NdB6 ceramic nanoparticles: First principles calculations, mechanochemical synthesis and strain engineering

Boztemur B., Mansoor M., Kaya F., Huang M., Tekoğlu E., Öveçoğlu M. L., ...More

Journal of Materials Research and Technology, vol.24, pp.5571-5587, 2023 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 24
  • Publication Date: 2023
  • Doi Number: 10.1016/j.jmrt.2023.04.165
  • Journal Name: Journal of Materials Research and Technology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Directory of Open Access Journals
  • Page Numbers: pp.5571-5587
  • Keywords: CALPHAD, Defect structure, Density functional theory, Nd boride powders, Strain engineering, Superplasticity
  • Istanbul Technical University Affiliated: Yes


Borides are usually hard and brittle materials; however, we report the synthesis of superplastic nanostructured NdB6 ceramic powders, counter to the conventional wisdom that borides are always brittle. We investigate that through strain engineering, NdB6 can be made extremely ductile if the lattice is compressively strained and highly defected, based on transmission electron microscopy (TEM) and density functional theory (DFT) calculations. In this study, the synthesis conditions were designed based on CALPHAD modelling, and the superplastic NdB6 powders were successfully obtained through mechanochemical synthesis (MCS) of Nd2O3, B2O3 and Mg initial materials in a high-energy ball mill. Following MCS, the powders were purified in a hydrochloric acid (HCl) containing aqueous solution in order to leach out MgO by-product. The purified powders were characterized using X-ray diffractometry (XRD), Helium (He) gas pycnometry, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), particle size analysis (PSA) and magnetometry techniques, which demonstrated NdB6 nanoparticles with an average particle size of 118 nm belonging paramagnetic behavior at cryogenic temperatures. DFT calculations have been carried out through to investigate the structural, mechanical, electronic, optical, thermodynamic and magnetic properties of NdB6. The impact of various defects was examined, which revealed the significance of boron vacancies and compressive strains in the superplastic form of NdB6.