The nanocrystalline La 0.8 Sr 0.2 MnO 3 (LSM) is prepared by varying the revolutions per minute and milling time of planetary monomill during the mechanochemical method. The LSM forms in a relatively shorter milling time with an increase in the milling speed from 250 to 600 rpm. The structural phase transition from orthorhombic to rhombohedral phase in the LSM prepared by ball milling at the speed 250 rpm for 36 h is seen due to sintering it at 700°C for 4 h. The crystallite size reduces with the increase in both the milling speed and the milling time individually or combined. The microhardness (HV) and sintered density increase with the reduction in the crystallite size. The temperature-activated transition temperature is suppressed by reducing the grain size in the nanometer range. The electrical dc conductivity increases with the reduction in the grain/crystallite size.

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The samples belonging to La 1−x Sr x MnO 3 series, prepared by combustion route without using fuel, exhibit crystal structural phase transition with the change in Sr content. Less than 40 mol% Sr is partially substituted in the crystal structure of LaMnO 3 . The structural phase transition from rhombohedral to cubic, cubic to tetragonal, and tetragonal to orthorhombic takes place on 40, 60, and 80 mol% addition of Sr. The highest electrical conductivity in La 0.4 Sr 0.6 MnO 3 is understood to be due to the maximum concentration of polaron. The polarons are formed due to the conversion of Mn 3+ to Mn 4+ so as to achieve electroneutrality after substitution of Sr 2+ for La 3+ .

Tm3+‐doped La2O3 phosphors with different doping concentration are prepared by co‐precipitation method. The prepared phosphor is characterized by X‐ray powder diffraction (XRD), SEM, Fourier transform infrared (FT‐IR) spectroscopy, and photoluminescence (PL) techniques. The XRD analysis confirms the formation of La2O3. PL measurement shows that the phosphor exhibit characteristic Tm3+ bright blue emission attributed to transition from 1D2 → 3F4 of Tm3+ ions, at 363 nm excitation. The Commission International de I'Eclairage (CIE) chromaticity color coordinates of prepared phosphor is calculated and presented. The excitation peak located at 363 nm matches with the emission wavelength of near UV‐LED chip, this indicates that the prepared phosphor is a promising blue light‐emitting candidate for eco‐friendly solid state lighting (W‐LED) application.

Nanocrystalline α-Fe2O3 is synthesized by sol-gel technique. The prepared nanomaterial was characterized by X-ray diffraction (XRD), SEM, TEM, Fourier Transform Infrared (FTIR) spectroscopy, Vibrating Sample Magnetometry (VSM) and photoluminescence (PL) techniques. X-ray powder diffraction analysis confirmed the formation of α-Fe2O3. Electron microscopy showed spherical morphologies with an average particle size of 30-40 nm. The magnetic property of the prepared material was studied by VSM at room temperature. VSM study shows superparamagnetic nature of the synthesized nanoparticles. Photoluminescence (PL) emission spectra show intense broad emission band centered at 570 nm with 393 nm excitation indicating its usefulness for w-LED application. The CIE-chromaticity color coordinates of prepared material were calculated. The photocatalytic activity of the α-Fe2O3 nanoparticles was analyzed and the nanopowder exhibited good photocatalytic activity for the removal AO7 from its aqueous solution.