In a remarkable advance poised to reshape solid-state cooling technologies, researchers have unveiled a novel multilayer capacitor (MLC) that achieves substantial electrocaloric (EC) effects across a broad temperature range near ambient conditions. This breakthrough is realized through the ingenious partial substitution of the conventional lead scandium tantalate (PST) ceramic with lead magnesium tungstate (PMW), a move that facilitates low-temperature sintering while preserving the critical B-site cation order. The innovation promises enhanced performance efficiency without the burden of the long, costly annealing traditionally required for PST-based MLCs, marking a significant leap forward in scalable electrocaloric cooling solutions.
Electrocaloric effects, driven by the reversible thermal changes in dielectric materials subjected to electric fields, offer a promising alternative to conventional refrigeration systems. However, practical deployment has been historically hindered by challenges in material processing and device stability under cycling. The key limitation originates from the high-temperature sintering of PST essential for densification, which unfortunately disrupts the delicate ordering of B-site cations—namely high-valence and low-valence ions critical for sustaining latent heat changes. Restoring this disrupted order demands protracted annealing steps exceeding a month, imposing severe cost and time inefficiencies.
The researchers have circumvented this bottleneck by delicately tuning the ceramic composition via partial substitution of PST with PMW. This adjustment exploits the ionic size and valence differences inherent in the B-site cations—Sc³⁺ (0.75 Å) and Ta⁵⁺ (0.64 Å) in PST, alongside Mg²⁺ (0.66 Å) and W⁶⁺ (0.60 Å) in PMW—to maintain a robust B-site ordering even after sintering. By optimizing the sintering temperature to an intermediate 1,250°C, significantly lower than PST’s traditional 1,400°C, the researchers not only achieve adequate densification but critically circumvent the destruction of cation ordering. This eliminates the onerous annealing step altogether, streamlining MLC manufacturing for electrocaloric applications.
Unlike pure PST MLCs that require a 42-day annealing protocol post a 1,400°C sintering cycle to recover cation ordering—and pure PMW MLCs sintered at much lower temperatures (950°C) that maintain ordering but suffer in densification—this PST–PMW solid solution elegantly balances both densification and structural integrity. This balance enables operating within a processing window that preserves functionality while optimizing manufacturing throughput and scalability. This composite structure reportedly maintains strong B-site order and facilitates high breakdown fields necessary for device durability, opening avenues for practical, high-performance EC devices.
The electrocaloric performance under cyclic electric fields further underscores the superiority of these MLCs. Operating with a voltage of 600 V—consistent with voltages applied in PST MLC prototypes—the PST–PMW capacitors exhibit repeatable and robust EC effects. During rigorous testing, including over 322 bipolar cycles totaling 644 voltage applications and exhaustive fatigue tests surpassing 15 million cycles, there was no discernible degradation in EC performance. Such stability is crucial for real-world refrigeration or heat pump designs requiring long operational lifetimes without performance loss.
Crucially, the PST–PMW MLCs demonstrate a markedly attenuated hysteresis typically associated with first-order phase transitions in ferroelectric materials. This anhysteretic, single-phase behavior translates to EC effects that exceed those of pure PST devices by a striking margin—120–160% improvement relative to 23% in the PST-only baseline. This means the composite devices offer larger effective cooling spans and operate efficiently over a wider temperature range without the energy losses typical of hysteresis. The ability to supercritically drive the EC response enhances operational flexibility across ambient and even elevated temperatures.
Moreover, the results suggest considerable headroom for future performance improvements. Since the observed electrocaloric effects at 600 V did not reach saturation, it is anticipated that processing advances aimed at increasing the breakdown voltage will yield even larger cooling effects. This potential positions the PST–PMW system as a platform technology where materials engineering can synergistically raise both capacity and operational voltage thresholds. Enhanced breakdown strength could enable compact, energy-efficient, and scalable EC cooling solutions with unprecedented temperature spans.
The implications of this development resonate beyond the specific PST–PMW materials system. The strategy here—leveraging valence and ionic size mismatches to guide low-temperature sintering while preserving critical atomic ordering—introduces a versatile materials design paradigm. This approach to solid solution engineering and sintering optimization could be broadly applicable to other functional ceramics, including piezoelectric and ferroelectric materials targeting various energy conversion and thermal management applications. Achieving tailored microstructures with minimal processing costs is a coveted goal in advanced ceramics, and this work provides a compelling blueprint.
On the device integration front, the direct replacement of PST MLCs with these PST–PMW composites in current EC prototypes stands to deliver immediate performance enhancements without drastic changes in voltage or form factor. This allows industry partners and technology developers to adopt the improved materials with minimal disruption, accelerating the commercialization of EC cooling devices offering diversified operational temperature spans. Cooling from above to below ambient temperature—a feature elusive in prior materials—is now feasible, broadening the practical appeal of solid-state refrigeration.
Additionally, the study elucidates the underpinning electrothermal mechanisms that jointly sustain latent heat and dipolar order modulation, factors essential for maximizing EC entropy changes. By striking a refined balance between structural order and disorder, the researchers effectively tune the Curie temperature and associated phase transitions to optimize EC responsivity. This careful manipulation of phase behavior through compositional engineering underscores the nuanced interplay of chemistry, thermodynamics, and processing in designing next-generation functional ceramics.
Future work is poised to explore how these insights extend to multilayer capacitor architectures with even finer electrode layering and film thickness optimization. Enhanced geometric control coupled with improved materials properties could translate to higher cooling power densities and efficiencies, critical parameters for portable cooling devices and on-chip thermal management. The exceptional fatigue resistance documented here bodes well for sustained device lifetimes, a key requirement for long-term commercial viability.
In summary, this pioneering development transforms the landscape of electrocaloric materials technology by unlocking widely tunable, efficient, and fatigue-resistant solid-state cooling near room temperature. The combination of a materials science breakthrough—enabling low-temperature sintering without destroying ordering—and comprehensive device-level validation positions PST–PMW MLCs as frontrunners for future electrocaloric cooling applications. The accessibility of this synthetic strategy foreshadows a wave of innovations that extend electrocaloric effects and potentially inspire other functional ceramic applications across electronics, energy, and environment sectors.
Subject of Research: Electrocaloric effects in multilayer capacitors for solid-state cooling applications
Article Title: Electrocaloric effects across room temperature in multilayer capacitors
Article References:
Guo, M., Farenkov, V., Chen, X., et al. Electrocaloric effects across room temperature in multilayer capacitors. Nature (2026). https://doi.org/10.1038/s41586-026-10492-w
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41586-026-10492-w
Keywords: electrocaloric effect, multilayer capacitors, PST, PMW, B-site ordering, low-temperature sintering, solid-state cooling, ferroelectric ceramics, fatigue resistance, breakdown voltage
