In situ characterization of the nitridation of dysprosium during mechanochemical processing

• Published in: Journal of alloys and compounds 2015-01, Vol.619, p.253-261
• Main Authors: Jaques, Brian J., Osterberg, Daniel D., Alanko, Gordon A., Tamrakar, Sumit, Smith, Cole R., Hurley, Michael F., Butt, Darryl P.
• Format: Article
• Language: English
• Subjects: Alloys; Ball mills; Ceramics; Dysprosium; Footprints; Gas–solid reactions; Inorganic materials; Mechanochemical processing; Nitride materials; Nitrides; Phases; Rare earth alloys and compounds; X-ray diffraction
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.08.193

•A nitridation reaction in a high energy planetary ball mill was monitored in situ.•Dysprosium mononitride was synthesized from Dy at low temperatures in short times.•Ideal gas law and in situ temperature and pressure used to assess reaction extent.•It is proposed that reaction rate is proportional to the creation of new surface. Processing of advanced nitride ceramics traditionally requires long durations at high temperatures and, in some cases, in hazardous atmospheres. In this study, dysprosium mononitride (DyN) was rapidly formed from elemental dysprosium in a closed system at ambient temperatures. An experimental procedure was developed to quantify the progress of the nitridation reaction during mechanochemical processing in a high energy planetary ball mill (HEBM) as a function of milling time and intensity using in situ temperature and pressure measurements, SEM, XRD, and particle size analysis. No intermediate phases were formed. It was found that the creation of fresh dysprosium surfaces dictates the rate of the nitridation reaction, which is a function of milling intensity and the number of milling media. These results show clearly that high purity nitrides can be synthesized with short processing times at low temperatures in a closed system requiring a relatively small processing footprint.