# Talk:Piezoelectricity

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## Electron microscopes

There is no reference to the use of Piezoelectrics in Scanning Tunneling Microscopes and similar instruments although the article mentions its use in Optical Instruments. - Torris 10/18/2006

## US vs Japan research methods

I'm confused by the philosophical discussion about U.S. research methods v.s. Japanese research methods. Isn't this an article about piezoelectricity?

This paragraph is not about philosophy or research methods, but possibly an example of how legislation like patent laws, military secrecy, and other regulations on the free flow of information may interfere with a society’s ability to derive technology from a physical fact. If this is verifiable the paragraph should be rewritten with stronger focus on this aspect and carry references to other existing articles discussing the same problem. --EugenNJ 13:40, 14 February 2007 (UTC)

## Voltage or current?

Shouldn't the definition be about stress-induced voltage rather than current? I would assume that most crystals don't have many free electrons, so it's not clear how they could generate much of a current. Voltage however is clear: you take a crystal with symmetrical charge distribution, the stress creates an asymmetrical charge distribution which is the same as a voltage. AxelBoldt, Wednesday, April 24, 2002

Is this why it happens? If so, it would be good to put that in the article explained in a bit more detail. As it is, there is no explanation of why the piezoelectric effect happens, only a description of it. 128.118.68.50 20:41, 7 July 2006 (UTC)

One more question connected with this is whether a "constant stress" leads to "constant voltage" from a peizoelectric material? There are lot of examples of vibrations, ultrasound etc which convey the meaning that a constant voltage from a battery applied to a peizo will result in a "vibration". This seems contrary to the definition of peizoelectric effect as stated. Could you kindly correct this. (144.189.5.201 12:39, 27 December 2006 (UTC))

Constant stress, T, leads to constant electric displacement, D, as in: Di=dij Tj + epislonij Ej. Electric displacement is related to the charge induced on the surface of the material. A battery applied to a piezo will not result in a vibration, unless the battery's output is converted into an A.C. signal. Ultrasonic output can be generated if this A.C. signal has a frequency in the ultrasound range. --Nathaniel 02:47, 17 January 2007 (UTC)

## Name and redirects

Piezoelectric effect redirects to piezoelectricity, and pyroelectric effect redirects to pyroelectricity, but ferroelectricity redirects to ferroelectric effect. These should all be consistent. The "-ity" sounds rather odd to me, and I think " effect" is better. Any opinions? –radiojon 15:02, 2004 Apr 16 (UTC)

I agree that we should be consistent. There is probably a subtle difference between the "x effect" and "x-electricity", so we need to record both forms somehow. I would say that the "x effect" is an abstract concept meaning "the process by which e.g. squeezing a crystal creates electricity", while "x-electricity" is a concrete thing, the electricity that you get as the result of the effect. I think this means that the title of the article should be the "x effect", as you said above, but let's acknowledge the existence of the "x-electricity" form somewhere in each article. -- Heron 15:29, 5 Jul 2004 (UTC)
Well, actually it is not that straightforward, because for the case of ferromagnetism, we would need to have ferromagnetic effect (for which the page does not exist) redirecting to magnetism. Incidentally, ferroelectricity (electric dipoles) is the analogue of ferromagnetism (magnetic dipoles). --Nathaniel 02:27, 17 January 2007 (UTC)

## pronunciation

everyone pronounces it differently. there are two "proper" ways:

• pie ee zoe
• pee ay zoe

and it is not named after someone, as i heard somewhere:

From Greek piezein, to press tight, squeeze. See sed- in Indo-European Roots.

- Omegatron 15:23, Oct 15, 2004 (UTC)

- THIS SHOULD BE IN THE MAIN WIKIPEDIA ENTRY AS IT IS SO OFTEN MISPRONOUNCED!!! I tried putting in there but someone took it out :(

I agree. I mostly hear pee-zoe and sometimes pee-ay-zoe or pee-etzoe. Never heard pie-ee-zoe. 93.97.48.217 (talk) 20:14, 24 April 2009 (UTC)

## piezoelectricity on a small scale

Can someone who knows include information on how small the materials can be made and still create a voltage differential under pressure? For instance, can piezoelectric sensors be made small enough and sensitive enough to record the impact of a single gas molecule on the surface of the sensor? --Flatline 12:39, August 4, 2005 (UTC)

I think this issue is at the forefront of research in ferroelectric (and presumably piezoelectric) crystals. Here is an interesting article: Unusual phase transitions in ferroelectric nanodisks and nanorods, Ivan I. Naumov, L. Bellaiche, and Huaxiang Fu, Nature (London) 432, 737 (2004). --User:huckit

