doi:

DOI: 10.3724/SP.J.1077.2014.13516

Journal of Inorganic Materials (无机材料学报) 2014/29:7 PP.711-716

Preparation of Ultra-fine NdB6 Powders by Combustion Synthesis and Its Reaction Mechanism


Abstract:
Ultrafine powders NdB6 were prepared by combustion synthesis with B2O3, Nd2O3 and Mg as raw materials. The effects of reaction atmosphere, sample pressure and raw materials ratio on the reaction product morphology and phases were studied. Characterizations by XRD and SEM show that the products consist of NdB6, MgO and a little amount of Mg3B2O6 and Nd2B2O6. After reaction with sulphuric acid at low concentration to eliminate the latter three components, the pure NdB6 is obtained (purity 99.1%). As the preparation pressure increases, the NdB6 particle sizes become small. When the sample pressure is 20 MPa, the average particle size is less than 500 nm. The preparation reaction process is as follows: firstly, Mg reduces Nd2O3 to generate Nd and MgO; and then, the reaction between Mg and B2O3 are ignited to generate B and MgO; at the same time, the generated Nd and B are reacted to produce NdB6. The apparent activation energy of the reaction is 691.59 kJ/mol and the reaction order is 3.2.

Key words:combustion synthesis,neodymium hexaboride,ultrafine powder,reaction mechanism

ReleaseDate:2016-07-11 11:25:02



[1] JI X H, ZHANG Q Y, XU J Q. et al. Rare-earth hexaborides nanostructures: recent advances in materials, characterization and investigations of physical properties. Progress in Solid State Chemistry, 2011, 39(2): 51-69.

[2] GYGAX F N, SCHENCK A. Dynamics of positive muons in CaB6. Journal of Alloys and Compounds, 2005, 404-406(11): 360-364.

[3] BLOMBERG M K, MERISALO M J, Korsukova M, et al. Single crystal X-ray diffraction study of NdB6, YbB6 and EuB6. Journal of Alloys and Compounds, 1995, 217: 123-127.

[4] KUBO Y, ASANOB S, HARIMAC H. Fermi surfaces in antiferromagnetic compounds NdIn3 and NdB6. Condensed Matter,

[5] KANAKALA R, ESCUDERO R, ROJAS G, et al. Mechanisms of combustion synthesis and magnetic response of high-surface-area hexaboride compounds. ACS Applied Materials & Interfaces, 2011, 3(4): 1093-1100.

[6] MARIAN R, JOSEF S, EVA S, et al. Heat capacity of NdB6. Journal of Magnetism and Magnetic Materials, 2007, 310: 595-597.

[7] DING Q W, ZHAO Y M, XU J Q, et al. Large-scale synthesis of neodymium hexaboride nanowires by self-catalyst. Solid State Communications, 2007, 141: 53-56.

[8] LU J Q, QIN J N, LU W J, et al. In situ preparation of (TiB+ TiC+Nd2O3)/Ti composites by powder metallurgy. Journal of Alloys and Compounds, 2009, 469(1/2): 116-122.

[9] LIU YANG. Synthesis of NdB6 and Fabrication Techniqueof in situ (TiB+TiC+Nd2O3)/Ti Composites by Powder Metallurgy, Shanghai Jiaotong University Press, 2007: 12-25.

[10] LIU Y, LU W J, QIN J N, et al. A new route for the synthesis of NdB6 powder from Nd2O3-B4C system. Journal of Alloys and Compounds, 2007, 431(1/2): 337-341.

[11] ZHAO XD, LIU X Y, LIN F, et al. A new route for the synthesis of boron-rich rare-earth boride NdB6 under high pressure and high temperature. Journal of Alloys and Compounds, 1997, 249: 247-250.

[12] DOU ZHIHE, ZHANG TING’AN, LIU YAN, et al. Preparation of CeB6 nano-powders by self-propagating high-temperature synthesis (SHS). Journal of Rare Earths, 2011, 29(11): 986-989.

[13] ZHANG TING-AN, DOU ZHIHE. Growth mechanism of TiB2 powder prepared by SHS-metallurgy, Journal of Inorganic Material, 2006, 21(3): 583-590.

[14] Li Yuzeng. Thermal Analysis. Beijing: Qinghua University Press, 1987: 207-219.

1993, 188(2): 132-135.