Extended Data Fig. 2: The heat-capacity setup.
From: RETRACTED ARTICLE: Evidence of near-ambient superconductivity in a N-doped lutetium hydride
Top, schematic rendering of the new a.c calorimetry technique (not to scale). The sample is surrounded by a NaCl insert with a heater and thermocouple making contact with the sample. a, View of the preparation as seen from the side showing the thermocouple making contact with the sample inside the DAC. b, View of the preparation as seen from the top of the sample area showing the configuration of heater, thermocouple and Pt leads. Bottom left, heat-capacity setup before loading sample. The thermocouple consists of a shorted alumel/chromel pair. The heater pair consists of a shorted metal, nichrome, Ti or Pt. When driven at frequency f, the sample temperature modulates at frequency 2 × ƒ, which manifests as a voltage on the thermocouple pair that can be measured by a lock-in amplifier. Bottom right, after the sample is loaded, in contact with both the heater and the thermocouple, a small piece of NaCl is placed on top to thermally insulate it from the diamond.
