# Non-magnetic regenerator material of silver oxide for 4 K cryocoolers

https://mdr.nims.go.jp/datasets/3adcd11b-1138-4380-9ad4-0d28d868ed6c

## Files

- [Cryogenics_36_2023_103756.pdf](https://mdr.nims.go.jp/filesets/8b295953-e0aa-4317-9f6e-3c48aa6ef5ea/download) ([Detail](https://mdr.nims.go.jp/filesets/8b295953-e0aa-4317-9f6e-3c48aa6ef5ea.md))

## Id

3adcd11b-1138-4380-9ad4-0d28d868ed6c

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2025-08-09T06:53:15.700018Z

## Updated at

2025-08-18T07:30:44.359765Z

## Published at

2025-08-18T07:21:28.529831Z

## Doi



## First published url

https://doi.org/10.1016/j.cryogenics.2023.103756

## Date published

2023-10-12

## Recorded date published

2023-12

## Resource type

journal_article

## Manuscript type

vor

## Collection



## Title

- title: Non-magnetic regenerator material of silver oxide for 4 K cryocoolers
  title_type: original
  lang: en

## Description

- description: 'In regenerative cryocoolers, magnetic specific heat is often utilized
    for heat regeneration at cryogenic temperature, such as below 20 K. Magnetic regenerator
    materials of rare earth compound which have sufficient specific heat enabled cryocooler
    to reach below 4 K. However, the magnetic noise emitted from the magnetic materials
    during the refrigeration cycle affects the performance of noise-sensitive devices.
    In this study, we propose a non-magnetic regenerator material having “optical
    phonon degree of freedom” even at cryogenic temperatures, in which silver oxide
    (Ag2O) is selected. Ag2O decomposes at temperature above 410 K in ambient atmosphere,
    whereas we succeeded in fabricating a sintered Ag2O bulk and small particles of
    the size of 0.5 mm with high-density more than 90%. Specific heat measurement
    down to 100 mK was performed for the sintered bulk sample of Ag2O. Below 10 K,
    a non-Debye behavior was observed, suggesting the contribution from optical phonon
    modes. Calculation of the phonon density of state (phDOS) performed by the Evolution
    Strategy algorithm in addition to the first-principles calculation reveals that
    phDOS has several distinct peaks at low energies, and the low-energy optical phonons
    contribute to the non-Debye behavior. The low temperature specific heat of Ag2O
    enhanced by the optical phonons is larger than conventional non-magnetic regenerator
    materials when compared in terms of specific heat per volume. Moreover, the calculation
    of cooling performance of cryocooler using Ag2O particles is found to be reached
    below 4.2 K. This study shows that non-magnetic material with low temperature
    specific heat enhanced by optical phonon mode can be used as a regenerator material
    for regenerative cryocoolers. '
  description_type: abstract
  lang: und

## Creator

- name: Sotaro Nishioka
  role: author
  orcid: https://orcid.org/0000-0002-6728-4293
  organization: National Institute for Materials Science
- name: Shinji Masuyama
  role: author
- name: Akiko T. Saito
  role: author
  orcid: https://orcid.org/0000-0001-5920-5965
  organization: National Institute for Materials Science

## Contact agent



## Publisher

organization: Elsevier BV

## Managing organization



## Keyword

- subject: Regenerator material
  schema: not_defined
- subject: Optical phonon
  schema: not_defined
- subject: Cryocooler
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

## Other identifier(s)



## Data origin

- data_origin_type: other

## Embargo



## Journal

- title: Cryogenics
  issn: '00112275'
  volume: '136'
  article_number: '103756'

## Conference



## Related item



## Funding

- funder_name: National Institute for Materials Science
- identifier: JP21H01267
  funder_name: Japan Society for the Promotion of Science

## Instrument



## Instrument operator



## Instrument managing organization



## Measurement method



## Specimen



## Chemical composition



## Structure for specimen



## Structural feature for specimen



## Specific property for specimen



## Process for specimen treatment



## Computational method



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## Fileset

- id: 8b295953-e0aa-4317-9f6e-3c48aa6ef5ea
  filename: Cryogenics_36_2023_103756.pdf
  content_type: application/pdf
  size: 2433416
  md5: 88b1aa64328c4954eae067000e5d9ffd

## Thumbnail

fileset_id: 8b295953-e0aa-4317-9f6e-3c48aa6ef5ea
filename: Cryogenics_36_2023_103756.pdf