Crystal structure and resistivity studies on PrBa2 ?x
Pr
x
Cu3O7 ?y
oxide system |
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Authors: | S K Malik C V Tomy Ram Prasad N C Soni K Adhikari |
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Affiliation: | (1) Tata Institute of Fundamental Research, 400 005 Bombay, India;(2) Bhabha Atomic Research Centre, 400 085 Bombay, India |
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Abstract: | The compound PrBa2Cu3O7 −y
is not superconducting while most other RBa2Cu3O7 −y
(R=rare earth) compounds exhibit superconductivity in the 90K range. The system PrBa2 −x
Pr
x
Cu3O7 −x
has been prepared to study the effect of excess Pr at the Ba site on the structure, resistivity and magnetic behaviour of
this system. It is observed that single-phase compounds in the above series form forx=0·8—that is up to the composition Pr1·8Ba1·2Cu3O7 −y
. While stoichiometric PrBa2Cu3O7 −y
is orthorhombic, the compounds with excess Pr show tetragonal structure. Four-probe dc resistivity measurements show that
all the single-phase compounds in the above series do not exhibit superconductivity and are semiconducting down to 12 K. Magnetic
susceptibility measurements reveal deviation from Curie-Weiss behaviour starting at a characteristic temperature, which is
taken to be the ordering temperature (T
N
) of the Pr moments. BothT
N
and overall resistivity decrease with increasingx and may have a common origin. |
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Keywords: | PrBa2 − x Pr x Cu3O7 − y structure resistivity magnetism |
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