Scientists in the group have discovered highly unexpected low compressibility of osmium, stiffer than diamond, in collaboration with theorists.

Squeezed at high temperatures and pressures, carbon dioxide transforms from a molecular solid to a polymeric solid with a structure like quartz [Science, 283,1510 (1999)]. Raman spectroscopy indicates each carbon atom is bonded to four oxygen atoms, yielding a three-dimensional network like the quartz polymorph of silicon dioxide. The fundamentally different state of CO₂ shows interesting nonlinear optical behavior, strongly emitting light at a wavelength that corresponds to the second harmonic of the exciting laser. Once formed, the quartzlike CO₂ remains stable at room temperature at pressures above 1 GPa and the researchers hope to able to isolate it at ambient pressures in the near future. One can expect that this new material has high thermal conductivity, just like diamond, and is also a very good candidate for a superhard material similar to diamond and cubic-boron nitride.