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The structure and magnetic properties of MnFe(2)O(4) ferrites have been investigated using five different preparation methods, including the ceramic technique, flash combustion, co-precipitation, sol-gel and citrate methods. The characteristics of one sample prepared by different methods have been studied to select the better method, i.e. the one that is the simplest and does not require an elaborate instrumental set-up. The results indicated that the citrate method gives the lowest value for the lattice parameter and particle size (14.1 nm), while the highest values are obtained with the ceramic method. The smallest nanosizes were obtained in the citrate and flash methods (14.1 and 40.7 nm, respectively).

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Zirconia doped Hydroxyapatite (HAP) nanocrystals [Ca10(PO4)6−x(ZrO2)x(OH)2]; (0 ≤ x ≤ 1 step 0.2) were synthesized using simple low cost facile method. The crystalline phases were examined by X-ray diffraction (XRD). The crystallinity percentage decreased with increasing zirconia content for the as-synthesized samples. The existence of zirconia as secondary phase on the grain boundaries; as observed from scanning electron micrographs (FESEM); resulted in negative values of microstrain. The crystallite size was computed and the results showed that it increased with increasing annealing temperature. Thermo-gravimetric analysis (TGA) assured the thermal stability of the nano crystals over the temperature from room up to 1200 °C depending on the zirconia content. The corrosion rate was found to decrease around 25 times with increasing zirconia content from x = 0.0 to 1.0. Microhardness displayed both compositional and temperature dependence. For the sample (x = 0.6), annealed at 1200 °C, the former increased up to 1.2 times its original value (x = 0.0).

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