Palladium-based Ferroelectrics

钯基铁电体

• 批准号: 1795382
• 金额: --
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1795382
• 关键词: Palladium; based; Ferroelectrics

The student will fabricate and characterize samples of lead-zirconate titanate (PZT) and lead titanate with up to 30% palladium substituted at the perovskite B-site, replacing titanium. Growth will be in the form of ceramic powders, pressed into pellets, with electrodes sputtered on. Characterization will emphasize dielectric measurements (permittitivity and loss) as functions of temperature from cryogenic levels ca. T=20K to elevated levels (>500C), and it will also include magnetic measurements, electron microscopy, X-ray studies, and probably specific heat measurements.Analysis will be in terms of existing models for multiferroic, magnetoelectric crystals, including the model of Blinc et al. Since Pd is normally not magnetic but is known to become magnetic under applied electric fields and/or uniaxial mechanical stress, the 2016 model of Tula Paudel and Evgeny Tsymbal will also be used. Their density functional calculations imply that for simultaneous magnetism and ferroelectricity to occur, some of the Pd must be in +4 valence state and some in +2, and moreover, that it cannot all go into the Ti+4 site; instead some must go off-center in the oversized Pb+2 site.Although Pd is expensive, the intended devices are thin-film memories, and the Pd amounts are so small that the added cost would be only a few pence per chip. Since PZT is the leading room-temperature ferroelectric device material (e.g., for automobile fuel injectors), this suggests the potential for large-volume real commercial products.

学生将制造和表征锆钛酸铅（PZT）和钛酸铅的样品，其中在钙钛矿B位点取代高达30%的钯，取代钛。生长将以陶瓷粉末的形式进行，压制成颗粒状，电极溅射在其上。表征将强调介电测量（磁导率和损耗）作为低温水平下温度的函数。T= 20 K到升高的水平（> 500 C），它还将包括磁性测量、电子显微镜、X射线研究，可能还有比热测量。分析将根据多铁性磁电晶体的现有模型进行，包括Blinc等人的模型。由于Pd通常不具有磁性，但已知在施加电场和/或单轴机械应力下具有磁性，Tula Paudel和Evgeny Tsymbal的2016款也将被使用。他们的密度泛函计算表明，要同时发生磁性和铁电性，一些Pd必须处于+4价态，一些处于+2价态，而且，它不能全部进入Ti+4位;相反，一些必须在超大的Pb+2位置偏离中心。尽管Pd昂贵，但预期的器件是薄膜存储器，并且Pd的量很小，使得每个芯片的增加成本仅为几便士。由于PZT是主要的室温铁电器件材料（例如，对于汽车燃料喷射器），这表明了大容量真实的商业产品的潜力。