Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-019-01757-4 Comparison of structural and optical properties of CeO 2 and CeO 2 :Eu 3+ nanoparticles synthesized via sol–gel and fame spray pyrolysis methods Serdar Yildirim 1,2,3  · S. Alper Akalin 1,3  · Sibel Oguzlar 1  · Merve Zeyrek Ongun 4  · Caglar Ozer 3  · Mustafa Erol 2,3 Received: 3 April 2019 / Accepted: 25 June 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Over the last decades, a considerable attention has been drawn on the cerium dioxide (ceria, CeO 2 ) due to promising changes in physical and chemical properties in nanoscale. The researches on CeO 2 and its structural and morphological modifcations have brought about remarkable applications as optical devices, sensors, medical equipments and luminescent materials. For instance, rare earth (RE) ion-doped cerium oxides have exhibited enhanced peculiar optical, catalytic and magnetic proper- ties with respect to the dopant-free CeO 2 nanoparticles. Herein we aimed to compare characteristics of undoped (CeO 2 ) and europium (Eu 3+ ) doped ceria (CeO 2 :Eu 3+ ) nanoparticles synthesized by sol–gel (SG) and one-step fame spray pyrolysis (FSP) methods. In this work, fabricated nanoparticles were evaluated in terms of the structural, morphological, chemical and optical properties by using X-ray difraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron (XPS) and photoluminescence spectroscopy (PL), respectively. Nanoparticles in the intended crystalline CeO 2 structure were obtained for both methods. Spherical particles in nanoscale (particle size < 100 nm) and sharp edged blocky particles in sub-micron size (particles size range 200–1000 nm) were produced through FSP and SG, respectively. Nevertheless, no signifcant dif- ference due to the diference in particle size was observed in optical properties. On the other hand, Eu 3+ doped particles of both methods exhibited longer decay time than the undoped particles. 1 Introduction Recently, there has been considerable interest in prepa- ration, characterization and applications of metal oxide nanoparticles that play a key role in several technologies. The metal oxide nanoparticles that used in the piezoelec- tric, optoelectronic and sensor applications show excellent chemical and physical specifcations because of having lim- ited size and high edge surface sites. There are many types of metal oxide nanoparticles as MgO, Al 2 O 3 , CeO 2 , ZrO 2 , AgO, NiO and TiO 2 oxide. Al 2 O 3 material has importance as a catalyst component; MgO has wide application for as a scrubber for air pollutant gases; ZrO 2 has application as a solid electrolyte, gas sensor as well as a catalyst; TiO 2 is one of the most common oxide material used for various kinds of industrial applications about catalysis, photocatalysis, organic synthesis and etc. [1]. Among them, cerium dioxide (ceria, CeO 2 ) nanoparticles particularly plays a major role in a wide variety of technological applications as; catalysis, luminescence-based optical sensors, biology and medical applications thanks to distinct physical, chemical and optical properties [2, 3]. Today, pristine ceria and its metal incorpo- rated modifcations have also been attracted attention owing to their strong optical properties and the excitation of the activator ions by energy transfer. Moreover, incorporation of rare earth ions into cerium dioxide, led to act as luminescent activators due to the strong emission lines based on their sharp 4–4f intra-shell transitions [4]. As a rare earth, europium (Eu 3+ ) have been incorporated of into cerium dioxide structure by several groups. Li and co-workers reported that Eu 3+ concentration in CeO 2 crystal * Serdar Yildirim serdar.yildirim@deu.edu.tr 1 Center for Fabrication and Application of Electronic Materials, Dokuz Eylul University, Buca, 35390 Izmir, Turkey 2 Department of Metallurgical and Materials Engineering, Dokuz Eylul University, Buca, 35390 Izmir, Turkey 3 Department of Nanoscience and Nanoengineering, Dokuz Eylul University, Buca, 35390 Izmir, Turkey 4 Izmir Vocational High School, Chemistry Technology Program, Dokuz Eylul University, Buca, 35390 Izmir, Turkey