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Title: Structural, magnetic, and transport properties of R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] solid solutions, where R = La, Nd, Gd, Er, and Y: Rare-earth-dependent metal-to-semiconductor transitions

Abstract

Compositionally homogeneous solid solutions of formula R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] (where R = La, Nd; 0 [<=] x [<=] 1) have been prepared by the dc arc-melting method. The La system showed a negative deviation from Vegard's Law due to BaO deficiencies, whereas the members of the Nd series were stoichiometric and showed a linear relationship between x and the lattice constant [alpha]. Single-phase oxygen deficient cubic Y[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] phases were obtained (where O [<=] x [<=] 0.4 and O < [delta] [<=] 0.15). Two compositionally dependent phase transitions occur in the La and Nd systems: tetragonal (P4mm)-to-cubic (Pm3m) at very low values of x (0.05) which is second order and cubic (Pm3m)-to-orthorhombic (Pbnm) at high values of x which appears to be first order. HREM and electron diffraction studies showed no evidence for A-site ordering, microdomain ordering, or superstructure formation in the cubic regions. Four-probe resistivity measurements showed metallic conductivities for a majority of the samples between R[sub 300] and 4 K with R[sub 300] [approx] 10[sup [minus]2][minus]10[sup [minus]4] [Omega]cm. Metallic conductivity correlates with the perovskite tolerance factor [t=(r[sub A] + r[sub O])] and occurs when 0.93 < t < 1.02 with semiconducting or insulating behavior occurringmore » outside this range. Superconductivity was not observed above 4 K in any of the samples. The effective magnetic moments of the Nd[sup 3+] ions in the Nd[sub x]Ba[sub 1-x]TiO[sub 3] phases (ca. 3.3 [mu][sub B]) for x [<=] 0.9 were close to the free ion value (3.62[mu][sub B]). Electron localization is discussed in terms of structural parameters and electronic effects. 26 refs., 8 figs., 5 tabs.« less

Authors:
; ; ; ; ; ; ;  [1]
  1. Univ. of Maryland, College Park, MA (United States)
OSTI Identifier:
5150564
Resource Type:
Journal Article
Journal Name:
Chemistry of Materials; (United States)
Additional Journal Information:
Journal Volume: 4:5; Journal ID: ISSN 0897-4756
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BARIUM OXIDES; PHASE TRANSFORMATIONS; ERBIUM OXIDES; GADOLINIUM OXIDES; LANTHANUM OXIDES; NEODYMIUM OXIDES; TITANIUM OXIDES; CUBIC LATTICES; ELECTRIC CONDUCTIVITY; ELECTRON MICROSCOPY; STOICHIOMETRY; TETRAGONAL LATTICES; ALKALINE EARTH METAL COMPOUNDS; BARIUM COMPOUNDS; CHALCOGENIDES; CRYSTAL LATTICES; CRYSTAL STRUCTURE; ELECTRICAL PROPERTIES; ERBIUM COMPOUNDS; GADOLINIUM COMPOUNDS; LANTHANUM COMPOUNDS; MICROSCOPY; NEODYMIUM COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; RARE EARTH COMPOUNDS; TITANIUM COMPOUNDS; TRANSITION ELEMENT COMPOUNDS; 360202* - Ceramics, Cermets, & Refractories- Structure & Phase Studies; 360204 - Ceramics, Cermets, & Refractories- Physical Properties

Citation Formats

Eylem, C, Saghi-Szabo, G, Chen, Bai-Hao, Eichhorn, B, Peng, Jian-Liang, Greene, R, Salamanca-Riba, L, and Nahm, S. Structural, magnetic, and transport properties of R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] solid solutions, where R = La, Nd, Gd, Er, and Y: Rare-earth-dependent metal-to-semiconductor transitions. United States: N. p., Web.
Eylem, C, Saghi-Szabo, G, Chen, Bai-Hao, Eichhorn, B, Peng, Jian-Liang, Greene, R, Salamanca-Riba, L, & Nahm, S. Structural, magnetic, and transport properties of R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] solid solutions, where R = La, Nd, Gd, Er, and Y: Rare-earth-dependent metal-to-semiconductor transitions. United States.
Eylem, C, Saghi-Szabo, G, Chen, Bai-Hao, Eichhorn, B, Peng, Jian-Liang, Greene, R, Salamanca-Riba, L, and Nahm, S. . "Structural, magnetic, and transport properties of R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] solid solutions, where R = La, Nd, Gd, Er, and Y: Rare-earth-dependent metal-to-semiconductor transitions". United States.
@article{osti_5150564,
title = {Structural, magnetic, and transport properties of R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] solid solutions, where R = La, Nd, Gd, Er, and Y: Rare-earth-dependent metal-to-semiconductor transitions},
author = {Eylem, C and Saghi-Szabo, G and Chen, Bai-Hao and Eichhorn, B and Peng, Jian-Liang and Greene, R and Salamanca-Riba, L and Nahm, S},
abstractNote = {Compositionally homogeneous solid solutions of formula R[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] (where R = La, Nd; 0 [<=] x [<=] 1) have been prepared by the dc arc-melting method. The La system showed a negative deviation from Vegard's Law due to BaO deficiencies, whereas the members of the Nd series were stoichiometric and showed a linear relationship between x and the lattice constant [alpha]. Single-phase oxygen deficient cubic Y[sub x]Ba[sub 1-x]TiO[sub 3[minus][delta]] phases were obtained (where O [<=] x [<=] 0.4 and O < [delta] [<=] 0.15). Two compositionally dependent phase transitions occur in the La and Nd systems: tetragonal (P4mm)-to-cubic (Pm3m) at very low values of x (0.05) which is second order and cubic (Pm3m)-to-orthorhombic (Pbnm) at high values of x which appears to be first order. HREM and electron diffraction studies showed no evidence for A-site ordering, microdomain ordering, or superstructure formation in the cubic regions. Four-probe resistivity measurements showed metallic conductivities for a majority of the samples between R[sub 300] and 4 K with R[sub 300] [approx] 10[sup [minus]2][minus]10[sup [minus]4] [Omega]cm. Metallic conductivity correlates with the perovskite tolerance factor [t=(r[sub A] + r[sub O])] and occurs when 0.93 < t < 1.02 with semiconducting or insulating behavior occurring outside this range. Superconductivity was not observed above 4 K in any of the samples. The effective magnetic moments of the Nd[sup 3+] ions in the Nd[sub x]Ba[sub 1-x]TiO[sub 3] phases (ca. 3.3 [mu][sub B]) for x [<=] 0.9 were close to the free ion value (3.62[mu][sub B]). Electron localization is discussed in terms of structural parameters and electronic effects. 26 refs., 8 figs., 5 tabs.},
doi = {},
url = {https://www.osti.gov/biblio/5150564}, journal = {Chemistry of Materials; (United States)},
issn = {0897-4756},
number = ,
volume = 4:5,
place = {United States},
year = {},
month = {}
}