August 2000 - techniques

Calibration of temperature in non ambient experiments

At the recent workshop on controlled environment XRD a request was made to keep a list of materials to calibrate the temperature of a non ambient diffraction machine. It is intended to keep this list updated by adding to it any data supplied by users that they have successfully used for calibration. The current list has been built up over recent years at successive non ambient workshops.

Send any additions or corrections to djtaylor@lineone.net

The list has been split into two parts.

(1) The International Temperature Scale 1990 list which gives very accurate information mainly on freezing point and often used for the accurate calibration of thermocouples.
(2) Materials with phase changes or melts which are used to calibrate a furnace over a range of temperatures.

(1)International Temperature Scale 1990 (ITS90)

Fixed Point	State		 	Temp  K		 Temp °C

Mercury	Triple Point		234.3156	 	-38.8344
Water		Triple Point		273.16			0.01
Gallium	Melting Point	302.9146		29.7646
Indium		Freezing Point	429.7485		156.5985
Tin		Freezing Point	505.078		231.928
Zinc		Freezing Point	692.677		419.527
Aluminium	Freezing Point	933.473		660.323
Silver		Freezing Point	1234.93		961.78
Gold		Freezing Point	1337.33		1064.18
Copper		Freezing Point	1357.77		1084.62

(2)Phase change Calibration materials

Material	Temperature°C	Transition

KNO3		129		Tr>Trig
KClO4		300		ortho>cubic
Pb		327		melt
KNO3		334		melt
PbTiO3		490		Tet>cubic
K2SO4		583		ortho>hex
K2Cr2O7	665		ortho>hex
KI		681		melt
NaCl*		801		melt
BaCO3		810		ortho>cubic
Fe		910		bcc>fcc
Mn		1135		fcc>bcc
CaF2		1360		melt

* Note it has been reported that sublimation can be a problem with cool surfaces being covered in a deposit of NaCl

Dave Taylor