Pub Date : 2026-04-01Epub Date: 2026-02-04DOI: 10.1016/j.cryogenics.2026.104297
Takeshi Araki
Applications of ReBa2Cu3O7-x coils are eagerly anticipated in view of the limited availability of helium. However, the stability of the fabricated ReBa2Cu3O7-x wires appears to suffer from non-uniformity. Countless observations and evaluations have failed to resolve this issue until now. Although many TEM observations have been reported, the observed areas were limited, and local-area studies have not solved the problem. A new method is needed to evaluate the overall uniformity of ReBa2Cu3O7-x at the nanoscale. Recently, we discovered micro-voltage signals when measuring less-uniform superconductors under rapidly increasing current (4 s to Ic) in a high magnetic field above 10 T. Under such extreme conditions, only less-uniform superconductor exhibited these voltage signals. The signals derive neither from the Lorenz force nor from electromagnetic waves. We presume the voltage signals are caused by transient phenomena attributable to temporarily formed magnetic fields perpendicular to the current flow. We named this voltage the inner bypass current voltage (Vibc). By analyzing Vibc, we were able to evaluate the uniformity of AMSC wires, films with clustered atom-replaced pins (CARP), and physically deposited superconductors. We have established a method for comparing the uniformity at the nanoscale and propose a new index of standard uniformity at the nanoscale (SUN). We were able to improve the nanoscale uniformity of superconductors based on SUN.
{"title":"Evaluation of nanoscale uniformity in ReBa2Cu3O7-x superconductors","authors":"Takeshi Araki","doi":"10.1016/j.cryogenics.2026.104297","DOIUrl":"10.1016/j.cryogenics.2026.104297","url":null,"abstract":"<div><div>Applications of ReBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> coils are eagerly anticipated in view of the limited availability of helium. However, the stability of the fabricated ReBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> wires appears to suffer from non-uniformity. Countless observations and evaluations have failed to resolve this issue until now. Although many TEM observations have been reported, the observed areas were limited, and local-area studies have not solved the problem. A new method is needed to evaluate the overall uniformity of ReBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> at the nanoscale. Recently, we discovered micro-voltage signals when measuring less-uniform superconductors under rapidly increasing current (4 s to <em>I</em><sub>c</sub>) in a high magnetic field above 10 T. Under such extreme conditions, only less-uniform superconductor exhibited these voltage signals. The signals derive neither from the Lorenz force nor from electromagnetic waves. We presume the voltage signals are caused by transient phenomena attributable to temporarily formed magnetic fields perpendicular to the current flow. We named this voltage the inner bypass current voltage (<em>V</em><sub>ibc</sub>). By analyzing <em>V</em><sub>ibc</sub>, we were able to evaluate the uniformity of AMSC wires, films with clustered atom-replaced pins (CARP), and physically deposited superconductors. We have established a method for comparing the uniformity at the nanoscale and propose a new index of standard uniformity at the nanoscale (SUN). We were able to improve the nanoscale uniformity of superconductors based on SUN.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104297"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-10DOI: 10.1016/j.cryogenics.2026.104310
Xinpeng Na, Yangzhou Du, Zhenqian Zhang, Yong Li, Lingwei Li
We herein provided experimental investigation of a polycrystalline DyAgSi compound regarding its structural, magnetic and magnetocaloric (MC) properties. The DyAgSi compound crystalizes in a hexagonal ZrNiAl-type structure (space group: P62m) and undergoes an antiferromagnetic transition around TN ∼ 10 K. Large reversible low-temperature MC effect were realized in DyAgSi compound. The MC parameters of maximum isothermal magnetic entropy change and refrigerant capacity of DyAgSi under external field change of 0–7 T are identified as 10.1 J/kgK and 342.3 J/kg, respectively. These values are comparable with some high-performing rare-earth-based cryogenic MC materials. Our studies illustrated that the DyAgSi compound may considerable for cryogenic magnetic cooling.
