Why does X-ray Diffraction Show Disappearing Peaks in CaCoH3?

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The discussion centers on the study of the perovskite hydride CaCoH3 using X-ray diffraction, specifically focusing on the phase transition behavior and electrical resistance characteristics. During the phase transition, it is noted that all diffraction peaks weaken and shift to higher energy, with the (111) and (222) peaks disappearing entirely. This disappearance may indicate a structural change or loss of crystallinity at the transition point. Additionally, the temperature dependence of electrical resistance shows a metallic behavior overall, but an increase in resistance is observed at low temperatures around 4K, suggesting insulating behavior up to 55mK, with a significant 70% increase in resistance. This behavior raises questions about potential superconductivity in the sample and the underlying mechanisms causing the resistance increase at low temperatures, particularly given that the sample is in powder form.
huyen
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Hope somebody can help me.
I am studing perovskite hydride CaCoH3 using X-ray diffraction. CaCoH3 crystallizes with a cubic in space group Pm-3m. At phase transtion point, all peaks weakened gradually, and shifted to higher energy.The (111) and (222) peaks become weak and disappeared . Why that peaks are disappear?.
 
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2. To study the temperature dependence of electrical resistance;
The R-T slope showed metallic. But the resistance revealed increase at lowtemperature around 4K, which show insulator up to 55mK (increase 70%). What is effect? I hope my sample beome superconductivity.
 
and Why the resistance increase at low temperature. My sample is powder
 

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