Optical, structural and magnetic characterization of Bi2−xCrxTe3 nanocrystals in oxide glass

• Published in: Materials chemistry and physics Vol. 241; p. 122323
• Main Authors: Araujo, C.M., Mikhail, H.D., Guimarães, E.V., Rastrello, L.R., Cano, N.F., Silva, A.C.A., Dantas, N.O., Silva, R.S.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-02-2020; Elsevier BV
• Subjects: Absorption spectra; Bi2Te3; Bismuth tellurides; Cr-doped; Crystal field theory; Electron paramagnetic resonance; Forbidden bands; Glass; Magnetic properties; Magnetic semiconductors; Nanocrystals; Optical properties; Structural analysis; Structural properties; Trivalent chromium; Bi2Te3; Cr-doped; Nanocrystals; Optical properties; Structural properties; Magnetic properties
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2019.122323

Chromium-doped bismuth telluride (Bi2−xCrxTe3) diluted magnetic semiconductor nanocrystals were successfully synthesized in a glass matrix by the fusion method with nominal Cr concentrations of x = 0.00, 0.05, and 0.10. Transmission electron microscopy confirmed the growth of nanocrystals with an average diameter of ~5.0 nm. Shifts in X-ray diffraction peaks with increasing x indicated substitutional inclusion of Cr ions (occupying Bi sites - CrBi) in the Bi2Te3 structure. The absorption spectra for x = 0.05 and 0.10 show two intense spin-allowed bands at ~425 and 635 nm and two minor spin-forbidden bands at ~650 and 685 nm. These bands were attributed to the Cr3+ d-d transitions, according to the crystal field theory. Finally, electron paramagnetic resonance spectra from the Bi2−xCrxTe3 nanocrystals displayed Cr3+ characteristics with spin 3/2 in the d3 state, thereby confirming the trivalent state of Cr ions in the Bi2Te3 structure.
•Cr3+-doped Bi2Te3 NCs were growth in borosilicate host glass.•Structural properties of Bi2-xCrxTe3 are investigated for x = 0.00, 0.05, and 0.10.•Cr3+ spin-allowed d–d transitions in the octahedrally-coordinated environment.•Quantum confinement and effects Exchange sp-d.