## Piezoelasticity?

I just searched Wikipedia and found no reference yet to the related subject of piezoelasticity. It would be useful to add a section to the main article. Likewise, no reference yet to another related term electroelastic. DFH 15:18:55, 2005-09-06 (UTC)

I could not find both the terms piezoelastic/piezoelasticity and electroelastic/electroelasticity in the dictionary [1]. Are you sure these terms exist? Perhaps the term "electroactive" should be used for electroelastic? EAP is the abbreviation for electroactive polymers, of which PVDF is an example. See [2] and [3]. Nathaniel 09:09, 23 September 2005 (UTC)

I don't know if it helps, but the correct term might be ferroelasticity. The piezoelectric effect couples the mechanical and electrical domains- so the terms 'piezoelasticity' and 'electroelasticity' (which I don't believe exist), might be referring to the direct and converse piezoelectric effect. Of course there is electrostriction, which is exhibited by all ferroelectric materials... this is

Hi! All the words you have written can be used: "electroelasticity" is quite used in mechanics. It simply means the coupling of electric and mechanical effects, so we don't need another article. Ceccorossi 16:37, 25 April 2007 (UTC)
As a person with no electrical/physical knowledge, I have the same problem as the original poster. I got here from "piezoelasticity" and I still don't know what it means. The article should at least mention the word, even if it only says "this is a synonym for (some other word)". 86.130.40.127 (talk) 23:11, 27 December 2013 (UTC)
I've not heard of "piezoelasticity" before but it sounds like a near synonym of "elasticity". Judging from its name, a piezoelastic material would be one that responds elastically (presumably as opposed to plastically) to pressure. Nothing to do with piezoelectricity in other words, which means it should not redirect here. Dondervogel 2 (talk) 00:24, 28 December 2013 (UTC)

## "PZT"

PZT is mentioned in the first paragraph of this article. What is it?

PZT could be lead zirconium titanate, a ceramic. --Yyy 15:20, 17 November 2005 (UTC)
Yes, that's correct. I have updated the link. PZT is a ceramic made from a combination of powders of PbO2, ZrO2, and TiO2 (hence PZT) in a certain ratio of about 0.52:0.48 of Zr:Ti to obtain the optimum piezoelectric effect. The powders have to be mixed & heated to a certain temperature to get them to form the new structure (the perovskite structure) of PZT--calcination & sintering. Nathaniel 07:46, 18 November 2005 (UTC)

The deformation for PZT is given as "of the order of nanometers." This is often true in MEMS (MicroElectroMechanical Systems). However, if the change is really 0.1% of the original dimension, then there is not a "typical" value for the deformation. If a deformation is to be given, the original dimension should be included as well.

It really needs to state the relevant conditions. When is it 0.1%? How can a thin piezo buzzer generate very loud sound if only moving that much? — Omegatron 14:53, 24 October 2006 (UTC)

If particle displacement is found according to:

${\displaystyle \xi ={\frac {p}{Z\cdot \omega }}}$

And Z for air is 410 Pa·s/m = 410 N·s/m3, and a buzzer on this page can generate 85 dB SPL at 2.3 kHz, the particle displacement should be:

${\displaystyle 85=20\,\log _{10}\left({\frac {p}{20\mu Pa}}\right){\mbox{ dB}}}$

so p = 0.4 Pa

${\displaystyle \omega =2\pi 2300=14450}$

displacement is 67.5 nanometers. Huh. 120 dB SPL or 100 Hz would be more like a few microns, though. — Omegatron 15:23, 24 October 2006 (UTC)

## Mathematical description

The tensorial description seems to have a typo (But an important one). Without being an expert, all the literature that I have checked so far gives the following expression for the coupled equations:

  {\displaystyle {\begin{aligned}{\boldsymbol {S}}&={\mathsf {s}}\,{\boldsymbol {T}}\color {red}{-}{\mathfrak {d}}^{t}\,\mathbf {E} \\\mathbf {D} &={\mathfrak {d}}\,{\boldsymbol {T}}+{\boldsymbol {\varepsilon }}\,\mathbf {E} .\end{aligned}}}


With a negative sign for the second term of the first equation, as opposed to having only positive signs as it shows currently on the entry. Am I missing something? (See, for instance: Kögl, M. and Gaul,L. Piezoelectric analysis with FEM and BEM 2001, in Smart Structures V. 429, Springer Vienna.) Belbojacopo (talk) 04:58, 23 August 2015 (UTC)

The negative sign occurs in the stress-charge form of the equations. The version in the article is the strain-charge form. Bbanerje (talk) 09:34, 24 August 2015 (UTC)

## Matrices

While I have not studied this effect, looking at the matrices, it looks like there are several typos. For example, there is a s_{44}^E term where one would expect s_{55}^E. Likewise, there is a d_{31) term where one would expect there to be d_{32). Is this correct?

