### Abstract

The impact of the (Ba + Sr)/Ti (A/B) ratio on the microwave-tunable characteristics of diffuse phase transition (DPT) ferroelectric Ba_{0.6}Sr_{0.4}TiO_{3} (0.6-BST) ceramics was investigated. The reduction in the lattice constant with increasing nonstoichiometry was attributed to introduced partial Schottky defects, i.e., (Formula presented.) and (Formula presented.). The magnitude of the dielectric constant, ε′, at room temperature in the absence of an applied electric field was governed by the shift in the dielectric maximum temperature, T_{m}, because T_{m} was close to room temperature for the 0.6-BST. The dielectric loss, tanδ, diminished as the ε′ decreased for 0.98≤A/B≤1.05, while the tanδ was much higher for A/B=0.95 having the greatest A-site vacancy loading. The negatively charged Vˮ_{Ba} and Vˮ_{sr} were mainly compensated by oxygen vacancies and likely partly compensated by holes, h^{•}, which contributed to the electrical conduction. The tunability, T, at 100 MHz was almost constant at 20%–25% for A/B≥1.00 despite the reduction of the ε′, whereas T decreased for A/B<1.00 to ca. 10% for A/B=0.95 having the greatest A-site vacancy loading. The results implied that the (Formula presented.) for larger A/B values was more efficient in generating nucleation sites in the polar nanoregions (PNRs) than the (Formula presented.) for smaller A/B values, thereby providing greater dipole polarization. Consequently, the figure of merit, FOM, reached its maximum of 250 at A/B=0.9875, which was ca. 155% higher than that of the stoichiometric BST.

Original language | English |
---|---|

Pages (from-to) | 1037-1043 |

Number of pages | 7 |

Journal | Journal of the American Ceramic Society |

Volume | 100 |

Issue number | 3 |

DOIs | |

Publication status | Published - Mar 1 2017 |

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### Keywords

- ferroelectricity/ferroelectric materials
- microwaves
- polarization

### ASJC Scopus subject areas

- Ceramics and Composites
- Materials Chemistry

### Cite this

_{0.6}Sr

_{0.4}TiO

_{3}ceramics.

*Journal of the American Ceramic Society*,

*100*(3), 1037-1043. https://doi.org/10.1111/jace.14700

**Effect of the (Ba + Sr)/Ti ratio on the microwave-tunable properties of Ba _{0.6}Sr_{0.4}TiO_{3} ceramics.** / Teranisi, Takasi; Kanemoto, Riku; Hayashi, Hidetaka; Kishimoto, Akira.

Research output: Contribution to journal › Article

_{0.6}Sr

_{0.4}TiO

_{3}ceramics',

*Journal of the American Ceramic Society*, vol. 100, no. 3, pp. 1037-1043. https://doi.org/10.1111/jace.14700

_{0.6}Sr

_{0.4}TiO

_{3}ceramics. Journal of the American Ceramic Society. 2017 Mar 1;100(3):1037-1043. https://doi.org/10.1111/jace.14700

}

TY - JOUR

T1 - Effect of the (Ba + Sr)/Ti ratio on the microwave-tunable properties of Ba0.6Sr0.4TiO3 ceramics

AU - Teranisi, Takasi

AU - Kanemoto, Riku

AU - Hayashi, Hidetaka

AU - Kishimoto, Akira

PY - 2017/3/1

Y1 - 2017/3/1

N2 - The impact of the (Ba + Sr)/Ti (A/B) ratio on the microwave-tunable characteristics of diffuse phase transition (DPT) ferroelectric Ba0.6Sr0.4TiO3 (0.6-BST) ceramics was investigated. The reduction in the lattice constant with increasing nonstoichiometry was attributed to introduced partial Schottky defects, i.e., (Formula presented.) and (Formula presented.). The magnitude of the dielectric constant, ε′, at room temperature in the absence of an applied electric field was governed by the shift in the dielectric maximum temperature, Tm, because Tm was close to room temperature for the 0.6-BST. The dielectric loss, tanδ, diminished as the ε′ decreased for 0.98≤A/B≤1.05, while the tanδ was much higher for A/B=0.95 having the greatest A-site vacancy loading. The negatively charged VˮBa and Vˮsr were mainly compensated by oxygen vacancies and likely partly compensated by holes, h•, which contributed to the electrical conduction. The tunability, T, at 100 MHz was almost constant at 20%–25% for A/B≥1.00 despite the reduction of the ε′, whereas T decreased for A/B<1.00 to ca. 10% for A/B=0.95 having the greatest A-site vacancy loading. The results implied that the (Formula presented.) for larger A/B values was more efficient in generating nucleation sites in the polar nanoregions (PNRs) than the (Formula presented.) for smaller A/B values, thereby providing greater dipole polarization. Consequently, the figure of merit, FOM, reached its maximum of 250 at A/B=0.9875, which was ca. 155% higher than that of the stoichiometric BST.

AB - The impact of the (Ba + Sr)/Ti (A/B) ratio on the microwave-tunable characteristics of diffuse phase transition (DPT) ferroelectric Ba0.6Sr0.4TiO3 (0.6-BST) ceramics was investigated. The reduction in the lattice constant with increasing nonstoichiometry was attributed to introduced partial Schottky defects, i.e., (Formula presented.) and (Formula presented.). The magnitude of the dielectric constant, ε′, at room temperature in the absence of an applied electric field was governed by the shift in the dielectric maximum temperature, Tm, because Tm was close to room temperature for the 0.6-BST. The dielectric loss, tanδ, diminished as the ε′ decreased for 0.98≤A/B≤1.05, while the tanδ was much higher for A/B=0.95 having the greatest A-site vacancy loading. The negatively charged VˮBa and Vˮsr were mainly compensated by oxygen vacancies and likely partly compensated by holes, h•, which contributed to the electrical conduction. The tunability, T, at 100 MHz was almost constant at 20%–25% for A/B≥1.00 despite the reduction of the ε′, whereas T decreased for A/B<1.00 to ca. 10% for A/B=0.95 having the greatest A-site vacancy loading. The results implied that the (Formula presented.) for larger A/B values was more efficient in generating nucleation sites in the polar nanoregions (PNRs) than the (Formula presented.) for smaller A/B values, thereby providing greater dipole polarization. Consequently, the figure of merit, FOM, reached its maximum of 250 at A/B=0.9875, which was ca. 155% higher than that of the stoichiometric BST.

KW - ferroelectricity/ferroelectric materials

KW - microwaves

KW - polarization

UR - http://www.scopus.com/inward/record.url?scp=85007281906&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85007281906&partnerID=8YFLogxK

U2 - 10.1111/jace.14700

DO - 10.1111/jace.14700

M3 - Article

AN - SCOPUS:85007281906

VL - 100

SP - 1037

EP - 1043

JO - Journal of the American Ceramic Society

JF - Journal of the American Ceramic Society

SN - 0002-7820

IS - 3

ER -