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Microscale heating platforms capable of generating localized temperature rises can find applications in wide‐ranging areas including nanomaterials synthesis and microscale thermometry. Here, commercially available optical calibration samples called Ronchi rulings, which consist of an array of chrome lines on a float glass substrate, are demonstrated to serve as reconfigurable Joule heaters. Electrical connections are formed by wire bonding onto the chrome to Joule heat individual lines and monitor their temperature rises using electrical resistance thermometry. Tests across multiple heater lines demonstrate a negative temperature coefficient of resistance with an average value of −6.93 × 10−4 ± 8.18 × 10−5 K−1. Under Joule heating, temperature rises exceeding 100 K are measured. To characterize the temperature gradient across the chrome line and glass, a noncontact optical thermometry technique based on the temperature‐dependent luminescence of upconverting nanoparticles (UCNPs) is used, producing temperature measurements that match finite element simulations. A 1:1 area ratio between the chrome lines and glass offers a high probability of finding UCNPs across both materials. The temperature rise on chrome determined from luminescence thermometry, electrical resistance thermometry, and simulations are also consistent. Furthermore, over 50% of the peak temperature rise is maintained along the neighboring glass region.
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A diamond anvil microassembly for Joule heating and electrical measurements up to 150 GPa and 4000 K
When diamond anvil cell (DAC) sample chambers are outfitted with both thermal insulation and electrodes, two cutting-edge experimental methods are enabled: Joule heating with spectroradiometric temperature measurement and electrical resistance measurements of samples heated to thousands of kelvin. The accuracy of temperature and resistance measurements, however, often suffers from poor control of the shape and location of the sample, electrodes, and thermal insulation. Here, we present a recipe for the reproducible and precise fabrication of DAC sample, electrodes, and thermal insulation using a three-layer microassembly. The microassembly contains two potassium chloride thermal insulation layers, four electrical leads, a sample, and a buttressing layer made of polycrystalline alumina. The sample, innermost electrodes, and buttress layer are fabricated by focused-ion-beam milling. Three iron samples are presented as proof of concept. Each is successfully compressed and pulsed Joule heated while maintaining a four-point probe configuration. The highest pressure-temperature condition achieved is ∼150 GPa and 4000 K.
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- Award ID(s):
- 2125954
- PAR ID:
- 10593956
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Journal of Applied Physics
- Volume:
- 135
- Issue:
- 9
- ISSN:
- 0021-8979
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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