[en] The 1D-orthorhombic polymer phase of C₆₀ was originally mentioned in 1995. The present work provides the first direct experimental quantitative evidences of the 1D-polymer chains, clearly seen by single-crystal diffraction. Geometrical details of the [2+2]-cycloaddition rings are compared with those of C₆₀ dimers and 2D-polymers. Another key structural parameter is the angle of rotation Ψ of the 1D chains about the polymerization axis. Single-crystal diffraction yields Ψ ∼ 78^o, whereas accurate synchrotron powder diffraction independently produces a similar Ψ ∼ 73^o. These values are in qualitative agreement with a former theoretical prediction (Ψ ∼ 61^o)

[en] The raman scattering technique is used for studying diamonds with a 0.04-0.1 at % boron impurity under a pressure up to 3 GPa in a chamber with sapphire anvils. The Raman frequency increases linearly with pressure for all samples with pressure coefficients of 2.947 cm^-1/GPa for pure diamond and 3.01 cm^-1/GPa for boron-doped samples. The Raman linewidths remain unchanged for pure diamond and for diamond with a boron concentration of about 0.04 at % and decrease linearly upon an increase in pressure for samples with a boron concentration of about 0.1 at %. The Raman spectra with a line profile corresponding to the Fano resonance do not change qualitatively up to a pressure of 3 GPa. In diamond samples with a boron impurity exceeding 0.1 at %, the boron concentration in the surface layer can be substantially higher than at the center of the sample

[en] Using two different high-pressure techniques, we have prepared boron-doped diamonds with atomic concentration of the dopant ranging from 0.04% to 4% (from 7x10¹⁹ to 7x10²¹ atom/cm³) and studied the lattice constants and thermal expansion of the diamonds in the temperature range from 90 to 300 K. Both sets of samples demonstrate the same increasing concentration dependence of the lattice parameter with maximum shift of the lattice constant about 0.011 A . We have established an abnormally high thermal expansion of the heavily boron-doped superconducting diamonds with respect to the undoped ones and a nearly linear correlation between lattice constant and critical temperature of the superconducting transition