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Title: Novel magnetic and optical properties of Sn{sub 1−x}Zn{sub x}O{sub 2} nanoparticles

In this work, we report on the effects of doping SnO{sub 2} nanoparticles with Zn{sup 2+} ions. A series of ∼2–3 nm sized Sn{sub 1−x}Zn{sub x}O{sub 2} crystallite samples with 0 ≤ x ≤ 0.18 were synthesized using a forced hydrolysis method. Increasing dopant concentration caused systematic changes in the crystallite size, oxidation state of Sn, visible emission, and band gap of SnO{sub 2} nanoparticles. X-ray Diffraction studies confirmed the SnO{sub 2} phase purity and the absence of any impurity phases. Magnetic measurements at room temperature showed a weak ferromagnetic behavior characterized by an open hysteresis loop. Their saturation magnetization M{sub s} increases initially with increasing Zn concentrations; however for x > 0.06, M{sub s} decreases. Samples with the highest M{sub s} values (x = 0.06) were analyzed using an Inductively Coupled Plasma Mass Spectrometer, looking for traces of any magnetic elements in the samples. Concentrations of all transition metals (Fe, Co, Mn, Cr, and Ni) in these samples were below ppb level, suggesting that the observed magnetism is not due to random inclusions of any spurious magnetic impurities and it cannot be explained by the existing models of magnetic exchange. A new visible emission near 490 nm appeared in the Zn doped SnO{sub 2} samples in the photoluminescence spectramore » which strengthened as x increased, suggesting the formation of defects such as oxygen vacancies. X-ray Photoelectron Spectroscopy (XPS) confirmed the nominal Zn dopant concentrations and the 2+ oxidation state of Zn in the Sn{sub 1−x}Zn{sub x}O{sub 2} samples. Interestingly, the XPS data indicated the presence of a small fraction of Sn{sup 2+} ions in Sn{sub 1−x}Zn{sub x}O{sub 2} samples in addition to the expected Sn{sup 4+}, and the Sn{sup 2+} concentration increased with increasing x. The presence of multi-valent metal ions and oxygen defects in high surface area oxide nanoparticles has been proposed as a potential recipe for weak ferromagnetism (Coey et al., New J. Phys. 12, 053025 (2010))« less
Authors:
; ; ; ; ;  [1]
  1. Department of Physics, Boise State University, Boise, Idaho 83725 (United States)
Publication Date:
OSTI Identifier:
22410162
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONCENTRATION RATIO; DOPED MATERIALS; FERROMAGNETISM; HYDROLYSIS; HYSTERESIS; MAGNETIZATION; NANOPARTICLES; OPTICAL PROPERTIES; PHOTOLUMINESCENCE; SURFACE AREA; TIN IONS; TIN OXIDES; VACANCIES; VALENCE; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY; ZINC IONS; ZINC OXIDES