HoB < inf > 4 < /inf > at high pressure and low temperature: An experimental and theoretical study

Abstract

Single crystals of HoB4 have been grown and used for synchrotron X-ray diffraction studies at pressures up to 23GPa and temperatures down to 100K. The experimental bulk modulus 195 ± 6GPa is in good agreement with 188.4 and 198.2GPa values calculated in the LSDA and LSDA+U approximations, indicating that mainly the boron sublattice determines the bulk modulus. The experimental c/a ratio decreases slightly with pressure, but the effect is small. An orthorhombic distortion begins at Tc ≈ 295K, i.e. at a temperature much higher than the Neel temperature TN1=7.1K. The behavior is interpreted in terms of built-in strains and crystal mosaicity. © 2011 Taylor & Francis.