Dielectric response and thermally stimulated depolarization current analysis of BaNd1.76Bi0.24Ti5O14 high-temperature microwave capacitors

Abstract

Thermally stimulated depolarization current (TSDC) measurements were carried out on BaNd 1.76 Bi 0.24 Ti 5 O 14 microwave dielectric ceramics to investigate the relationship between depolarization effects and microwave loss. At microwave frequency, BaNd 1.76 Bi 0.24 Ti 5 O 14 ceramics exhibit a high dielectric permittivity of 88, a Qf value of 8800 GHz, and a s f value of ?6.9 ppm/°C. The temperature dependence of dielectric properties indicates the loss value of 0.0015 at 1 MHz above 350°C. Utilizing TSDC technique, the origins of different relaxations in BaNd 1.76 Bi 0.24 Ti 5 O 14 ceramics were identified. Two TSDC relaxation peaks (peak A and peak B) are associated with trap charges and oxygen vacancies, respectively. Activation energies of the relaxation in the polarized specimens were also estimated from TSDC measurement results. Such defects significantly contribute to extrinsic loss.

Microwave dielectric properties and thermally stimulated depolarization of Al‐doped Ba4(Sm,Nd)9.33Ti18O54 ceramics

“…In general, three types of defects, including trap charges, defect dipoles, and space charges (mainly V .. O ), can be identified from the TSDC relaxation curves through the changes in peak position (T m , the temperature at which the absolute value of current density is maximized) and peak intensity (J m , the maximum of the absolute value of current density) as a function of E p . 10,20,[25][26][27] Three TSDC peaks appear in both Figure 4A,B, indicating that there are at least three relaxation mechanisms in the BSNT-zAl ceramics (z = 0 and 1.5). It is clear that the variations in the TSDC peaks in the range 75°C < T m < 110°C (referred to as peaks B 1 and B 2 ) and peaks in the range 180°C < T m < 205°C (referred to as peaks C 1 and C 2 ) are similar in pairs as shown in Figure 4A,B.…”

“…Figure shows the TSDC curves of the BSNT‐ z Al ceramics ( z = 0 and 1.5) under different polarization conditions (100 V/mm ≤ E p ≤ 350 V/mm). In general, three types of defects, including trap charges, defect dipoles, and space charges (mainly ), can be identified from the TSDC relaxation curves through the changes in peak position ( T m , the temperature at which the absolute value of current density is maximized) and peak intensity ( J m , the maximum of the absolute value of current density) as a function of E p . Three TSDC peaks appear in both Figure A,B, indicating that there are at least three relaxation mechanisms in the BSNT‐ z Al ceramics ( z = 0 and 1.5).…”

“…The microwave dielectric properties of Ba 4 (Sm 0.15 Nd 0.85 ) 9.33 Ti 18‐ z Al 3 z /4 O 54 (BSNT‐ z Al) ceramics and their correlation with the z value were determined. In addition, the thermally stimulated depolarization current (TSDC) technique can provide semiquantitative information of dielectrics on the types (such as trap charges, defect dipoles, and space charges), concentrations, and activation energies of the defects . At present, TSDC has been widely used to clarify the polarization mechanism of various types of dielectric ceramics and to explore the relationships between defects and dielectric performance.…”

“…In addition, the thermally stimulated depolarization current (TSDC) technique can provide semiquantitative information of dielectrics on the types (such as trap charges, defect dipoles, and space charges), concentrations, and activation energies of the defects. 2,10,[19][20][21][22][23][24][25][26][27] At present, TSDC has been widely used to clarify the polarization mechanism of various types of dielectric ceramics and to explore the relationships between defects and dielectric performance. In this study, the TSDC technique was also used to study the underlying defects and their effects on the microwave dielectric properties in the BSNT-zAl ceramics.…”