Structure, optical and ferromagnetic properties of Zn1−x−yMnxCryO nanoparticles diluted magnetic semiconductors synthesized by citrate sol–gel method

• Published in: Applied physics. A, Materials science & processing Vol. 127; no. 6
• Main Authors: Abo-Naf, S. M., Ibrahim, S., Marzouk, M. A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2021; Springer Nature B.V
• Subjects: Applied physics; Characterization and Evaluation of Materials; Chromium; Composition; Condensed Matter Physics; Conduction bands; Crystallites; Doping; Energy gap; Ferromagnetism; Hexagonal lattice; High resolution electron microscopy; Machines; Magnetic properties; Magnetic semiconductors; Magnetometers; Manganese ions; Manufacturing; Materials science; Nanomaterials; Nanoparticles; Nanotechnology; Optical and Electronic Materials; Optical properties; Paramagnetism; Physics; Physics and Astronomy; Processes; Sol-gel processes; Surfaces and Interfaces; Synthesis; Thin Films; Valence band; Wurtzite; X-ray diffraction; Zinc oxide; Nanoparticles; Ferromagnetism; ZnO; Diluted magnetic semiconductors (DMS); Spintronic; Sol–gel
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-021-04583-w

Citrate sol–gel method has been employed for synthesis of Zn 1˗ x ˗ y Mn x Cr y O nanomaterials. Binary Zn 0.9 Mn 0.1 O and Zn 0.9 Cr 0.1 O nanomaterials were prepared and their optical and magnetic properties were investigated as reference compositions for the individual behavior of both of Mn- and Cr doping, respectively. The synthesized nanoparticles were analyzed using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), ultraviolet–visible (UV–Vis) spectroscopy and vibrating sample magnetometer. For low Mn–Cr-codoping contents, i.e., 2 and 4%, XRD revealed formation of single-phase ZnO nanoparticles in the wurtzite type hexagonal lattice, whereas 10% doping concentration, either Mn- or Cr-single doping or codoping, resulted in formation of wurtzite ZnO as a major phase with ZnMnO 3 or/and ZnCr 2 O 4 secondary phases. From XRD and HRTEM, the produced nanomaterials have average crystallite sizes ranged from 15 to 35 nm. Applying Kubelka–Munk function, optical band gap energy ( E opt ) was determined. E opt of single Mn- and Cr-doped ZnO increased than that of bulk ZnO mainly due to Burstein–Moss effect, whereas it decreased in the codoped Zn 1− x − y Mn x Cr y O because of the negative and positive corrections in the conduction and valence band, respectively, brought about by alteration of the sp – d exchange interactions between the band electrons and the localized d -electrons of the Mn 2+ and Cr 3+ ions. Magnetization measurements indicated that Cr induced the paramagnetism, while Mn induced the RT ferromagnetism in the synthesized Zn 1− x − y Mn x Cr y O nanoparticles. The ferromagnetic Zn 1− x − y Mn x Cr y O compositions could be potential candidates for Mn–Cr-codoped ZnO-based DMS nanoparticles.