Observation of a Phase Transition at High Temperature under Various Atmospheres

Application Note B-XRD1117


In order to develop new materials that have desired properties, it is essential to evaluate the materials under various atmospheric environments. The infrared heating high-temperature attachment Reactor X has a corrosion-resistant sample chamber separated from the heater section, so it can be used to perform high-temperature XRD measurements under various atmospheres, such as hydrogen, ammonia, high humidity and so forth. Using Reactor X with a 2D detector capable of high-speed XRD measurement, it is possible to investigate in detail rapid phase transitions under heating in various atmospheres.  

Measurement and analysis

The redox reaction of a Cu powder sample was observed with Reactor X. The X-ray diffraction measurement (duration time: 1 min) was repeated while increasing the temperature at 50˚C/min from RT to 800˚C, at which point H₂ (4%) gas was introduced while keeping the temperature at 800˚C. Fig. 1 shows the obtained profiles. During the temperature increase from RT to 800˚C (from the lower to the middle part of Fig. 1 (left)), the diffraction peaks of Cu shifted to lower 2θ angles due to thermal expansion. Then the diffraction pattern changed to that of Cu₂O and CuO. After introducing H₂ gas (from the middle to the upper part of Figure 1 (left)), the diffraction pattern changed to Cu₂O and finally Cu. Figure 2 compares the transition of the mass fractions of Cu, Cu₂O and CuO. The chart indicates that the redox reaction of Cu occurred through states where Cu₂O coexisted.  

B-XRD1117 Figure 1 X-ray diffraction profiles and the heating and atmosphere condition

Figure 1: X-ray diffraction profiles (left) and the heating and atmosphere condition (right). 

B-XRD1117 Figure 2 Result of quantitative analysis by Rietveld method
Figure 2: Result of quantitative analysis by Rietveld method. 

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