As the world’s demand for refrigeration escalates, driven by population growth and technological advances, the environmental costs of traditional vapor-compression refrigeration technologies grow ever more concerning. Conventional systems predominantly employ fluorocarbon-based refrigerants, which contribute significantly to global warming due to their high global warming potential. In recent years, efforts to find viable, environmentally friendly alternatives have gained momentum, yet many existing solid-state caloric materials, though promising, have faced limitations related to cooling capacity and inefficient heat transfer mechanisms.

A groundbreaking development by Zhang, Liu, Gao, and colleagues, published in Nature, introduces an entirely new paradigm: harnessing an extreme barocaloric effect arising directly from pressure-induced dissolution and precipitation phenomena in ammonium thiocyanate (NH4SCN) aqueous solutions. This now unveiled thermodynamic mechanism bypasses the limitations posed by conventional solid-state phase transitions, offering dramatic improvements in temperature change, cooling capacity, and energy efficiency.

The authors demonstrate that when external pressure is applied to an NH4SCN aqueous solution, it triggers a reversible dissolution-precipitation process. This dynamic phase behavior leads to an unprecedented temperature drop of up to 26.8 Kelvin at near-ambient conditions, a value that surpasses all previously reported caloric materials. This exceptional temperature modulation is attributed to the large entropy changes associated with solvation and crystallization, amplified by precise pressure tuning.

This pivotal insight into dissolution-driven barocaloric response challenges the longstanding focus on solid-solid phase transitions in caloric refrigeration research. Unlike traditional barocaloric, magnetocaloric, or electrocaloric materials requiring indirect heat exchange via secondary fluids, the aqueous nature of this solution facilitates direct heat transfer. The self-circulating liquid phase enhances thermal conductivity and system integration, circumventing inefficiencies that previously hindered practical adoption.

Through meticulous experimental characterization paired with theoretical modeling, the research team designed a Carnot-like refrigeration cycle operating between solubility-driven phase boundaries. The cycle achieves a cooling capacity of 67 Joules per gram per cycle, coupled with an impressive second-law efficiency of 77%, a substantial leap from efficiencies reported in solid-state caloric technologies. Such high efficiency is attributable to the large latent heat and minimal irreversible losses, suggesting immense potential for real-world refrigeration applications.

Beyond its technical merit, the NH4SCN aqueous system exemplifies sustainability. The key components are non-toxic, abundant, and pose minimal environmental risk compared to fluorocarbon refrigerants. The operational simplicity and scalability of this approach further enhance its attractiveness as a viable alternative for residential cooling, commercial refrigeration, and possibly industrial heat management.

The implications extend deeply into the refrigeration sector’s carbon footprint reduction strategies. By leveraging a chemically driven caloric effect, this solution offers a pathway to achieve durable, low-carbon refrigeration devices without reliance on complex magnetocaloric or electrocaloric materials, which often require rare or costly elements. Moreover, the liquid-state system’s fast response and reversibility enhance flexibility and control in temperature regulation.

While the discovery marks a significant milestone, the researchers acknowledge challenges remain. Optimal engineering of system components to harness the pressure-tuned phase transitions rapidly and reversibly will be critical. Additionally, long-term cycling stability and integration into existing cooling infrastructure warrant further investigation. Nevertheless, the fundamental breakthrough in exploiting dissolution-linked barocaloric effects is poised to spur renewed innovation.

Scientific communities are already exploring potential expansions of this principle to other salt solutions and chemistries. Preliminary data suggest that similar pressure-responsive solubility transitions in alternative aqueous or even organic systems could yield tailored caloric properties suited for diverse temperature ranges and cooling capacities. This versatility further broadens the horizons for caloric refrigeration deployment.

In sum, this study represents a transformative leap toward sustainable refrigeration technology grounded in fundamental chemistry and thermodynamics. Its combination of extreme barocaloric performance, environmental benignity, and operational efficiency embodies the core aspirations of next-generation cooling methods to meet global sustainability goals. As further research and development accelerate, widespread adoption could dramatically curtail the ecological impacts of global refrigeration.

This work not only signals a fresh frontier in caloric materials but also challenges researchers and industry to reconceptualize refrigeration beyond traditional frameworks. The pressure-mediated dissolution approach integrates the best facets of caloric and solution chemistry into a powerful and practical refrigeration modality. Its emergence could redefine standards for low-carbon cooling technologies across sectors worldwide.

As this pioneering avenue matures, it will be essential to foster interdisciplinary collaborations encompassing material science, chemical engineering, and environmental policy to ensure scalable, economically feasible technologies reach consumers broadly. The profound potential of extreme barocaloric effects at dissolution heralds an exciting era in refrigeration innovation, marrying cutting-edge science with urgent climate imperatives.

Ultimately, the discovery reported by Zhang et al. stands as a beacon of ingenuity, demonstrating that unlocking nature’s complex phase equilibria through applied pressure can yield revolutionary functional materials and processes. The journey from laboratory feasibility to commercial refrigeration realities holds promise to reshape how humanity cools its homes, preserves food, and powers industrial processes—sustainably and efficiently.

Subject of Research: Barocaloric refrigeration via pressure-tuned dissolution and precipitation in ammonium thiocyanate aqueous solutions.

Article Title: Extreme barocaloric effect at dissolution.

