Extremely rapid isotropic irradiation of nanoparticles with ions generated in situ by a nuclear reaction

Jan Havlik,Vladimira Petrakova,Jan Kucera,Jan Kucka,Helena Raabova,Martin Hruby,Vaclav Stepan,Philipp Reineck,Dalibor Panek,Jan Stursa,Petr Cigler,Zuzana Zlamalova Cilova

doi:10.1038/s41467-018-06789-8

Abstract

Energetic ions represent an important tool for the creation of controlled structural defects in solid nanomaterials. However, the current preparative irradiation techniques in accelerators show significant limitations in scaling-up, because only very thin layers of nanoparticles can be efficiently and homogeneously irradiated. Here, we show an easily scalable method for rapid irradiation of nanomaterials by light ions formed homogeneously in situ by a nuclear reaction. The target nanoparticles are embedded in B2O3 and placed in a neutron flux. Neutrons captured by 10B generate an isotropic flux of energetic α particles and 7Li+ ions that uniformly irradiates the surrounding nanoparticles. We produced 70 g of fluorescent nanodiamonds in an approximately 30-minute irradiation session, as well as fluorescent silicon carbide nanoparticles. Our method thus increased current preparative yields by a factor of 102–103. We envision that our technique will increase the production of ion-irradiated nanoparticles, facilitating their use in various applications.

Highlights

Energetic ions represent an important tool for the creation of controlled structural defects in solid nanomaterials
The average linewidth of the neutron-irradiated particles was statistically not significantly different from the electron-irradiated samples. Another measure of the local strain in the diamond lattice is the splitting of the optically detected magnetic resonance (ODMR) signal at zero external magnetic field[56]. We find this zero-field splitting to be between 11.5 MHz and 12.2 MHz at room temperature for all samples (Fig. 3d), indicating that a comparable average local strain is present in all samples, irrespective of the irradiation method
To demonstrate the capability of our method to produce lattice defects in a different material, we focused on silicon carbide (SiC), one of the key materials used in development of next-generation photonic and electronic devices[5]

Summary

Introduction

Energetic ions represent an important tool for the creation of controlled structural defects in solid nanomaterials. Modification with energetic ions represents a key approach to the creation of a variety of functional nanostructured materials, which has enabled advances in numerous research fields. In optics, this approach is used to create lattice point defects, including vacancies, color centers[3,4], and single-photon emitters[5]. Nanoparticle powders exhibit poor thermal conductivity and may overheat under irradiation, necessitating the use of thin nanoparticle layers in the target to prevent thermally induced alterations of the nanoparticles[20] These reasons make scale-up of production extremely challenging, because only very thin layers of nanoparticles can be efficiently and homogeneously irradiated[3,21]

Methods

Results

Conclusion