High pressure behaviour of TbN: an X-ray diffraction and computational study

• Published in: Solid state communications Vol. 121; no. 8; pp. 447 - 452
• Main Authors: Jakobsen, J.M., Madsen, G.K.H., Jørgensen, J.-E., Staun Olsen, J., Gerward, L.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-03-2002; Elsevier
• Subjects: C. X-ray scattering; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; D. Electronic band structure; Exact sciences and technology; High pressure; Materials science; Physics; Pressure treatment; Pressure treatments; Structure of solids and liquids; crystallography; Treatment of materials and its effects on microstructure and properties; X-ray diffraction and scattering; 81.40.V; D. Electronic band structure; C. X-ray scattering; 721.20; 61.10; High pressure; Powders; Inorganic compounds; Pressure effects; Phase transformations; Binary compounds; XRD; Terbium nitrides; Rare earth compounds; Cesium chlorides; Sodium chlorides; APW calculations; Electronic structure; Equations of state; Strong correlation; Hydrostatic pressure; Density functional method; Plane waves; Bulk modulus; Local density approximation
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/S0038-1098(01)00506-3

In the present work, we report an X-ray powder diffraction study of TbN up to an applied hydrostatic pressure of 43
GPa. TbN was found to be stable in the B1 (NaCl structure) within the examined pressure interval, and the zero pressure bulk modulus was determined to be 176(7)
GPa. The electronic structure of ferromagnetic TbN has been studied using the linearized augmented plane-wave method. The calculated equilibrium volume and equation of state (EOS) for TbN agree poorly with experiment when the LDA and GGA versions of DFT were used. The agreement between the experimental and theoretical EOS is greatly improved by introducing an orbital dependent
U term into the energy-functional. The 4f electrons in TbN-B1 are atomic like and highly correlated, and ferro-magnetic TbN-B1 is found to be a magnetic half-metal. Calculations find the spin-down f-electrons in a hypothetical TbN-B2 (CsCl) structure to be itinerant and well described by standard DFT functionals. No pressure-induced phase transitions were found below 250
GPa with the LDA+
U and GGA+
U methods.