TheEEStory.com

Ok - we've had a lot of speculation on this thread. Here are my scientific "killer issues" with eestor's claims, revised to include all we now know.

this is not a thread of questions TO Mike - it is a thread of questions FOR him. (Listen to B's interview).

(1) The patent data. The extreme constancy of k with temperature is not easily believable. Zenn will know whether they measured k so very constant with temp. If not, why believe any of the rest of the patent data? Also the leakage data is even more unbelievable. Also the suggestion of high storage at 500V/um is unbelievable because the necessary polarization is not possible in BaTiO3 or any similar lattice.

(2) Paraelectric BaTiO3. It is not so very special. Many people have measured it, and the measured properties are not better than ferroelectric, although it is preferred for energy storage because it has less temperature dependence. If this is what is storing energy than we know certainly that the polarization is limited. All the papers say this is limited much lower than what is needed. But maybe eestor have something new. However if they do, and the energy is stored via ionic displacement, the displacement for their stated energy must be very large and lead to significant nonlinearity in k. So why do they think the energy density will be anything like that predicted in the patent? Note that certainly no other known mechanism could store the required energy density.

(3) Manufacturing. The EESU contains an awful lot of components. If any one goes short circuit it is an issue. Have eestor really sorted out reliable fuse etechnology to deal with this? How can they have tested it when they have not yet got a production line going with fully parametrised output?

(4) Voltage. Given that the patent data is suspect what reason does eestor have to expect ultra-high breakdown voltages from dielectric? I am not saying this is fundamantally impossible, but it is extraordinary.

(5) Safety. The EESU as specified is like a little bomb. it has an enormous power density. If short circuit all that energy will turn to heat. Are the regulatory issues for safety problematic? Are the technical issues to ensure safety problematic? Who will do this, eestor or those using the eesu? Is relying on statements in the patent (given the flakiness of the figures in it) wise?

Best wishes, Tom

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My question would be: Would Zenn be willing to relinquish first rights if EEStor came to them and told them that they could go to market much faster with uses other than EVs and thus make big money quicker for Zenn through ownership?

I just can't get this out of my head. I don't know how far along EEStor is, but it just seems that delivery of a non-EV product would have much less work involved. I'd hate for EEStor to miss opportunities because Zenn had their hands tied.

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Here is an easy to read chart from the patent.

Unlike a previous statement that says "The extreme constancy of k with temperature is not easily believable"
If you look at component 2 vs component 9 you'll see they are consistent but not "extremely" consistent.
Also notice not one component yields the same tested results.

It's unfortunate some misquote the patent data and then use their misquotes as a scare tactic. Feel free to cross reference the chart I put together against the patent data.

85° C, OV 85°C 3500 V 85° C 5000 V
1. 19,871 19,841 19,820
2. 19,895 19,866 19,848
3. 19,868 19,835 19,815
4. 19,845 19,818 19,801
5. 19,881 19,849 19,827
6. 19,856 19,828 19,806
7. 19,874 19,832 19,821
8. 19,869 19,836 19,824
9. 19,854 19,824 19,808
10. 19,877 19,841 19,814
K 19,869 19,837 19,818

Last edited Thu, 28 May 2009, 6:13pm by Eenigma

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Eenigma -

I can assure you that <1% change over three temperatures in this range is extremely constant.

It is not the consistency accross components, it is the constancy with temperature. But Zenn will know now whether this is true for their dielectric. If true it indicates a mechanism other than paraelectric BaTiO3.

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According to the header of the table, the temperature for all three columns is 85° C. It's the voltage that varies.

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Simpler questions.

CityZENN motive power to use 600V, as was said at the AGM?
AC or DC?

What type of Electric motor in the CityZENN?
AC, DC, PM, ...
What HP or kW?

Power Electronics:
Will ZENN or EEStor provide the power electronics from EESU operating voltages to the motive (600V) system?

What EESU operating voltage is being designed for?
Still 3500V (as per the '536 patent)?
Higher?
5000V?
10000V?

Is there an access mechanism to the EESU high voltage bus?
(For the 5 minute charge option)
How is that (safely) done.

Nature of the EESU package being prepared for:
Form factor?
Size / dimensions?
Weight?

Will the EESU be able to have variable capacity, depending on how many sub-EESU units are inserted or removed? If so, will vehicle owners be able to do that? Something only done by qualified personnel?

Size of sub-EESU units?
15 kWh? 5 kWh? 1kWh?
Same units as will be made for LEV?

