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|Title:||Effects of Ca doping on the Curie temperature, structural, dielectric, and elastic properties of Ba[sub 0.4]Sr[sub 0.6-x]Ca[sub x]TiO₃ (0≤x≤0.3) perovskites|
|Authors:||Zheng, R. K.|
Chan, Helen L. W.
Li, X. G.
Ferroelectric Curie temperature
|Publisher:||American Institute of Physics|
|Source:||Journal of applied physics, 26 Oct. 2005, v. 98, no. 8, 084108, p. 1-8.|
|Abstract:||The effects of Ca doping on the Curie temperature, structural, dielectric, and elastic properties of Ba[sub 0.4]Sr[sub 0.6−x]Ca[sub x]TiO₃ (0≤x≤0.3) has been studied. Powder x-ray diffraction revealed that the cubic lattice constant a decreases linearly with increasing x from 0 to 0.15, while showing an anomalous expansion between x=0.15 and x=0.18. This, together with the anomalies in the dielectric constants, Curie temperature T[sub C], and elastic constants observed for 0.15<x<0.18, suggests that a small amount of Ca ions substituted for Ti ions. Correlated with the evolution of a with x, T[sub C] increases linearly with increasing x from 0 to 0.15; while deviating from linear behavior for x>0.15, T[sub C] increases persistently up to x=0.25 and thereafter shows a decrease. These variations of T[sub C] with x have been interpreted in terms of Ca-doping-induced A-site cation size variance, a substitution of a small amount of Ca ions for Ti ions, and structural phase separation. Upon cooling the longitudinal elastic constant C[sub L] shows drastic softening near T[sub C], arising from the electrostrictive coupling between the polarization fluctuations and the elastic strains. Moreover, it was found that Ca doping induces the hardening of C[sub L] just below T[sub C], and the magnitude of the relative hardening of C[sub L] (i.e., ΔC[sub L]/C[sub L]) increases with increasing x, implying that the tetragonal ferroelectric phase was increasingly stabilized by Ca doping.|
|Rights:||© 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in R.K. Zheng et al., J. Appl. Phys. 98, 084108 (2005) and may be found at http://link.aip.org/link/?jap/98/084108.|
|Appears in Collections:||MRC Journal/Magazine Articles|
AP Journal/Magazine Articles
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