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Chang L, Wu C, Wang Q, Li T, Zhao D, Wang K, Wang Q, Pei W. Operating interfaces to synthesize L1 0-FePt@Bi-rich nanoparticles by modifying the heating process. NANOSCALE 2022; 14:11738-11744. [PMID: 35916325 DOI: 10.1039/d2nr01493a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A facile strategy to operate interfaces when synthesizing L10-FePt@Bi-rich nanoparticles (NPs) has been proposed. Two interfaces are indispensable to obtain the high ordering L10-FePt structure. One is the mismatched interfaces between the initial γ-PtBi2 nuclei and the disordered fcc-FePt phase. The other is the in situ grown coherent interfaces between the L10-FePt and Bi-rich phases. Increasing the heating rates when the temperature rises from 120 °C to 310 °C benefits the formation of mismatched interfaces and improves the uniformity of phases and composition in NPs. Reducing the heating rate at higher temperature ensures sufficient time for Bi to diffuse across the coherent interface, which facilitates the disorder-order transition of L10-FePt NPs. This study provides a new perspective on operating interfaces during the wet-chemical synthesis process.
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Affiliation(s)
- Ling Chang
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China.
- School of Metallurgy, Northeastern University, Shenyang 110819, China
| | - Chun Wu
- Key Laboratory of Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
- School of Materials Science and Engineering, Liaoning Technical University, Fuxin, 123000, China
| | - Qunshou Wang
- Key Laboratory of Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Ting Li
- Key Laboratory of Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Dong Zhao
- Key Laboratory of Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
| | - Kai Wang
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China.
| | - Qiang Wang
- Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China.
| | - Wenli Pei
- Key Laboratory of Anisotropy and Texture of Materials (Ministry of Education), School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
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Thermal stability and diffusion characteristics of ultrathin amorphous carbon films grown on crystalline and nitrogenated silicon substrates by filtered cathodic vacuum arc deposition. Sci Rep 2021; 11:13106. [PMID: 34162902 PMCID: PMC8222292 DOI: 10.1038/s41598-021-91903-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 06/02/2021] [Indexed: 11/13/2022] Open
Abstract
Amorphous carbon (a-C) films are widely used as protective overcoats in many technology sectors, principally due to their excellent thermophysical properties and chemical inertness. The growth and thermal stability of sub-5-nm-thick a-C films synthesized by filtered cathodic vacuum arc on pure (crystalline) and nitrogenated (amorphous) silicon substrate surfaces were investigated in this study. Samples of a-C/Si and a-C/SiNx/Si stacks were thermally annealed for various durations and subsequently characterized by high-resolution transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The TEM images confirmed the continuity and uniformity of the a-C films and the 5-nm-thick SiNx underlayer formed by silicon nitrogenation using radio-frequency sputtering. The EELS analysis of cross-sectional samples revealed the thermal stability of the a-C films and the efficacy of the SiNx underlayer to prevent carbon migration into the silicon substrate, even after prolonged heating. The obtained results provide insight into the important attributes of an underlayer in heated multilayered media for preventing elemental intermixing with the substrate, while preserving the structural stability of the a-C film at the stack surface. An important contribution of this investigation is the establishment of an experimental framework for accurately assessing the thermal stability and elemental diffusion in layered microstructures exposed to elevated temperatures.
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Wang J, Zuo Z, Huang L, Warsi MA, Xiao JQ, Hu J. Novel gradient-diameter magnetic nanowire arrays with unconventional magnetic anisotropy behaviors. Chem Commun (Camb) 2018; 54:7515-7518. [PMID: 29926027 DOI: 10.1039/c8cc02294a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fe-Co-Ni gradient-diameter magnetic nanowire arrays were fabricated via direct-current electrodeposition into a tapered anodic aluminium oxide template. In contrast to the magnetic behaviors of uniform-diameter nanowire arrays, these arrays exhibited tailorable magnetic anisotropy that can be used to switch magnetic nanowires easily and unconventional temperature-dependent coercivity with much better thermal stability.
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Affiliation(s)
- Jing Wang
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
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Nanostructure, structural stability, and diffusion characteristics of layered coatings for heat-assisted magnetic recording head media. Sci Rep 2018; 8:9807. [PMID: 29955072 PMCID: PMC6023885 DOI: 10.1038/s41598-018-27688-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 06/07/2018] [Indexed: 11/08/2022] Open
Abstract
The intense laser heating in heat-assisted magnetic recording (HAMR) has been a major hindrance to HAMR technology from becoming commercially viable. Thermal damage of the near-field transducer (NFT) and write pole (WP) embedded in the trailing edge of the magnetic head due to failure of the protective carbon overcoat after prolonged heating at an elevated temperature are major obstacles. Therefore, the main objective of this study was to develop an effective coating method for HAMR heads. This was accomplished by introducing a new class of layered coatings consisting of ultrathin amorphous carbon (a-C) overcoat, adhesion (SiN) layer, and buffer (NiCr or TaOx) layer sequentially deposited onto Au and FeCo base layers to mimic the layer stacking of NFT and WP elements, respectively. The structural stability of the a-C overcoats and diffusion characteristics of each comprising layer under conditions of heating at 350 °C for 30 min in an Ar atmosphere were investigated by high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). For most stacking configurations the HRTEM/STEM and EELS results generally revealed some layer intermixing and minute carbon atom rehybridization in the heated a-C overcoats. The findings of this investigation suggest that further optimization of the developed layered coatings can provide a viable solution to thermal damage of HAMR heads.
