Defect chemistry and dielectric properties of Yb{sup 3+}:CaTiO{sub 3} perovskite

Journal Article · Tue Jan 01 00:00:00 EST 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2828149· OSTI ID:21064499

Bassoli, M; Buscaglia, M T; Bottino, C; Buscaglia, V; Molinari, M; Maglia, F; Parravicini, G; Dapiaggi, M ^[1]

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1. Institute of Energetics and Interphases, National Research Council, Via De Marini 6, I-16149 Genoa (Italy)

The defect chemistry of Yb{sup 3+}:CaTiO{sub 3} solid solutions has been investigated both theoretically and experimentally. Three different incorporation mechanisms with similar solution energy were predicted for Yb{sup 3+} by atomistic simulation: (i) Ca site substitution with Ca vacancy compensation; (ii) Ti site substitution with O vacancy compensation; (iii) simultaneous substitution at both Ca and Ti sites with self-compensation. X-ray diffraction and scanning electron microscopy results strongly support the possibility to realize the above defect chemistries in CaTiO{sub 3} by changing the Ca/Ti ratio to force Yb{sup 3+} on the Ca site (Ca/Ti<1), on Ti site (Ca/Ti>1), or on both sites (Ca/Ti=1) according to the calculations. The temperature dependence of the relative dielectric constant (10{sup 2}-10{sup 5} Hz) of ceramics corresponding to predominant Yb substitution either at the Ca site or the Ti site is qualitatively similar to that of undoped CaTiO{sub 3}. The Curie-Weiss temperature is shifted to more negative values in comparison to CaTiO{sub 3}, suggesting that the compositions Ca{sub 1-3/2x}Yb{sub x}TiO{sub 3} and CaYb{sub x}Ti{sub 1-x}O{sub 3} are further driven away from the ferroelectric instability. In contrast, the dielectric properties (10{sup 2}-10{sup 5} Hz) of ceramics corresponding to Ca{sub 1-x/2}Yb{sub x}Ti{sub 1-x/2}O{sub 3} are radically different. The relative dielectric constant is increased of about one order of magnitude (2200 at 30 K), is almost independent of temperature, with a maximum variation of 20% in range of 20-300 K, and shows frequency dispersion above 150 K. The loss tangent at 20-300 K is <5% for frequencies {>=}1 kHz. The possible mechanism for the observed dielectric behavior is discussed.

• OSTI ID: 21064499
• Journal Information: Journal of Applied Physics, Vol. 103, Issue 1; Other Information: DOI: 10.1063/1.2828149; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM COMPOUNDS
CERAMICS
FERROELECTRIC MATERIALS
PERMITTIVITY
PEROVSKITE
SCANNING ELECTRON MICROSCOPY
SIMULATION
SOLID SOLUTIONS
SOLUTION HEAT
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TITANATES
VACANCIES
X-RAY DIFFRACTION
YTTERBIUM COMPOUNDS
YTTERBIUM IONS