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The thermodynamic analysis of the [K.sup.} reversible processes for ion exchanges in [K.sub.h][Fe.sub.k][[Fe[[(CN).sub.6].sub.l]*m[H.sub.2]O host compounds (Prussian blue) is presented. The fact that the simple model like the lattice-gas model used in analysis could be applied to [K.sup.} ion intercalation supports the idea that there is no interaction between the guest and the host material at more anodic potentials than 0.20 V with respect to the saturated calomel reference electrode, at least for low concentrations of [K.sup.}.

An investigation on the crystal structure and thermoelectric properties of type-I clathrate compounds in the Ba-Ga-Ge system is conducted as a function of Ga content. The absolute values of electrical resistivity and Seebeck coefficient increase, while that of lattice thermal conductivity decreases with the increase in the Ga content.

A single crystal of 1,6-hexanediol Dianin's clathrate is studied by Brillouin spectroscopy to obtain its complete elastic tensor. Dianin's clathrates and its clathrand provide a unique system of study in which guests of varying size, shape, and functionality can be incorporated into nearly isostructural host lattices.

Trimethylene oxide (TMO) forms structure I or structure II hydrates depending on stoichiometry and affords the opportunity to compare and contrast the temperature dependence of the crystal structure parameters for the two major hydrate structure types occluding a common guest module. Changes with respect to temperature were observed in structure I and not in structure II.

A study was conducted on the origin of metallization of c-axis resistivity upon intercalation of Iodine into Bi2Sr2CaCu2O(sub 8+gamma) by performing I LI-edge angle-resolved X-ray absorption spectroscopic (XAS) analysis. The analysis suggests that there is a significant anisotropy in the 1 5p hole distribution of the intercalated iodine layer.

The (super 23)Na and (super 29)Si NMR spectra of the sodium-silicon clathrate materials Na(sub 8)Si(sub 46) and Na(sub x)Si(sub 136) are studied in detail. NMR, XPS and XANES results showed an interaction between Na atom and the Si framework of the clathrates.

The synthesis of A(sub 8)(sup II)B(sub 16)(sup III)B(sub 30)(sup IV) clathrates, study of their formation mechanisms and measurements of their transport properties over the temperature range 100-870 K is reported. Results show that the calculated effective masses of the clathrates range from 0.9 to 3 of the free electron mass.

Single-crystalline samples of type-VIII clathrate [Ba.sub.8][Ga.sub.16-x][Al.sub.x][Sn.sub.30] are grown from Sn flux to analyze the structural and thermoelectric properties from 300 to 600 K. The Seebeck coefficients of all samples are largely negative and the large thermopower has coexisted with the metallic behavior in the electrical resistivity.

Several studies are conducted to explain the thermal expansion taking place in the different series of thermoelectric type-I-clathrates. The thermal expansion is shown to be highly dependent on the temperature and the thickness of the clathrates.

The type-VIII [Sr.sub.8][Al.sub.x][Ga.sub.y][Ge.sub.46-x-y] samples with various concentrations are prepared to examine their thermoelectric properties. The type-VIII clathrate had a smaller effective mass, a higher mobility and a higher lattice thermal conductivity than those of the type-I clathrate and the difference in transport properties between the type-I and type-VIII clathrates is discussed.

Powder inelastic neutron scattering (INS) is used for determining the guest atom 'rattling' energy in thermoelectric clathrates [Ba.sub.8][Y.sub.x][Ge.sub.46-x] ([Y.sub.x] = [Ni.sub.6], [Cu.sub.6], [Zn.sub.8], [Ga.sub.16]) under different applied conditions. Chemical pressure is exerted by the atomic substitution and the volume reduction induced by the physical pressure has increased the energy of the guest atom rattling mode.

First principles calculations are used for examining both type I and II silicon clathrates. The mean free paths and thermal conductivities of the clathrates are larger than those of the diamond phase Si (d-Si) at low temperature and the Seebeck coefficients (S) of the clathrates are higher than that of d-Si in the temperature interval 300-1000 K.

A volumetric technique is employed to prepare the temperature-pressure phase diagram of a [D.sub.2]O-[D.sub.2] system at deuterium pressures up to 1.8kbar. The solubility of deuterium in heavy water, hexagonal-ice and the cubic clathrate ice is also studied.

The synthesis and chemical, structural and transport properties of [Ba.sub.8][Ga.sub.16][Si.sub.x][Ge.sub.30-x] type I clathrates with similar Ga-to-group IV element ratios but with increasing Si substitution are described. The results have described an additional method for tuning the electronic properties of [Ba.sub.8][Ga.sub.16][Ge.sub.30] for thermoelectric applications.

The crystal structure and thermoelectric properties of type-III clathrate compounds in the Ba-In-Ge system are evaluated as a function of In content. The findings demonstrate the changes in lattice thermal conductivity in terms of the low rattling frequency of the guest atom as well as the low Debye temperature of the cage framework.

The solid-state reaction is combined with the spark plasma sintering method in order to synthesize Zn-doping [Ba.sub.8][Ga.sub.16][Ge.sub.30-x] clathrates with different Zn contents. The effects of Zn content on thermoelectric transport properties are examined in order to develop the high thermoelectric performance p-type clathrate.

The thermoelectric properties of type-III clathrate compounds in the Ba-Al-Ge system were examined as a part of Al content. One of the results concluded that solid solubility of Al in the type-III clathrate compounds was found to be less than X=12.

The article discusses the results of the high-pressure Raman measurements conducted for the Ba doped type-III germanium clathrate [Ba.sub.24][Ge.sub.100] up to 26 GPa at room temperature.

Polycrystalline samples of [Sr.sub.8][Ga.sub.x][Ge.sub.46-x] clathrates with various carrier concentrations are prepared and their thermoelectric and transport properties are measured. The band gap of the samples is estimated to be 0.4-0.5 eV, their effective mass is a constant value of 3.1 [m.sub.e] at room temperature which decreases with increasing temperature and their electron Hall mobilities are 8-13 [cm.sup.2] [V.sup.-1] [s.sup.-1] at room temperature, increasingly slightly with decreasing carrier concentration.

The Czochralski method was used to grow a long crystal of the Ba8Ga16Ge30 clatharate which was cut into disks that were evaluated for thermoelectric performance. The seebeck coefficient and electrical and thermal conductivities all showed evidence of a transition from extrinsic to intrinsic behavior.