Type-VIII clathrate structure

K.K. Kishimoto, H. Yamamoto, K. Akai, T. Koyanagi, Effect of Ge substitution on carrier mobilities and thermoelectric properties of sintered p-t) pe BagGaig+ Snao-x-yGey with the type-VIII clathrate structure. 1. Phys. D Appl. Phys. 45, 445306 (2012)... 

Fig. 8.2 A view of the Type VIII clathrate structure type showing a view of the (a) unit cell down the a axis, and (b) the 20 vertex cage. The large (green) spheres are the guest ion and the small (yellow and red) spheres are the framework atoms...

D. Huo, T. Sakata, T. Sasakawa, M.A. Avila, M. Tsubota, F. Iga, H. Fukuoka, S. Yamanaka, S. Aoyagi, T. Takabatake, Structural, transport, and thermal properties of the single-crystalline type-VIII clathrate BagGaigSnao- Phys. Rev. B 71, 075113 (2005)... 

G.K.H. Madsen, K. Schwarz, P. Blaha, D.J. Singh, Electronic structure and transport in type-I and type-VIII clathrates containing strontium, barium, and europium. Phys. Rev. B 68, 125212 (2003)... 

Although most investigations focused on the pressure dependence of the clathrate-I structure, data on the bulk moduli are available for different clathrate structures (type-I, type-II, type-VIII, and type-IX), and various filler and framework elements and are collected in Table 10.2. In order to provide also other elastic quantities, in these cases an average Poisson s ratio, Vavg = 0.23, was assumed and Eqs. (10.3)-(10.7) in given or adapted form were used for further calculations. 

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