Untangling the role of the carbon matrix in the magnetic coupling of Ni@C nanoparticles with mixed FCC/HCP crystal structures

被引：2

作者：

Fadel, Mona ^{[1
]}

Martin-Jimeno, F. Julian ^{[2
]}

Fernandez-Garcia, M. P. ^{[1
]}

Suarez-Garcia, Fabian ^{[2
]}

Paredes, Juan Ignacio ^{[2
]}

Belo, J. H. ^{[3
]}

Araujo, J. P. ^{[3
]}

Adawy, Alaa ^{[4
]}

Martinez-Blanco, David ^{[5
]}

Alvarez-Alonso, Pablo ^{[1
,6
]}

Blanco, Jesus A. ^{[1
]}

Gorria, Pedro ^{[1
,6
]}

机构：

[1] Univ Oviedo, Dept Fis, Oviedo 33007, Spain

[2] INCAR CSIC, Inst Ciencia & Tecnol Carbono, C-Francisco Pintado Fe 26, Oviedo 33011, Spain

[3] Univ Porto, IFIMUP, Dept Fis & Astron, Fac Ciencias, Rua Campo Alegre 687, P-4169007 Porto, Portugal

[4] Univ Oviedo, Unidad Microscopia Elect & Nanotecnol, SCTs, Oviedo 33006, Spain

[5] Univ Oviedo, Unidad Difracc Rayos 10, SCTs, Oviedo 33006, Spain

[6] Univ Oviedo, IUTA, EPI, Gijon 33203, Spain

来源：

JOURNAL OF MATERIALS CHEMISTRY C | 2023年 / 11卷 / 12期

关键词：

D O I：

10.1039/d3tc00257h

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Nowadays, Ni@C nanostructured materials are attracting a great deal of attention due to their multiple catalytic or magnetic functionalities. In this article we report on the investigation of the correlation between the microstructure and magnetic properties of Ni nanoparticles embedded in a carbon matrix. The samples were obtained following a two-step procedure that ensures protection against nanoparticle oxidation, and was carried out in the following way: (i) the synthesis of a nickel-imidazole-based metal-organic framework (MOF) by a simple method in an aqueous medium at moderate temperature (95 degrees C); and (ii) carbonization of the MOF at different temperatures between 400 and 600 degrees C to obtain a carbon-supported hybrid material, containing Ni nanoparticles with an "artichoke-like" morphology, where a Ni-FCC core is surrounded by "bracts" of Ni-HCP and Ni3C. The average size of the nanoparticle slightly changes from 7 to 10 nm as the carbonization temperature is increased, but the Ni-FCC core diameter ranges from 3 to around 6 nm. We show how the information obtained on the evolution of the magnetic behaviour with carbonization temperature, using X-ray diffraction and electron microscopy, complements each other by providing consistent structural and magnetic characteristics of the investigated Ni@C nanoparticles. In fact, this joint analysis allows us to explain the formation and transformation of different Ni-based crystalline phases along the synthesis process, including Ni3C and Ni with both hexagonal and cubic crystalline structures. The amount of conventional Ni-FCC is below 10 wt% for the sample treated at 400 degrees C and it can reach up to 50 wt% for that treated at 600 degrees C. Finally, based on our current findings we propose an explanation for understanding the magnetic properties of Ni@C, in which the Ni-FCC core spins mainly govern the magnetic coupling of the whole system.

引用

页码：4070 / 4080

页数：11