The intrinsic competition among multiple charge-transfer (CT) pathways in copper-phenylacetylide (PhC₂Cu) has hindered the desirable development of its photoactive properties, whereas substantial spectral and temporal overlap among these pathways has obscured direct mechanistic understanding. Herein, hydrostatic pressure is employed as a clean and reversible external stimulus to continuously compress the one-dimensional Cu(I)-Cu(I) ladder in pristine PhC₂Cu without modifying its chemical composition. In situ high-pressure photoluminescence and transient absorption spectroscopy reveal a pressure-induced evolution of CT from copper to the acetylide carbon. High-pressure crystallographic analysis and X-ray absorption near-edge structure measurements demonstrate that anisotropic contraction of the Cu(I) ladder reconstructs the copper coordination environment and consequently modulates the relative contributions of metal-to-ligand CT pathways. These structure-dependent electronic dynamics provide direct insight into the CT mechanism of PhC₂Cu and establish hydrostatic pressure as a general and non-destructive strategy for investigating CT processes in one-dimensional (1D) coordination compounds.

The preparation of dense Si₃N₄-based ceramics has attracted great attention because of the achievable improvements in their mechanical properties and high-temperature oxidation resistance. In this work, advanced dense boron-containing α/β-Si₃N₄/Si monoliths were prepared via a high pressure‒high temperature technique in which polymer-derived amorphous SiBN powders were used as raw materials. The crystallization behavior and phase transformation of the polymer-derived amorphous samples were studied in the temperature range from 1400 to 1800 °C. The results demonstrate that the incorporation of boron in the Si₃N₄ matrix suppresses the phase transformation from α-Si₃N₄ to β-Si₃N₄. Furthermore, the mechanical properties of the as-prepared samples were measured, and the maximum hardness and fracture toughness of boron-rich SiBN samples reached 14.8 GPa and 7.96 MPa·m^1/2, respectively. The hardness of the obtained boron-rich SiBN samples is stable up to 300 °C. In addition, the oxidation behavior of the samples prepared at 1400 and 1600 °C was investigated at 1400 °C for 50 h. The results show that the incorporation of boron significantly improved the oxidation resistance of the samples because of the formation of borosilicate/cristobalite. This work provides guidance for the synthesis of boron-containing α/β-Si₃N₄-based ceramics with excellent mechanical properties and oxidation resistance.