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Induced room-temperature ferromagnetic behavior (RT-MF) of Gd doped CdTe (GDC) quantum dots (QDs) is reported. Pure CdTe QDs were synthesized by colloidal route using thiol stabilizers in an aqueous medium. The magnetic moments were induced by the inclusion of Gd in CdTe QDs. The effect of Gd ion substitution in CdTe lattices was characterized by X-ray diffraction which confirmed the formation of cubic zinc blende structure. The optical response of the prepared QDs was studied via UV–vis absorption spectroscopy, which indicated that Gd ion substitution alters the optical response toward a longer wavelength; this is further confirmed by corresponding emission analysis through Fluorescence emission spectroscopy. Quantum yield measurements confirmed that the GDC QDs give better quantum yield than pure CdTe QDs through the substitution of Gd ions. The formation of CdTe QDs with Gd ion substitution was confirmed by binding energy analysis through X-ray photoelectron spectroscopy. RT-MF of GDC QDs was revealed by vibrating-sample magnetometer measurement. Hence, the prepared GDC QDs were determined to be a vital DMS material for room-temperature spintronics applications.

Europium doped cadmium sulphide (Cd 0.98Eu 0.2S) nanostructures were synthesised by chemical co-precipitation method using ethylene glycol (EG) and deionized water (Eu:CdS-1), and isopropyl alcohol (IPA) and deionized water (Eu:CdS-2) as mixed solvents. It has been found that the nanostructure of the europium doped CdS can be controlled by simply varying the mixed solvent system. Powder XRD pattern reveals the formation of hexagonal (wurtzite) and cubic (zinc blende) structure for Eu:CdS-1, and Eu:CdS-2, respectively. The crystallite size of the sample prepared using IPA and deionized water was measured to be 2.64 nm which is much smaller than that of the sample prepared using EG and deionized water as mixed solvent (3.65 nm). Morphology of the materials can also be changed from flower shaped crystals to paddy like structures by varying the mixed solvents. Band gap values of Eu 3+ doped CdS nanocrystals synthesized from two different solvents were estimated using UV-reflectance spectra. The size and crystallinity of the samples were confirmed by HRTEM and SAED analysis. A significant change in the PL emission of the CdS nanocrystals was observed for the europium doped CdS which is mainly due to the presence of Eu 3+ ions which also play a significant role in the energy transfer process. It was also observed that the shift in the emission and efficiency depends on size and shape of the synthesised nanoparticles. Refereed/Peer-reviewed

Structural, optical and Raman scattering studies have been performed on the Dy substituted zinc oxide (ZnO) thin films (1, 3 & 5 wt%) fabricated through a sol gel based spray pyrolysis technique on preheated glass substrates. The hexagonal crystal structure with (002) preferred orientation was confirmed from the X-ray diffraction analysis for the undoped and Dy doped ZnO films. The crystallinity of the films decreased with increasing Dy content with a corresponding decease in the intensity of (002) orientations. Reduction in grain size with increase in Dy content was observed. The shift of E2 (high) mode observed in the Raman spectra towards the lower wave numbers with increase in Dy concentration was correlated with the increase in stress on the ZnO matrix upon Dy substitution. The optical band gap was found to increase from 3.17 eV to 3.27 eV with a transparency of 80% for higher Dy concentrations. A blue shift in the NBE emission was also observed for Dy doping. Refereed/Peer-reviewed