With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have attracted increasing attention. For regular ceramic particles as fillers, it is necessary to achieve the highest filling fraction to obtain high thermal conductivity, yet leading to higher production cost and reduced mechanical properties. In this paper, AlN whiskers with a high aspect ratio were successfully prepared using a modified direct nitriding method, which was further paired with AlN particles as fillers to prepare the AlN/ epoxy composites. It is indicated that AlN whiskers could form bridging links between AlN particles, which favored the establishment of thermal pathways inside the polymer matrix. On this basis, we constructed the 3D AlN skeletons as a thermal conductivity pathway by the freeze-casting method, which could further enhance the thermal conductivity of the composites. The synergistic enhancement effect of 1D AlN whiskers and directional filler skeletons on the composite thermal conductivity was further demonstrated by the actual heat transfer process and finite element simulations. More significantly, the experimental results showed that the addition of one-dimensional fillers could also effectively improve the thermal stability and mechanical properties of the composites, which was beneficial for preparing high-performance TIMs.

As the rapid development of advanced foldable electronic devices, flexible and insulating composite films with ultra-high in-plane thermal conductivity have received increasing attention as thermal management materials. Silicon nitride nanowires (Si 3 N 4 NWs) have been considered as promising fillers for preparing anisotropic thermally conductive composite films due to their extremely high thermal conductivity, low dielectric properties, and excellent mechanical properties. However, an efficient approach to synthesize Si 3 N 4 NWs in a large scale still need to be explored. In this work, large quantities of Si 3 N 4 NWs were successfully prepared using a modified CRN method, presenting the advantages of high aspect ratio, high purity, and easy collection. On the basis, the super-flexible PVA/Si 3 N 4 NWs composite films were further prepared with the assistance of vacuum filtration method. Due to the highly oriented Si 3 N 4 NWs interconnected to form a complete phonon transport network in the horizontal direction, the composite films exhibited a high in-plane thermal conductivity of 15.4 W•m −1 •K −1 . The enhancement effect of Si 3 N 4 NWs on the composite thermal conductivity was further demonstrated by the actual heat transfer process and finite element simulations. More significantly, the Si 3 N 4 NWs enabled the composite film presenting good thermal stability, high electrical insulation, and excellent mechanical strength, which was beneficial for thermal management applications in modern electronic devices.

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In this study, we successfully prepared red‐emitting AlN:Mn2+ spherical phosphors by using nitrogen pressure–assisted carbothermal reduction–nitridation method. The optimum preparation parameters were explored by changing nitrogen pressure, CaF2 content, reaction temperature, and the amount of MnCO3. It was confirmed that uniform spherical shape, large particle size, less impurity content, and suitable Mn2+ concentrations could effectively enhance the luminous intensity of AlN:Mn2+ phosphors. The structural compositions of the AlN:Mn2+ phosphors were characterized by X‐ray diffraction and X‐ray photoelectron spectroscopy, indicating that Mn2+ ions were successfully doped into AlN lattice by substitution of Al3+ ions, thus providing the red‐emitting luminescence centers. Based on the experimental results, we further proposed the underlying growth mechanism of spherical AlN phosphors. It was suggested that an adequate amount of liquid Ca‐aluminates was essential to achieve uniform spherical morphology and high fluorescence efficiency.