I want to measure the thermal conductivity of CdMnTe single crystals for various Mn concentrations. I wish to analyse the change in in thermal properties for the variation in Composition. I am looking for a suitable instrumentation facility.
Hello Manivel,
How large can you grow these?
A steady-state apparatus could be built (I'd use Peltiers to establish a 1D temperature gradient across small thin samples) - and depending on how accurately these data need to be, I might do it all in vacuo.
Hello Manivel,
if the electrical conductivity is high enough, then you can use the Wiedemann-Franz-law to determine the thermal conductivity:
k = L*sigma*T L = 2,45*10-8 W Ohm K-2
The electrical conductivity can be measured.
Otherwise I recommend the Laser Flash method, but you must find a lab.
I use 3-Omega-method, but this is a preparative work.
Yours
R. Mitdank
James Garry
Dear Prof. James Garry,
Thank you for your reply. I am growing single crystals of 120 mm and 60 mm in length. But I can cut the same as thin wafers of thickness up too 1mm. I am planning to do the PPMS Thermal transport property measurements.
Thank you...
Manivel R
Rüdiger Mitdank
Dear Prof. Rudiger Mitdank,
Thank you for your reply. I am planning to do the PPMS Thermal transport property measurements. As you said I am also searching some labs to do the measurements.
Thank you...
Manivel R
Good morning Manivel,
The details of the technique might matter.
I'm personally very familiar with equilibrium methods - creating a static temperature gradient across a sample, and measuring the power needed to maintain that gradient.
It's pleasingly simple, needs just a heater (powered by known voltage and current) and two arrays of thermometers to measure the gradient. If the geometry of the sample is known, the thermal conductivity is readily found.
I own a double-sided guarded thermal conductivity system - and can advise, if the idea appeals, to how one might make something similar quite quickly.
Of course, the details (desired accuracy, available time/budget) are also important - and so using an existing apparatus makes good sense. What is the device that you'll use for these samples?
With my regards;
-James
Dear Prof.James,
Good morning
I am planning to use the physical property measurement system (PPMS). It is a readily available system. But getting access to this particular system is quite a complicated one. By measuring the thermal transport properties of the grown crystal, I can get to know the parameters like specific heat capacity, Thermal conductivity, and so on. Thank you so much for your reply.
Yours sincerely
Manivel Rajan
'Morning Manivel,
>It is a readily available system
But how does it actually measure the thermal conductivity of a sample?
Does it use a heat flux sensor, or a semi-static temperature method (guarded hot-plate), or a laser 'flash' method?
All techniques have their pros/cons.
If access to this 'PPMS' is not easy, depending on how well (ie, what accuracy) you want those data, you could build relatively simple devices to get fair estimates for those qualities.
Are you looking for data at room-temperature, cryogenic, or elevated temperatures?
Dear Prof.James,
Thank you for your suggestions.
I am planning to do it at room temperature only.
Based on the availability of the instrumental facility, I will do it.
Yours Sincerely
Manivel R
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