Structure and magnetic properties of bulk nanocrystalline Dy metal prepared by spark plasma sintering

Abstract

The structure and magnetic properties were studied for bulk nanocrystalline dysprosium (Dy) metal prepared by spark plasma sintering method. All the as-prepared samples have hexagonal close packed structure. A decrease in grain size results in remarkable changes in magnetic ordering temperature of the nanocrystalline Dy metal. At 5K, the magnetization drops by 3.35%, and the coercive force increases by three times for nanocrystalline Dy compared to those of coarse-grained bulk Dy sample. These results indicate the remarkable influence of the nanostructure on the magnetism of Dy due to finite size effect.

Magnetic properties of Dy nanoparticles and Al2O3-coated Dy nanocapsules

“…5d). Compared with bulk Dy, the Néel temperature T N of Dy nanocapsules decreases remarkably to 150 K, while the T SPM-AFM increases abnormally to 105 K. This phenomenon is similar with the shift in bulk nanocrystalline Dy with the average grain size of 10 nm and Dy nanoparticles with the diameter of 12 nm (Shevchenko and Christodoulides 1999;Yue et al 2008). Thinking about the average core size of 17.6 nm in Dy nanocapsules is about four times the helix period of Dy, one understands that such a deviation is due to the breaking of the helical ordering and the incomplete rotation of spins along the c axis.…”

The influence of oxygen and nitrogen contamination on the densification behavior of cryomilled copper powders during spark plasma sintering

“…Inspection of the scientific literature reveals that nc metallic powders of various compositions have been successfully produced by mechanical milling or cryomilling, followed by consolidation via SPS [17][18][19][20][21][22][23][24][25]. However, changes to the chemistry of the powders during milling, and particularly during SPS, are seldom discussed, and moreover, the final relative density of SPS-consolidated bulk material is often calculated and reported on the basis of the theoretical density of the pure metal or alloy with a nominal composition (i.e., ignoring the chemistry changes that are induced by the milling environment and during SPS).…”

Structural and magnetic properties of bulk nanocrystalline Erbium metal

“…Similar phenomena have been observed and reported in previous studies for Dy and Tb nanocrystalline samples. 6,7,10 …”

“…As a result, some nanostructured heavy rare earth metals, including Gd, Tb, and Dy, have been prepared and widely studied for their structure and magnetic properties. [1][2][3][4][5][6][7][8][9][10] As one of the heavy rare earth elements, Erbium (Er) had been intensively studied for its complex magnetic structures and magnetic properties. [11][12][13][14][15][16][17][18] Er metal has hexagonal close packed (hcp) crystal structure, and it undergoes three differentmagnetic phase transitions below 100 K. At T N of 85 K, a c-axis modulated sinusoidal structure appears; then with decreasing temperature at T B of 52 K a basal plane modulated structure, namely a quasi anti-phase domain magnetic structure; finally at T C of 20 K a conical ferromagnetic structure.…”