| The physical properties of a single crystal relative to a polycrystalline material are often dramatically different, due to the effect of grain boundaries and surface characteristics. Therefore, single crystals play an important role in research studies of intrinsic properties and crystallographic structure as well as in technological applications. Many of superconducting compounds are highly anisotropic, so single crystals have been essential for determining the directionality of key properties. In this work, high-quality single crystals of NaxCoO2 and Bi2Sr2-xLaxCuO6+δwere grown by using floating zone (FZ) method. The crystal growth and physical properties of the single crystals were studied.For the NaxCoO2, the single crystals with sodium content x=0.58-0.95 were obtained by using floating zone technique. A careful study of the singe crystal growth was carried out. Thermogravimetry/differential thermal (DTA-TG) analysis was used to study the phase formation and establish the process for synthesizing. To ensure homogeneous and pure phase of a feed rod prepared prior to the growth of a high-quality single crystal, all the processes were carefully controlled and examined using X-ray diffraction (XRD). High-temperature optical microscopy (HTOM) and DTA-TG analysis was employed to observe melting and crystallizing behaviors of NaxCoO2. The results indicate that the compound melts incongruently. The growth behavior and crystal habit were investigated by analyses of X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) and polarized light microscope. The grain size and quality of crystals improve gradually with the growth length. The crystals show preferential growth behavior. The [100] direction of the grains is favorable to develop along the growth direction, exhibiting the (001) face perpendicular to the growth direction.The optimum conditions of the crystal growth for different sodium contents were investigated. We found a big difference of the optimum conditions between the growth of high sodium-content (x≥0.9) and low sodium-content (x< 0.9) compounds. Upon the optimum conditions applied, we obtained the crystal ingots of NaxCoO2 with sizes up to～Φ6×200 mm, in which one large grain was observed to extend from the position at growth length of～8cm to the end region. A series of high-quality single crystals ofα-,β-,γ-andα-NaxCoO2 (0.58≤x≤0.95) were obtained. For the growth of a-NaxCoO2 single crystals, selection of starting materials is important. Two different sources of Na (Na2CO3 and Na2O2) were employed. The experiments indicates that using a more activate Na2O2 is helpful to the formation of pure a-NaxCoO2.The magnetic properties of the single crystals of NaxCo02 were characterized using a superconducting quantum interference device (SQUID). The susceptibility of Na0.65CoO2 increasing with decreasing temperature, showing a "Curie-Weiss-like" behavior at higher temperatures before increasing more sharply at the lower temperature. The compound was found to be paramagnetic for x=0.93. Similar antiferromagnetic transitions with compositional-independence TN～22 K were observed in NaxCo02 with x=0.75,0.78 and 0.82 under the magnetic field along the a axis, while different magnetic behaviors were found under the magnetic field perpendicular to the a axis, indicating complex magnetic properties.The electrochemical technique was employed to de-intercalate Na in which an aqueous solution of NaOH was used as an electrolyte. After partly extracting sodium from NaxCoO2 (0.70≤x≤0.78), the compound with composition NaxCoO2 (0.21≤x≤0.55) could be obtained and then hydrated to form the superconducting phase NaxCoO2·1.3H2O. The magnetic and electrical properties of Na0.5CoO2 were studied. Two successive phase transitions were observed at temperatures Tc1=88 K and Tc2=53 K, which correspond to the antiferromagnetic ordering and a metal-insulator transition, respectively. The superconducting transition temperature Tc from 2.9 to 4.5 K were observed in the hydrated phases of NaxCoO2·1.3H2O with x from 0.25 to 0.45, respectively. The maximum value of Tc=4.5 K was found in the sample with x～0.33.This thesis also contains the study on growth and characterization of Bi2Sr2-xLaxCuO6+δsingle crystals. High-quality and various La-doped Bi2Sr2-xLaxCuO6+δ(x=0.0-0.90) single crystals were obtained by floating zone method. Analysis of the thermal behavior indicated an incongruent melt for all the pure and doped compounds. Chemical compositions including the La-doping in the as-grown crystals were accurately determined to study the effect of doping on the structural, chemical and superconducting property of the compounds. The variation of the composition is observed to be significantly higher at the initial parts and tends to be flat starting from 6 cm to the end of the ingot. The segregation coefficient of La respect to Sr was estimated to be～1.02. With increasing La content, the lattice parameter c decreases linearly. The La-doping value of 0.41 gives rise in the optimum Tc～33 K. Raman spectra were performed to show the high-frequency modes 627 cm-1 softened with increasing the doping level of La.
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