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Nano ceramics of pure TiO 2 and Dy 3+ , Eu 3+ and Tb 3+ doped TiO 2 are prepared by hydrothermal method and these are characterized by using X-ray diffractometer (XRD), UV-Visible spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and photoluminescence spectroscopy. XRD analysis revealed that the average particle size of the pure TiO 2 and Dy 3+ , Eu 3+ and Tb 3+ doped TiO 2 are in the range of 45-35 nm and confirms the anatase phase. The FESEM and HRTEM analysis confirm that the obtained ceramics are in nano regime. The absorption spectrum revealed that the bandgap of the TiO 2 ceramics are in the range 3.14-3.2 eV. The PL analysis showed that the doping of Dy 3+ , Eu 3+ and Tb 3+ had improved the luminescence behavior than the pure TiO 2 nanoparticles. Overall, by doping 0.5 mol% concentration of rare earth (RE) greatly alters the structural morphology and directly influence the luminescence behavior of TiO 2 and suitable for advanced optoelectronic applications. The color purity of the studied samples is found to be 91% for Dy 3+ , 84% for Eu 3+ and 73% for Tb 3+ at the excitation of 345 nm, 376 nm and 350 nm respectively. The single-doped sample Eu 3+ : TiO 2 , Tb 3+ : TiO 2 and Dy 3+ : TiO 2 samples showed orange-red, blue-green and white emissions respectively.

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X-band electron spin resonance (ESR) studies of (Cr04)2-doped, X-irradiated single crystais of ferroelectric ammonium sulphate ((NH,),SO,, Tc = 223 K) at 300 and 208 K are reported. The paramagnetic centre responsible for the ESR spectrum is identified to be W+. Superhyperfine interaction of the unpaired electron with two equivalent protons is observed. The spin-Hamiltonian parameters which are nearly axial a t 300 K, with 911 < g 1 indicating a dra+ orbital ground state, acquired rhombic character below Tc indicating a distortion of the sulphate tetrahedron. An increase in the value of the proton superhyperfine constant in the ferroelectric phase is indicative of stronger hydrogen bonding.

Present paper reports the study on luminescence and optical behaviour of samarium doped lanthanum oxychloride (LaOCl:Sm 3+ ) nanophosphor for their potentiality in display devices. The conventional solid state route was employed to synthesize the phosphor La 1-x Sm x OCl (x=0, 0.01, 0.03, 0.05, 0.07 and 0.09). Tetragonal phase of the prepared compound was confirmed by PXRD. An agglomerated and spherical like structure were seen of the samples from FE-SEM analysis. The Wood and Tauc relation was employed to find out band gap energy and is around 4.23 eV. At an excitation wavelength of 408 nm, a high intense peak of emission was observed at 608 nm for transitions ( 4 G 5/2 → 6 H 7/2 ) of Sm 3+ ions in the PL spectra. Colour co-ordinates (X,Y) were used for the analysis of measured photoluminescence spectra. For the optimized concentration of Sm 3+ (La 1-x Sm x OCl with x=0.05), the intensity parameters (Ω 2 , Ω 4 and Ω 6 )were determined. The trend of Ω 6 >Ω 4 >Ω 2 was observed. An emission cross section and Branching ratio are found to be 3.98×10 −22 cm 2 and 59% respectively for 4 G 5/2 → 6 H 7/2 transition that makes it suitable for laser designs and application. The obtained results reveal that the LaOCl phosphor doped with samarium can be used on the screens of optical electronic systems and also is suitable for emission of reddish orange colour.

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