Substitution-induced midgap states in the mixed oxidesRxBa1

S. W. Robey

¹

,

Lawrence T. Hudson

²

,

C. Eylem

³

et al.

Photoemission study of the metallic state of lightly electron-doped SrTiO3

“…From an analysis of optical-conductivity spectra [5,6] and transport and magnetic measurements [7] of Sr 1Àx La x TiO 3 (0 6 x 6 1), it was concluded that this system behaves as a Fermi liquid for small doping (x < 0:5). Even for very small x (down to x ¼ 0:1), however, this conclusion contradicts most previous photoemission results on metallic Sr 1Àx R x TiO 3 (R ¼ La [8,9] and Nd [10,11]) and metallic Ba 1Àx R x TiO 3Àd (R ¼ Y, La, and Nd [12,13]). It was shown that a prominent state induced by doping electron carriers appears at the binding energy of about 1.5 eV below the Fermi level (E F ), which cannot be explained by a simple picture of d-band filling or by the Fermi liquid behavior as suggested by the optical spectra.…”

“…UPS spectra around E F enlarged 25 times are also shown. many previous photoemission studies on the scraped surfaces have not shown the metallic state clearly [8][9][10][11][12][13].…”

“…From a comparison between the UPS spectra for the fractured surface and those for the scraped surface, it was shown that the spectral intensity of the metallic state is considerably suppressed by scraping the surface. Because of the extreme sensitivity to the surface preparations, most previous photoemission studies on the scraped surfaces have not shown the metallic state clearly [8][9][10][11][12][13].…”

Neutron structural characterization and transport properties of oxidized and reduced La0.5Sr0.5M0.5Ti0.5O3 (M = Mn, Fe) perovskites: Possible electrode materials in solid-oxide fuel cells

“…RTiO 3 compounds can be viewed as distorted perovskites with orthorhombic structure (GdFeO 3 -type). The substitution of aliovalent cations for R leads to changes in the properties; for instance, in the stoichiometric LaTiO 3 , the substitution of divalent ions (Ba 2þ and Sr 2þ ) for La 3þ results in novel transport and magnetic properties, [6][7][8] whereas substitution of Na þ , i.e., La 0.5 Na 0.5 TiO 3 produces paraelectricity. 9 In the field of SOFC, despite the high electronic conductivity, Sr-substituted LaTiO 3 exhibits low electrocatalytic activity for fuel oxidation.…”

Structure and Dielectric Properties of Eu-Doped Barium Titanate Ceramics

“…RE ions are trivalent in most of their compounds, 14,15 and generally occupy Ba sites of BaTiO 3 . Charge equilibrium may be compensated by electrons, [16][17][18] A-site Ba vacancies, 19,20 B-site Ti vacancies 1,2,21,22 or the 3d 1 Ti 3ࢪ mode, [23][24][25] due to the different preparation techniques and ratios of starting compositions.…”