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Abstract Cobalt-doped ZnO nanoparticles having chemical formula Zn (1- x) Co x O (x = 0.05, 0.10, 0.15, 0.20) were prepared by means of auto-combustion synthesis. Formation of monophasic wurtzite structure material was confirmed from XRD data. Inclusion of the Co2+ ions in the ZnO matrix produced several fascinating effects in the structural, physical and magnetic properties of the nanoparticles. The lattice constants ' a ' and ' c ' got inflated and the average crystallite size shriveled from 25 nm to 17 nm with the increase of Co concentration ' x ' in the sample. The FT-IR spectra showed the characteristic absorption bands in the range of 400 cm−1 to 576 cm−1 due to formation of Zn O and Co O stretching bonds in the samples. Scanning Electron Microscope (SEM) images show agglomerates of particles that are spherical in nature. Energy dispersive spectroscopy (EDS) spectra of the samples giving molecular weight percentages of the elements Zn, Co and O in the samples are in agreement with the calculated percentages within the limit of permissible error. Hysteresis, FC, and ZFC measurements made on the samples, exhibit presence of ferromagnetic phase in the materials. Energy band gap estimates made with the help of UV spectroscopy indicated a decreasing trend of band gap with increasing ' x ' in the sample. Photoluminescence studies carried out with excitation wavelength of 318 nm gave several emission peaks ranging from green to violet emissions. This observation confirms the presence of vacancies (defects) in the nanoparticle samples. Luminescence decay time recorded was in the range microseconds for all the samples. Highlights • Zn (1- x) Co x O (x = 0.05, 0.10, 0.15, 0.20) DMS material with particle size 17 nm–25 nm were prepared by auto-combustion method. • The band gap was found to decrease with increase in cobalt concentration ' x ' in the samples. • x related PL spectra with excitation wavelength 318 nm was observed in Violet, Blue and Green regions with lifetimes in μs. • Samples with x = 0.10, 0.15, 0.20 were found to be ferromagnetic. • The ZnO semiconductor nanoparticles exhibited enhanced ferromagnetic properties useful for applications. [ABSTRACT FROM AUTHOR]

Monophasic In (2- x) Nd x O 3 nanoparticle samples (x = 0, 0.10, 0.15, 0.20) with cubic bixbyite structure were prepared using auto-combustion method. A sizable increase in lattice constant ' a', and cell volume 'V' with a corresponding decrease in crystallite size ' t ', ranging from 52 nm to 44 nm was observed with increasing Nd3+concentration in the material. Scanning Electron Micrographs exemplified the formation of spherically shaped particles in the materials. Energy dispersive X-ray spectroscopy established the presence of In, Nd and O in the samples. Fundamental absorption bands were identified in the range of 400 cm−1 to 700 cm−1whereas energy band gap decreased from 3.22 ± 0.09 eV to 3.14 ± 0.12 eV with increasing Nd3+ concentration in the sample. Induction of ferromagnetic character in the host matrix, which is an essential artifice of DMS materials, was a manifestation of magnetic hysteresis studies. FC and ZFC measurement further ascertained the evolution of the Nd3+ dependent ferromagnetic phase in the materials. • In(2- x)Nd x O3 (x =0,0.10,0.15,0.20) nanosamples were prepared by combustion method. • Monophasic material with Nd3+ based lattice stretching was shown by XRD analysis. • Nd3+ concentration dependent ferromagnetic behaviour was observed in the samples. • Band gap decreases with increase in Nd3+ concentration. [ABSTRACT FROM AUTHOR]