Room temperature ferromagnetism and gas sensing in ZnO nanostructures: Influence of intrinsic defects and Mn, Co, Cu doping

Mhlongo, G.H.; Shingange, Katekani; Tshabalala, Zamaswazi P.; Dhonge, Baban P.; Mahmoud, Fawzy A.; Mwakikunga, Bonex W.; Motaung, David E.

doi:10.1016/j.apsusc.2016.08.138

Cited by 140 publications

(67 citation statements)

References 59 publications

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“…112 The aim of this topical review is to critically evaluate the design and structure of SMON-based gas sensors that may help guide the design of new devices. The performance of these SMON based gas sensors operated at RT could be improved significantly by modifying the SMONs using noble metal nanoparticles, [113][114][115][116] metal ions, [117][118][119] composites of multiple SMONs [120][121][122][123] and carbon nanomaterials. [124][125][126] In addition, not only the quantity of chemisorbed oxygen species, 127 defects 128 and element compositions 129,130 on the surface of SMONs, but also the structural properties, i.e., porosity, 131 heterojunction properties [132][133][134] and conductivity 135,136 can affect the RT gas sensing performance.…”

Section: Yongqing Fumentioning

confidence: 99%

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

et al. 2019

Mater. Horiz.

558

328

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Section: Yongqing Fumentioning

confidence: 99%

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

et al. 2019

Mater. Horiz.

558

328

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“…6, Table 3). In general, defects present in ZnO based nanostructures are oxygen vacancies, Zn vacancies, Zn interstitials and adsorbed molecules [31] and can be analysed according to the several transitions located between the valence and conduction band. To understand the origin of the emission peaks of the spectral region 350-800 nm, Gaussian fitting method of the broad visible emission was adopted to study the individual effects on the properties of ZnO nanostructures.…”

Section: Structural Analysis -Photoluminescencementioning

confidence: 99%

Structural, morphological, magnetic and electrical properties of Ni-doped ZnO nanoparticles synthesized by co-precipitation method

Dasari

Godavarti

Mote³

2018

PAC

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Weak ferromagnetic behaviour was obtained in a systematic way at room temperature by doping of where x = 0.00, 0.05, 0.15 and 0.20). The obtained results were correlated with conductivity and impedance studies. Diamagnetic to ferromagnetic change was observed with increased concentration of nickel. X-ray diffraction analysis confirmed wurtzite ZnO structure of prepared nanopowders while microstrain was increased with nickel concentration. Incorporation of nickel in ZnO structure was confirmed using EDAX analysis, while FTIR spectroscopy provided further information on functional groups. Transmission electron microscopy images showed that the particle sizes are in the range of 12-20 nm, and scanning electron microscopy analyses that grain size decreases with increase in nickel concentration. Photo luminescence studies confirmed the presence of V O and Zn i defects in the prepared samples. It was concluded that the defect induced strain, grain boundaries and lower particle sizes are the reasons for weak ferromagnetic behaviour of the investigated samples.

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“…As demonstrated by equations (3) and 4 For Co doped samples an additional band at 3.15eV is visible. This band could be related to zinc interstitials [23,55]. In general, undoped ZnO sample shows more oxygen vacancy related lumi-nescence bands [55,59] and peaks of doped ZnO samples are con-nected with cation sublattice related defects.…”

Section: Resultsmentioning

confidence: 94%

“…5). This band is very typical for ZnO and originates from the recombination of photo-excited holes with singly-ionized oxygen vacancies [23,55,56] and the higher intensity of this band would indicate a larger oxygen vacancy concentration [56,57].…”

Section: Resultsmentioning

confidence: 99%

Solvothermal synthesis derived Co-Ga codoped ZnO diluted magnetic degenerated semiconductor nanocrystals

Šutka

Käämbre

Joost

et al. 2018

Journal of Alloys and Compounds

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Here we are reporting solvothermal synthesis derived diluted magnetic and plasmonic Co-Ga co-doped ZnO nanocrystals with high magnetization values (from 1.02 to 4.88 emu/g) at room temperature. Co-Ga co-doped ZnO nanocrystals show up to 2 fold increase in saturation magnetization compared to Co doped ZnO nanocrystals at the same Co concentration, with the observed room temperature magneti-zation higher than previously reported values for multifunctional magnetic and plasmonic nanocrystals, and the effect of Ga suggesting some role of the correspondingly introduced itinerant charge. While at the lowe st Ga content the nanoparticles appear homogeneously doped, we note that already a moderate Ga content of several percent triggers a fraction of Co to segregate in metallic form in the bulk of the nanoparticles. However, the amount of segregated Co is not sufficient to account for the total effect, whereas a dominating contribution to the observed magnetism has to be related to itinerant charge mediated exchange interactions.

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Room temperature ferromagnetism and gas sensing in ZnO nanostructures: Influence of intrinsic defects and Mn, Co, Cu doping

Cited by 140 publications

References 59 publications

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

Structural, morphological, magnetic and electrical properties of Ni-doped ZnO nanoparticles synthesized by co-precipitation method

Solvothermal synthesis derived Co-Ga codoped ZnO diluted magnetic degenerated semiconductor nanocrystals

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