{"title":"Magnetic properties and magnetocaloric effect in DyAgSi compound","authors":"Xinpeng Na, Yangzhou Du, Zhenqian Zhang, Yong Li, Lingwei Li","doi":"10.1016/j.cryogenics.2026.104310","DOIUrl":"10.1016/j.cryogenics.2026.104310","url":null,"abstract":"<div><div>We herein provided experimental investigation of a polycrystalline DyAgSi compound regarding its structural, magnetic and magnetocaloric (MC) properties. The DyAgSi compound crystalizes in a hexagonal ZrNiAl-type structure (space group: <em>P6<sub>2</sub>m</em>) and undergoes an antiferromagnetic transition around <em>T</em><sub>N</sub> ∼ 10 K. Large reversible low-temperature MC effect were realized in DyAgSi compound. The MC parameters of maximum isothermal magnetic entropy change and refrigerant capacity of DyAgSi under external field change of 0–7 T are identified as 10.1 <!--> <!-->J/kgK and 342.3<!--> <!-->J/kg, respectively. These values are comparable with some high-performing rare-earth-based cryogenic MC materials. Our studies illustrated that the DyAgSi compound may considerable for cryogenic magnetic cooling.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104310"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-10DOI: 10.1016/j.cryogenics.2026.104309
Zhenyu Lin, Hongwei Ji, Xingya Chen
Large-scale hydrogen liquefaction systems typically use the Claude cycle, where the hydrogen turbo-expander reduces energy consumption via isentropic expansion. Existing studies mainly improve expander efficiency but often neglect feasibility under real operating conditions, leaving optimization potential largely untapped. This study proposes a collaborative optimization strategy that simultaneously maximizes isentropic efficiency and minimizes deviation of the characteristic ratio from its target value. By integrating the mean-line method with Multi-Objective Genetic Algorithm (MOGA), this work establishes an optimization framework for the preliminary design of hydrogen turbo-expanders. Compared with the conventional mean-line method, the optimized design increases isentropic efficiency by 5.02% (from a baseline of 81.75%) while keeping the characteristic ratio close to 0.68. This improvement boosts performance while satisfying operational stability requirements. Computational Fluid Dynamics (CFD) simulations of the internal flow field and loss distribution confirm the reliability and effectiveness of the proposed method. Sensitivity analysis shows that the optimized design offers better adaptability to high-load conditions.
{"title":"Preliminary design optimization of a turbo-expander based on a multi-objective genetic algorithm","authors":"Zhenyu Lin, Hongwei Ji, Xingya Chen","doi":"10.1016/j.cryogenics.2026.104309","DOIUrl":"10.1016/j.cryogenics.2026.104309","url":null,"abstract":"<div><div>Large-scale hydrogen liquefaction systems typically use the Claude cycle, where the hydrogen turbo-expander reduces energy consumption via isentropic expansion. Existing studies mainly improve expander efficiency but often neglect feasibility under real operating conditions, leaving optimization potential largely untapped. This study proposes a collaborative optimization strategy that simultaneously maximizes isentropic efficiency and minimizes deviation of the characteristic ratio from its target value. By integrating the mean-line method with Multi-Objective Genetic Algorithm (MOGA), this work establishes an optimization framework for the preliminary design of hydrogen turbo-expanders. Compared with the conventional mean-line method, the optimized design increases isentropic efficiency by 5.02% (from a baseline of 81.75%) while keeping the characteristic ratio close to 0.68. This improvement boosts performance while satisfying operational stability requirements. Computational Fluid Dynamics (CFD) simulations of the internal flow field and loss distribution confirm the reliability and effectiveness of the proposed method. Sensitivity analysis shows that the optimized design offers better adaptability to high-load conditions.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104309"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rapid development of hydrogen propulsion for aerospace has created demanding requirements for enabling lightweight, efficient liquid hydrogen (LH2) storage. The National Aeronautics and Space Administration (NASA) and others are seeking to reduce mass by developing composite cryogenic tanks to replace metallic varieties. However, the inclusion of composites, adhesives, and metallic flanges complicates the management of residual strains that arise from thermal mismatch, curing, and thermal cycling. If left unaddressed, these strains result in interfacial damages such as microcracking, delamination, and debonding, which in turn compromise long-term performance. This comprehensive review discusses the factors that control the generation of residual strain between composites and metals in composite–adhesive–flange joints, including coefficients of thermal expansion mismatch between carbon fiber-reinforced polymer composites, cryogenic adhesives, and metals, as well as curing, thermal gradients in the joints, and environmental