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Study of the metal-insulator transition in Y1-xAx TiO3 (A=Ca, Sr and Ba)
, A. Poddar, B. Roy
Published in
Volume: 358
Issue: 1-2
Pages: 17 - 22
The systematic variation of the transport properties of Y 1-xAxTiO3 (A=Ca, Sr and Ba) was explored as a function of 3d band filling n(=1-x) by measurement of X-ray diffraction, resistivity and thermopower. The end compound YTiO3 is a Mott-Hubbard insulator with 3d1 configuration for Ti and is converted into strongly correlated metallic state by substituting Y 3+ by A2+ ions. The X-ray diffraction data reveal that Y1-xCaxTiO3 and low doped Y 1-xSrxTiO3 are orthorhombic and high doped Y1-xSrxTiO3 are pseudo tetragonal whereas the compounds of the Y1-xBaxTiO3 series are cubic. The resistance measurement shows that in the tolerance factor range 0.93≤t≤1.02, the Y1-xAxTiO3 are metallic but beyond the range they are insulating. The normalised resistance of the correlated metallic samples is proportional to T2 similar to the behavior of a Fermi liquid. In the insulating phase the activated type hopping mechanism is observed in the high temperature region. For all the samples the thermopower (S) follows a relation S=S0+BT in the linear region where the T-linear term corresponds to Mott's relation for metals. The thermopower results indicate that the metal-insulator transition occurs due to the enhancement of the effective mass. © 2003 Elsevier B.V. All rights reserved.
About the journal
JournalJournal of Alloys and Compounds