Sample mounting

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Sapphire plates

sapphire plates The sample on this holder is annealed by a Ta spiral closed between two insulating sapphire plates.

The sample of maximum 10×10 mm2 size is clamped by two wires that are fixed by screws to the base plate. Therefore the sample is permanently grounded and the spectra can be measured during annealing.
sapphire plates The thermocouple is touching the sample surface which makes the temperature reading more accurate than on the pocket sample holder. However, the error can be up to 50 K/°C so you can consider spot-welding of the thermocouple to the sample if your material permits to.

Maximum temperature is about is about 500 °C/800 K. Maximum annealing current is 5 A.
sapphire plates Example of stainless steel disc sample mounted.
sapphire plates

Assembly:

item count name material notes
S 1 sample   up to 10×10 mm² surface
1 1 baseplate molybdenum  
2A 1 thermocouple
pins		 alumel
(magnetic)		 must stick out 3.8-4 mm below the baseplate bottom surface
2C 1 chromel
(non magnetic)
3a 6 ceramic
spacers		 alumina thinner
3b 2 thicker
4 8 nut molybdenum M1.2 thread
5 1 thermocouple chromel
(non magnetic)
alumel
(magnetic)		 0.1-0.25 mm diameter wires, spot-welded together
and touching the sample surface or spot-welded to it
6 4 rod molybdenum M1.2 thread
7a 1 annealing
contacts		 tungsten brushed on the left side, see surfaces highlighted in yellow;
must be 3.6-3.8 mm above the baseplate top surface
7b 1
8 1 heater tantalum 0.25 mm diameter wire
9 2 clamp tantalum 0.25 mm thickness
10 1 cage tantalum holding the sapphihe plates in place
11 2 plate sapphire 10×10×0.4 mm³, insulating the heater from both sides
12 2 clamp tantalum 0.5 mm diameter
13 2 screw molybdenum M1.2 thread
sapphire plates For the correct thermocouple pin contact the pins must stick out 3.8-4 mm below the baseplate bottom surface
sapphire plates For the correct connection the annealing contacts must be 3.6-3.8 mm above the baseplate top surface. This distance (if 3.5 mm or lower) can be increased by placing tiny spacers made of properly thick wire below the bottom ceramic spacers (3a) or swapping the thin ceramic spacers (3a) with the thicker ones (3b)

Last Updated on Thursday, 09 March 2023 10:32