| Autor: |
Shanker Ram, Susmita Misra, Arundhati Sengupta |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Journal of Nano Research. 28:101-108 |
| ISSN: |
1661-9897 |
| DOI: |
10.4028/www.scientific.net/jnanor.28.101 |
| Popis: |
A transition metal ion Cr4+(3d2 spins) doped ZrO2 of small crystallites presents tailored magnetic, electrical and optical properties useful for magnetodielectric and spintronic applications. A liquid polymer precursor gel (Cr4+ and Zr4+ complex with glycerol) when heated in an autoclave at a small pressure 0.6-0.7 atm at 420–470 K results in a compound Zr0.8Cr0.2O2 with an average 5 nm crystallite size of a stabilized cubic (c)-ZrO2-type phase (after 2 h annealing at 773 K in air). A broad Raman band is observed at ~300 cm-1 in acoustic and transverse optic phonons characteristic of the c-ZrO2-type structure, with a prominent O–Cr–O stretching band at 878 cm-1 in a ferromagnetic order. A CrO2/Cr2O3 surface layer exhibits two weak bands at ~1011 cm-1 and 1032 cm-1. The sample exhibits an ‘S’-shaped ferromagnetic hysteresis loop (does not saturate below 60 kOe fields) at 5 K, with a magnetization M = 85.79 emu/g (in the CrO2 part) at 60 kOe and coercivity Hc = 100 Oe. With warming above 5 K, the loop converges progressively with only a weak ferromagnetism at room temperature, M = 9.08 emu/g and Hc = 54.2 Oe. As a pinning barrier, the uncompensated spins in the surface layer supports coercivity at low temperature. A model magnetic structure describes the magnetic properties in correlation to the microstructure. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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