exposure. Experimental and simulation techniques strain gages, Digital Image Correlation (DIC), X-ray or neutron diffraction, and FEA are evaluated against their performance in determining stress fields and failure predictions. Mitigation strategies can be classified as material modification, design optimization, and process improvement. Fillers such as carbon nanotubes (CNTs), graphene, or MXenes improve the toughness and thermal stability of the adhesive, whereas joint design changes, including tapers, spew fillets, and reverse tapers, can lower peel and shear stresses. The development of smart composites, such as self-sensing adhesives with FBGs and sensors based on CNTs and negative co-efficient of thermal expansion (CTE) fillers enables in situ monitoring and adaptive stress redistribution at cryogenic temperatures. This review provides a roadmap to minimize residual strain and guarantee the reliability of next-generation hydrogen storage for aerospace missions and sustainable energy.
{"title":"A comprehensive review on the mitigation of residual strain in the composite–adhesive–flange interface of liquid hydrogen storage tanks","authors":"Ananth Selvan , Indran Suyambulingam , Arun Srinivasan , Sunesh Narayanaperumal , P. Senthamaraikannan","doi":"10.1016/j.cryogenics.2026.104298","DOIUrl":"10.1016/j.cryogenics.2026.104298","url":null,"abstract":"<div><div>The rapid development of hydrogen propulsion for aerospace has created demanding requirements for enabling lightweight, efficient liquid hydrogen (LH<sub>2</sub>) storage. The National Aeronautics and Space Administration (NASA) and others are seeking to reduce mass by developing composite cryogenic tanks to replace metallic varieties. However, the inclusion of composites, adhesives, and metallic flanges complicates the management of residual strains that arise from thermal mismatch, curing, and thermal cycling. If left unaddressed, these strains result in interfacial damages such as microcracking, delamination, and debonding, which in turn compromise long-term performance. This comprehensive review discusses the factors that control the generation of residual strain between composites and metals in composite–adhesive–flange joints, including coefficients of thermal expansion mismatch between carbon fiber-reinforced polymer composites, cryogenic adhesives, and metals, as well as curing, thermal gradients in the joints, and environmental exposure. Experimental and simulation techniques strain gages, Digital Image Correlation (DIC), X-ray or neutron diffraction, and FEA are evaluated against their performance in determining stress fields and failure predictions. Mitigation strategies can be classified as material modification, design optimization, and process improvement. Fillers such as carbon nanotubes (CNTs), graphene, or MXenes improve the toughness and thermal stability of the adhesive, whereas joint design changes, including tapers, spew fillets, and reverse tapers, can lower peel and shear stresses. The development of smart composites, such as self-sensing adhesives with FBGs and sensors based on CNTs and negative co-efficient of thermal expansion (CTE) fillers enables in situ monitoring and adaptive stress redistribution at cryogenic temperatures. This review provides a roadmap to minimize residual strain and guarantee the reliability of next-generation hydrogen storage for aerospace missions and sustainable energy.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104298"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-06DOI: 10.1016/j.cryogenics.2026.104306
Hongyu Lv , Liang Chen , Yunkai Li , Ze Zhang , Shuangtao Chen , Yu Hou
Cryogenic liquids, characterized by boiling points well below ambient temperature, are highly susceptible to evaporation losses due to external heat infiltration. Ineffective mitigation of these losses during storage and transport leads to substantial energy waste. However, the design of low-heat-leakage insulation structures for cryogenic containers remains a significant research challenge. To address this, a high-precision heat leakage measurement platform was designed and constructed to test the insulation performance of cryogenic systems. The system features a configurable vapor-cooled shield (VCS), enabling comparative experiments with and without the VCS. The results show that under various conditions, the composite insulation structure with VCS reduces heat flux by approximately 20% compared to conventional multilayer insulation. The study also clarifies the influence of VCS structure and configuration on insulation performance, identifying the optimal structure as a U-shaped VCS placed at the 21st layer within the multilayer insulation structure for the liquid nitrogen temperature range. Based on interlayer temperature distribution, it is demonstrated that in the liquid nitrogen experiment, the VCS primarily improves insulation by suppressing heat conduction through solids and residual gases. This research confirms the significant insulation advantages of VCS, offering key experimental support and structural optimization insights for large-scale storage and transportation of liquid hydrogen and other cryogenic media.
