High temperature crystal structure of sanidine; Part I, A radiative microfurnace for single-crystal X-ray diffraction, acquiring control of the temperature against chi -angle movement

A new microfurnace using a Pt-radiative heater, regulated by T correction linked to the chi -angle movement, has been designed for high-T XRD experiments on single crystals. The thermocouple T which maintains the desired crystal T and which apparently eliminates the 'chimney effect' is computed for each reflection from the chi -correction factors previously determined for the heater. Operating T up to approximately 1100 degrees C can be maintained to within + or - 5 degrees C for long periods of time. As an example of the application of this apparatus, the structure of sanidine is described in part II.