Featured Research

from universities, journals, and other organizations

Nanomaterials: Bringing crystals into line

Date:
October 25, 2012
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
The temperature-controlled alignment of tiny crystals could help harness their collective properties for nanotechnology applications.

The temperature-controlled alignment of tiny crystals could help harness their collective properties for nanotechnology applications.

The unique magnetic properties of cobalt phosphide nanowires stand them in good stead as future components of high-performance devices. Unlike bulk materials, these ultrasmall elongated crystals consist of single-domain structures that account for their superparamagnetism -- a temperature-induced magnetism that arises in a magnetic field. To maintain and fully exploit this behavior, scientists must generate materials composed of precisely positioned and oriented building blocks. Such superstructures are now available, thanks to the development of a method that uses temperature changes to align individual nanowires. Ming-Yong Han from the A*STAR Institute of Materials Research and Engineering, Sinapore, led the research.

Current nanocrystal self-assembly approaches involve depositing a crystal suspension on a solid surface, and then slowly evaporating the solvent. Theoretically, the evaporation enhances the relatively weak attraction forces that exist between the nanocrystals, forcing them to align. However, high degrees of alignment of anisotropic structures -- those exhibiting direction-dependent physical properties -- remain difficult to achieve.

"We took a distinct pathway from the slow evaporation approach," says Han. His team's strategy followed similar principles to those used in chemical synthesis. First, they reacted a cobalt derivative with the phosphide precursor trioctylphosphine (TOP) at high temperature. This produced TOP-coated nanowires. Next, they stored the solution in which the nanowires formed at various temperatures. These storage, or 'aging', temperatures produced larger, well-defined superstructures with different alignments.

Washing the nanowires without the latter step resulted in random arrangements or small assemblies (see image). After cooling and aging the reaction mixture at room temperature for two hours, the team observed superstructures composed of nearly one million vertically standing nanowires. In this arrangement, each nanowire was surrounded by six others in a honeycomb pattern. When cooled to room temperature and then refrigerated, the reaction mixture produced extended sheets of nanowires aligned side-by-side horizontally.

The superstructures resisted any high temperature, ultrasound, or organic solvent treatment, indicative of strong cohesive forces between the nanowires. Further investigations revealed that, during the self-assembly, the TOP molecules continually adsorbed and desorbed from the nanowires, bringing them in close contact. This caused irreversible chemical bonds to form between the nanocrystals, facilitating and enhancing their alignment.

The team is currently testing the performance of the superstructures against that of the randomly oriented nanowires to explore their potential use as sensors or electrical components called inductors. "We are also trying to extend this methodology to self-assemble other systems, with a hope to establish a more universal method for aligning anisotropic nanocrystals," adds Han.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering.


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. Shuang-Yuan Zhang, Enyi Ye, Shuhua Liu, Suo Hon Lim, Si Yin Tee, Zhili Dong, Ming-Yong Han. Temperature and Chemical Bonding-Directed Self-Assembly of Cobalt Phosphide Nanowires in Reaction Solutions into Vertical and Horizontal Alignments. Advanced Materials, 2012; 24 (32): 4369 DOI: 10.1002/adma.201201618

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Nanomaterials: Bringing crystals into line." ScienceDaily. ScienceDaily, 25 October 2012. <www.sciencedaily.com/releases/2012/10/121025160853.htm>.
The Agency for Science, Technology and Research (A*STAR). (2012, October 25). Nanomaterials: Bringing crystals into line. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2012/10/121025160853.htm
The Agency for Science, Technology and Research (A*STAR). "Nanomaterials: Bringing crystals into line." ScienceDaily. www.sciencedaily.com/releases/2012/10/121025160853.htm (accessed August 2, 2014).

Share This




More Matter & Energy News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Tesla, Panasonic Ink Deal To Make Huge Battery 'Gigafactory'

Tesla, Panasonic Ink Deal To Make Huge Battery 'Gigafactory'

Newsy (July 31, 2014) The deal will help build a massive battery factory that Tesla says will produce 500,000 lithium batteries by 2020. Video provided by Newsy
Powered by NewsLook.com
Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
7 Ways to Use Toothpaste: Howdini Hacks

7 Ways to Use Toothpaste: Howdini Hacks

Howdini (July 30, 2014) Fresh breath and clean teeth are great, but have you ever thought, "my toothpaste could be doing more". Well, it can! Lots of things! Howdini has 7 new uses for this household staple. Video provided by Howdini
Powered by NewsLook.com
Smoked: 2015 Ducati Diavel Vs 2014 Chevy Corvette Stingray Drag Race

Smoked: 2015 Ducati Diavel Vs 2014 Chevy Corvette Stingray Drag Race

Cycle World (July 30, 2014) The Bonnier Motorcycle Group presents Smoked; a three part video series. In this episode the 2015 Ducati Diavel takes on the 2014 Chevy Corvette Stingray Video provided by Cycle World
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins