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Metal-insulator transition in Bi-Pb-Sr-Ca-Y-Cu-O caused by a change in the structural modulation

1994; American Physical Society; Volume: 50; Issue: 4 Linguagem: Inglês

10.1103/physrevb.50.2696

1095-3795

Noburu Fukushima, Masahiko Yoshiki,

Magnetic and transport properties of perovskites and related materials

A metal-insulator transition was observed in the layered cuprate ${\mathrm{Bi}}_{2\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Pb}}_{\mathit{x}}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{0.3}$${\mathrm{Y}}_{0.7}$${\mathrm{Cu}}_{2}$${\mathrm{O}}_{8+\mathit{d}}$, where the carrier concentration is not changed but the structural modulation was relaxed with increasing lead content x. Resistivity measurements and x-ray-photoelectron-spectroscopy (XPS) valence-band spectra manifested the occurrence of the metal-insulator transition; XPS core-level spectra, together with the results of a chemical analysis, confirmed that in this system the degree of the electron filling is constant. This metal-insulator transition is believed to arise from the change in the Cu-O-Cu bonding angle, as well as those in some nonlayered transition-metal perovskites.