Nanoelectromechanics of Piezoresponse Force Microscopy

To achieve quantitative interpretation of Piezoresponse Force Microscopy (PFM), including resolution limits, tip bias- and strain-induced phenomena and spectroscopy, analytical representations for tip-induced electroelastic fields inside the material are derived for the cases of weak and strong indentation. In the weak indentation case, electrostatic field distribution is calculated using image charge model. In the strong indentation case, the solution of the coupled electroelastic problem for piezoelectric indentation is used to obtain the electric field and strain distribution in the ferroelectric material. This establishes a complete continuum mechanics description of the PFM contact mechanics and imaging mechanism. The electroelastic field distribution allows signal generation volume in PFM to be determined. These rigorous solutions are compared with the electrostatic point charge and sphere-plane models, and the applicability limits for asymptotic point charge and point force models are established. The implications of these results for ferroelectric polarization switching processes are analyzed.Comment: 81 pages, 19 figures, to be published in Phys. Rev.

The Russian Small Satellite for Hyperspectral Monitoring of Gas Pipelines

Abstract: A project of the hyperspectral small satellite about 120 kg mass based on the modern technology is presented. The project is dedicated for “Gazprom” pipelines sensing to evaluate their condition, early recognize failures and make recommendations for preventive service. The satellite is planned to provide of 5 meter resolution in 700 spectral lines of 0.3 - 1.6 μm range. The paper consists of two parts. The first part describes a small satellite which is an enhanced version of the microsatellite presented at Berlin’s IAA Symposium in 1996. To test instruments and to check the ideas employed for the development of the satellite’s onboard hyperspectral unit, an airborne version of the device was fabricated and used for northern located gas pipelines monitoring. The flight testing is successfully performed on August-September, 2000 and 2001. In the second part the results of testing of the airborne version of the hyperspectral instrument are presented. Measurement data have been processed, analyzed and used to prove the choice of small satellite characteristics. The small satellite project is developed under support of Gazprom’s Program of Aerospace Monitoring and the Federal Space Program of the Russian Aerospace Agency.Note: Research direction:Theoretical and applied problems of mechanic