Size-Induced Structural Phase Transition at ∼6.0 nm from Mixed fcc–hcp to Purely fcc Structure in Monodispersed Nickel Nanoparticles

Tarachand,; Sharma, Vikash; Singh, Jaiveer; Nayak, Chandrani; Bhattacharyya, D.; Kaurav, Netram; Jha, S. N.; Okram, G. S.

doi:10.1021/acs.jpcc.6b10745

Cited by 26 publications

(19 citation statements)

References 49 publications

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“…Upon closer examination of the peak around the Ni−Ni for reduced NiHAP(0.5) and NiHAP(2.0) samples, slight shift in peak away from the Ni−Ni peak with reference to the Ni foil (∼2.095 Å) can be observed. The NiHAP(0.5) peaks shifted to 2.069 Å, which is close to the Ni fcc structure at approximately 2.095 Å [19] . Interestingly, the NiHAP(2.0) peak shifted to 2.072 Å, closer towards Ni−O 1.5 Å peak.…”

Section: Resultsmentioning

confidence: 65%

“…The first shell Ni−Ni coordination number decreases in the following order: NiHAP(0.5) (7.869)>NiHAP(2.0) (7.088)>NiHAP(0) (5.872). Past literature reports had reported coordination number decreases correspondingly with smaller nanoparticle size [19–20] . The increase of OA ratio from 0.5 to 2.0 have resulted in lower nanoparticle size which corresponds to lower coordination number as more low‐coordination surface atoms are present.…”

Section: Resultsmentioning

confidence: 91%

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Influence of Surface Formate Species on Methane Selectivity for Carbon Dioxide Methanation over Nickel Hydroxyapatite Catalyst

et al. 2020

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Absence of mechanistic understanding of carbon dioxide (CO2) methanation reaction on nickel hydroxyapatite (NiHAP) and the nature of nickel chemical state hampers the enhancement of catalytic activity and selectivity for such material. A varying amount of oleic acid (OA) addition on NiHAP is found to have a strong influence on the chemical state of nickel as evidenced from x‐ray spectroscopy (XPS) and x‐ray absorption spectroscopy (XAS). The chemical state of nickel influences the amount of surface intermediate species which affects methane formation as observed in infra‐red spectroscopy. This suggests that varying amount of OA can influence the chemical state of nickel which is important in influencing the type of reaction intermediates on the NiHAP surface. Langmuir‐Hinshelwood model is validated for proposed reaction mechanism for the better performing catalyst. The findings reported here is useful for designing a hydroxyapatite‐based catalyst for CO2 utilization.

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Section: Resultsmentioning

confidence: 65%

Section: Resultsmentioning

confidence: 91%

Influence of Surface Formate Species on Methane Selectivity for Carbon Dioxide Methanation over Nickel Hydroxyapatite Catalyst

et al. 2020

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“…In general, the electronic, phononic, magnetic, and geometric effects are the major microscopic driving forces that contribute cooperatively to the overall stability of the densely packed transition metals. These driving forces usually appear in the form of d-band occupation, dynamical stability, spin ordering, and strain as the descriptors and account for the effects of most physicochemical parameters such as chemical composition, pressure, temperature, size, and surface and interface effects [46,[62][63][64][65]. These parameters will be discussed in detail in Section 3.4.…”

Section: Strainmentioning

confidence: 99%

“…For the chemical synthesis of noble metal NCs with na- [38], 2H [33] nometer sizes, the surface energy may play a decisive role in determining the densely packed structures of the NCs, in contrast to the internal volumetric energy [64]. To be noted, the abovementioned fundamental driving forces for the formation and stabilization of various packing modes usually function cooperatively under a specific physicochemical parameter or condition.…”

Section: General Strategies For Crystal Phase Engineeringmentioning

confidence: 99%

Crystal phase regulation in noble metal nanocrystals

Chen

Cheng

et al. 2019

Chinese Journal of Catalysis

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Noble metal nanocrystals (NCs) are often densely packed in their most stable forms that are determined by a combination of effects arising from the electronic, magnetic, geometric, and phononic properties of the NCs. These packing modes usually include the densest packed polytypes of Barlow packings and more open or distorted packings with slightly lower atomic packing factors. The structural modulation strategies of NCs towards the better performances for diverse applications are usually limited to the crystal size, shape, and surface control, which have been robustly studied and documented. An exciting emerging field related to structural engineering of noble metal NCs turns out to be the crystal phase control, which allows the chemical synthesis of energetically high-lying phases of NCs and leads to intriguing performances in catalysis and energy conversion. This article provides a comprehensive review of crystal phase regulation that endows both noble metal and noble-metal-based alloy NCs with unique electronic structures and enhanced performances. The basic principles, general design rationale, synthetic approaches, and structural characterizations for a variety of successful case studies related to crystal phase engineering are reviewed and discussed. In the end, the perspectives and challenges associated with the development of a more controllable chemical synthetic strategy towards the high-energy phases of noble metal NCs are put forward.

