【摘要】 以K2WO4、WO3和W粉为原料,用混合微波方法制备了钾钨青铜KxWO3样品.随着名义钾含量x的增加,KxWO3样品的晶体结构由六方(0.20≤x≤0.33)转变为四方(0.50≤x≤0.60).四方相样品均显示金属型导电特性.在六方相样品K0.2WO3中观测到了明显的电荷密度波(CDW)转变,转变温度为265K,其余六方相样品则为半导体型导电特性.在x=0.20不变的条件下,以Ca部分替代K制备了(K1-2 yCay)0.2WO3(名义钙含量y=0.1,0.2,0.3)样品,其主相仍为六方相.当0<y≤0.2时,六方相的晶胞参数a和c随y的增加而增大.从电阻率-温度曲线上可以看出,名义钙含量的变化会影响样品中的CDW转变.更多还原

【Abstract】 The potassium tungsten bronzes KxWO3 were prepared from K2WO4,WO3and W powders using a hybrid microwave method.With the increase of nominal potassium content x,the crystal structure of Kx WO3transforms from hexagonal(0.20≤x≤0.33)to tetragonal(0.50≤x≤0.60).All samples with tetragonal structure show metallic behavior.Samples with hexagonal structure show semiconducting behavior and the charge density wave(CDW)transition is observed in K0.2WO3around 265K.The Ca-doped samples(K1-2 yCay)0.2WO3(nominal Ca content y=0.1,0.2and 0.3)were also prepared and their major phase is still hexagonal.The lattice parameters a and c of samples(K1-2yCay)0.2WO3increase when y inreases from 0to 0.2.The CDW transition observed from theρ~Tcurves of Ca-doped samples can be influenced by changing the nominal Ca content y.更多还原