Palladium is a fission product.

[NNadir]

The paper I will discuss in this very brief post is this one: Enhancement of Thermoelectric Properties in Pd–In Co-Doped SnTe and Its Phase Transition Behavior. (Wang et al ACS Appl. Mater. Interfaces 2019 11 37 33792-33802)

I don't have time this morning for much more than this.

Thermoelectric devices are well known and have been utilized, most famously in the space program, for the direct conversion of heat into electricity.

As an advocate of the last, best hope of saving the planet, nuclear energy, I follow the science around these devices rather closely.

The historical thermoelectric devices, including those that powered the Voyager spacecraft - with which we are still in contact after many decades - had low energy efficiency: Typically the heat energy converted to electrical energy was less than 10%. The efficiency of these devices is described in science and engineering by a parameter known as the Seeback coefficient, usually referred to by the somewhat confusing symbol "ZT" which is not an algebraic product.

I consider that all of the components of so called "nuclear waste" are valuable and need to be recovered, both as useful radioactive materials and as non-radioactive materials.

It is possible to isolate non-radioactive palladium from fission products in the case where fast separation of ruthenium is undertaken, since ruthenium-106 has a relatively short half-life, roughly a year. This is possible for fluid phased reactors of a type that has been popularly discussed among modern nuclear engineers. Ru-106 decays to stable palladium-106.

However the isolation of palladium from used nuclear fuel that has been foolishly allowed to accumulate without being put to use will contain a long lived radioactive isotope, Pd-107, which decays with a long half life to stable Ag-107. I believe that this palladium is also useful and that the risk associated with its radioactivity is vanishingly small if it is utilized in devices, which is why this paper caught my eye.

In the fast fission of plutonium - which in my view is the key to making nuclear fuel inexhaustible - about 6% of the fission products are palladium. (Natural palladium contains the 102 isotope which is observationally stable but probably radioactive with an a half-life so long as to be undetectable. Used nuclear fuel will contain this mass number in the form of stable ruthenium-102)

Here is figure 10 from the paper:



Here is the caption:

Figure 10. a) ZT values as a function temperature for Sn1.03–2xPdxInxTe; b) ZT contrast

From the conclusion of the paper:

In summary, we first confirmed that the existence of Pd can introduce the valence band convergence of SnTe, proven by first-principles calculation, and then carried out the experiment of doped Pd. In addition to valence band convergence and no deterioration of conductivity, chemical bond softening and grain refinement can also be introduced into SnTe doped with Pd. Moreover, the neutron and synchrotron powder diffraction experiments show that the significant change in the thermal conductivity of the codoped system is caused by local structural distortion. This persistent local structural distortion and the instability strongly affect the high temperature thermal conductivity, which affects overall thermoelectric performance. Therefore, we obtain a low thermal conductivity in this work. For instance, doped 2.5 mol % of In and Pd can reduce the thermal conductivity to 1.13 Wm–1K–1. The purpose of improving thermoelectric performance can be achieved by adjusting local structural distortion. Finally, due to the above synergistic effect, the ZT value of the Sn0.98Pd0.025In0.025Te sample reached 1.51 at 800 K.

This is a very high ZT value. To save the world from climate change, it is necessary to utilize high temperature nuclear reactors with high thermal efficiency in a combined cycle fashion, with some of the energy being utilized to make chemical fuels that can be obtained from hydrogen and carbon oxides, both CO and CO2. CO2 can also be reduced to carbon for use in materials, which is essentially combustion in reverse.

Temperatures of 800 K are readily accessible under these conditions, and may be utilized in the cooling phases necessary in the thermochemical conversion of carbon oxides to economically viable closed cycles approaches to carbon utilization.

It's cool I think.

None of this is likely to happen by the way, since fear and ignorance are obviously triumphant in modern times, but it is feasible that ignorance will fail, both on the right, where it is politically popular, and on the left, where anti-nuclear stupidity is popular.

I hope you will have a wonderful weekend.

[DFW]

1. I didn't get much of that, but can maybe help make "ZT" less confusing

Anyone from the Netherlands or South Africa involved in the research by any chance?

That "Seeback" coefficient--"see back" in Dutch (or Afrikaans) would literally translate as "zie terug." That would provide a "ZT" that has nothing to do with any mathematical formula. Just a simple abbreviation.

[NNadir]

2. This reminds me of a funny story told about Robert Oppenheimer.

Oppenheimer had great fluidity with languages, and most famously taught himself Sanskrit.

When he was a professor at Berkeley, he had to go to Europe for a year, and asked a colleague to teach one of his courses. His colleague asked what text he should use for the course, and Oppenheimer suggested a book.

His colleague said, "But Oppenheimer, the book is in Dutch."

"Yes," said Oppenheimer, "but it's easy Dutch."

