Distorted thermal properties: Thermoelectric devices can convert waste heat into electricity, providing one path for improving energy efficiency. Jiang et al. leveraged entropy engineering to synthesize a single-phase high-entropy alloy with attractive thermoelectric properties. By increasing the number of elements in the alloy, the resulting disorder helps to stabilize against breakdown into multiple phases. The disordered and distorted crystal lattice suppresses thermal transport while maintaining the electrical properties, which boosts the heat-conversion efficiency of the material. Science , this issue p. 830

Lower-cost thermoelectrics: Thermoelectric materials convert heat to electricity, making them attractive for heat harvesting or cooling applications. However, many high-performance thermoelectrics are made of expensive or toxic materials. He et al. found that a material composed of primarily tin and sulfur could be optimized to have relatively good thermoelectric properties. Introducing about 10% selenium to tin sulfide helped tune these properties by electronic band manipulation. This material is a step toward more earth-abundant, less toxic, and lower-cost thermoelectrics than the telluride-based materials currently in use. Science , this issue p. 1418

Lead-based piezoelectric materials are currently facing global restrictions due to their lead toxicity. Thus it is urgent to develop lead-free substitutes with high piezoelectricity and temperature stability, among which, potassium-sodium niobate [(K,Na)NbO₃, KNN] has the most potential. It is very difficult to simultaneously achieve high piezoelectric performance and reliable stability in KNN-based systems. In particular, the structural/physical origin for their high piezoelectricity is still unclear, which hinders property optimization. Here we report the achievement of high temperature stability (less than 10% variation for electric field-induced strain from 27 °C to 80 °C), good fatigue properties (stable up to 10⁶ cycles) as well as an enhanced piezoelectric coefficient (d₃₃) of 525 pC N⁻¹ in (1 − x)(K_1−yNa_y)(Nb_1−zSb_z)O₃–xBi_0.5(Na_1−wK_w)_0.5HfO₃ (KNNS–BNKH) ceramics through manipulating the rhombohedral–tetragonal (R–T) phase boundary. The structural origin of their high piezoelectric performance can be attributed to a hierarchical nanodomain architecture, where the local structure inside nanodomains comprises R and T nanotwins. The physical origin can be attributed to low domain wall energy and nearly vanishing polarization anisotropy, facilitating easy polarization rotation among different states. We believe that the new breakthrough will open a window for the practical applications of KNN-based ceramics.