Significant room-temperature ferromagnetism in porous ZnO films: The role of oxygen vacancies

Hou, Xue; Liu, Huiyuan; Sun, Hongyu; Liu, Lihu; Jia, Xiaoxuan

doi:10.1016/j.mseb.2015.06.003

Cited by 26 publications

(10 citation statements)

References 36 publications

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“…19 A few reports also claimed the appearance of ferromagnetism in pure ZnO, termed as d 0 magnetism. 23,24 However, the issue that persists in the form of the nature of magnetism (whether intrinsic or extrinsic), its origin, and reproducibility is still under debate. TM ions in ZnO usually undergo phase segregation in the form of their oxides and sometimes form magnetic clusters/impurities which contribute to the magnetism while contradicting this, according to some experimental ndings, the RTFM is purely intrinsic.…”

Section: Introductionmentioning

confidence: 99%

Influence of Cu doping on the local electronic and magnetic properties of ZnO nanostructures

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Influence of Cu doping on the local electronic and magnetic properties of ZnO nanostructures

et al. 2020

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“…It is obviously found that the ε′ and ε″ of porous LiFe 5 O 8 microspheres are significantly higher than those of LiFe 5 O 8 particles, demonstrating that the porous LiFe 5 O 8 microspheres possess higher dielectric loss compared with LiFe 5 O 8 particles. It could be attributed to the presence of many vacancies in porous LiFe 5 O 8 microspheres, which causes multiple reflections, dipole polarizations, and interfacial polarizations produced by the formation of defects. , The μ′ and μ″ of LiFe 5 O 8 particles and porous LiFe 5 O 8 microspheres are relatively stable with increasing the frequency. The RL values of LiFe 5 O 8 particles and porous LiFe 5 O 8 microspheres over 2–18 GHz with various thicknesses can be obtained using eqs and .…”

Section: Resultsmentioning

confidence: 99%

“…It could be attributed to the presence of many vacancies in porous LiFe 5 O 8 microspheres, which causes multiple reflections, dipole polarizations, and interfacial polarizations produced by the formation of defects. 51,52 The μ′ and μ″ of LiFe 5 O 8 particles and porous LiFe 5 O 8 microspheres are relatively stable with increasing the frequency. The RL values of LiFe 5 O 8 particles and porous LiFe 5 O 8 microspheres over 2−18 GHz with various thicknesses can be obtained using eqs 1 and 2.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Electromagnetic Wave Absorption Properties of Composites of Reduced Graphene Oxide with Porous LiFe₅O₈ Microspheres

Lin

Dong

Zong

et al. 2018

ACS Sustainable Chem. Eng.

103

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A novel three-dimensional composite of reduced graphene oxide sheets and porous LiFe 5 O 8 microspheres was fabricated via a facile, green, and highly tunable strategy, and the microstructure, composition, and microwaveabsorbing performances of the rGO/porous LiFe 5 O 8 composite were characterized and investigated. The experimental results indicate that the porous LiFe 5 O 8 microspheres are dispersed on the thin rGO sheets uniformly. Compared with the pure LiFe 5 O 8 particles and porous LiFe 5 O 8 microspheres, the as-prepared rGO/porous LiFe 5 O 8 composites exhibit outstanding microwave-absorbing performances including efficient bandwidth and reflection loss. The rGO/porous LiFe 5 O 8 composite (S-50) displays a maximum reflection loss of −53.4 dB at 12.2 GHz with a coating layer thickness of 2.2 mm and a broad effective bandwidth of 3.5 GHz (from 10.4 to 13.9 GHz). The outstanding microwave-absorbing performances are assigned to employing magnetic microflowers with multi-interfaces to improve impedance matching, which is ascribed to strong relaxation loss, electrical loss, and magnetic loss. This further confirms that the rGO/porous LiFe 5 O 8 composites could be potential candidates for lightweight microwave-absorbing materials.

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“…Theoretically, the PL spectra of ZnO films or ZnO nanorods have two major components: One is due to near-band-edge emission originating from an exciton transition, while the other is a broad visible band due to defect emissions arising from structural defects or impurities [24,25]. The PL spectrum of ZnO has a significant peak at around 387.5 nm in the UV region (Figure 4), which arises from exciton emissions and is a good indicator of the quality of a particular ZnO thin film [26,27]. It can be seen from Figure 4 that ALD-ZnO had good crystallinity even at temperatures as low as 70 °C.…”

Section: Resultsmentioning

confidence: 99%

The Role of ALD-ZnO Seed Layers in the Growth of ZnO Nanorods for Hydrogen Sensing

Hsieh

2019

Micromachines

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Hydrogen is one of the most important clean energy sources of the future. Because of its flammability, explosiveness, and flammability, it is important to develop a highly sensitive hydrogen sensor. Among many gas sensing materials, zinc oxide has excellent sensing properties and is therefore attracting attention. Effectively reducing the resistance of sensing materials and increasing the surface area of materials is an important issue to increase the sensitivity of gas sensing. Zinc oxide seed layers were prepared by atomic layer deposition (ALD) to facilitate the subsequent hydrothermal growth of ZnO nanorods. The nanorods are used as highly sensitive materials for sensing hydrogen due to their inherent properties as oxide semiconductors and their very high surface areas. The low resistance value of ALD-ZnO helps to transport electrons when sensing hydrogen gas and improves the sensitivity of hydrogen sensors. The large surface area of ZnO nanorods also provides lots of sites of gas adsorption which also increases the sensitivity of the hydrogen sensor. Our experimental results show that perfect crystallinity helped to reduce the electrical resistance of ALD-ZnO films. High areal nucleation density and sufficient inter-rod space were determining factors for efficient hydrogen sensing. The sensitivity increased with increasing hydrogen temperature, from 1.03 at 225 °C, to 1.32 at 380 °C after sensing 100 s in 10,000 ppm of hydrogen. We discuss in detail the properties of electrical conductivity, point defects, and crystal quality of ALD-ZnO films and their probable effects on the sensitivity of hydrogen sensing.

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Significant room-temperature ferromagnetism in porous ZnO films: The role of oxygen vacancies

Cited by 26 publications

References 36 publications

Influence of Cu doping on the local electronic and magnetic properties of ZnO nanostructures

Influence of Cu doping on the local electronic and magnetic properties of ZnO nanostructures

Synthesis, Characterization, and Electromagnetic Wave Absorption Properties of Composites of Reduced Graphene Oxide with Porous LiFe₅O₈ Microspheres

The Role of ALD-ZnO Seed Layers in the Growth of ZnO Nanorods for Hydrogen Sensing

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Significant room-temperature ferromagnetism in porous ZnO films: The role of oxygen vacancies

Cited by 26 publications

References 36 publications

Influence of Cu doping on the local electronic and magnetic properties of ZnO nanostructures

Influence of Cu doping on the local electronic and magnetic properties of ZnO nanostructures

Synthesis, Characterization, and Electromagnetic Wave Absorption Properties of Composites of Reduced Graphene Oxide with Porous LiFe5O8 Microspheres

The Role of ALD-ZnO Seed Layers in the Growth of ZnO Nanorods for Hydrogen Sensing

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Synthesis, Characterization, and Electromagnetic Wave Absorption Properties of Composites of Reduced Graphene Oxide with Porous LiFe₅O₈ Microspheres