XPS depth profile analysis of non‐stoichiometric NiO films

Oswald, Steffen; Brückner, W.

doi:10.1002/sia.1640

Cited by 261 publications

(152 citation statements)

References 22 publications

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“…39 In addition, a weak splitting peak of Ni 2p3/2 peak was also observable at ∼855.3 eV, which is due to the presence of oxidation state of Ni 3+ . 40,41 But the above XRD measurements show that no any other impurity phases were observed in all annealed samples within the detection limit of X-ray diffractometer. This indicated that there are only very few amount of Ni 43,44 or theoretical calculation.…”

Section: Resultsmentioning

confidence: 70%

Vacancy-Induced Ferromagnetic Behavior in Antiferromagnetic NiO Nanoparticles: A Positron Annihilation Study

Chen¹,

Chen²,

Zhang³

et al. 2017

ECS J. Solid State Sci. Technol.

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Pure NiO nanoparticles were subjected to isochronal thermal treatments in open air from 100 to 1000 • C. X-ray diffraction (XRD) patterns indicate that all annealed samples exhibit a single phase of face-centered cubic (FCC) crystalline structure, obvious grain growth occurs only above 400 • C and the average crystallite size increases from 20 to 80 nm. X-ray photoelectron spectroscopy (XPS) shows that only very few amount of Ni 3+ and no impurity element have been found in the annealed samples. Positron annihilation measurements reveal that large number of Ni-vacancy defects exist in the grain surface region. These surface defects begin to recover after annealing above 400 • C, and most of them are removed at 1000 • C. Room temperature ferromagnetism is obviously observed for the samples annealed at 100 and 400 • C. The saturation magnetization gradually decreases with the increase of the annealing temperature, and it almost disappears at 800 and 1000 • C. The disappearance of ferromagnetism shows good coincidence with the recovery of Ni-vacancies. Our results suggest that the anomalous ferromagnetic behavior in NiO nanoparticles might be due to the surface Ni-vacancy defects instead of grain size effects. 2 It is well known that the bulk AF materials are magnetically compensated and have zero net magnetic moment in zero applied field, while fine particles of an AF material should display either weak ferromagnetism (FM) or superparamagnetism (SPM).3 Since Richardson and Milligan first reported anomalous magnetic properties in NiO nanoparticles, 4 ferromagnetic behaviors were found in an increasing number of AF nanomaterials. Consequently, it is important to investigate the magnetic mechanism of AF nanomaterials extensively. Among the various nanostructured AF transition metal monoxides, NiO has been widely investigated, because it is a unique metal-deficient p-type semiconductor presenting a wide band-gap (3.6-4.0eV), and its bulk form possesses a relatively high Néel temperature T N (523 K). As a consequence, it can cause high storage density of magnetic recording media due to allowing magnetic stability at very low volumes far above room temperature. 17 In the recent few decades, great efforts have been devoted to exploring the unexpected magnetic properties in NiO nanomaterials, such as large magnetic moments, enhanced coercivity, spin glass freezing and hysteretic loop shifts. However, up to now the underlying mechanism for the FM is still unclear. It has been reported that the FM might come from the surface and finite size effects, or a net magnetic moment probably arises from uncompensated spins. Several models, such as the two-sublattice model, 3 multi-sublattice model, 10 and core-shell model 9,12-14,18-24 have been used to illustrate the anomalous properties of NiO nanoparticles. However, different groups reported that * Electrochemical Society Fellow.z E-mail: czy2004hust@163.com; chenzq@whu.edu.cn; mascher@mcmaster.ca surface effects and size effects on the ferromagnetic properties of the nanomater...

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Section: Resultsmentioning

confidence: 70%

Vacancy-Induced Ferromagnetic Behavior in Antiferromagnetic NiO Nanoparticles: A Positron Annihilation Study

Chen¹,

Chen²,

Zhang³

et al. 2017

ECS J. Solid State Sci. Technol.