How many CityZENNs are in process?
Both right and left hand driver's seat models?

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Eenigma wrote:

Here is an easy to read chart from the patent.

Unlike a previous statement that says "The extreme constancy of k with temperature is not easily believable"
If you look at component 2 vs component 9 you'll see they are consistent but not "extremely" consistent.
Also notice not one component yields the same tested results.

It's unfortunate some misquote the patent data and then use their misquotes as a scare tactic. Feel free to cross reference the chart I put together against the patent data.




85° C, 85°C 3500 V 85° C 5000 V
1. 19,871 19,841 19,820
2. 19,895 19,866 19,848
3. 19,868 19,835 19,815
4. 19,845 19,818 19,801
5. 19,881 19,849 19,827
6. 19,856 19,828 19,806
7. 19,874 19,832 19,821
8. 19,869 19,836 19,824
9. 19,854 19,824 19,808
10. 19,877 19,841 19,814
K 19,869 19,837 19,818

Correct, it is the Voltage that changes. However, this is still extremely constant over a wide voltage range (3.5kV to 5kV, as the first column is at unspecified voltage).
It is so consistent, <1% variation that it can not be real. In real lab environment it would be hard to measure to <1% the same sample twice at the same voltage, before and after lunch break.
The tight variation in the chart shows, in my opinion, that someone was very keen to convince someone else of something, while both parties never had set foot in a test lab ever before.

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ee-tom wrote:

(1) The patent data. The extreme constancy of k with temperature is <b>not easily believable</b>. Zenn will know whether they measured k so very constant with temp. If not, why believe any of the rest of the patent data? Also the leakage data is even more <b>unbelievable</b>. Also the suggestion of high storage at 500V/um is <b>unbelievable</b> because the necessary polarization is not possible in BaTiO3 or any similar lattice.

"You keep using that word. I do not think it means what you think it means." ~ Inigo Montoya

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HHII,
Unless the manufacturing process spits out very precise duplicates and the test equipment is precise. No?

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The patent app in question pre-dates the "manufacturing" era.

Real life test tolerances ar not due to equipment limitations, in general, but rather to slight variations in the test setup, environmental conditions, sample-to-sample variations. While it is not impossible to accomplish electrical measurements with 10E-4 precision, it requires controlled environment making the whole effort way to expensive.
To put the numbers in perspective, in this particular situation (k vs V,T), and based on my experience, a +/- 5% variation sample-to-sample would seem reasonable and sufficient to satisfy the claim of a careful experiment.

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e'er wrote:

My question would be: Would Zenn be willing to relinquish first rights if EEStor came to them and told them that they could go to market much faster with uses other than EVs and thus make big money quicker for Zenn through ownership?

I just can't get this out of my head. I don't know how far along EEStor is, but it just seems that delivery of a non-EV product would have much less work involved. I'd hate for EEStor to miss opportunities because Zenn had their hands tied.

I don't think this is a problem at all due to the licensing idea EEStor is proposing. Zenn gets the first delivered EESU and the first units from EEStor's production line. But, once they deliver an EESU to Zenn and the cat is out of the bag. There is nothing to prevent them from helping LM build the first licensed production line in a LM facility. In fact if the EESU meets or exceeds the ED specs EESTOR has published, they won't be able to license customer production lines fast enough.

If EEStor can deliver EESU's at the end of the year or early next year that meet or exceed the specs and can be sold for $300-$500/kWh, they will be hiring operators to answer the phones. Remember, the Volt 16kWh battery pack provides a usable 8kWh is ~10 cubic feet in volume and weighs 400lbs while costing GM "hundreds less than $1000/kWh" let's say $700/kWh or $11,200 total. The EESU for the same application might be 15kWh, with 14kWh available, it would weigh about 100lbs, and have a volume of about 1 cubic foot, at $400/kWh it would cost $6,000. This EESU would extend the range from 40 miles EV to 70 miles, while lowering the weight of the Volt by 300lbs (huge amount in the automotive world) and reducing the manufacturing cost of the Volt by $5200 per car. And this is with a price 4x higher what EESTOR predicts per kWh in low volume. There will be no problem selling every EESU that rolls off the end of as many production lines as EEStor can license.

Last edited Thu, 28 May 2009, 4:26pm by Cobraphx

Well, the v constant with voltage table is also very suspicious given the v high energy density. Does not seem possible.

