二维钾、钠紫青铜单晶A0.9Mo6O17(A=K,Na)的热电势特性

在８０—２８０Ｋ范围内对准二维钾、钠紫青铜单晶的热电势与温度的关系进行了研究，发现：（１）对钾紫青铜，在１０５Ｋ附近热电势有符号变化，并且在高温正常金属相，热电势Ｓ具有较小的负值，可以用经验关系Ｓ＝ＡＴ＋Ｂ来描述，自由电子为支配载流子；而在Ｔ＜１０５Ｋ的低温ＣＤＷ态，Ｓ为正值，可表示为Ｓ＝Ａ′Ｔ＋Ｂ′／Ｔ的形式，载流子的声子曳引热电势占支配作用．（２）对钠紫青铜，在Ｔ＞８０Ｋ范围内Ｓ与Ｔ具有很好的线性关系，没有观察到Ｐｅｉｅｒｌｓ相变，电子为支配载流子．对造成两者差异的根源，也作了初步探讨 关键词：

THERMOELECTRIC POWER PROPERTIES OF QUASI TWO DIMENSIONAL POTASSIUM/SODIUM PURPLE BRONZE- CRYSTALS A0.9MoO17(A=K,Na)

Temperature dependence of thermoelectric power S in quasi-two dimensional potassium/sodium purple bronzes has been studied in the temperature range 80—280K.It′s found that:(1)in potassium purple bronze,S has a sign change at 105K,above which S is the small negative value and can be described by the form of S=AT+B,the dominant carriers are free electrons,in the CDW state below 105K,S is positive,and can be described by S=A′T+B′/T,the phonon-drag of the carriers is dominant; (2)in sodium purple bronze,in the studied temperature range above 80K,S has a good linear relation with temperature,no phase transition was observed,electrons may be the dominant carriers.In addition,the origins of the difference of the properties for both these isostructural crystals are also discussed briefly.