Ba₄Ln₂Fe₂Ta₈O₃₀ (Ln=Pr, Eu): Temperature‐Stable Low Loss Dielectrics with a Tungsten Bronze Structure

Abstract

The dielectric ceramics Ba4Pr2Fe2Ta8O30 and Ba4Eu2Fe2Ta8O30 with a tetragonal tungsten bronze structure were synthesized and characterized. Dielectric and ferroelectric behaviors indicated that the ceramics are paraelectric above room temperature. Dielectric measurement showed that the present ceramics have high‐temperature stability, a comparatively low temperature coefficient of dielectric constant (τɛ) of −30 and −63 ppm/°C, with a high dielectric constant (ɛr) of 110 and 87.6 together with a low dielectric loss (tan δ) of 0.0010 and 0.0012 (at 1 MHz) for Ba4Pr2Fe2Ta8O30 and Ba4Eu2Fe2Ta8O30, respectively. These results indicated that the Ba4Ln2Fe2Ta8O30 (Ln=Pr, Eu) ceramics might be promising in temperature‐stable multilayer ceramic capacitors.

Dielectric Properties of Ba4Sm2Fe2M8O30 (M=Nb, Ta) with Tetragonal Bronze Structure

“…In a previous work, 22 we found two Fe-containing TB-structured tantalates exhibiting comparable temperature stability. So, it is interesting to explore the other tantalate with potential temperature stability.…”

Temperature‐stable unfilled tungsten bronze dielectric ceramics: Ba3.5Sm1.5Fe0.75Nb9.25O30

“…1,2 Traditional high-temperature capacitors based on BaTiO 3 are specific to higher working temperatures of 125, 150, and 175°C for X5R, X7R, and X8R respectively. 12,13 Only few pure materials has been reported to exhibit good thermal stability. In order to meet high-temperature working conditions of dielectrics, development of X9R specifications capacitors become necessary.…”

“…10,11 Generally, temperature stability is often achieved by ion substitution or by introducing a secondary phase. 12,13 Only few pure materials has been reported to exhibit good thermal stability. Among them, some filled TB ceramics such as Ba 4 have been reported as temperature-stable dielectrics.…”