But I thought there was a table with k at different temperatures in which case Zenn would have the ability to verify it! I remember all the table exhibited near ideal beheviour. Tom

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Heinrich -

The suspicious nature of the patent data is not so much sample to sample - which depends on many things - but constancy with temperatures and voltage. Those are both highly unexpected.

Also the leakage, which is extraordinarily low.

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e'er wrote:

My question would be: Would Zenn be willing to relinquish first rights if EEStor came to them and told them that they could go to market much faster with uses other than EVs and thus make big money quicker for Zenn through ownership?

I just can't get this out of my head. I don't know how far along EEStor is, but it just seems that delivery of a non-EV product would have much less work involved. I'd hate for EEStor to miss opportunities because Zenn had their hands tied.

Eestor producing as advertised is unlikely, for reasons well-explained by the SMEs here who have discussed hte issue (You know who you are).

IF they can nonetheless confound the SMEs (a not completely impossible occurrence, made more likely by various reasons proffered by the boosters - again - you know who you are as well).

The notion that tiny Zenn Motor Company, with its handful of employees, will be able to put an Eesu-powered vehicle on the road less than a year after receiving the milestone-triggering prototype boggles the imagination and gets about as close to impossibility as it is possible to imagine.

IF Eestor can produce anything remotely close to what they've been advertising, ZMC's share of Eestor will be worth untold sums of money.

Zenn would be foolish to pass up the boost its Eestor stock would receive from public delivery to a company with the resources to exploit it.

ee-tom wrote:

Those are both highly unexpected.

But not impossible?

I'll go back to the blue LED, everyone in the industry thought it nearly impossible to make a blue LED using gallium nitride. The scientific understanding of LEDs and the crystal structure of gallium nitride ruled the material out as a viable choice for a working LED. That was the case until Nichia started selling blue LEDs that were produced using gallium nitride.

So it is certainly possible that EESTOR have exactly what they claim to have. Not highly probable, maybe, but not impossible.

The lunch break part was a joke eenigma! All I'm saying is that it is unlikely to get results (in k testing) varying by less than 1% even running 2 consecutive tests on the same sample, let alone 10 samples and 0-3.5-5kV.

Had the "results" in the chart been limited to a more earthly 2 decimal places and some decent variation, they would be more palatable. The way they made the chart is overdone. Try to publish test results like this in a physics journal and the reviewers will call you bluff at the speed of e-mail.

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I believe the consistency and precision of the results is due to the measuring method.
I tried to explain this in the thread “How to measure permittivity” Perhaps I failed. Perhaps nobody read it. Who knows?

Regards,

PeterP

Mike,
1. Will Zennergy be a self contained system as to be easily integrated into any "glider" or future EV design.

2. Will it be a Zenn policy to establish proprietary standards as opposed to open standards? Will "zenn inside" be like a mac or a PC

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HeinrichII wrote:

The patent app in question pre-dates the "manufacturing" era.

Real life test tolerances ar not due to equipment limitations, in general, but rather to slight variations in the test setup, environmental conditions, sample-to-sample variations. While it is not impossible to accomplish electrical measurements with 10E-4 precision, it requires controlled environment making the whole effort way to expensive.
To put the numbers in perspective, in this particular situation (k vs V,T), and based on my experience, a +/- 5% variation sample-to-sample would seem reasonable and sufficient to satisfy the claim of a careful experiment.

HHII,
Predates manufacturing era? Then wouldn’t early generation products have defects that would result in larger variation if “bench” made or produced by early generation techniques… print heads? Point is, if first “one off” products were produced to specs that deliver the claimed results, one would expect later generations to improve. EETom suggests the results were faked or erroneous… What if the early product was simply damn good? Doesn’t the small variation suggest precise duplication even in early processes and shouldn’t that bode well for increased precision in future manufacturing techniques?
Not my field, but +/- 5% is 10% and seems very imprecise in a moderately high tech lab environment, regardless of cost, IMVHO.

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ee-tom wrote:

...the suggestion of high storage at 500V/um is unbelievable because the necessary polarization is not possible in BaTiO3 or any similar lattice.

Your formulae in the "Back to Basics" thread led to a calculation showing we had a plausible mechanism for getting to 350V/um , which involved the Ti ion moving 3.4 Angstoms in the (1,1,1) direction. Since there is no reason why the Ba ion should not also move along the same line when gently nudged by the Ti ion then they would both have to move an extra 1.9 Angstroms. There needs to be a further movement of the Ba ion having to move an additional 0.8 Angstrom to avoid ionic radius overlap with the Ti ion approaching it (would be 1um but this movement also gives a small polarisation). This extra 0.8 Angstrom Ba displacement is needed for 350V/um as well.

