Abstract
Combustion synthesis method was used to prepare NdB6 ultra-fine powders with B2O3, Nd2O3 and Mg powders as the raw materials. The basic thermodynamic data of NdB6 were estimated. The standard formation heat of NdB6 is −357.48 kJ·mol−1. The values of the heat capacity and the standard entropy are 96.87 and 86.60 J·K−1·mol−1, respectively. The adiabatic temperature of the reaction is 2726 K, which is higher than the thermodynamic criterion of 1800 K. This indicates that the combustion synthesis reaction of the B2O3–Nd2O3–Mg system could spontaneously take place by itself to generate NdB6. The NdB6 powders were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry–thermogravimetry (DSC–TG). The results indicate that the combustion products consist of NdB6, MgO, and a few Mg3B2O6 and Nd2B2O6. The leached products consist of single NdB6 phase, and its purity is 98.6 wt%. When the sample preparation pressure is 20 MPa, the average particle size of NdB6 powders is less than 500 nm. The antioxidant ability of NdB6 is very strong, which is oxidized step by step. The apparent activation energies of the oxidation reactions are 986.14 and 313.83 kJ·mol−1, respectively. In addition, the reaction orders are 4.10 and 3.75, respectively.
Similar content being viewed by others
References
Ji XH, Zhang QY, Xu JQ, Zhao YM. Rare-earth hexaborides nanostructures: recent advances in materials, characterization and investigations of physical properties. Prog in Solid State Chem. 2011;39(2):51.
Gygax FN, Schenck A. Dynamics of positive muons in CaB6. J Alloys Compd. 2005;404–406(11):360.
Blomberg MK, Merisalo MJ, Korsukova M, Gurin VN. Single crystal X-ray diffraction study of NdB6 YbB6 and EuB6. J Alloys Compd. 1995;217(1):123.
Kubo Y, Asanob S, Harimac H. Fermi surfaces in antiferromagnetic compounds NdIn3 and NdB6. Condens Matter. 1993;188(2):132.
Kanakala R, Escudero R, Rojas G, Ramisetty M, Graeve OA. Mechanisms of combustion synthesis and magnetic response of high-surface-area hexaboride compounds. ACS Appl Mater Interfaces. 2011;3(4):1093.
Reiffers M, Šebek J, Šantavá E, Shitsevalova N, Gabáni S, Pristáš G, Flachbart K. Heat capacity of NdB6. J Magn Magn Mater. 2007;310(S2):595.
Ding QW, Zhao YM, Xu JQ, Zou C. Large-scale synthesis of neodymium hexaboride nanowires by self-catalyst. Solid State Commun. 2007;141(2):53.
Lu JQ, Qin JN, Lu WJ, Liu Y, Gu JJ, Zhang D. In situ preparation of (TiB + TiC + Nd2O3)/Ti composites by powder metallurgy. J Alloys Compd. 2009;469(1–2):116.
Liu Y. Synthesis of NdB6 and fabrication technique of in situ (TiB + TiC + Nd2O3)/Ti composites by powder metallurgy. Shanghai: Shanghai Jiaotong University; 2007. 12.
Liu Y, Lu WJ, Qin N, Zhang D. A new route for the synthesis of NdB6 powder from Nd2O3–B4C system. J Alloys Compd. 2007;431(1–2):337.
Zhao XD, Liu XY, Lin F, Liu WN, Su WH. A new route for the synthesis of boron-rich rare-earth boride NdB6 under high pressure and high temperature. J Alloys Compd. 1997;249(1–2):247.
Kubaschewski O, Alcoc CB. Thermodynamics Chemistry of Metallurgy. 3rd ed. Beijing: Metallurgical Industry Press; 1985. 216.
Ye DL. Metallurgy Thermodynamics. Changsha: Central South University of Technology Press; 1987. 36.
Merzhnov AG, Aerson AE. The present state of the thermal ignition theory review. Combust Flame. 1971;16(1):89.
Dou ZH, Zhang TA, Liu Y, Guo YN, He JC. Preparation of CeB6 nano-powders by self-propagating high-temperature synthesis (SHS). J Rare Earths. 2011;29(11):986.
Dou ZH, Zhang TA. Growth mechanism of self-propagating metallurgy method to prepare TiB2 powder. J Inorg Mater. 2006;21(3):583.
Acknowledgments
This research was financially supported by the National Natural Science Foundation of China (Nos. 51002025 and 51422403).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Dou, ZH., Zhang, TA., Fan, SG. et al. A new method of preparing NdB6 ultra-fine powders. Rare Met. 41, 2363–2369 (2022). https://doi.org/10.1007/s12598-015-0596-0
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12598-015-0596-0