{"title":"Experimental investigation of thermal insulation mechanisms and structural characteristics of vapor-cooled shields","authors":"Hongyu Lv , Liang Chen , Yunkai Li , Ze Zhang , Shuangtao Chen , Yu Hou","doi":"10.1016/j.cryogenics.2026.104306","DOIUrl":"10.1016/j.cryogenics.2026.104306","url":null,"abstract":"<div><div>Cryogenic liquids, characterized by boiling points well below ambient temperature, are highly susceptible to evaporation losses due to external heat infiltration. Ineffective mitigation of these losses during storage and transport leads to substantial energy waste. However, the design of low-heat-leakage insulation structures for cryogenic containers remains a significant research challenge. To address this, a high-precision heat leakage measurement platform was designed and constructed to test the insulation performance of cryogenic systems. The system features a configurable vapor-cooled shield (VCS), enabling comparative experiments with and without the VCS. The results show that under various conditions, the composite insulation structure with VCS reduces heat flux by approximately 20% compared to conventional multilayer insulation. The study also clarifies the influence of VCS structure and configuration on insulation performance, identifying the optimal structure as a U-shaped VCS placed at the 21st layer within the multilayer insulation structure for the liquid nitrogen temperature range. Based on interlayer temperature distribution, it is demonstrated that in the liquid nitrogen experiment, the VCS primarily improves insulation by suppressing heat conduction through solids and residual gases. This research confirms the significant insulation advantages of VCS, offering key experimental support and structural optimization insights for large-scale storage and transportation of liquid hydrogen and other cryogenic media.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104306"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-29DOI: 10.1016/j.cryogenics.2026.104296
Takashi Hirayama , Yutaro Koike
In regenerative cryocoolers, the regenerator is composed of stacked layers of the regenerator material in the form of wire meshes or spheres, and the voids of the regenerator are filled with a working fluid, such as helium gas. Widespread experiments have been carried out in the temperature range above room temperature on the friction factor which indicates flow resistance generated by the working gas as it passes through the regenerator. However, it remains unclear whether these experimental formulae are still valid in the cryogenic temperature range in which GM cryocoolers operate, where experimental uncertainty can become significant. Therefore, a new system was developed to measure the friction factor at cryogenic temperatures. The developed system was used to measure the friction factor in zinc spheres which are a typical regenerator material. The measurements revealed that the friction factor varied at cryogenic temperatures compared with that at room temperature. This variation was attributed to changes in the porosity within the regenerator. This paper describes the details of the developed system and the results of the experiments. These results provide necessary verification for applying room-temperature correlations to cryogenic regenerators.
