Suppression of high-temperature dielectric loss by designed thermal annealing treatment in (Bi1/2Na1/2)TiO3 ceramics. Issue 4 (April 2022)

• Record Type: Journal Article
• Authors: Lee, Ju-Hyeon; Lee, Geon-Ju; Hoang, An-Phuc; Frömling, Till; Pham, Thuy-Linh; Lee, Jong-Sook; Jo, Wook
• Is Part Of: Journal of the European Ceramic Society. Volume 42:Issue 4(2022)
• Page Start: 1388
• Page End: 1395
• Publication Date: 2022-04
• Subjects: Bismuth sodium titanate -- High temperature dielectrics -- Dielectric loss -- Defect engineering; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2021.12.029
• Languages: English
• ISSNs: 0955-2219

Abstract

Highlights: The stoichiometry of BNT based ceramics was shown to be achieved by intentionally introduced Na deficiency. The origin of the exponentially increasing dielectric loss in BNT at elevated temperatures was identified. The kinetically frozen-in oxygen vacancies are shown to be effectively removed by a thermal annealing at and above 700 ℃. Abstract: Dielectrics for automobile applications generally require high temperature reliability. Bi1/2 Na1/2 TiO3 -based materials are excellent high-temperature dielectric candidates with relatively large temperature-insensitive dielectric responses and a maximum dielectric permittivity temperature as high as 300 °C. However, they suffer from a high dielectric loss that increases exponentially above 200 °C due to ionic conduction from thermally activated oxygen vacancy migration. Here, we demonstrate that the impact of ionic conduction on dielectric loss can be effectively suppressed by introducing a sodium deficiency and thermal annealing An appropriate combination of both treatments elevated the temperature insensitivity of the dielectric loss up to ∼ 300 °C. A systematic investigation using impedance spectroscopy correlated with microstructure analysis revealed that the sodium deficiency and thermal annealing affected the mobile oxygen vacancy concentration differently.