminant from some bundled TaS2 nanotubes mounted on a different area of the sample stage in the SEM. Regardless of the bundle's origin, the image demonstrates just how transparent, and therefore thin, these sheets can be. The appearance of the bundle as seen through the upper sheet is smeared out, but not significantly dimmer compared to viewing it directly. This degree of transparency is similar to that of single-molecule thick materials [9].

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