So the total Ti ion movement would be 5.3 Angstroms and the total Ba ion movement would be 2.7 Angstroms both well within the 6.8 Angstrom length of the unit cell in (1,1,1) orientation.

Since this still leaves both ions within the unit cell, then there is no obvious reason why this would lead to conduction and breakdown.

So this is a plausible mechanism for getting to 500V/um and it would be better to remove the words "not possible", or preferably take this point out altogether.

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Eenigma,

I just noticed your post #21 on this thread. Thank you for your comments!

Regards,

PeterP

Technopete wrote:

ee-tom wrote:

...the suggestion of high storage at 500V/um is unbelievable because the necessary polarization is not possible in BaTiO3 or any similar lattice.

Your formulae in the "Back to Basics" thread led to a calculation showing we had a plausible mechanism for getting to 350V/um , which involved the Ti ion moving 3.4 Angstoms in the (1,1,1) direction. Since there is no reason why the Ba ion should not also move along the same line when gently nudged by the Ti ion then they would both have to move an extra 1.9 Angstroms. There needs to be a further movement of the Ba ion having to move an additional 0.8 Angstrom to avoid ionic radius overlap with the Ti ion approaching it (would be 1um but this movement also gives a small polarisation). This extra 0.8 Angstrom Ba displacement is needed for 350V/um as well.

So the total Ti ion movement would be 5.3 Angstroms and the total Ba ion movement would be 2.7 Angstroms both well within the 6.8 Angstrom length of the unit cell in (1,1,1) orientation.

Since this still leaves both ions within the unit cell, then there is no obvious reason why this would lead to conduction and breakdown.

So this is a plausible mechanism for getting to 500V/um and it would be better to remove the words "not possible", or preferably take this point out altogether.

It does not help the ion moving max length across the lattice, since it is symmetric this would store no energy.

It was really pushing it imagining enough movement for 2500J/cc. I would be inclined to call that impossible. The point is that the hamiltonian must be monotonic increasing for all displacements up to the maximum.

At 500V/um the energy (eestor calculations) goes up X2. I reckon this is not possible.

BTW - why did I have the figure of 7000J/cc in my head? And is the eestor figure for energy density device-level? in which case to be precise we need to add on at least 10%.

Best wishes, Tom

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Cobraphx wrote:

e'er wrote:

My question would be: Would Zenn be willing to relinquish first rights if EEStor came to them and told them that they could go to market much faster with uses other than EVs and thus make big money quicker for Zenn through ownership?

I just can't get this out of my head. I don't know how far along EEStor is, but it just seems that delivery of a non-EV product would have much less work involved. I'd hate for EEStor to miss opportunities because Zenn had their hands tied.

I don't think this is a problem at all due to the licensing idea EEStor is proposing. Zenn gets the first delivered EESU and the first units from EEStor's production line. But, once they deliver an EESU to Zenn and the cat is out of the bag. There is nothing to prevent them from helping LM build the first licensed production line in a LM facility. In fact if the EESU meets or exceeds the ED specs EESTOR has published, they won't be able to license customer production lines fast enough.

If EEStor can deliver EESU's at the end of the year or early next year that meet or exceed the specs and can be sold for $300-$500/kWh, they will be hiring operators to answer the phones. Remember, the Volt 16kWh battery pack provides a usable 8kWh is ~10 cubic feet in volume and weighs 400lbs while costing GM "hundreds less than $1000/kWh" let's say $700/kWh or $11,200 total. The EESU for the same application might be 15kWh, with 14kWh available, it would weigh about 100lbs, and have a volume of about 1 cubic foot, at $400/kWh it would cost $6,000. This EESU would extend the range from 40 miles EV to 70 miles, while lowering the weight of the Volt by 300lbs (huge amount in the automotive world) and reducing the manufacturing cost of the Volt by $5200 per car. And this is with a price 4x higher what EESTOR predicts per kWh in low volume. There will be no problem selling every EESU that rolls off the end of as many production lines as EEStor can license.

