Preparation And Properties Of Layered Sr-Bi-Ti-O Ferroelectric Materials

As we know, ferroelectric material owns characteristic of polarization, which can circumrotate with the exterior AC electric field, and this advantage can be used in the memory system, thus, a lot of attention has been given to the families of ferroelectrics for their use in the nonvolatile ferroelectric random access memory (FeRAM). Among these ferroelectrics, one class of ferroelectric materials of recent interest is the bismuth layer-perovskite ferroelectrics(BLSF) due to their high Curie temperature, large remnant polarization, low coercive field, low leakage current, long retention, minimal tendency to imprint, and little fatigue with usual platinum electrode. However, different layered BLSF owns its vital shortcoming, thus, it is very important to ameliorate the relative properties in some available way such as doping, replacement, intergrowth. All of these ways should be founded on the structure and properties of homogeneous BLSF, in consideration of these aspects, this paper is just to know the form mechanism, and relative properties induced by the internal structure, which are of great importance and of practical significance.In this work, homogeneous BLSF material SrmBi4Tim+3O3m+3(m=3, 4, 5 and 6) were systemic researched. Firstly, BTO and SBTm (m= 4, 5 and 6) ceramics were prepared, the optimal calcine temperature is 800℃, and the best sintering temperature are 900, 1090, 1180 and 1190℃ for m=3, 4, 5 and 6 respectively. With m increasing from 3 to 6, the dielectric constant increased, while the dissipation factor and curie temperature decreased, besides, the remanent polarization decreased with increasing m, and is also dependend on the even or odd m.Secondly, Sr3Bi4Ti6O21(SBT6) were synthesized by sol-gel derived powders, and A site Pb doped Pb3xSr3(1-x)Bi4Ti6O21 ceramics were prepared according to the same way. For the radius of Pb2+ is much larger than that of Sr2+, the lattice parameter along c axis increased with m increasing from 3 to 6, and the relative curie temperature, dielectric constant and dissipation factor decreased with the amount of Pb increasing.Lastly, A site Pb doping BTO thin films were prepared with sol-gel method. For the larger radius Pb2+ than that of Sr2+, the oxygen vacant induced by the low electrovalence Pb2+ and the large polarization factor a of Pb2+, the structure, dielectric properties and ferroelectric properties of the material alternated regularly with different amount of Pb.