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This work highlights the results obtained from different characterizations for the Mg-based spinel ferrite, MgFe2O4 nanomaterials prepared by ball milling followed by annealing at different temperatures, 800 °C, 900 °C, 1000 °C, and 1100 °C each for 2 h. From XRD analysis, the structural data such as lattice parameter, average crystalline size, micro-strain, and dislocation density of different MgFe2O4 samples are obtained. While the produced as-milled powder revealed the majority of the peaks are cubic MgFe2O4 phase materials, the annealed samples yielded phase pure nanocrystalline cubic spinel MgFe2O4 materials. The photoluminescence (PL) intensity of emission peak seen at ~ 417 nm (λexcitation = 375 nm) for different nanocrystalline MgFe2O4 materials varies regardless of the annealing temperatures. The FT-IR results imply the intrinsic stretching vibrations of the Fe–O at the tetrahedral site for these spinel materials. A gradual increase of the saturation magnetization was observed for the present MgFe2O4 materials upon increasing the annealing temperature. These nanocrystalline MgFe2O4 materials may have potential applications in magnetic fluid (hyperthermia) and near-infrared (NIR) pigment applications. [ABSTRACT FROM AUTHOR]

In this interesting article, the synthesis of nanocrystalline Gd₂Ti₂O₇ material by ball milling followed by annealing, characterization and its application are reported. The Rietveld structural refinement data confirm the cubic pyrochlore Gd₂Ti₂O7 phase with lattice parameter, a = 1.022(9) nm. The particle size observed by HRSEM image concurs with the average crystalline sizes of particles extracted from XRD data. The optical properties of pyrochlore nanocrystalline Gd2Ti207 material are explored from UV-visible, FT-IR, NIR, PL, and Raman spectroscopic measurements. From the present investigation, it is identified that the Gd₂Ti₂O7 nanopowder may be used as solar reflective as well as color pigment due to its high NIR reflectivity (85-95%) under the wavelength of 750-2500 nm.