Really? You think that they could make an EESU for a vehicle just as quickly as they could make one that sat next to a power plant? Suspension, enclosure and charging time would not have to be addressed to near the extent in the latter as they would the former. No crash tests, many less safety issues, not to mention possibly missing the boat on other uses. I'm not sure how quickly the grid is going to get its facelift, but I suspect once another energy storage product is put in place, they wouldn't be willing to switch until at least the life of that product is over. How long will that life be and how much more time would there be on EEStor's patents then?

Even vacuum cleaner EESUs would require much less work than vehicles, as would trains, cargo ships, emergency lighting and emergency generators. To me, there would just seem to be much more work in getting an EV EESU to market than there would many other applications. I'm just not sure that EEStor doesn't eventually reach a point where it might be in Zenn's best interest to say, "OK, go ahead and announce, sell licenses for these other uses and we'll get ours when these other issues are resolved".

Now, if you can convince me that there are prototypes that are being tested for all the extra issues involved for EV EESU's as we speak, then all of these issues are not relavent. I'm not inclined to think there are at this time.

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wasmaba wrote:

Not my field, but +/- 5% is 10% and seems very imprecise in a moderately high tech lab environment, regardless of cost, IMVHO.

+/- 5% is usually considered a precision capacitor

+ 80 / -20 % is a fairly common specification.

Robert

e'er wrote:

Really? You think that they could make an EESU for a vehicle just as quickly as they could make one that sat next to a power plant? Suspension, enclosure and charging time would not have to be addressed to near the extent in the latter as they would the former. No crash tests, many less safety issues, not to mention possibly missing the boat on other uses. I'm not sure how quickly the grid is going to get its facelift, but I suspect once another energy storage product is put in place, they wouldn't be willing to switch until at least the life of that product is over. How long will that life be and how much more time would there be on EEStor's patents then?

Even vacuum cleaner EESUs would require much less work than vehicles, as would trains, cargo ships, emergency lighting and emergency generators. To me, there would just seem to be much more work in getting an EV EESU to market than there would many other applications. I'm just not sure that EEStor doesn't eventually reach a point where it might be in Zenn's best interest to say, "OK, go ahead and announce, sell licenses for these other uses and we'll get ours when these other issues are resolved".

Now, if you can convince me that there are prototypes that are being tested for all the extra issues involved for EV EESU's as we speak, then all of these issues are not relavent. I'm not inclined to think there are at this time.

Their three licensed customers are Zenn and LM and LighEV, do you think that LM's specs for military applications require less safety and looser charging capabilities than the automotive applications? Remember, they delayed once to improve the process for military applications.

So in a way you are probably correct, if they had ignored their licensed customers and made an EESU for a market they have no paying customer for and no contractual obligation with, maybe we'd already have EESUs. But I don't think the BOD and their investors would have agreed to this plan.

My point was that delivery of the first production EESUs to Zenn, doesn't necessarily preclude LM from producing them on a licensed production line in parallel just a couple weeks behind EEStor's line. But you are right, until a new licensee comes along and pays to get in on the action, stationary EESU applications will be left behind until EEStor produces EESUs faster than Zenn can buy them.

Good point, Cobra. It seems to me that EEStor is working at all of the most difficult applications when they could be working on the ones that would see the soonest release date. They probably should have approached The Hoover Vacuum Company first or maybe LawnBoy. lol

LightEV would have been upset, but I suspect the Zenn Board would have been more accepting had they told them we can make $$$$$$$$$$$$$$ from the power companies and then put 200,000,000 EESUs in vacuums long before we can get you an EESU for your CityZenn. I suspect there are many times more vacuums in the World than there are cars. I think I own about 5 vacuums myself(counting a shampooer that also vacuums up the water.

But, my main point is that since no one gets one before Zenn, EEStor has to go through a lot more work before we ever see an EESU. I do understand that they could be working on other uses at the same time (and LMT probably is), but even if they are finished, we won't see one until the ones for Zenn are ready and approved for use on our highways.

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A revolutionary new technology for vacuums is presented every weekend on TV infomercials. I think an EESU introduction there would fall on deaf ears.

All kidding aside, the most free advertising for this product you will get is in an automotive application. This will give Eestor the most bang for the buck when they do their IPO.

flukey wrote:

All kidding aside, the most free advertising for this product you will get is in an automotive application. This will give Eestor the most bang for the buck when they do their IPO.

