Encapsulation of nitride phosphors into sintered phosphate glass by pressureless firing and hot isostatic pressing

Abstract

The encapsulation conditions of Eu2+‐doped calcium silicon nitride ((Ca0.90Eu0.10)2Si5N8) and strontium silicon nitride ((Sr0.98Eu0.02)2Si5N8) phosphors into phosphate glass ((50‐x)Na2O–xZnO–5B2O3–45P2O5; x = 10‐40) were examined by pressureless sintering (normal or infrared firing) and subsequent oxygen‐assisted hot isostatic pressing. The evaluation of water resistivity, as well as glass transition temperature (Tg), indicated that the excellent water resistivity and low Tg (313°C) could be achieved at x = 30. The colorless and clear glass body could be fabricated by infrared firing at 370°C for 20 minutes in air, followed by the hot isostatic pressing at 370°C for 24 hours (80%Ar + 20%O2, pressure: 130 MPa). The encapsulations of 3.0 mass% (Ca0.90Eu0.10)2Si5N8 and (Sr0.98Eu0.02)2Si5N8 into the glass body produced reddish orange light emission (peak wavelength: 604 nm under excitation wavelength of 423 nm) and red‐light emission (617 nm under 383 nm), respectively, showing higher chemical and thermal stability of nitride phosphors in the glass matrix.

Translucent YAG:Ce-SiO2 Composites Prepared by Pressureless Sintering: Structures, Luminescence Properties, and Applications in the White LEDs/LDs

“…Various glass compositions have been developed to encapsulate commercial LED phosphors, such as silicate, phosphate, tellurite, and borate. − However, the glass network modifiers (such as Na + , Zn 2+ , and Ca 2+ ions) lead to severe interfacial reactions between glass matrix and phosphor particles because of high reactivity and diffusivity . Besides, advanced sintering technologies are adopted beyond conventional pressureless sintering, such as hot-pressing sintering, spark plasma sintering (SPS), and gas pressure sintering. − It is noticeable that these high-pressure consolidation techniques usually require sophisticated equipment and processes, and the expected high transparency is seldom obtained. Therefore, it is significant to develop a luminescence-efficient and cost-effective glass ceramic phosphor.…”

Amplified Spontaneous Emission from Perovskite Quantum Dots Inside a Transparent Glass

“…However, the need for a higher sintering temperature (>800 °C) for full densification, will induce a strong interfacial reaction between phosphors particles and glass matrix, resulting in corrosion of phosphors. Although lots of researches are carried out to lower the sintering temperature to inhibit the interfacial reaction by adopting low-melting glasses (e.g., phosphate, tellurite, and low-silica glass), [25][26][27] the melting temperature is still as high as hundreds of degrees. This prevents the majority of semiconductor nanocrystals with excellent optoelectronic properties from being directly incorporated into glass to take advantage of the merits of both precursors.…”

Transparent glass and glass‐ceramic in the binary system NaPO3‐Ta2O5

“…Phosphate glasses are low cost materials and can be easily prepared by melting at low temperature . In addition, these glasses allow a compositional flexibility and the insertion of different elements, such as alkali, transition metals, and rare‐earth ions without hamping their glass forming ability.…”

“…The addition of network modifiers and intermediate compounds can change the structural, thermal, and optical properties of phosphate glasses, increasing the range of applications. Pure phosphate matrixes exhibit high thermal expansion coefficients, high hygroscopicity, and low thermal stability against crystallization, which limit their use for certain optical applications. The insertion of transition metal oxides can improve these properties, as reported in niobium, zinc, tungsten, and molybdenum phosphate glasses.…”