Granular GMR Sensors of Co-Cu and Co-Ag Nanoparticles Synthesized through a Chemical Route Using NaBH4
✍ Scribed by Ram, S. ;Frankwicz, P.S.
- Book ID
- 101386118
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 172 KB
- Volume
- 188
- Category
- Article
- ISSN
- 0031-8965
No coin nor oath required. For personal study only.
✦ Synopsis
Granular Co 100--x Cu x and Co 100--x Ag x , x = 25 to 85, are obtained by co-reduction of the metal cations dispersed in water with NaBH 4 as the reducing agent. In either series, the as prepared sample has an fcc structure. The formation of it in this structure in this reaction is sensitive to its composition and other experimental conditions. No amorphous phase is present in a significant amount to appear in X-ray diffraction. Impurities from elemental Co or Cu persist in Co, x < 25, or Cu, x > 75, rich compositions. A significant magnetoresistance (MR) appears in 10 to 30 nm diameter granules in the samples at x = 70 to 90. The maximum value of it is found to be 48% in Co 100-x Cu x , at x % 15, and 38% in Co 100--x Ag x , at x % 25, at 2 to 5 K. Both of the series are ferromagnetic with magnetic moment as high as 1.85m B (1.63m B at 295 K) per Co atom (which compares to the 1.75m B value in fcc Co) and the coercivity as high as 60 kA m --1 (41 kA m --1 at 295 K) at 2 K. Even if part of this huge MR extends to persist to room temperature along with the other magnetic properties would be sufficient enough for applications in read or write head and related devices and components.