Influence of missing guest and host atoms on the mechanical and electronic properties of type-I clathrate compound Ba8Si46

Multiple magnetic transition and magnetocaloric properties in the mixed valence Eu8CuNi2.5Si42.5 type I clathrate compound

“…The Type I clathrate structure is shown in the inset of Fig. 1 (a) [ 22 ]. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)…”

Lattice Dynamics Study of Phonon Instability and Thermal Properties of Type-I Clathrate K8Si46 under High Pressure

“…By the model of partially occupied Si sites they explained the transition pressure and change of Raman spectra of both K 8 Si 46 and Ba 8 Si 46 [20]. Moreover, our recent work showed that 6 c sites lattice vacancies increased the compressibility of clathrate greatly while guest atoms vacancies hardly had any influence on this property [19]. Experimentally, by performing high quality in situ high-pressure angle-dispersive X-ray powder diffraction measurements, Li et al found a highly disordered Si framework from analysis of the obtained anomalously large Si thermal parameters [13].…”

“…Various mechanisms (e.g., the change of hybridization between guest atoms and frame cages [ 12 ] and an electronic topological transition [ 14 , 15 ]) for this high pressure phase transition have been proposed to explain this phenomenon for Ba 8 Si 46 . In our recent work [ 19 ], detailed investigations have been performed to study the effect of forming lattice vacancies on the mechanical and electronic properties of Ba 8 Si 46 under high pressure. The results indicate that the compressbility of Ba 8 Si 46 is governed by the Si framework and the pressure induced escape of host Si atoms would cause the sudden volume collapse during the compress, which is consistent with the explanation from Iitaka et al according to their atomistic model [ 20 ].…”

First-Principles Investigation of the Impact of High Pressure on the Structural, Electronic and Elastic Oroperties of the Type-VIII Barium-Doped Silicon Clathrate Ba8Si46.

“…Electronic properties are highly affected by the presence of pressure, the metallic character of the compound is not changed throughout the pressure range, however, the interaction between barium atoms and their surrounding Si environment becomes stronger with pressure, and as a consequence, the Fermi level decreases. Elastic properties are also affected by pressure, the major mechanical properties were computed for relaxed and stressed materials, and our results showed that the type-VIII Ba8Si46 is relatively hard and resistant against deformation [17] GGA-PBE (ABINIT) c: data from ref [45] GGA-PBE (QUANTUM-ESPRESSO) d: data from ref [30] e: data from ref [46] LDA (SIESTA) f: data from ref [47] Hartree-Fock HF (CRYSTAL 95) g: data from ref [36] h: data from ref [34] i: data from ref [48] and shear forces and might collapse if pressure exceeds 24 GPa, however, our predictions are to be confirmed through experiments.…”

“…As can be noticed from figure 3, the cell volume tend to normally decrease when pressure is increased, however, the behavior is not linear, from 0 GPa to 5 GPa, the volume is drastically reduced by about 31%. High pressure behavior for type-I Ba8Si46 by Zhang et al [36] and K8Si46 by Tse et al [37] were studied by means of DFT codes. In both studies similar behaviors were observed with higher mechanical stability for the barium doped clathrate as a result of the larger Ba atoms and hence stronger interaction with the Si cage.…”