Article References:
Zhang, K., Liu, Y., Gao, Y. et al. Extreme barocaloric effect at dissolution. Nature (2026). https://doi.org/10.1038/s41586-025-10013-1

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41586-025-10013-1

Keywords: barocaloric effect, sustainable refrigeration, ammonium thiocyanate, dissolution precipitation, caloric materials, pressure-tuned phase transitions, cooling capacity, energy efficiency

Solid-state thermoelectric refrigeration has long been regarded as a potentially game-changing technology due to its ability to operate without moving parts, reducing energy consumption and minimizing noise. Historically, however, commercially available thermoelectric materials have faced performance limitations, hindering their broader application in high-efficiency systems. APL’s CHESS materials, developed over a decade of research, address these challenges head-on, achieving nearly double the efficiency of conventional thermoelectric materials at room temperature. This significant leap forward in material performance opens doors to a wide variety of applications in industries that demand compact and efficient cooling solutions.

In a recent publication in Nature Communications, APL’s collaborative research team conducted rigorous tests comparing refrigeration modules built using traditional bulk thermoelectric materials to those crafted with CHESS thin-film materials. The findings were nothing short of revolutionary. They discovered that the new CHESS materials demonstrated nearly 100% improvement in thermal efficiency when confronted with standard cooling demands of everyday refrigerator systems. This efficiency improvement translates to a substantial upgrade in the performance metrics of refrigeration technologies, enabling these systems to deliver better cooling while consuming less energy.

The CHESS mechanism capitalizes on nano-engineered features that elevate heat-pumping capacity, which is crucial for the performance of any refrigeration system. By implementing advanced engineering techniques, the researchers were able to create thin films that excel in moving heat through specialized semiconductor materials. This innovative technology not only heralds a new era for thermoelectric devices but sets a new benchmark in energy efficiency that is critically needed in our increasingly technology-driven world. The need for reliable cooling solutions continues to grow as global temperatures rise and urban populations expand, creating mounting pressure on existing cooling technologies.

One of the most compelling aspects of the CHESS technology is its scalability. Unlike traditional systems that rely heavily on bulky components and chemical refrigerants, CHESS materials can be integrated into smaller, more efficient devices without compromising performance. This means that as the technology matures, it could easily transition from small-scale applications—such as portable refrigerators—to large systems capable of cooling entire buildings. This adaptability emphasizes not only the flexibility of the technology but also its importance in addressing environmental concerns associated with conventional cooling methods, which often involve harmful substances and energy-inefficient operations.

The research team leveraged advanced manufacturing techniques to fabricate these materials, employing metal-organic chemical vapor deposition (MOCVD). This established method is widely used in the production of high-efficiency solar cells, demonstrating its capacity for large-scale manufacturing. The employment of MOCVD means that the CHESS materials can be produced in bulk, leading to reduced production costs and accelerated market entrance. This financial viability is essential for ensuring that new technologies can compete with and eventually supplant older, less environmentally-friendly systems.

The CHESS materials come in incredibly small quantities, requiring merely 0.003 cubic centimeters per refrigeration unit—approximately the size of a grain of sand. This efficiency in material usage underscores not only the innovative nature of the CHESS technology but also its potential impact on the supply chain of cooling products. This drastic reduction in required materials can facilitate production scalability while driving down costs, thus enhancing accessibility across various market segments.

Looking ahead, the implications of the research extend beyond mere refrigeration solutions. The ability of CHESS materials to convert temperature differences, such as human body heat, into usable power introduces exciting possibilities. This feature could support a range of applications, particularly in wearable technology where efficient energy conversion is essential. The integration of such materials could unlock new ways to power devices, allowing for self-sustained systems that capitalize on ambient energy—broadening the horizons of energy harvesting technologies.

Continuing research in this field will not only focus on increasing the efficiency of thermoelectric materials to challenge traditional mechanical cooling systems but will also explore the integration of artificial intelligence to optimize cooling systems further. By employing smart technologies, it may be possible to enhance energy efficiency dramatically, catering to compartmentalized cooling needs within modern HVAC systems. This integration represents a proactive approach to evolving existing technologies to meet consumer demands while adhering to environmental sustainability.

The success of this collaborative project between the APL researchers and industry experts from Samsung Electronics signals a transformative shift in cooling technology. It emphasizes that high-efficiency solid-state refrigeration is not just a scientific curiosity but a commercially viable solution that can be manufactured at scale. As this technology continues to develop, it stands poised to make a substantial impact on sectors yearning for energy-efficient and sustainable cooling solutions amid rising global temperatures.

In conclusion, the advancements achieved through the development of CHESS materials mark a significant step forward, not only in terms of thermoelectric cooling devices but also regarding broader applications in energy harvesting and electronics. With ongoing efforts to refine and commercialize these innovations, APL and its partners aim to establish a new era in thermoelectric technology, one that is capable of addressing modern challenges while paving the way for sustainable solutions in the energy landscape.

Subject of Research: Development of thermoelectric materials and refrigeration technology
Article Title: Groundbreaking Advancements in Thermoelectric Materials for Refrigeration
News Publication Date: May 21, 2023
Web References: N/A
References: N/A
Image Credits: Johns Hopkins APL/Ed Whitman

Keywords

Thermoelectric materials, solid-state cooling, refrigeration technology, nanotechnology, energy efficiency, environmental sustainability.