Pure silica glass is a highly promising inorganic material for a range of applications in fields including microfluidics and photonics, owing to its remarkable characteristics, such as high transparency, stability, electrical insulation, and low thermal expansion. In the glass industry, large-sized pure silica glass is commonly produced using melting and quenching techniques, such as selective laser melting and precision glass molding methods. These traditional fabrication techniques suffer from the low producibility, difficulty to produce complex structures, as well as high energy consumption. To overcome such technical limitations, scientists developed the additive manufacturing (AM) techniques to easily shape and high-throughput fabricate silica glass at low temperatures. In their strategy, amorphous silica nanopowder is mixed with photopolymers or thermoplastics to obtain silica-organic nanocomposites with a high silica loading. Such hybrid composites are structured at low temperatures (< 150 ℃) via various AM technologies to obtain centimeter-sized or micro-sized green bodies with tailored shapes. Subsequently, the printed structures are densified into silica glass after a series of debinding and sintering processes at temperatures below 1300 ℃. Furthermore, the development of phosphor-in-silica glass (PiSG) led to the creation of spectral converters that combine the high luminescence efficiency of phosphors with the excellent chemical/thermal stabilities of silica glass, facilitating the production of high-power and stable light-emitting-diodes (LEDs). The manufacture of PiSG is often achieved using sophisticated and expensive high-pressure and high-vacuum techniques (e.g., spark plasma sintering), which produce PiSG with a low productivity and limited shapes. In order to fabricate PiSG with customized shapes, AM/sintering technology was developed through incorporating the phosphor powder into silica-organic nanocomposites, which is transformed into translucent PiSG after sintering. Recently, transparent silica glass and PiSG with customized shapes were produced using AM/sintering methods. These innovative techniques allow for facile shaping and production of silica glass and PiSG at relatively low temperatures. Among AM/sintering techniques, injection molding (IM)/sintering method is characterized by its rapid molding, energy efficiency and cost-effectiveness, making it suitable for large-scale industrial production of silica glass and PiSG with intricate shapes and tailored sizes. It is interesting to note that the molding time of hybrid composite using IM equipment is much shorter than other AM technologies, which requires only 5 s to mold one piece. This makes IM technology promising approach for high-throughput fabrication of silica glass and PiSG.

This review focuses on the latest developments in the fabrication of silica glass and PiSG utilizing IM/sintering method. Additionally, we provide an overview for the potential applications of injection-molded silica glass and PiSG in the fields of microfluidics and photonics. At first, we highlight the detailed experimental procedures for the fabrication of silica glass via IM/sintering technology and how such technique succeeded in the manufacture of centimeter-sized and micro-sized silica glass with complex structures and high productivity. In addition, we discuss the influence of water debinding process on the quality of the injection-molded silica glass. Water debinding serves a dual purpose: it enhances silica nanoparticle packing by augmenting surface charge and molecular order, and it minimizes the formation of micro-pores by reducing the volume of polymers available for decomposition during thermal debinding. This overall reduction in pore population facilitates the subsequent densification process during sintering. Afterwards, the development of IM/sintering for the manufacture of PiSG using different phosphor powders, e.g., Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce), Mg₂Al₄Si₅O₁₈:Eu²⁺ (MAS:Eu), Y₃Al₅O₁₂:Cr³⁺ (YAG:Cr), and persistent phosphors, was discussed. The results showed that the interfacial interaction between phosphor particles and silica glass was well suppressed during sintering process and thus the luminescence performance of phosphor was retained in PiSG samples. Therefore, the PiSG spectral converters fabricated by IM followed by pressureless sintering exhibited a high luminescence efficiency, moderate transparency, and superior chemical and thermal stabilities. Furthermore, the fabrication of efficient and stable PiSG color converters by IM/sintering, enables the construction of high-power LEDs with long lifetime, covering the visible and near-infrared (NIR) spectral regions for lighting and bioimaging applications. This implies that IM/sintering technology may play a crucial role in the high-throughput fabrication of silica glass and PiSG that enables the production of cheap LEDs and microfluidic devices for numerous practical applications.