My son, who takes time out of his engineering studies to teach himself various languages, notably Chinese, loves this story.

Thank you for your comment. Seeback is the name of a scientist who discovered the effect. He lived in the early 19th century. I'd guess that the ZT is not a pun on his name, but I could be wrong.

We have, in science, many conventions based on languages other than English. For instance, in chemistry, we designate certain kinds of isomers as "E" - from the German "Entgegen" and "Z" "Zusammen." And then there is Bremsstrahlung radiation, and many other such terms.

Until unrestrained racism killed it in the 1930's, Germany was the center of physical science. When I was a kid, there was enough of a residue of that fact, that chemistry majors at many universities were required to take courses in German.

There are sad stories about David Hilbert in his last years, remarking to a Nazi administrator that "there is no mathematics in Germany anymore."

That is a tragic story; and a lesson that well should be applied in our times.

Today I would imagine that German chemistry students need to take courses in English. I know this is true of Chinese chemists.

It is regrettable that most Americans speak only one language. It weakens us greatly.

Anyway, about "ZT."

Unfortunately, the use of "ZT" for an introductory level college student can be misleading......especially when - as is often the case - it is used in an equation. I will confess when I first began to study thermoelectric devices, I was confused.

[DFW]

3. Too bad about my theory. As for Seeback as a name

There is a common German name "Seebach (lakestream)". It has several variations (none with a K in German), and there is quite a large family of minor nobility background in the area of Thüringen with than name.

ZT could be an abbreviation for anything in that case. Z could stand for Zentral (central), Zutreffend (relevant, pertinent), Zugefügt (added on), lots of things. Germans love their abbreviations. The East German dictators were formally "Vorsitzender der ZK der SED der DDR." I will give them this--that is a lot less cumbersome than saying "Vorsitzender der Zentralkomitee der Sozialistischen Einheitspartei Deutschlands der Deutschen Demokratischen Republik."

[NNadir]

4. Well, it was an interesting guess on your part, and a clever pun. Perhaps...

...another possibility is "zum Temperatur." I have, if I recall correctly, seen it written with a lower case z, as zT.

Again, it comes from the age when world science was dominated by Germans, with some due respect being paid to the English who were almost as important.

[DFW]

5. In German, proper nouns are capitalized

That's why "zur Temperatur" would be abbreviated "zT." Same with "zum Beispiel (for example)." In German they abbreviate it "zB."

[NNadir]

6. Yes, thank you, I know that.

I have reading knowledge of German, at least technical German, not fluid but passable; I speak it very poorly and whenever I've been in Germany, people generally forgive me and speak English.

You've certainly inspired me to understand why it's "ZT." I never thought about it, but poking around, it seems to be one of those rare things that you can't find out with either Google or Google Scholar.

But thanks...

My son is much better than I am at languages. I can read technical papers in French and German, but struggle some, but he can read fluidly in many languages.

His French is excellent, much better than mine, his Spanish passable spoken, his reading very good, his reading knowledge of Chinese apparently superior to many of his ABC (American Born Chinese) friends, although he's not really comfortable speaking it, although his Chinese friends are encouraging him to do it. He spent a week in Hungary recently and came back and gave me a little lecture on correct Hungarian pronunciation. He's been interested in Italian, and last summer, while working in France with some Brazilian graduate students, got by with some Portuguese which he reports is "close enough" to Spanish. (I was surprised that he spoke Spanish, which I found out when asking him about a layover in Madrid.) He seems to have a good feel for Japanese.

I envy him.

He doesn't, however, speak a word of German. I've told him I think he should learn German, and he's put it on his agenda. He's been talking about going to graduate school in Europe; I'm hoping he'll stay in America though.

I assume your German is flawless, since your wife is German and I glean that you live and work in Germany. That's very cool. I'm sure you reflect well on Americans, which is important since we all will suffer if thought to be Trumpers.

I have a good Chinese friend who spent ten years in industrial labs in Japan, and speaks three languages. I envy him. He enriches our country.

I have always loved my country for its immigrants and the culture they bring. Regrettably many of their children lose the language in one or two generations. My wife's grandparents lived in the US but never spoke a word of English; they spoke Italian. My wife doesn't speak a word of Italian. That's too bad. My father-in-law spoke it but did not give the language to his daughters.

I do hope your children are fluidly bilingual. We all need to be close in this world, if we are to survive, together, as a species. A love of language helps, because to embrace a language is to embrace a culture and to embrace culture is to understand our mutual humanity.

I recall an interview I heard during the Bosnian war, where a reporter in Sarajevo, Bosnian I think, remarked that if a multicultural country like Yugoslavia could fall apart into racial hatred, Americans should watch out. I thought it impossible; I thought it absurd.

I was wrong, very wrong.