Novel magnetic and optical properties of Sn{sub 1−x}Zn{sub x}O{sub 2} nanoparticles
- Department of Physics, Boise State University, Boise, Idaho 83725 (United States)
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 spectra 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))
- OSTI ID:
- 22410162
- Journal Information:
- Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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