Effect of ZnO particle size on the sintering behavior, phase evolution, and optical properties of transparent borosilicate glazes en en This study investigates the influence of zinc oxide (ZnO) particle size on the properties of SiO2–Al2O3–B2O3–ZnO–CaO–K2O transparent glass–ceramic glazes. Two ZnO sources were employed, including synthesized nano-sized ZnO (~500 nm) and commercial micro-sized ZnO (>1 μm). The results indicate that nano-sized ZnO enhances melting reactivity and modifies the crystallization behavior of the glaze systems compared with micro-sized ZnO. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses revealed differences in phase evolution and crystal morphology depending on ZnO particle size. Nano-sized ZnO promoted finer and more homogeneous crystalline distributions, while micro-sized ZnO resulted in coarser crystalline structures. Furthermore, the optical and surface properties of the glazes were strongly influenced by the balance between densification and crystallization during firing. The results demonstrate that ZnO particle size plays a significant role in controlling the thermal behavior, phase evolution, microstructure, and surface quality of transparent borosilicate glazes. 26 34 Raziye Salami Ceramics Department, Materials and Energy Research Center (MERC), Karaj Iran Aida Faeghinia Ceramics Department, Materials and Energy Research Center (MERC), Karaj Iran a.faeghinia@merc.ac.ir Zahra Khakpour Ceramics Department, Materials and Energy Research Center (MERC), Karaj Iran Mohammad Zakeri Ceramics Department, Materials and Energy Research Center (MERC), Karaj Iran Zinc oxide Glass-ceramic glazes Crystallization behavior Microstructure evolution Borosilicate glass system Transparent ceramics Vol 6 No 1 Paper 3.pdf [1] F.G. Melchiades, B.T. Rego, S.M. Higa, H.J. Alves, A.O. 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