Na_xCoO_2晶体的制备、结构和物性  

GROWTH,STRUCTURE AND PROPERTIES OF Na_xCoO_2 CRYSTALS

作　　者：陈学枝[1] 沈静琴[1] 赵松睿[1] 许祝安[1] 

机构地区：[1]浙江大学理学院物理系,杭州310027

出　　处：《低温物理学报》2004年第3期190-193,共4页Low Temperature Physical Letters

基　　金：国家自然科学基金 (项目编号 :10 2 2 5 4 17)资助的课题~~

摘　　要：本文以氢氧化钠 (NaOH )为溶剂 ,用高温溶液电解法成功生长出了α相和γ相的NaxCoO2 单晶 .通过少量SrCO3的添加 ,可以人为控制晶体产品的晶体学相 .以NaOH为溶剂生长出γ相NaxCoO2 晶体 ,添加SrCO3则生长出α相NaxCoO2 晶体 .对单晶样品的电阻率的测量发现 ,α相NaxCoO2 的电阻率随温度降低而升高 ,呈半导体特性 ,而γ相NaxCoO2 的电阻率则随温度降低而降低 ,呈金属性 .α相NaxCoO2 的热电势低于同温度下γ相NaxCoO2 热电势 ,在 30 0K时分别为 30 μV/K和 70 μV/K左右 ,但均随温度降低而减小 ,即热电势的温度关系均表现为金属型行为 .γ-and α -phase Na x CoO2 crystals have been grown by a electrosynthesis method. By adding SrCO 3 to the flux, the Na x CoO 2 crystal can be selected to grow into different phase. Crystals grown from a flux of pure NaOH and crystals grown from a flux of NaOH mixed with SrCO 3 were identified by X-ray diffraction (XRD) as γ -Na x CoO 2 and α -Na x CoO 2 respectively. The in-plane electrical resistivity of α -Na x CoO 2 increases with decreasing temperature, exhibiting the semiconductor properties, while that of γ -Na x CoO 2 decreases with decreasing temperature, exhititing the metal properties. The in-plane thermoelectric power S(T) of α -Na x CoO 2 is lower than that of γ-Na x CoO 2. The S(T) at 300K is 30μV/K for α -Na x CoO2 and 70μV/K for γ-Na x CoO 2, and both decrease with decreasing temperature.

关 键 词：晶体生长 热电材料 热电势 氢氧化钠 高温溶液电解法 钴酸钠晶体 

分 类 号：O73[理学—晶体学]