{"title":"Experimental observation of friction factor variation in regenerators at cryogenic temperatures","authors":"Takashi Hirayama , Yutaro Koike","doi":"10.1016/j.cryogenics.2026.104296","DOIUrl":"10.1016/j.cryogenics.2026.104296","url":null,"abstract":"<div><div>In regenerative cryocoolers, the regenerator is composed of stacked layers of the regenerator material in the form of wire meshes or spheres, and the voids of the regenerator are filled with a working fluid, such as helium gas. Widespread experiments have been carried out in the temperature range above room temperature on the friction factor which indicates flow resistance generated by the working gas as it passes through the regenerator. However, it remains unclear whether these experimental formulae are still valid in the cryogenic temperature range in which GM cryocoolers operate, where experimental uncertainty can become significant. Therefore, a new system was developed to measure the friction factor at cryogenic temperatures. The developed system was used to measure the friction factor in zinc spheres which are a typical regenerator material. The measurements revealed that the friction factor varied at cryogenic temperatures compared with that at room temperature. This variation was attributed to changes in the porosity within the regenerator. This paper describes the details of the developed system and the results of the experiments. These results provide necessary verification for applying room-temperature correlations to cryogenic regenerators.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104296"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-29DOI: 10.1016/j.cryogenics.2026.104295
Yudong Bao , Huakai Liu , Junhong Tang , Wenqing Du
Cryoprobes play a crucial role in enhancing the success rate of cryosurgery and reducing patient discomfort.However, the safety and precision requirements of cryosurgery pose significant challenges for the development of cryoprobes.This paper is the first to systematically review the heat transfer model of frozen probes and propose strategies for advancing internal heat transfer mechanisms and bioheat transfer models for biological tissues. This paper classifies and studies internal heat transfer mechanisms, including single-probe and multi-probe, and summarises the latest research progress in biological heat transfer models.This paper classifies and studies internal heat transfer mechanisms, including single-probe and multi-probe, and summarises the latest research progress in biological heat transfer models.Finally, future research directions for cryoprobe technology are proposed, including heat transfer mechanisms, cryoprobe material optimisation, tissue-specific heat transfer optimisation, heat transfer detection and feedback, etc. Promote the development of precision cryosurgery and facilitate cross-disciplinary innovation between medicine and engineering.
{"title":"A systematic review of bioheat transfer models in cryosurgery","authors":"Yudong Bao , Huakai Liu , Junhong Tang , Wenqing Du","doi":"10.1016/j.cryogenics.2026.104295","DOIUrl":"10.1016/j.cryogenics.2026.104295","url":null,"abstract":"<div><div>Cryoprobes play a crucial role in enhancing the success rate of cryosurgery and reducing patient discomfort.However, the safety and precision requirements of cryosurgery pose significant challenges for the development of cryoprobes.This paper is the first to systematically review the heat transfer model of frozen probes and propose strategies for advancing internal heat transfer mechanisms and bioheat transfer models for biological tissues. This paper classifies and studies internal heat transfer mechanisms, including single-probe and multi-probe, and summarises the latest research progress in biological heat transfer models.This paper classifies and studies internal heat transfer mechanisms, including single-probe and multi-probe, and summarises the latest research progress in biological heat transfer models.Finally, future research directions for cryoprobe technology are proposed, including heat transfer mechanisms, cryoprobe material optimisation, tissue-specific heat transfer optimisation, heat transfer detection and feedback, etc. Promote the development of precision cryosurgery and facilitate cross-disciplinary innovation between medicine and engineering.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104295"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-02-11DOI: 10.1016/j.cryogenics.2026.104311
Yunhui Wang , Tingwei Wan , Yanan Zhao , Zuhua Chen , Zhenxing Li , Heng Tu , Jun Shen , Guochun Zhang
Two hydrated sulfate crystals, K2Mn(SO4)2·4H2O and NH4Cr(SO4)2·12H2O, were grown from the aqueous solution by the spontaneous nucleation and the slow cooling method. Their magnetic and magnetocaloric properties were systematically investigated by measuring magnetic susceptibility (χ) and magnetization (M), and thermal behaviors were also surveyed by the thermogravimetric analysis (TG)-differential scanning calorimetric (DSC) measurements. At 2 K and μ0ΔH = 7 T, the maximum magnetic entropy changes (−ΔSM) reach 36.22 J·kg⁻1·K⁻1 for K2Mn(SO4)2·4H2O and 22.37 J·kg⁻1·K⁻1 for NH4Cr(SO4)2·12H2O, respectively. Moreover, under the magnetic field changes of 7 T, the relative cooling capacity (RCP) and refrigeration capacity (RC) values reach 219.1 J·kg⁻1 and 160.8J·kg⁻1 for K2Mn(SO4)2·4H2O, 101.6 and 76.9J·kg⁻1 for NH4Cr(SO4)2·12H2O. The results indicate that the hydrated sulfate crystals have potential significant applications as refrigerants in the field of low-temperature magnetic refrigeration.
