Fabrication of bismuth silicate Bi2SiO5 ceramics as a potential high-temperature dielectric material

Bismuth silicate Bi2SiO5 (BSO) is known as an interesting new type of ferroelectric oxide; however, bulk ceramics of BSO have never been obtained because it easily decomposes at high temperature. In this study, we fabricated BSO ceramics for the first time using a sol-gel technique and investigated their potential as a dielectric material for high-temperature capacitor applications. A precursor powder was prepared by a sol-gel synthesis route using tetraethyl orthosilicate and bismuth nitrate pentahydrate as raw materials and then sintered under a small uniaxial pressure of 5 MPa with an addition of CH3COOLi as a sintering aid. A BSO ceramic with the highest relative density of 88.5% was obtained at a very low sintering temperature of 620 degrees C with preventing significant thermal decomposition. A crystal structure analysis revealed that the obtained BSO ceramic belongs to the ferroelectric monoclinic phase. The dielectric permittivity of the ceramic showed a superior temperature stability (+/- 5%) at temperatures up to 200 degrees C, followed by a sharp peak attributed to the ferroelectric-paraelectric phase transition at around 390 degrees C. The BSO ceramic also showed slim and pinched polarization hysteresis loops due to the random grain orientation and domain wall clamping, leading to a high energy storage efficiency over 75% at temperatures up to 100 degrees C.

Automated summary

In this study, Bismuth silicate (BSO) ceramics were successfully fabricated for the first time using a sol-gel technique, achieving a high relative density and preventing thermal decomposition at low temperature. The BSO ceramic exhibited superior temperature stability and high energy storage efficiency, attributed to a sharp phase transition and unique polarization hysteresis loops.