Cold sintering is a newly developed low-temperature sintering technique that has attracted extensive attention in the fabrication of functional materials and devices. Low sintering temperatures allow for a substantial reduction in energy consumption, and simple experimental equipment offers the possibility of large-scale fabrication. The cold sintering process (CSP) has been demonstrated to be a green and cost-effective route to fabricate thermoelectric (TE) materials where significant grain growth, secondary phase formation, and element volatilization, which are prone to occur during high-temperature sintering, can be well controlled. In this review, the historical development, understanding, and application of thermoelectric materials produced via cold sintering are highlighted. The latest attempts related to the cold sintering process for thermoelectric materials and devices are discussed and evaluated. Despite some current technical challenges, cold sintering provides a promising and sustainable route for the design of advanced high-performance thermoelectrics.

With the rapid development of the electronics industry, the demand for dielectric materials with high permittivities, low losses, and excellent electrical breakdown strengths prepared via low-temperature fabrication techniques is increasing. Herein, we propose a one-step cold sintering process route to improve the comprehensive performance of BaTiO₃−based ceramics by integrating polyetherimide (PEI). Dense BaTiO₃–PEI nanocomposites can be prepared via a cold sintering process at 250 °C using Ba(OH)₂∙8H₂O and H₂TiO₃ as the transient liquid phase. The grain growth of BaTiO₃ is inhibited, and thin PEI layers less than 10 nm in size are located at the grain boundaries. The dissolution‒precipitation process triggered by the transient liquid phase and viscous flow assisted by PEI dominates the cold sintering mechanism of the (1−x)BaTiO₃–xPEI nanocomposites. The dielectric properties are stable over a broad temperature range up to 200 °C. Compared with BaTiO₃, 80% BaTiO₃–20% PEI has superior performance, with a relative permittivity of 163 and a low dielectric loss of 0.014, and the electrical breakdown strength is increased by 80.65% compared with BaTiO₃. Overall, the cold sintering process provides a potential way to develop dielectric nanocomposites with excellent comprehensive performance.

Composite coatings or films with polytetrafluoroethylene (PTFE) are typically utilized to offer superhydrophobic surfaces. However, the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods. Herein, we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method, cold sintering process (CSP), at 300 ℃. (1–x) ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol% are densified with relative density of over 97%. Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases, which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites. For the 60 vol% ZnO–40 vol% PTFE ceramic composite, superhydrophobic properties are optimized with static water contact angles (WCAs) and sliding angles (SAs) of 162° and 7°, respectively. After abrading into various thicknesses (2.52, 2.26, and 1.99 mm) and contaminating with graphite powders on the surface, WCA and SA are still maintained with a high level of 157°–160° and 7°–9.3°, respectively. This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.

A series of high-k [(Na_0.5Bi_0.5)_xBi_1−x](W_xV_1−x)O₄ (abbreviated as NBWV(x value)) solid solution ceramics with a scheelite-like structure are synthesized by a modified solid-state reaction method at the temperature range of 680–760 ℃. A monoclinic (0 ≤ x < 0.09) to tetragonal scheelite (0.09 ≤ x ≤ 1.0) structural phase transition is confirmed by X-ray diffraction (XRD), Raman, and infrared (IR) analyses. The effect of structural deformation and order–disorder caused by Na⁺/Bi³⁺/W⁶⁺ complex substitution on microwave dielectric properties is investigated in detail. The compositional series possess a wide range of variable relative permittivity (ε_r = 24.8–80) and temperature coefficient of resonant frequency (TCF value, −271.9–188.9 ppm/℃). The maximum permittivity of 80 and a high Q×f value of ~10,000 GHz are obtained near the phase boundary at x = 0.09. Furthermore, the temperature-stable dielectric ceramics sintered at 680 ℃ with excellent microwave dielectric properties of ε_r = 80.7, Q×f = 9400 GHz (at 4.1 GHz), and TCF value = −3.8 ppm/℃ are designed by mixing the components of x = 0.07 and 0.08. In summary, similar sinterability and structural compatibility of scheelite-like solid solution systems make it potential for low-temperature co-fired ceramic (LTCC) applications.