Low Poling Field Research Articles

X-ray diffraction studies of domain alignments in modified PZT

Modified PZT samples were poled at different voltages and the structures were analyzed with X-ray diffraction techniques. The results show that in the present studies the 90° domains were more readily aligned in the direction of poling than were the 180° domains. Explanations of these features were based on the refined structural co-ordinates of a powdered sample. Calculations of the shifts in atomic positions during domain alignment were indeed less for the 90° domain at low poling field and suggest the alignment of these domains was energetically more favourable.

Investigation of piezoelectricity distribution in PVDF by means of pressure-pulse techniques

Abstract Charge, polarization or piezoelectricity profiles in thin dielectrics can be directly determined by means of piezoelectrically-generated pressure steps1-3 (PPS's) or pulses (PPP's) and laser-induced pressure pulses4-6 (LIPP's). These recently developed high-resolution methods have been applied to the same piezoelectric PVDF samples, demonstrating the feasibility, advantages, and limitations of the new techniques for the study of piezoelectricity distributions. For relatively low poling fields, the piezoelectric activity of thermopoled PVDF films is often confined to a layer near the positively-biased surface. The same effect is observed for poling with a positive corona discharge. With high-field corona poling, the piezoelectric activity extends throughout the PVDF film.

Investigation of piezoelectricity distributions in poly(vinylidene fluoride) by means of quartz- or laser-generated pressure pulses

The direct determination of charge, polarization, or piezoelectricity profiles in thin dielectrics is now possible if piezoelectrically generated pressure steps or pulses and laser-induced pressure pulses are employed. These recently developed high-resolution methods were applied to the same piezoelectric poly(vinylidene fluoride) (PVDF) samples. Comparison of the respective results demonstrates the feasibility, the advantages, and the limitations of the new techniques for the study of piezoelectricity distributions. It is confirmed that, for relatively low poling fields, the piezoelectric activity of thermopoled PVDF foils is often confined to a layer near the positively biased surface. The same effect is found for poling with a positive corona discharge. For high-field corona poling, the piezoelectric activity extends throughout the PVDF film.

Dielectric loss of poly(vinylidene fluoride) at low temperatures and effect of poling on the low temperature loss

Abstract Dielectric constant and loss of poly(vinylidene fluoride) (PVDF) were measured at 20 Hz. 110 Hz and 1 kHz in the temperatures ranging from 4.2 K to 300 K. Dielectric loss peaks (1 kHz) were observed respectively at 75 K (δ peak) for melt-crystallized PVDF with form I1 crystals and at 18 K (e peak) for rolled PVDF with oriented form 1 crystals. Activation energies were evaluated to be 12.6 and 1.9 kJ/mol for δ and e respectively. The height of e loss peak is suppressed by poling the sample at a rather low poling field. suggesting that the dipolar orientation in the form I crystal accompanying reduction of crystal detects occurs at the early stage of poling process.