The non-destructive investigation of rare earth doping-induced changes in the ZnO microstructure by X-ray diffraction
Cosmin Romanitan1*, Petronela Pascariu2, Oana Brincoveanu1, Andreea-Bianca Serban3, Mirela Suchea1.4* and Emmanouel Koudoumas1,4*
1 National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190 Voluntari, Romania
2 “Petru Poni” Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
3 Extreme Light Infrastructure-Nuclear Physics (ELI-NP), ‘Horia Hulubei’ National R&D Institute for Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, 077125 Măgurele, Ilfov, Romania
4 Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University (HUM), 71410 Heraklion, Crete, Greece
Abstract:
The integration of rare earth (RE) elements into ZnO matrices has emerged as a promising route for enhancing the material’s properties, such as the electronic, optical, and magnetic features, making them ideal for a broad range of applications, from optoelectronics to spintronics or photocatalysis. However, a proper understanding of the microstructural changes induced by RE doping is crucial for optimizing these properties and to ensure the full potential of nanomaterials in devices. Scanning electron microscopy (SEM) images reveal that the doping induces different grain morphology, such as sphere, rods or urchins along different dopant type or concentrations. Moreover, the interpretation of the experimental X-ray diffraction (XRD) pattern in the framework of Rietveld refinement offers a powerful, analytically and non-destructive approach to evaluate the dopant-induced changes for the prepared RE elements-ZnO nanocomposites.
In this study, we present a comprehensive analysis of the microstructure of ZnO doped with various rare earth elements (such as Pr, La, Nd, Er, Ce and Sm) using the Rietveld refinement. The results highlight the effect of RE doping on the lattice expansion/contraction, the size of the crystalline domains, and the evolution of secondary phases. The formation of the secondary phases, such as Pr6O11, La2O3, CeO2, Er2O3 or Sm2O3 along different dopant concentration is confirmed by X-ray photoelectron spectroscopy (XPS), by the investigation of the oxidation state of dopant ions. The findings not only contribute to the fundamental understanding of RE-doped ZnO but also offer valuable insights into the broader application of XRD in materials science for the non-destructive evaluation of complex, doped systems.
Acknowledgments:
IMT’s contribution was supported by PNRR/2022/C9/MCID/I8 CF23/14 11 2022 contract 760101/23.05.2023 financed by the Ministry of Research, Innovation and Digitalization in “Development of a program to attract highly specialized human resources from abroad in research, development, and innovation activities” within the – PNRR-IIIC9-2022 - I8 PNRR/2022/Component 9/investment 8 and partially supported by the Romanian Ministry of Research, Innovation and Digitalisation through the μNanoEl, Cod: 23 07 core Programme. A.B. Serban acknowledge the support by PN 23.21.01.06 sponsored by the Romanian Ministry of Research, Innovation, and Digitization.
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