中文摘要：

成功制备了超导临界温度为27K的Ko．sFe2Se2晶体，并详细研究了晶体C轴向的载流子输运特性．结合X射线衍射、光学显微镜下的形貌、变温电阻率的测试结果表明，样品存在有“相分离”，但是这类层状铁基超导体材料的两个相不是简单沿C轴向层状交替排布的，而应该是沿着C轴向存在弱联系的金属相链接通路，金属相部分形成近3维的空间网状链接模式．热导率测试和复阻抗谱Z（W，TO）的研究表明超导晶体沿着c轴方向存在有大量的相界面，所束缚的极化电荷致使相对介电常数达到10。数量级，相应地在10MHz附近出现负的相位特征．

英文摘要：

We have successfully prepared the iron-based superconductor K0.8Fe2Se2 crystals （Tc = 27 K） and studied the carrier transport properties along the c-axis in detail. Samples are characterized by XRD, SEM and temperature-dependent resistivity. The result shows that there is “phase separation” in the samples. Based on the experimental results, the iron-based superconductor is not a simple two phases alternating along the c-axis, but the metal phases should have weak-link channels along the c-axis, forming a nearly 3D special net mode. Studies of the thermal conductivity and the complex impedance spectrum z（omega, To） suggest that the superconducting crystals have a lot of grain boundaries along the c-axis direction, the bound polarization charges result in relative dielectric constant of about 10^6 in magnitude and negative phase characteristics in the vicinity of 10 MHz.