Superhard MgB2 bulk material with a golden metallic shine was synthesized by high-pressure sintering (8h, 5.5GPa) and different temperatures. Appropriate pressure and temperature conditions for synthesizing polycrystalline MgB2 with high hardness were investigated. The samples were characterized by means of atomic force microscopy and X-ray diffraction. The Vickers hardness, bulk density, and electrical resistivity were measured at room temperature (table 1).

Superhard MgB2 Bulk Material Prepared by High-Pressure Sintering. H.A.Ma, X.P.Jia, L.X.Chen, P.W.Zhu, G.Z.Ren, W.L.Guo, X.Q.Fu, G.T.Zou, Z.A.Ren, G.C.Che, Z.X.Zhao: Journal of Physics - Condensed Matter, 2002, 14, 11181-4

 

Table 1

Properties of MgB2 as a Function of Synthesis Conditions 

 

 

Conditions

Hv (kg/cm2)

d (g/cm3)

ρ (Ωm)

5.5GPa, 8h, 700C

2153.3

2.70

3.03 x 10-6

5.5GPa, 8h, 800C

4109.5

2.71

2.42 x 10-6

5.5GPa, 8h, 1000C

1448.8

2.88

2.75 x 10-6