Nanoscale clusters and phonon anomalies in relaxor-ferroelectric

弛豫铁电体由于其高介电常数、压电和光电系数而成为关键的多功能材料，这是包括RAM在内的许多技术应用的基础。他们表现出扩散相变在一个很宽的温度范围内，频率依赖性的介电常数最大值和微妙的结构各向异性长相干探测辐射。局部化学变化、极团形成和动力学以及独特的弛豫性质之间的相互作用仍然远未得到很好的理解。极化拉曼光谱、同步辐射X射线衍射以及压电响应力显微镜（PFM）将应用于掺杂的铅基钙钛矿型单晶弛豫体，以分析铁性团簇的化学诱导变化。我们的研究将主要集中在La掺杂的PbSc_（0.5）B“_（0.5）O_3（B”= Ta，Nb）以及PbZn_（1/3）Nb_（2/3）O_3-PbTiO_3。PFM分析也将在之前的项目MI 1127/1-1期间对Ba和Ru掺杂弛豫铁电体进行研究。该项目中取得的成果将进一步深入了解负责弛豫性质的原子簇，并将对创新技术重要材料的设计具有重要意义。

Relaxor ferroelectrics are key multi-functional materials because of their high dielectric permittivity, piezoelectric and optoelectic coefficients, which are basis of a number of technological applications including RAMs. They exhibit diffuse phase transitions over a broad temperature range, frequency dependence of the dielectric-permittivity maximum and subtle structural anisotropy to long-coherence probe radiation. The interplay between local chemical variations, polar-cluster formation and dynamics, and the unique relaxor properties is still far from being well understood. Polarised Raman spectroscopy, synchrotron X-ray diffraction as well as piezoresponse force microscopy (PFM) will be applied to doped lead-based perovskite-type single-crystal relaxors, in order to analyse the chemically-induced changes in the ferroic clusters. Our research will focus mainly on La-doped PbSc0.5B”0.5O3 (B” = Ta, Nb) as well as on PbZn1/3Nb2/3O3-PbTiO3. PFM analyses will be conducted also on Ba- and Ru- doped relaxor-ferroelectrics investigated during the previous project MI 1127/1-1. The results achieved within this project will give further insights into the atomic clustering responsible for the relaxor properties and will be of high significance for the design of innovative technologically important materials.