• Research Paper

    Steady Shear Rheology and Shear-Induced Microstructural Evolution of Aggregated Magnetic Inks
    Young Sil Lee
    The microstructural transitions of aggregated magnetic inks under shear flow were characterized using a microstructure-based model and validated by experimental data. To … + READ MORE
    The microstructural transitions of aggregated magnetic inks under shear flow were characterized using a microstructure-based model and validated by experimental data. To describe the shear-dependent viscosity and structural dynamics, an elastic floc model was developed within the context of weakly aggregated dispersions. This approach enabled the determination of aggregate dimensions relative to the applied shear rate, providing insight into the structural response of magnetic inks. Findings indicate that floc size is inversely proportional to the particle volume fraction, yet it is surprisingly insensitive to long-range magnetic interactions. We report two shear-induced yielding regimes: the first corresponds to the breakage of the network’s physical connectivity, where inter-floc interactions maintain a residual framework, while the second corresponds to the total rupture of flocs. A comparison of the steady and dynamic shear measurements suggests that the linear viscoelastic region is fundamentally limited by the secondary yielding threshold. This model provides a comprehensive understanding of shear thinning as a synergistic effect of floc deformation and disintegration. - COLLAPSE
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    27 June 2026

  • Research Paper

    Effect of Ultrafine SiO2 Powder on the Hydration Process of Hemihydrate Gypsum and Its Waterproofing Mechanism
    Wenrong Yuan, Qianbao Chen, Jiacan Lin, Liangting Geng, Xuan Wu, Renguo Dou, Won-Chun Oh
    In this study, phospho-silica (SiO2) particles with different characteristic particle sizes were added as raw materials to manufacture β-hemihydrate gypsum … + READ MORE
    In this study, phospho-silica (SiO2) particles with different characteristic particle sizes were added as raw materials to manufacture β-hemihydrate gypsum (β-HPG) through high-temperature firing and pulverization. The effect of patterns and mechanisms of nano-SiO2 with different particle sizes and loading levels (0 to 1.5 %) on the hydration and curing processes of semi-hydrated gypsum, as well as the macroscopic properties and microstructure of cured products, were systematically investigated. The phase composition, chemical structure, pyrolysis behavior, and microstructure evolution of hydrated products were comprehensively characterized by combining them with microscopic analysis methods through tests of macroscopic properties. Results show that the addition of nano-SiO2 significantly reduced the standard consistent moisture requirement of β-semi-hydrated gypsum and optimized the rheological properties of the slurry, while effectively improving the physical properties of cured products, reducing moisture absorption and improving water resistance. Among them, nano-SiO2 with a particle size of 30 nm showed an optimal comprehensive modification effect. The novelty of this study lies in the systematic evaluation of particle-size-dependent effects (15 nm-2 µm) of ultrafine SiO2 on the hydration, mechanical performance, and water resistance of β-hemihydrate gypsum, and the elucidation of why 30 nm particles exhibit optimal comprehensive modification. This study provides a systematic theoretical basis and technical support for the high-value utilization of phosphogypsum and the development of high-performance gypsum-based building materials. - COLLAPSE
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    27 June 2026

  • Research Paper

    Interfacial and Optical Properties of CsPbBr3 Active Layer on Nanoporous GaN Electron Transport Layer

    나노포러스 GaN 전자수송층 기반 CsPbBr3 활성층의 계면 및 광학적 특성 분석

    Kwang Jae Lee

    이광재

    Nanoporous semiconductor structures provide a large interfacial area and tunable surface properties, enabling effective control of material/interface interactions. In this study, nanoporous … + READ MORE
    Nanoporous semiconductor structures provide a large interfacial area and tunable surface properties, enabling effective control of material/interface interactions. In this study, nanoporous GaN (NP GaN) was employed as an electron transport layer (ETL) to incorporate CsPbBr3, and the resulting interfacial and optical characteristics were systematically investigated. NP GaN with a controlled pore fraction (ρpore = 3.7~36.8 %) was fabricated via electrochemical (EC) etching. Cross-sectional SEM analysis revealed that the pore morphology evolves significantly with etching time, forming vertically aligned porous networks with increased pore density, connectivity, and diameter, which enables efficient infiltration of the CsPbBr3 precursor into the NP framework. Consequently, CsPbBr3 on NP GaN exhibits higher photoluminescence (PL) intensity, reduced full width at half maximum (FWHM), and improved internal quantum efficiency (IQE) from 4.9 % to 15.6 %. Temperature-dependent PL (TDPL) analysis revealed suppressed thermal quenching, accompanied by increased activation energy and reduced non-radiative recombination. These results demonstrate that NP GaN effectively modulates interfacial structure and carrier recombination behavior, providing a viable strategy for enhancing the optical performance of perovskite materials. - COLLAPSE
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    27 June 2026
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Journal Informaiton Korean Journal of Materials Research Korean Journal of Materials Research
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