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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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Layered titanates with one-dimensional (1D) shapes have been an important class of nanomaterials due to their combination of 1D and 2D fascinating properties. Among many layered titanates, lepidocrocite-type layered titanates have significant advantages such as superior intercalation and exfoliation properties, while the synthesis of the 1D-shape forms is still challenging. Here, we report on a facile one-pot hydrothermal conversion of a lepidocrocite-type layered titanate into the corresponding nanowire-shape form. The reaction mechanism involves the decomposition of the starting layered titanate into 1D small segments which assemble into the nanowire. This new nanowire shows properties resulting from the combination of 1D and 2D nanostructural features, excellent cation exchange ability, and high photoinduced charge separation and photocatalytic efficiency. As a demonstration, we evaluate the nanowire as a sequestrating material capable of collecting toxic cations, like Cd2+, from water and photoreducing them (immobilizing them tightly). We find that the nanowire shows an efficient and ultrafast photoimmobilization activity, whereas the starting layered titanate and a benchmark TiO2 photocatalyst (P25) show no activity under the identical conditions. The photoimmobilization rate (within 1 min) is considerably faster than the cation exchange rates reported for state-of-the-art cation exchangers (with no photoimmobilization ability). The nanowire used for photoimmobilization reactions is easily recovered from water by decantation, showing the possible practical use for safe disposal of toxic cations in the environment.

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