We present generalized theoretical analysis and experimental realization of active quality factor control for the self-oscillating quartz tuning-fork (QTF). The quality factor Q and resonance frequency can be controlled by adding a phase shifted signal of proper gain with respect to the QTF motion. It is demonstrated that the analysis of QTF can be extended to other quartz resonators which are analyzed by an equivalent circuit-a combination of a parallel circuit of an harmonic L-R-C and a stray capacitance C0. Finally, we suggest the prospect of several applications by using the active Q control of QTF such as increasing force sensitivity, reducing scanning time in scanning probe microscopy, and feedback cooling of electromechanical resonator.

Electrical characterization of CaCu3Ti4O12 (CCTO) ceramics with scanning probe based techniques has been carried out. In particular, conductive atomic force microscopy (C-AFM) and scanning impedance microscopy (SIM) have been used to demonstrate the presence, shape and size in CCTO ceramics of the different electrically domains, both at the grain boundaries and within the grains. The electrical characteristics of single grains and of single domains have been evaluated and it has been observed that the conductive grains are surrounded by insulating grain boundaries.

In this paper we report on the investigation of electrostatic forces between a conductive probe and semiconducting materials by means of Kelvin probe force microscopy measurements. Due to the formation of an asymmetric electric dipole at the semiconductor surface, the measured KPFM bias is related with the energy difference between Fermi energy and respective band edge. Quantitative Kelvin probe force microscopy measurements on semiconductors, namely on a conventional dynamic random-access memory cell and on a cross-sectionally prepared Si epilayer structure, are presented.