Scientists at the Lawrence Berkeley National Laboratory in California, USA, have discovered that nanocrystals of germanium embedded in silica glass don't melt until the temperature rises almost 200 degrees Kelvin above the melting temperature of germanium in bulk. What's even more surprising, these melted nanocrystals have to be cooled more than 200 K below the bulk melting point before they resolidify. Such a large and nearly symmetrical "hysteresis" -- the divergence of melting and freezing temperatures above and below the bulk melting point -- has never before been observed for embedded nanoparticles.

Workers in Russia and Los Alamos, USA report in Nature superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2500-2800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond (carbon) is a bulk, type-II superconductor below the superconducting transition temperature T_c 4 K.

Boron has one less electron than carbon and, because of its small atomic radius, is relatively easily incorporated into diamond. The boron acts as a charge acceptor and the resulting diamond is effectively hole-doped.

In a letter to Nature [2004, 427, 225], E. Kim and M. H. W. Chan (Pennsylvania State University, USA) note that when liquid ⁴He is cooled below 2.176 K, it undergoes a phase transition and becomes a superfluid with zero viscosity. They claim that in addition to superflow in the liquid phase, superflow can also occur under some conditions in the solid phase of one of the helium isotopes (⁴He), and present results to back this up. In other words - evidence for a "supersolid". A supersolid behaves like a superfluid (flows without resistance) although it has crystalline solid characteristics.

See Nature for further datails.