Influence of Cr2O3 additive and sintering temperature on the structural characteristics and piezoelectric properties of Bi4Ti2.95W0.05O12.05 Aurivillius ceramics

In this paper, Cr2O3 (0-0.4 wt%) as an additive was added into Bi4Ti2.95W0.05O12.05 (BITW) for preparing a kind of W/Cr co-doped BIT (BITW-yCr) Aurivillius ceramics, both W6+ and Cr3+ are considered to substitute Ti4+ in the [TiO6] octahedron of BIT. Besides the orthorhombic Bi4Ti3O12 as the major phase, BITW-yCr ceramics also contain the cubic Bi2Ti2O7 as the second phase which was formed due to the doping effect of WO3, but its formation could be depressed by the addition of less Cr2O3. Additionally, the cell parameters of BITW ceramics are also changed by the incorporation of Cr2O3, as the distortion degree of the orthorhombic structure (a/b) increases firstly and then decreases with its addtional amount (y). On the other hand, the grain growth of BITW-yCr ceramics is mainly controlled by the sintering process, there a higher sintering temperature results in a larger grain size. In comparison to BIT ceramics, BITW-yCr ceramics with less Cr-addition (y=0-0.2) require a higher sintering temperature to attain the best dense state, moreover, as y increases, the sintering temperature to gain the highest piezoelectric activity also increases. Finally, BITW-0.2Cr which was sintered at 1150 °C exhibits a higher piezoelectric activity than the others, which could be attributed to its larger orthorhombic distortion and larger grain size, its ideal piezoelectric constant (d33=28 pC/N) provides it with great applying potentiality.