Structure and Dielectric Properties of Re_0.02Sr_0.97TiO₃ (Re = La,Sm,Gd,Er) Ceramics for High‐Voltage Capacitor Applications

Abstract

Rare-earth-doped strontium titanate ceramics yielding the formula Re 0.02 Sr 0.97 TiO 3 (Re-ST, Re = La, Sm, Gd, Er) were prepared by solid-state reaction route. All Re-ST ceramics had single cubic perovskite structure similar to pure SrTiO 3 (ST). The grain size of Re-ST ceramics dramatically decreased to 1-10 lm, depending on different rare-earth elements, as compared to~30 lm of pure ST. The relative dielectric constant of Re-ST ceramics (e r = 2750-4530 at 1 kHz) showed about 10-15 times higher than that of pure ST (e r = 300 at 1 kHz), whereas the dielectric loss of Re-ST ceramics still remained lower than 0.03 (at 1 kHz) at room temperature. Under 0-1.63 3 10 6 V/m bias electric field testing conditions, the e r of Re-ST ceramics at room temperature changed within 14%. The P-E results indicated that the Re-ST ceramics were linear dielectrics. Together with their relatively high breakdown strength (E b > 1.4 3 10 7 V/m), the Re-ST ceramics could be very promising for high-voltage capacitor applications. Meanwhile, the temperature stability of the e r of Re-ST ceramics was evaluated in a temperature range of À60°C-200°C.

Influence of Chemistry and Misfit Dislocation Structure on Dopant Segregation at Complex Oxide Heterointerfaces

“…Donor doping ( n ‐type) can be carried out by replacing Sr 2+ with trivalent dopants, whereas replacing Ti 4+ with the same trivalent dopants leads to acceptor doping ( p ‐type) . For instance, donor trivalent dopants Er, Sm, La, Y, Gd, Nd, Sm, Eu, Dy, Tm, Yb, Lu, and Pr have been studied at A ‐site (replacing Sr 2+ ) in STO for various applications such as ferroelectrics, magnetism, oxygen sensors, and SOFC anode materials. On the other hand, samples with addition of acceptor trivalent dopants Y, Fe, Mn, Al, Cr, Sm, and Pr at B ‐site in STO were investigated for ionic conductivity applications as the charge compensating mechanism is the formation of oxygen vacancies.…”

Dielectric breakdown characteristics of sol–gel derived SrTiO3 films

“…There are effective ways to refine the microstructure of dielectrics, such as incorporation of glass additives [2] and modification of composition by chemical substitution and etc. [5].…”

“…Simultaneously no remanence energy left in the linear dielectrics after discharging. SrTiO 3 has cubic perovskite structure at room temperature and undergoes a phase transition from cubic to tetragonal at 110 K. Strontium titanate, which has an intermediate high dielectric constant and low dielectric loss, is considered to be one of the most promising dielectric materials for energy storage [5]. In general, the energy density of a linear dielectric is defined as U = 0.5e 0 e r E 2 , where e 0 , e r , E are the permittivity of free space, the relative dielectric constant and the applied electric field, respectively.…”

High dielectric constant polyimide derived from 5,5′‐bis[(4‐amino) phenoxy]‐2,2′‐bipyrimidine

“…The mostly used high dielectric constant materials for high energy density capacitors are ceramics . However, the disadvantages of percolative, fragile, and heavy nature of the ceramic materials limited their applications to some extent.…”