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Sub-Kelvin Resolution X-ray Diffraction Thermometry Defies the Existence of Nanoscale Hotspots in Induction Heated Magnetic Nanoparticles

Hanson, Lise G. ; Veile, Thomas ; Hansen, Bianca L. ; Varón, Miriam ; Ravn-Feld, Mikkel ; Larsen, Mikkel C. ; Gjørup, Frederik H. LU orcid ; Jørgensen, Mads R.V. LU orcid ; Christensen, Niels B. and Haldrup, Kristoffer , et al. (2026) In ACS Nano 20(9). p.7414-7425
Abstract

A number of recent experiments have indicated that magnetic nanoparticles can become locally hotter than their nonmagnetic surroundings during induction heating. While such nanoscale hotspot-effect is particularly attractive for applications within biomedicine and catalysis, its existence is a topic of scientific controversy. To address this, we here present simultaneous measurements of the internal temperatures of magnetic nanoparticles and their solid support material during induction heating. The supports are dry, nonmagnetic, and nonconductive porous powders serving to separate the magnetic nanoparticles. The temperatures are measured by in situ synchrotron X-ray diffraction, utilizing that thermal expansion of the materials cause a... (More)

A number of recent experiments have indicated that magnetic nanoparticles can become locally hotter than their nonmagnetic surroundings during induction heating. While such nanoscale hotspot-effect is particularly attractive for applications within biomedicine and catalysis, its existence is a topic of scientific controversy. To address this, we here present simultaneous measurements of the internal temperatures of magnetic nanoparticles and their solid support material during induction heating. The supports are dry, nonmagnetic, and nonconductive porous powders serving to separate the magnetic nanoparticles. The temperatures are measured by in situ synchrotron X-ray diffraction, utilizing that thermal expansion of the materials cause a shift in their X-ray diffraction peak positions. With a subkelvin temperature resolution and a time resolution of 0.1 s, we find no measurable temperature difference between magnetic nanoparticles and support, i.e., no significant hotspots, in agreement with existing theory. We obtain the same result for three different combinations of magnetic nanoparticles and supports. We encourage further use of X-ray diffraction thermometry in combination with other localized thermometry techniques to clarify whether potentially nonthermal effects could have been incorrectly ascribed to a local temperature increase in previous experimental studies.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
hotspots, induction heating, local temperature difference, magnetic hyperthermia, magnetic nanoparticles, thermometry, X-ray diffraction
in
ACS Nano
volume
20
issue
9
pages
12 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:41739579
  • scopus:105032184909
ISSN
1936-0851
DOI
10.1021/acsnano.5c10818
language
English
LU publication?
yes
id
94f34e0d-3b6c-4f6c-9890-6b97c9db9365
date added to LUP
2026-04-17 15:15:39
date last changed
2026-05-29 19:53:12
@article{94f34e0d-3b6c-4f6c-9890-6b97c9db9365,
  abstract     = {{<p>A number of recent experiments have indicated that magnetic nanoparticles can become locally hotter than their nonmagnetic surroundings during induction heating. While such nanoscale hotspot-effect is particularly attractive for applications within biomedicine and catalysis, its existence is a topic of scientific controversy. To address this, we here present simultaneous measurements of the internal temperatures of magnetic nanoparticles and their solid support material during induction heating. The supports are dry, nonmagnetic, and nonconductive porous powders serving to separate the magnetic nanoparticles. The temperatures are measured by in situ synchrotron X-ray diffraction, utilizing that thermal expansion of the materials cause a shift in their X-ray diffraction peak positions. With a subkelvin temperature resolution and a time resolution of 0.1 s, we find no measurable temperature difference between magnetic nanoparticles and support, i.e., no significant hotspots, in agreement with existing theory. We obtain the same result for three different combinations of magnetic nanoparticles and supports. We encourage further use of X-ray diffraction thermometry in combination with other localized thermometry techniques to clarify whether potentially nonthermal effects could have been incorrectly ascribed to a local temperature increase in previous experimental studies.</p>}},
  author       = {{Hanson, Lise G. and Veile, Thomas and Hansen, Bianca L. and Varón, Miriam and Ravn-Feld, Mikkel and Larsen, Mikkel C. and Gjørup, Frederik H. and Jørgensen, Mads R.V. and Christensen, Niels B. and Haldrup, Kristoffer and Frandsen, Cathrine}},
  issn         = {{1936-0851}},
  keywords     = {{hotspots; induction heating; local temperature difference; magnetic hyperthermia; magnetic nanoparticles; thermometry; X-ray diffraction}},
  language     = {{eng}},
  number       = {{9}},
  pages        = {{7414--7425}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Nano}},
  title        = {{Sub-Kelvin Resolution X-ray Diffraction Thermometry Defies the Existence of Nanoscale Hotspots in Induction Heated Magnetic Nanoparticles}},
  url          = {{http://dx.doi.org/10.1021/acsnano.5c10818}},
  doi          = {{10.1021/acsnano.5c10818}},
  volume       = {{20}},
  year         = {{2026}},
}