Large-volume atmosphere-controlled high-temperature x-ray diffraction furnace

A new fully automated powder diffraction furnace that operates from 20 to 1600°C under controlled atmosphere or vacuum is reported. The diffraction furnace provides a large heated volume and stable sample positioning, thus minimizing systematic errors in the powder diffraction patterns and temperature control. The thermal expansion of alumina over the temperature range of 20–1420°C was used to evaluate the temperature and sample positioning errors. Analysis of 16 datasets collected over the course of 7 months, including some full-pattern Pawley refinements and Rietveld analysis, demonstrates that the thermal expansion of Al 2 O 3 can be determined with good accuracy up to at least 1420°C. The specimen displacement was determined as a function of temperature using full-pattern fitting and remains well under 100 µm across the 20–1420°C temperature range. Heating rates of up to 1200°C min −1 can be achieved without overshoot. Cooling rates of 600°C min −1 are possible at temperatures above 1300°C, while cooling rates of approximately 60°C min −1 are possible down to ∼700°C. Atmosphere control is possible, and oxygen partial pressures of less than 10 −5 atm can be obtained routinely under a blanket gas.