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“…Although the increase of nickel hydroxide depended on the holding time in the bath, the peak position of nickel oxide (854.5 eV) was barely observed. 13) Furthermore, the Ni 2p peak was hardly observed for the surface of the device, and a small nickel peak was observed in the layer for the device kept in the bath. This result suggests that magnesium oxide is present predominantly near the surface, as shown in Fig.…”

Section: Surface State Analysis By Xpsmentioning

confidence: 98%

“…13) When the device was kept in the bath, the hydroxide state of nickel (856.6 eV) gradually appeared in the layer. 13) The layer consisted of a mixture of metallic nickel and nickel hydroxide, as shown in Fig. 7(d).…”

Section: Surface State Analysis By Xpsmentioning

confidence: 99%

Surface Analysis of Electrochromic Switchable Mirror Glass Based on Magnesium-Nickel Thin Film in Accelerated Degradation Test

et al. 2011

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With the capability to change between reflective and transparent states, electrochromic switchable mirrors are expected to have numerous applications in optical devices, electronics devices and new energy-saving windows. If conventional windows can be adapted to incorporate switchable mirror technology, the solar radiation coming into a room could be effectively controlled, owing to features of the reflective state. Conventional windows are often subjected to environmental conditions such as high temperature and humidity. Considering practical use, we investigated the effects of the environment on the optical switching properties of the device in accelerated degradation tests using a thermostat/ humidistat bath at a constant temperature of 313 K and constant relative humidity of 80%. When the device was kept in the bath for 950.4 ks, it lost its optical switching properties. This result was associated with the degradation of the surface layer of the Mg 4 Ni thin film, which became rougher with increasing bath duration. We confirmed that the layer contained species in non-metallic states of oxide and hydroxide. Furthermore, the degradation mechanism to form the mixture state depended on the holding time in the bath.

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Section: Xps Depth Profile Analysismentioning

confidence: 99%

“…30,31 For sputter depth profiling, Ar ions of 4 keV and a scan size of 2 mm × 2 mm were performed. As Oswald and Bruckner 30 illustrated, these conditions could result in a typical sputter rate of 3-5 nm min − 1 in as-prepared CdX nanosheet films. As shown in Figures 5a and b, the atomic concentrations of Cd, S and Ag are maintained at the approximate ratio of~55.4: 43.1: 1.5 in the CdS Oriented attachment of nanoparticles H Qian et al nanosheet film as the sputtering proceeds into the film.…”

Section: Xps Depth Profile Analysismentioning

confidence: 99%

Oriented attachment of nanoparticles to form micrometer-sized nanosheets/nanobelts by topotactic reaction on rigid/flexible substrates with improved electronic properties

Zhao

Dai

et al. 2015

NPG Asia Mater

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We report a topotactic reaction strategy to achieve the oriented attachment (OA) of colloidal metal chalcogenide quantum dots into micrometer-sized nanosheets and nanobelts (up to 6-7 μm) on both mechanically rigid and flexible substrates. The nonstoichiometric composition, crystallization and Ag doping were controlled. The strong surface adsorption of cations and thiol ligands facilitated micrometer-scale three-dimensional OA. The cations induced the formation of electrostatic forces, cation passivation on the nanosheet surface and overlap packing of the nanosheets, enabling good contact with the substrates and improved electron transport without severe obstruction of organic insulating barriers. The observation of weak anti-localization phenomena and Hall effect sensitivity (up to 188%) of non-stoichiometric Ag 2-δ Te nanosheet films as well as the improved I-V and photoresponse properties of Ag-doped CdX nanosheet films confirm efficient electron transport. The stable I-V properties of these nanosheet films on flexible substrates, even under bending forces, testify to their potential in flexible device applications.

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XPS depth profile analysis of non‐stoichiometric NiO films

Cited by 261 publications

References 22 publications

Vacancy-Induced Ferromagnetic Behavior in Antiferromagnetic NiO Nanoparticles: A Positron Annihilation Study

Vacancy-Induced Ferromagnetic Behavior in Antiferromagnetic NiO Nanoparticles: A Positron Annihilation Study

Surface Analysis of Electrochromic Switchable Mirror Glass Based on Magnesium-Nickel Thin Film in Accelerated Degradation Test

Oriented attachment of nanoparticles to form micrometer-sized nanosheets/nanobelts by topotactic reaction on rigid/flexible substrates with improved electronic properties

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