By making use of the fact that domain-wall motions do not produce volumetric changes, an experimental method is introduced to directly and quantitatively determine the domain-wall and intrinsic contributions to the piezoelectric and dielectric responses of a ferroelectric material. Utilizing this method, the contributions from the domain walls and intrinsic part as well as their temperature dependence for lead zirconate-titanate (PZT) 52/48 and PZT-500 ceramics are evaluated. The data show that at temperatures below 300 K, the large change in the dielectric and piezoelectric constants with temperature is due to the change in the domain-wall activities in the materials. The results confirm that most of the dielectric and piezoelectric responses at room temperature for the materials studied is from the domain-wall contributions. The data also indicate that in PZT-500, both 180° wall and non-180° walls are possibly active under a weak external driving field.

Recent advances in nanoscience have demonstrated that fundamentally new physical phenomena may be found when the size of samples shrinks. In the area of superconductivity, the reduction of sample size has led to the observation of the paramagnetic Meissner effect in micronsize superconductors (1), the quantization of the Bose condensate in submicron samples (2), and ultimately the suppression of superconductivity in nanometer-scale superconductors (3,4). In this regime, it has also been recognized that the sample topology has particularly strong effects on superconductivity, as reflected in the characteristic features of the phase diagrams for singly-and doubly-connected samples (5,6).A unique feature of doubly-connected superconductors (independent of the sample size) is

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The symmetry-predicted nonzero components of the piezoelectric coefficient, dielectric constant, and elastic compliance matrices have been determined on poly(vinylidene fluoride/trifluoroethylene)(75/25) copolymer at room temperature and a frequency of 500 Hz. The temperature dependence of each of the complex piezoelectric coefficients and complex dielectric constants has been measured in the temperature range of −100 to 65 °C. The frequency dependence of these coefficients has also been measured at room temperature. It is found that the relaxation observed in the tensile piezoelectric coefficients of this material is different from that of the dielectric constants, whereas the relaxation of the piezoelectric shear constants shows behavior similar to that of the dielectric constants.

We have developed a lithography-free, all-dry process for fabricating graphene devices using an ultrathin quartz filament as a shadow mask to avoid possible contamination of graphene during lithographic process. This technique was used to prepare devices for electrical transport as well as planar tunnel junction studies of n-layer graphene (nLG), with n = 1, 2, 3 and higher. We observed localization behavior and an apparent reduction of density of states (DOS) near the Fermi energy in nLG.There has been a flurry of recent work 1,2 on films of 1-layer graphene (1LG), motivated by the pioneering work of Geim and coworkers 3 and Kim and coworkers 4 . Surprisingly, 1LG was found to host a two-dimensional electron gas with a band structure featuring zero effective mass 5 . Two types of unconventional integer quantum Hall effects (IQHE) were observed in 1LG 1,2 and in 2-layer graphene (2LG) 6 devices, respectively. Theoretical calculation indicates that n-layer graphene (nLG) with n > 2 are also interesting 5 .The highest mobility reported for 1LG devices is around 10,000 cm 2 /Vs at high gate voltages 2 , which is remarkable. However, it may not be sufficiently high to allow the observation of certain physical phenomena, such as fractional quantum Hall effect (FQHE). So far, all graphene devices reported in the literature were prepared by e-beam lithography. Multiple steps are required to pattern a device, including coating with organic materials, which may subject the graphene to possible contamination and add unwanted disorder to the device. It is therefore desirable to pursue alternative graphene device fabrication. Using ultrathin quartz filaments as shadow masks, we have developed a method to fabricate graphene devices, aiming at raising the mobility of the devices. Our method is lithography-free, all dry, and simple to implement. Devices fabricated were measured using a DC technique with a typical excitation current of 1 µA in a dip probe in which the sample was cooled by direct contact with 4 He liquid or gas.Two methods have been used to create graphene samples -exfoliation either mechanically in air 7 or chemically in solutions 8 , and thermal decomposition of SiC 9 . Our nLG flakes were created by mechanical exfoliation in air from freshly cleaved highly oriented pyrolytic graphite (HOPG) 10 . Heavily N-doped silicon with a 300-nm-thick thermally grown SiO 2 top layer was used as substrates. Thin graphene flakes were