Nanoscale ferroelectric properties

Bayart, A., Saitzek, S., Chambrier, M.-H., Shao, Z., Ferri, A., Huv, M., Pouhet, R., Tebano, A., Roussel, P., and Desfeux, R. (2013) Microstructural investigations and nanoscale ferroelectric properties in lead-free Nd2Ti20y thin films grown on SrTiOs substrates by pulsed laser deposition. CrystEngComm, 15 (21), 4341-4350. 

Size effect is another factor that strongly influences the properties of ferroelectric nanostructures, and the issue of a critical size for ferroelectricity has been actively discussed [4, 6, 11-14, 35]. For a long time it was believed that ferroelectricity was suppressed in small particles and thin films [1], and there was a critical size in order of few tens of nanometers below which a spontaneous polarization cannot be sustained in a material. Recent experimental and theoretical smdies [36 8] demonstrated that ferroelectricity exists down to vanishingly small sizes, much smaller than previously thought. These studies revealed that the issue of critical size is very complex, and electrical and mechanical boundary conditions play an essential role in nanoscale ferroelectricity. 

UV Raman studies of ferroelectricity in strain-free non-stoichiometric and nominally stoichiometric SrTiOs films, in combination with dielectric, ferroelectric, nonlinear optical and nanoscale piezoelectric property measurements highlighted the sensitive role of stoichiometry when exploring strain and epitaxy-induced electronic phenomena in oxide films, heterostmctures, and interfaces. 

Microstructure and Nanoscale Piezoelectric/Ferroelectric Properties in Ln2Ti207 (Ln = Lanthanide) Thin Films with Layered Perovskite Structure... 

Piezoelectric/ferroelectric properties of Ln2Ti20y (Ln = La, Pr, Nd, or Sm) thin films were investigated at the nanoscale using a modified commercial atomic... 

Microstructure and nanoscale piezoelectric/ferroelectric properties in La2Ti207 thin films grown on (110)-oriented doped Nb SrTi03 substrates. Adv. Eng. Mater., 13 (10), 961-969. 

Gautier, B., Duclere, J.-R., and Guilloux-Viry, M. (2003) Nanoscale study of the ferroelectric properties of SrBi2Nb209 thin films grown by pulsed laser deposition on epitaxial Pt electrodes... 

In addition to the high k of many relaxor compositions they also have a broad peak in the permittivity versus temperature range, even in the absence of additives and even in the form of single crystals. This behavior is attributed to nanoscale (-lOnm)-ordered regions, which are too small to yield the sharp phase transition of normal ferroelectrics. As a result, spontaneous polarization and associated ferroelectric properties are retained over a very broad temperature range. Another attractive feature of relaxors is that dense polycrystalline ceramics are achievable at relatively low sintering temperatures (<900°C), which allows a significant reduction in the amount of Pd used in Ag-Pd metallizations for electrodes in multilayer capacitors (see Section 31.7). 

The major trends in ferroelectric photonic and electronic devices are based on development of materials with nanoscale features. Piezoelectric, electrooptic, nonlinear optical properties of fe are largely determined by the arrangement of ferroelectric domains. A promising way is a modification of these basic properties by means of tailoring nanodomain and refractive index superlattices. 

As is the case in many fields, for example, microelectronics, catalysis, and medidne, much interest has developed in understanding the role of nanodimensions in influencing and ideally optimizing properties. In this chapter, attention is focused on the impact of nanoscale dimensions on the properties of electrically conductive electroceramics and the implications that this may have on applications. This is particularly relevant since electroceramics, by their nature, are dominated by boundaries (grain boundaries, electrode interfaces, surfaces, etc.), with the notable exception of epitaxial thin films, which are optimized for dielectric and ferroelectric applications but are beyond the scope of this chapter [5]. Some boundaries are detrimental to... 

Desfeux, R., Ferri, A., Legrand, C, Maes, L., Costa, D.A., PouUain, G., Bouregba, R., Soyer, C., and Remiens, D. (2008) Nanoscale investigations of switching properties and piezoelectric activity in ferroelectric thin films using piezoresponse force microscopy. Int. J. Nanotechnol, 5 (6/7/8), 827. 

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