Abstract:
A series polycrystalline samples of Sr
14(Cu
1-xZn
x)
24O
41(
x=0,0. 01,0. 02,0. 03) were prepared by standard solidstate reactions. X-ray diffraction(XRD) patterns show that a single phase can be achieved in all samples and their lattice parameters have weak fluctuation with the change of doping content
x. X-ray photo-electron spectroscopy results show that the valence of copper ions in Sr
14Cu
24O
41 is + 2 and Zn doping has no effect on the valence of copper ions. Magnetic susceptibility measurements in a temperature range from 10 to 300 K show that Zn doping decreases the magnetic susceptibility of the Sr
14Cu
24O
41 system. Experimental fitting results show that the contribution to magnetic susceptibility of the Curie-Weiss term,the value of coupling energy in dimers
JD,the number of dimers NDand the number of free Cu
2+ ion spins in the CuO
2 spin chain per formula unit
NF all decrease with the increase of doping content x. Further analysis indicates that the number of Zn
2+ ions which substitute Cu
2+ ions in dimers is less than the number of Zn
2+ ions which substitute free Cu
2+ ions. Electrical resistivity measurements show that the Sr
14Cu
24O
41 system is semiconducting,Zn doping decreases the electrical resistivity of the Sr
14Cu
24O
41 system,and the decreasing level increases with the increase of doping content x,but no metal-insulator transition occurs in this system. We think that the decrease in electrical resistivitymaybe results from decoupling of dimers in the spin chain due to Zn
2+ ion doping. It means that the charge order super structure is destroyed,so more holes are released and transferred into the spin ladder then participate in conducting.