Subcoercive-field dielectric response of $0.5({\text{Ba}}_{0.7}{\text{Ca}}_{0.3}{\text{TiO}}_3)-0.5({\text{BaZr}}_{0.2}{\text{Ti}}_{0.8}{\text{O}}_3)$ thin film: peculiar third harmonic signature of phase transitions and residual ferroelectricity

Abstract

Sub-coercive field non-linearities in $0.5({\text{Ba}}_{0.7}{\text{Ca}}_{0.3}{\text{TiO}}_3)-0.5({\text{BaZr}}_{0.2}{\text{Ti}}_{0.8}{\text{O}}_3)$ (BCTZ 50/50) thin film elaborated using pulsed laser deposition are studied using permittivity and phase angle of the third harmonic measurements as function of the AC measuring field $E_{AC}$ and temperature. The global phase transition temperature $T_{max}$ for which the permittivity is maximum, decreases from 330 K to 260 K when $E_{AC}$ increases. Rayleigh analysis of the AC field dependence of the relative permittivity shows a regular decrease of the domain wall motion contributions as temperature increases up to $T_{max}$ and an even more pronounced decrease above $T_{max}$. This measurement reveals that the ferroelectric behavior subsists 70 K above the global phase transition. The phase angle of the third harmonic at temperatures below 275 K, is characteristic of a conventional ferroelectric and from 275 K to $T_{max}=$ 330 K of a relaxor. Above $T_{max}$, the thin film exhibits a peculiar phase angle of the third harmonic, which consists of $-180°\to -225°\to +45°\to 0°$ instead of the $-180°\to -90°\to 0°$ found for relaxor. This peculiar behavior is observed only on heating, and is tentatively attributed to changes in the correlations between polar nanoregions.

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Cited by in corpus (1)

• Enhancement of piezoelectric properties in a narrow cerium doping range of ${\text{Ba}}_{1-x}{\text{Ca}}_x{\text{Ti}}_{1-y}{\text{Zr}}_y{\text{O}}_3$ evidenced by high throughput experiment