That's true, the public at large will really understand what the EESU means when they see the CityZenn (or maybe a Shelby Supercars Ultimate Aero EV) on Letterman, Leno and Oprah. Not even one in a thousand would take note if the news took a camera to a power plant and showed a box with wires coming out of it, Saying that this has the ability through load balancing to possibly lower their electricity price by 10%, or increase the utilities profit by the same amount. Normal Americans will take no notice, but an electric car they can drive for a week or more between charges for about the same price as they last car they bought, that they will notice.

e'er wrote:

But, my main point is that since no one gets one before Zenn, EEStor has to go through a lot more work before we ever see an EESU. I do understand that they could be working on other uses at the same time (and LMT probably is), but even if they are finished, we won't see one until the ones for Zenn are ready and approved for use on our highways.

I agree with you, if someone like GE had been the first licensee instead of Zenn, we might already have EESUs in the marketplace. Due to the lower parts count, lower complexity and power handling of the electronics involved if for no other reason. But I can understand why Dick ended up where he did.

ee-tom wrote:

The point is that the hamiltonian must be monotonic increasing for all displacements up to the maximum.

Yes, apart from sheer and extreme co-incidence, how on earth could the dielectric constant stay constant with voltage (energy, displacement)? And is this a significant clue in refining a mechanism?.

There will be a small smoothing effect from thermal vibrations, but it seems to be an order of magnitude too low.

The Boltzman thermal energy is 8.3 J/mole/degree per degree of freedom, so at 85 degrees C it is 8.3 x (273 + 85) J/mole = 2971 J/mole (=3KJ/mole) per degree of freedom. For 400 moles of BaTiO3, then this is around 1.2MJ per degree of freedom.

The number of degrees of freedom should be 5 for the atoms in each molecule x 3 for each spatial coordinate (x, y, z), giving 15 (independent) degrees of freedom that might affect polarisation. So the Boltzman thermal energy affecting polarisation at 85 degrees is around 18MJ for an EESU compared with its 180MJ energy storage capacity.

What this means is that there will be a distribution of displacements in the polarised BaTiO3, and this will presumably have the effect of smoothing out part of any change in dielectric constant with increasing displacement. However, the effect ought to be too small to apply across the range of 0v to 5000v.

It is the same effect that keeps the BaTiO3 in the paraelectric phase above the Curie point.

There may be more degrees of freedom for rotations of the individual ions too, but it is not obvious how this might cause statistical variations in the polarisation of individual molecules.

ee-tom wrote:

It does not help the ion moving max length across the lattice, since it is symmetric this would store no energy.
.....
At 500V/um the energy (eestor calculations) goes up X2. I reckon this is not possible.

If the Ba ion was also moving more than half-way along the lattice this would have to be a major concern. It could be that the Ti / Ba separation provides the bulk of the restoring force to discharge the unit. In that case the large Ti displacement may not act as a conduction mechanism.

The Born dynamic charge mechanism means the movement of the Ti ion displaces a few electrons from an O ion ahead to one behind. This displacement might continue as the Ti ion passes through the narrow point of a triangle of O ions, even when there are three sets of O ions to consider (ahead, adjacent, behind).

The above would imply that energy is stored in compression of the spacing between Ba and Ti but half the polarisation is an accidental by-product of induced electron displacements in Ti and O shared molecular orbitals.

There are a few possibilities for refining the crude model above, but it is too early to determine whether this would help matters.

ee-tom wrote:

BTW - why did I have the figure of 7000J/cc in my head? And is the eestor figure for energy density device-level? in which case to be precise we need to add on at least 10%.

There is certainly an adjustment for CMBT vs device level energy storage.

There's a bigger issue to tackle as well.

Your formula with the PeterP adjustment does not square with the Zawy/Y_Po calculation of surface charge required to offset the external electric field. At 3,500v they calculated that 50 excess external electrons would accumulate on the - electrode surface per 4 x 4 Angstrom square during charging. With a k of 22,500 these would be amost completely offset by a net movement of the same number of positive charges towards this electrode, and vice versa for the positive electrode.

In the (1,1,1) orientation (longer and thinner by x1.7) this equates to 30 electrons per molecule, whereas the Born dynamic charge calculations gives an offsetting charge of 7.5 electrons. So the two calculations are out by a factor of four approximately, even including the PeterP adjustment.

It might be just a factor of two out, depending on whether, When charging a capacitor with a charge Q, it is sufficient to externally move a charge of 0.5 x Q from one plate to another, or whether you have to externally move 1 x Q between the plates. But it needs reconciling. Sorry, haven't had time to do the maths and can't seem to think it out.

Regards,
Peter

Last edited Sat, 30 May 2009, 7:12am by Technopete

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