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Writer's pictureVert Arbusto

16 Aug 2021. Piezoelectric, as related to the SR.



I have been explaining to people for the past 2 years, that the widespread phantom-tinnitus, and phantom-vertigo are not coming from the Schumann Resonances.

Atmospheric electromagnetics is a huge, wide spectrum.

The SR is a small sub-set of frequencies (0.3-~39.9 Hz). Essentially, these are background "hums" within the atmosphere.

There is a huge variety of domestic electronics around the modern human, most of which is unshielded. Schumann-series harmonics are the weakest in intensity of all the atmospheric electromagnetics, operating in the pico- range.

If the ringing were caused by the SR, this sensation would have already been existing. Earth's alleged rising frequencies is not a suitable explanation, especially since this is not what the scaled amplitude bursts on the Tomsk SR is showing us.

From the beginning, I have been stating that it's not the SR causing the ringing and vertigo sensations, it's the remainder of the atmospheric electromagnetics.

This is a very interesting article, considering how much electromagnetics are in our ambient atmosphere, in addition to the exploration of polymers being piezoelectric.

The only cure for the ringing/vertigo sensations is to ground into Earth the accumulated charge of the body, which can act as a capacitor.

This material is for the more advanced students of this phenomena.

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Piezoelectric cellular polymer films: Fabrication, properties and applications

Ouassim Hamdi, Frej Mighri, Denis Rodrigue, Department of Chemical Engineering, Université Laval, Quebec, G1V0A6, Canada, Published: 03 September 2018

2. Piezoelectricity

- 2.1. Fundamentals

The term piezoelectricity is a combination of two words: "piezo" which is a Greek word meaning pressure, and "electricity", obviously referring to electrical charges.

In fact, piezoelectric materials can convert mechanical energy into electrical energy [22,23].

As shown in Figure 1, the piezoelectric effect can occur in all directions and can be divided in two main effects: the direct piezoelectric effect, corresponding to the production of electrical charges under mechanical stress, and the inverse piezoelectric effect associated to the deformation of a material when subjected to an electric field.

Crystals, such as quartz (SiO2), were the first piezoelectric materials discovered around 1880 [25].

Their piezoelectricity comes from the displacement of atoms in their unit cells. When no stress is applied on the material, the positive and negative charges are equally distributed so that there is no potential difference.

However, when a deformation is applied, the barycenters of the positive and negative charges are separated, hence, a change in the electric dipole moments occurs.

The charges no longer cancel each other out and a potential difference exists.

Ferroelectrics constitute another piezoelectric family and represent the largest number of piezoelectric materials [26]. Their piezoelectric activity manifests itself as a result of external polarization [26,27,28].

In fact, ferroelectrics are materials having a spontaneous electric polarization below their ferroelectric Curie temperature (TC).

At temperatures above TC, the crystals are nonpolar and no longer ferroelectric, thus behaving like normal dielectrics. On the other hand, the polarization of ferroelectrics can be reoriented by the application of an external electrical field.

Ferroelectrics are made of several very small randomly oriented ferroelectric domains (formed by self-assembly) so that the electric fields created cancel each other and there is no net polarization on the material.

Each domain contains some polarized crystals in the same direction and every domain is separated from others by domain walls.

The internal dipoles are reoriented by the application of an external electric field, leaving a remnant polarization after field removal [26,27,28].

This remnant polarization (electric dipoles) also changes when a stress is applied, leading to piezoelectricity.

The most well-known ferroelectric materials are ceramics, such as PZT.

Some polymers have also shown ferroelectric properties due to their polar structure containing molecular dipoles.

Similar to ceramic materials, these dipoles can be reoriented and kept in a preferred orientation state by an external electric field.

PVDF is one of the most commonly used piezoelectric polymers exhibiting considerable flexibility in comparison with PZT, but has a poor d33 coefficient [26,27,28].

To improve the polymers' piezoelectric sensitivity, cellular structures were explored.

Their development in the late 1980 was a response to the growing need to have piezoelectric materials combining the interesting properties of polymers and high piezoelectric coefficients [29,30].

The internal structure of polymer films is a two-phase morphology made from a solid polymer (continuous phase or matrix) and gaseous cells (dispersed phase or bubbles).

When the polymer surfaces surrounding the voids are charged with an external electric field, the charged polymer foam behaves like a ferroelectric material.

In fact, applying a large electric field across the film ionizes the gas molecules in the voids, thus opposite charges are accelerated and accumulated on each side of these voids.

Such "artificially" embedded dipoles respond to mechanical stress (direct piezoelectric effect) or an externally applied electrical field (inverse piezoelectric effect) similar to piezoelectric materials [31].

More details of the poling procedure will be discussed in Section 3.3.

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