Dear Franklin,

In summary, yes a thermal transistor is analogous to an electrical transistor. For that you need a material with two clear thermal states (thermal conductivity) , a way to switch between the two and a way to control it. A very good example of that has been just published by Aditya Sood here:

https://www.nature.com/articles/s41467-018-06760-7

Kind regards,

Julian

Hi Julian,

Thank you for your reply !, I did take a look of the attached paper, but this kind of transistor operates in a wet medium , can we call it a "wet transistor" ?

I think it uses an electrolyte as a liquid thermoelectric ... ?

I'm looking specifically for "dry" solid's state thermal transistors, made of conventional semiconductors as PbS, CdS, Bi2Te, PbTe, etc.

Do you have another reference more related about what im looking ?

Do you know more about thermal transistors build up from conventional thermoelectric materials ?

I want to make a thermal transistor made of CdS and PbS , first I'm gonna process the materials to ensure they have good thermoelectric properties (in particular, seebeck coefficient and ZT, )

The other question I have,

you said a thermal transistor is analogous to the electric transistor ,

but, in heat transfer, not just electrons conduct heat, phonons do too, and phonons have very different behavior than electrons, in the sense that an electric field is not needed to move phonons from one place to another, and heat will be anyways conducted .

My questions of the fundamentals of the operation of thermal transistors are focused more on that direction.

Regards ! , :)

Dear Franklin,

The basic functioning of thermal and electrical transistors is the same (a transport mechanism that has 2 differentiated states and a way to control that transport in a channel). In a normal transistor the on and off states are pretty much ideal (there are several orders of magnitude in the conductivity of the channel between states) and the control on the switch is almost ideal (ok, I am not talking here about charge trapping, capacitive couplings, etc). In a thermal transistors achieving something similar is rather difficult or

impossible. The heat flow (the equivalent to the current) is not characterised by a single carrier, but by a combination of electron transport, vibrations ( phonons in crystalline materials, propagons/diffusons/locons in amorphous), and finally radiation. The electronic contribution,if any, can be switched off using electromagnetic fields as in normal transistors. However switching off the other two contributions becomes really challenging. The diffusive part (vibrations) requires to somehow control how the atoms interact to each other in the material. A way to do that is by a controlled diffusion of a third material in to the lattice as in the above-mentioned paper. In a "dry" version you will need to look for something triggering a reversible phase change resulting in very different vibrational spectra for each state or something similar. As far as I know there is no easy way to do that, and the concepts proposed by Li in his seminal work have not been properly implemented yet.

Kind regards,

Julian

https://aip.scitation.org/doi/abs/10.1063/1.2191730

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.99.177208

Dear Julian ,

Thank you for your comments, I understand now the general scenario a little bit more, I see your points.

I'm gonna give a read to these two papers, I guess, as you have said; the ideas are not new, but to implement the experimentations it'll be somehow difficult (if not unlikely, as you said).

Is interesting that you have mentioned radiation as a third component of the Heat diffusion current from one material to the other, this part is almost never considered. However, the Energy transfer by radiation is strongly dependent of the physical properties of the material's surface (i.e. emissivity, reflectivity, absorptivity, etc. ) . Wouldn't be possible to control this contribution using materials known as thermal barriers?

In the case of the atomic' vibrations component, I guess the problem is bigger. Maybe what we have to do is to focus more on the material's engineering in a more novel ways. Maybe the introduction of nanostructures on the material could let us control in partly the heat transported by the atomic vibrations ... somehow, I don't know.

Best Ragards !

Uriel,

Dear Franklin,

you are right, radiation may open some paths in this field, but how to use it in real world applications is even more challenging than diffusion I'm afraid. There are some theoretical works on this, thought. For instance see this work from Philippe Ben-Abdallah :

Article Near-Field Thermal Transistor

Dear Franklin,

This will be a game changer for application in thermal management.

A thermal transistor, a device whose thermal conductance can be modulated in real-time using an external stimulus, has the potential for transformative applications in dynamic thermalmanagement, energy harvesting, and phonon logic. It is imagined that thermal transistors could be arranged in circuits to compute using heat logic, much as semiconductor transistors compute using electricity. It may be connected to computer chips would switch on and off to help limit the heat damage in sensitive electronic devices.

If we talk about electrochemical thermal transistor, An Electrochemical Thermal Transistor is the ability to actively regulate heat flow at the nanoscale(this is most challenging) could be a game changer for applications in thermal management and energy harvesting. Such a breakthrough could also enable the control of heat flow using thermal circuits, in a manner analogous to electronic circuits.

Hope content is helpful for you.

Ashish

Dear Ashish Thakur :

Thank you for your explanation with details. My interest originated when I was about to start participaing in one of the thesis projects in my Lab. At that time I haven't heard the term 'Thermal Transistor' before, so I started to look around for this device in scientific articles. It turned out that what we would trying to make wouldn't be a Thermal Transitor, but a Thermoelectric Transistor, which is a total different thing.

However, I got very interested on the subject and I got about 3 interesting articles about it, even I leanrt that there are different types of Thermla Transistor (as you mentioned one kind), there is the Thermal Quantum Transistor, or the Near-Field Thermal Transistor, I believe.

Now, I ended my participation on this project, and I am about to finish my PhD, which I did in a different subject (Thermoelectric devices). But, I would love to find myself working in the field of Phononics in the future of my professional carrer as a researcher.

Thank you for the information Sr. By the way, would be possible you to have some literature about this, wouldn't ? If so, I'll appreciate if you can share some with me.

Best Regards !

I'm also following this question.