{"title":"Magnetocaloric properties of K2Mn(SO4)2·4H2O and NH4Cr(SO4)2·12H2O crystals","authors":"Yunhui Wang , Tingwei Wan , Yanan Zhao , Zuhua Chen , Zhenxing Li , Heng Tu , Jun Shen , Guochun Zhang","doi":"10.1016/j.cryogenics.2026.104311","DOIUrl":"10.1016/j.cryogenics.2026.104311","url":null,"abstract":"<div><div>Two hydrated sulfate crystals, K<sub>2</sub>Mn(SO<sub>4</sub>)<sub>2</sub>·4H<sub>2</sub>O and NH<sub>4</sub>Cr(SO<sub>4</sub>)<sub>2</sub>·12H<sub>2</sub>O, were grown from the aqueous solution by the spontaneous nucleation and the slow cooling method. Their magnetic and magnetocaloric properties were systematically investigated by measuring magnetic susceptibility (<em>χ</em>) and magnetization (<em>M</em>), and thermal behaviors were also surveyed by the thermogravimetric analysis (TG)-differential scanning calorimetric (DSC) measurements. At 2 K and <em>μ<sub>0</sub>ΔH</em> = 7 T, the maximum magnetic entropy changes (−Δ<em>S<sub>M</sub></em>) reach 36.22 J·kg⁻<sup>1</sup>·K⁻<sup>1</sup> for K<sub>2</sub>Mn(SO<sub>4</sub>)<sub>2</sub>·4H<sub>2</sub>O and 22.37 J·kg⁻<sup>1</sup>·K⁻<sup>1</sup> for NH<sub>4</sub>Cr(SO<sub>4</sub>)<sub>2</sub>·12H<sub>2</sub>O, respectively. Moreover, under the magnetic field changes of 7 T, the relative cooling capacity (RCP) and refrigeration capacity (RC) values reach 219.1 J·kg⁻<sup>1</sup> and 160.8J·kg⁻<sup>1</sup> for K<sub>2</sub>Mn(SO<sub>4</sub>)<sub>2</sub>·4H<sub>2</sub>O, 101.6 and 76.9J·kg⁻<sup>1</sup> for NH<sub>4</sub>Cr(SO<sub>4</sub>)<sub>2</sub>·12H<sub>2</sub>O. The results indicate that the hydrated sulfate crystals have potential significant applications as refrigerants in the field of low-temperature magnetic refrigeration.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104311"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peak trapped field intensity and uniform field distribution are mutually critical parameters determining the viability of REBCO bulks in functional devices. In this study, the magnetic trapped field (Btr) of REBCO bulk superconductors has been investigated using the MATLAB-based numerical simulations. Emphasis is placed on how the superconducting bulk dimensions, air–gap height, and the number of units in an array influence the Btr. A computational model was established by decomposing the superconducting bulk into finite concentric square loops and use the Biot-Savart law. The findings are as follows: (1) For a square bulk, the maximum value of the Btr-m saturates when the thickness-to-side ratio is about 1.4; (2) With the same volume, the maximum Btr-m decreases from 0.86 T (one bulk) to 0.38 T (four-unit array), a drop of about 55.81%; (3) The uniformity of the Btr was observed to first increase and then decrease as the air–gap height increased. The peak uniformity was achieved at an air–gap height of 6 mm, beyond which uniformity degraded by more than 70%. These results highlight a trade-off between material cost and electromagnetic performance, guiding optimization of superconducting bulk arrays for magnetic levitation and high-field magnets.
