Magnetic susceptibility and thermal stability of particle size of nanocrystalline tungsten carbide WC |
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Authors: | A S Kurlov S Z Nazarova A I Gusev |
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Institution: | (1) Institute of Solid-State Chemistry, Ural Division, Russian Academy of Sciences, ul. S. Kovalevskoĭ 18, Yekaterinburg, 620041, Russia |
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Abstract: | The magnetic susceptibility χ of coarse-grained and nanocrystalline tungsten carbides was studied in the temperature range 300–1250 K. The temperature dependence of the susceptibility χ(T) of coarse-grained carbide WC is typical of weak Pauli paramagnets and has no specific features. The χ(T) dependence of nanocrystalline carbide (n-WC) in the range 550–920 K exhibits features associated with annealing of microstrains, which leads to a decrease in the contribution of orbital paramagnetism to the magnetic susceptibility of n-WC and initiates precipitation of minor impurities of iron and cobalt as superparamagnetic particles. A nanocrystalline n-WC powder retains a stable particle size of ~55 nm after long annealing at temperatures of 300 to 1200 K, whereas microstrains relax at 550–920 K. |
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