It is correct for only the 4mm and 6mm point groups. A more generalized matrix equation is probably better. Polaron | Talk 03:23, 1 July 2006 (UTC)
most commercial PZT materials fall into these point groups. So s_{12}^E=s_{21}^E, s_{44}^E=s_{55}^E, etc. The generalized matrix equation can easily be created by removing all the zeros and putting back the constants 11, 12, 13, ... 21, 22, 23, ... 31, 32, 33... However, the average person who is using such materials may want to know which constants are equal, which constants are equal to zero, etc. I have made the change on the wikipedia site to indicate that the equations in this simplified form applies to the 6mm crystal class. --Nathaniel 10:57, 29 July 2006 (UTC)
This section and the Crystal classes section need a little background info for the rest of us. — Omegatron 14:52, 24 October 2006 (UTC)

## Confusion with Reverse Piezoelectric effect and Converse

In this article it states that the piezoelectric effect works in reverse (apply voltage and the crystal grows in size slightly). Then later on it states that "Piezoelectric materials also show the opposite effect, called converse piezoelectricity, where the application of an electrical field creates mechanical deformation in the crystal." Now, it is just me or do these two things sound extremely the same? Is there a difference between applying a volatage and applying an electrical field? I have heard about the Piezoelectric effect working in reverse, it is in fact published in the the book tittled "Crystals and Crystal Growing" a book published by the M.I.T. Press. Does anyone have any more information? If not, I am going to look into converse piezoelectric effect and if I do not find sufficient source then I may remove that bit of the article.

in the converse piezoelectric effect, you apply a voltage/electric field to create a deformation in the crystal. in the piezoelectric effect, you apply a deformation to the crystal and charge is generated on the surface of the crystal. applying an electric field is carried out by applying a voltage to the surface of the piezoelectric crystal. all piezoelectric materials exhibit both the piezoelectric effect and the converse piezoelectric effect. --Nathaniel 11:01, 29 July 2006 (UTC)
I think the anon is asking if there's a difference between the "reverse" and "converse" effects. — Omegatron 13:53, 29 July 2006 (UTC)
Nowhere does this article refer to a 'reverse piezoelectric effect', which is a shame because that's what the OUP's A Dictionary of Physics calls it. However, there are lots of websites that, like ours, call it the 'converse piezoelectric effect'. I am sure that the two terms refer to the same thing. I don't see any confusion within our article, though - it consistently calls it the latter. --Heron 16:47, 29 July 2006 (UTC)
Difference between "reverse" and "converse". — Omegatron 14:50, 24 October 2006 (UTC)

"Piezoelectric materials also show the opposite effect, called inverse piezoelectricity, where the application of an electrical field creates mechanical deformation in the crystal." Is this the same as converse piezoelectricity or just a typographic mistake? Mingmasterz 00:21, 8 February 2007 (UTC)

Probably a typo, or at most a non-standard teminology. I have changed it to "converse." 134.67.6.11 12:22, 20 June 2007 (UTC)

## Triboluminescence

How is this related to Triboluminescence? --Gbleem 09:05, 6 October 2006 (UTC)

I don't think they are very related. Triboluminescence involves breaking a crystal's asymmetrical bonds, creating an electric discharge due to the triboelectric effect? Piezoelectricity involves a voltage generated by mechanically stressing a crystal without breaking any bonds. — Omegatron 14:48, 24 October 2006 (UTC)

## Microphones

"Ceramic electret microphones could be made small and sensitive."

Electrets are not piezoelectric. Was piezoelectric microphone intended? — Omegatron 14:18, 24 October 2006 (UTC)
There's also a list of polymer electret materials. Why? — Omegatron 14:44, 24 October 2006 (UTC)

## Flashing quartz Ute rattles

Is the flashing caused by triboluminescence (cracks in the crystal structure causing electrical discharges from the triboelectric effect) or from piezoelectricity (deformation of the crystal creating voltages and causing electrical discharges, like piezo ignition)? See Talk:Ute tribe#Comment on piezoelectricity for discussion. — Omegatron 04:03, 26 November 2006 (UTC)

## Suggestions

I'm writing as a simple user, not in any way an expert. After reading this article I am still left with the following two questions:

- Could we get any simple conversion factors for the most common piezoelectric materials in usage to estimate the electric energy that could be harvested from a certain amount of applied force (for a given size - area or volume or both - of material)? And conversely, what amount of physical distortion can we expect from a given current applied?

- Does the piezoelectric effect - in this case electric energy from material stress - take place only while the material is being compressed, or also when it has been compressed and continues to lie in a stable state under continuous stress?

I will be grateful if someone could explain the above issues in the article.