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Yeo RJ, Dwivedi N, Zhang L, Zhang Z, Lim CYH, Tripathy S, Bhatia CS. Superior wear resistance and low friction in hybrid ultrathin silicon nitride/carbon films: synergy of the interfacial chemistry and carbon microstructure. NANOSCALE 2017; 9:14937-14951. [PMID: 28952649 DOI: 10.1039/c7nr03737f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Amorphous carbon-based films are commonly investigated as protective nanocoatings in macro- to nano-scale devices due to their exceptional tribological and mechanical properties. However, with further device miniaturization where even thinner coatings are required, the wear durability of the nanocoating rapidly degrades at the expense of lower thickness. Here we discover that for sub-10 nm coating thicknesses, a hybrid bi-layer film structure, comprising a high sp3-bonded amorphous carbon top layer and a silicon nitride (SiNx) bottom layer, consistently outperforms its single-layer amorphous carbon counterpart in terms of wear durability on a commercial tape drive head, while exhibiting low, stable friction and excellent wear resistance on a flat ceramic substrate. The superior performance of the hybrid film is attributed to the constructive synergy of the sp3-rich carbon microstructure and an enhanced interfacial chemistry arising from additional interfacial bonding. Moreover, a high energy C+ ion treatment step, introduced either directly to the substrate or to the SiNx layer before carbon deposition, also aids in increasing atomic mixing that contributes to further improvement in the wear resistance. This study highlights the importance of both the carbon microstructure and interfacial chemistry in the design of wear-durable nanocoatings at few-nanometer thicknesses, particularly for aggressive wear conditions.
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Affiliation(s)
- Reuben J Yeo
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583.
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Maity N, Kuila A, Chatterjee DP, Mandal D, Nandi AK. An insight into the schizophrenic self-assembly of thermo and proton sensitive graphene oxide grafted block copolymer. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/pola.28358] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Nabasmita Maity
- Polymer Science Unit, Indian Association for the Cultivation of Science; Jadavpur, Kolkata 700032 India
| | - Atanu Kuila
- Polymer Science Unit, Indian Association for the Cultivation of Science; Jadavpur, Kolkata 700032 India
| | - Dhruba P. Chatterjee
- Polymer Science Unit, Indian Association for the Cultivation of Science; Jadavpur, Kolkata 700032 India
| | - Debasish Mandal
- Polymer Science Unit, Indian Association for the Cultivation of Science; Jadavpur, Kolkata 700032 India
| | - Arun K. Nandi
- Polymer Science Unit, Indian Association for the Cultivation of Science; Jadavpur, Kolkata 700032 India
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Dwivedi N, Yeo RJ, Yak LJK, Satyanarayana N, Dhand C, Bhat TN, Zhang Z, Tripathy S, Bhatia CS. Atomic Scale Interface Manipulation, Structural Engineering, and Their Impact on Ultrathin Carbon Films in Controlling Wear, Friction, and Corrosion. ACS APPLIED MATERIALS & INTERFACES 2016; 8:17606-17621. [PMID: 27267790 DOI: 10.1021/acsami.6b03325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Reducing friction, wear, and corrosion of diverse materials/devices using <2 nm thick protective carbon films remains challenging, which limits the developments of many technologies, such as magnetic data storage systems. Here, we present a novel approach based on atomic scale interface manipulation to engineer and control the friction, wear, corrosion, and structural characteristics of 0.7-1.7 nm carbon-based films on CoCrPt:oxide-based magnetic media. We demonstrate that when an atomically thin (∼0.5 nm) chromium nitride (CrNx) layer is sandwiched between the magnetic media and an ultrathin carbon overlayer (1.2 nm), it modifies the film-substrate interface, creates various types of interfacial bonding, increases the interfacial adhesion, and tunes the structure of carbon in terms of its sp(3) bonding. These contribute to its remarkable functional properties, such as stable and lowest coefficient of friction (∼0.15-0.2), highest wear resistance and better corrosion resistance despite being only ∼1.7 nm thick, surpassing those of ∼2.7 nm thick current commercial carbon overcoat (COC) and other overcoats in this work. While this approach has direct implications for advancing current magnetic storage technology with its ultralow thickness, it can also be applied to advance the protective and barrier capabilities of other ultrathin materials for associated technologies.
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Affiliation(s)
- Neeraj Dwivedi
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117583
| | - Reuben J Yeo
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117583
| | - Leonard J K Yak
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117583
| | - Nalam Satyanarayana
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117583
| | - Chetna Dhand
- Singapore Eye Research Institute , Singapore -169856
| | - Thirumaleshwara N Bhat
- Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03 Singapore 138634
| | - Zheng Zhang
- Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03 Singapore 138634
| | - Sudhiranjan Tripathy
- Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03 Singapore 138634
| | - Charanjit S Bhatia
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117583
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