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“…The isolated islands had fcc crystal structure and crystallographic orientations dictated by that of the substrate. On a related subject, Tarachand et al investigated phase structure and magnetism in nickel nanoparticles grown by thermal decomposition, and reported that the particles are hcp/fcc mixture below 6 nm, but pure fcc above that size. A similar trend on the instability of hcp nickel had been reported earlier by Tian et al This was shown to have significant effects on the magnetism of the particles, which underscores the importance of crystal structure control in nickel thin films.…”

Section: Introductionmentioning

confidence: 99%

In Situ Synchrotron X‐Ray Diffraction Analysis of Phase Transformation in Epitaxial Metastable hcp Nickel Thin Films, Prepared via Plasma‐Enhanced Atomic Layer Deposition

Motamedi

Bosnick

Cadien

et al. 2018

Adv Materials Inter

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thickness and the crystal structure are necessary requirements. [15,16] Epitaxial growth of magnetic thin films enables the precise control of strain and crystal orientation, both of which have critical effects on the magnetization of thin films. [17,18] Another important benefit of epitaxial growth is limiting the grain boundary diffusion, which is shown to play a critical role in interlayer diffusion of the multilayer ultrathin films. [19,20] In order to fully realize the benefits of the ultrathin magnetic films, they need to be grown in an epitaxial fashion with a fine-tuned crystal structure and orientation. This subject is explored in the present paper.Plasma-enhanced atomic layer deposition (PEALD) is a method for the deposition of Ni films that offers several advantages over more mainstream deposition methods, such as sputtering and chemical vapor deposition (CVD). These advantages include precise thickness control, relatively low growth temperature, and conformality, i.e., the ability to deposit a film with a uniform thickness over a non-flat substrate. [21][22][23] All of these benefits make this method suitable for growing ultrathin films, where thickness and structure are critical parameters. [24] The authors have previously reported the plasma-enhanced ALD growth and characterization of nickel thin films with quasi-epitaxial crystal structure. [25] As reported, increasing the deposition temperature resulted in improving the crystallinity of the films. At deposition temperature of 360 °C, chemically pure nickel films were deposited. Crystal structure analysis showed the films had a polycrystalline textured structure with a strong out-of-plane orientation relationship with the sapphire substrate. However, full epitaxial growth was not achieved. This issue has been addressed in this paper.Apart from the above-mentioned publication, there have been other recent reports on nickel deposition. Park et al. [26] recently reported on PEALD of nickel thin films using [Ni(dpdab) 2 ] and NH 3 plasma, with the films reportedly having a fcc polycrystalline structure. In a separate study, Suturin et al. [27] demonstrated the deposition of epitaxial nickel islands on CaF 2 at 600 °C, using an electron beam source. The isolated islands had fcc crystal structure and crystallographic orientations dictated by that of the substrate. On a related subject, Tarachand et al. [28] investigated phase structure and magnetism in nickel nanoparticles grown by thermal decomposition, and reported that the Ultrathin metal films have a wide variety of applications, especially in microelectronics. A key method to deposit these films is plasma-enhanced atomic layer deposition (PEALD), which is known for its ability to deposit thin films conformally and at relatively low temperatures. Building on the recent work, an improved recipe is reported on for the development of nickel PEALD technology, through which fully epitaxial nickel thin films are deposited. The effect of continuous heating on the phase structure and agglomeration in the met...

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Size-Induced Structural Phase Transition at ∼6.0 nm from Mixed fcc–hcp to Purely fcc Structure in Monodispersed Nickel Nanoparticles

Cited by 26 publications

References 49 publications

Influence of Surface Formate Species on Methane Selectivity for Carbon Dioxide Methanation over Nickel Hydroxyapatite Catalyst

Influence of Surface Formate Species on Methane Selectivity for Carbon Dioxide Methanation over Nickel Hydroxyapatite Catalyst

Crystal phase regulation in noble metal nanocrystals

In Situ Synchrotron X‐Ray Diffraction Analysis of Phase Transformation in Epitaxial Metastable hcp Nickel Thin Films, Prepared via Plasma‐Enhanced Atomic Layer Deposition

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