-- Also, is there any relationship between crystal size/mass and electrical output? I assume the output of a large mass w/ small stress would be silimar to a small mass w/ large stress; is this correct? The math was over my head, but it seemed to me that mass wasn't part of any equation in the article. Could someone explain this(or the equations) in lay-terms please. Mingmasterz 01:14, 8 February 2007 (UTC)

## "Ultrasonic transducers" section:

"When several elements are stacked upon each other and to the end a blade is placed we can drive the crystal and with the displacement achieved we will have an ultrasonic cutter. This kind of tool is useful when cutting plastic materials or similars as soft material doesn't get affected by the ultrasonic vibration; in fact the cut happens to a local melting of the material due to friction and no application of heat." I assume this is written by someone whose first language isn't english and knows nothing of grammar, punctuation or chosing the right words... could someone who knows what the heck they're trying to say rewrite this into decent english.--KX36 17:45, 17 March 2007 (UTC)

Plus, that's not a transducer; it's an actuator. I'm inclined to just delete it since it's not very informative and the statement about soft materials is factually questionable, in addition to being almost unintelligible. The gist is "stick a knife on a vibrating piezo and it chops". Tarchon 17:24, 25 April 2007 (UTC)

## Factual Accuracy Dispute

What is the source of this dispute? Is there actually a dispute? Or is it merely the requirement of a citation...because honestly, I think that whole section should go and be redone. The whole reference to electrets seems foolish. Electrets have nothing to do with piezoelectricity and this section is misleading. I would prefer for someone to discuss more (I could...but would need some research first...I'll look back in my solid state physics books) the symmetry issue, as a long list of materials is somewhat foolish. Its such a wide range of materials. --Lagrangian 23:23, 23 April 2007 (PST)

Looking over the edit history, the "dispute" tag was added at the same time that the citation request was added. That whole materials section needs to be edited -- it's kind of a random collection. 75.45.75.65 22:43, 10 June 2007 (UTC)

Don't have time to discuss at the moment but J. Chem Ed. 2007 p. 12 has some useful info.

## first Discovery of piezoelectricity ?

The french wiki says: The dicoverer of piezoelectricity is the monk René Just Haüy (1743-1822) in 1817, while studying spath of islande. True ? 20 may 2007

Damned good question. For what it's worth, I've always heard that the Curies discovered piezoelectricity. After poking around some, I infer from a few places (Antoine César Becquerel and René Just Haüy, among others) that Haüy did some basic work in crystal effects related to piezoelectricity (pyroelectricity, for example), but may not have dealt with piezoelectricity per se. However, I also find some places (like Britannica here that baldly state that Haüy did indeed discover piezoelectricity. 75.45.75.65 22:43, 10 June 2007 (UTC)
Here we go: [4]: "...Hauy and Becquerel tried to find a relationship also between mechanical stress and electric polarization but the findings they reported were far from conclusive. The experimental setups at the time were always prone to be perturbed by the omnipresent triboelectricity (electric charge due to fristion) on the insulators, such as amber."
Ok thanks, I recently deleted that bit on French Wiki considering I could not find any relevant source. Reading this, I guess it would be worth trying to have a look at the original work by Haüy though. I might be interested in doing this, but somewhat later Tizeff 12:49, 31 August 2007 (UTC)
It is not easy to have access to the original work of Haüy in 1817. However I could find some more information in a recent book (Leçons de physique, de chimie et d'histoire naturelle - l'Ecole normale de l'an III, which can be considered as pretty reliable. This book notably cites the 1817 paper as well as a later book by the same author. I updated the article of French wiki accordingly [5]. Tizeff 10:06, 8 November 2007 (UTC)
By the way, what's the source for the bit on David Brewster? 75.45.75.65 22:43, 10 June 2007 (UTC)

## Force comment

I delected the following sentence: "The bending forces generated by converse piezoelectricity are extremely high, of the order of tens of millions of pounds (tens of meganewtons), and usually cannot be constrained. The only reason the force is usually not noticed is because it causes a displacement of the order of a few nanometers (billionth of an inch)." First of all the placement was rather odd; second (and more importantly) it's a bit misleading because scale is not discussed (and neither is macroscopic construction, although I suspect this refers to a single crystal). I have no particular objection to the thought being rewritten ans reinserted if anyone cares to. 134.67.6.11 12:17, 20 June 2007 (UTC)

## Mechanism

I added a section called "Mechanism." I came to this page looking for why this effect happens, and found nothing until I noticed an explanation hiding in the "Crystal classes" section. Since I obviously don't know how this effect works, I don't know if that is a complete or accurate description of how or why crystals produce potential. I don't even know if "Mechanism" is the right term. However, what I did doesn't look bad, so I decided to be bold--if I did something wrong, it'll at least bring attention to this section. Twilight Realm (talk) 21:29, 11 December 2007 (UTC)