{"title":"Dimensions and array effects on trapped field optimization in REBCO bulk superconductors","authors":"Huihan Yang, Kuerban Wujiamuniyazi, Abulizi Abulaiti","doi":"10.1016/j.cryogenics.2026.104307","DOIUrl":"10.1016/j.cryogenics.2026.104307","url":null,"abstract":"<div><div>Peak trapped field intensity and uniform field distribution are mutually critical parameters determining the viability of REBCO bulks in functional devices. In this study, the magnetic trapped field (<em>B<sub>tr</sub></em>) of REBCO bulk superconductors has been investigated using the MATLAB-based numerical simulations. Emphasis is placed on how the superconducting bulk dimensions, air–gap height, and the number of units in an array influence the <em>B<sub>tr</sub></em>. A computational model was established by decomposing the superconducting bulk into finite concentric square loops and use the Biot-Savart law. The findings are as follows: (1) For a square bulk, the maximum value of the <em>B<sub>tr-m</sub></em> saturates when the thickness-to-side ratio is about 1.4; (2) With the same volume, the maximum <em>B<sub>tr-m</sub></em> decreases from 0.86 T (one bulk) to 0.38 T (four-unit array), a drop of about 55.81%; (3) The uniformity of the <em>B<sub>tr</sub></em> was observed to first increase and then decrease as the air–gap height increased. The peak uniformity was achieved at an air–gap height of 6 mm, beyond which uniformity degraded by more than 70%. These results highlight a trade-off between material cost and electromagnetic performance, guiding optimization of superconducting bulk arrays for magnetic levitation and high-field magnets.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"156 ","pages":"Article 104307"},"PeriodicalIF":2.1,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2026-01-16DOI: 10.1016/j.cryogenics.2026.104286
Ingrid Torres , Alex Krasnok
The performance and scalability of cryogenic microwave systems, particularly for quantum processors, are fundamentally limited by the thermal stability and loss of their constituent dielectric materials. While mixed titanate ceramics like MgTiO3–CaTiO3 (MCT) and (Zr,Sn)TiO4 (ZST) are primary candidates, their comparative performance as radiative antennas in the deep-cryogenic regime has remained uncharacterized. Here we present a side-by-side comparison of MCT and ZST operated as dielectric resonator antennas from 296 K down to 7 K–10 K under identical fixtures and protocols. While the MCT resonator exhibits large, nonlinear frequency drift (230 MHz by 10 K), pronounced thermal hysteresis, and a collapse of the loaded quality factor at low temperature—behavior consistent with incipient/relaxor-like losses—the ZST resonator demonstrates exceptional stability. Its resonant frequency shifts by only 30 MHz, its loaded -factor is enhanced by 20%–25%, and it shows negligible thermal hysteresis. Leveraging these properties, we operate the ZST disk as a radiative antenna at 10 K with only 1 mW input, establishing a through-window wireless link that detects room-temperature dielectric targets over multiple wavelengths via near-field frequency shifts and far-field magnitude modulations. Full-wave simulations are used to set a room-temperature baseline; window-related multipath is isolated experimentally via open/closed-window control measurements. This presents a viable path toward non-invasive cryogenic diagnostics and wireless interconnects that circumvent the thermal load of physical cabling. Our findings establish ZST as a foundational material for high-coherence cryogenic interfaces and provide a practical template for designing wireless cryogenic systems.
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