Investigation of instinctive defects in nitrogen enrich lanthanum silicon oxynitride glasses

Abstract

Oxynitride glasses are not yet commercialised primarily due to the impurities present in the network of these glasses. In this work, silicon and silicide defects in nitrogen-rich La-Si-O-N glasses were investigated. Glasses were prepared by heating powder mixture of La metal, Si 3 N 4 , and SiO 2 in a nitrogen atmosphere at 1650-1800°C. The obtained glasses containing an unprecedented amount of N content of up to 68 e/o and La up to 62 e/o in the glass network which reveals a broader glass-forming region in the system than previously reported. The microstructure and impurities in the glasses were examined by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) in conjunction with electron energy-loss spectroscopy (EELS). Analyses showed that the glasses contain a small amount of spherical La silicides particles, mostly amorphous or poorly crystalline, and having sizes typically ranging from 1 µm and less. The amount of silicide was estimated to be less than 2 vol.%. There was no systematic relation between silicide formation and glass composition or preparation temperature, but it was found that particle size decrease with increasing holding time. The limited transparency of high N-containing glasses is expected to have attribution of elemental Si and microscopy analyses, and Raman spectroscopy ascertained silicide particles. Furthermore, a metallic silicide formed by the decomposition of silicon oxide and silicon nitride, then the subsequent reaction of Si and La.

Properties, Bioactivity and Viability of the New Generation of Oxyfluoronitride Bioglasses

“…It can be observed that the replacement of oxygen by nitrogen results in significantly linear increas- es in these properties, but the data do not deviate from the overall tendency. The current results are also consistent with some other data on oxynitride glasses in the literature [14][15][16]. Density, glass transition temperature and mechanical properties have been shown to increase as nitrogen content increases.…”

“…The reduced mechanical potency and intrinsically delicate characteristics of these bioactive glasses have limited their implementation to non-weightbearing uses [11] such as ossicles in the middle ear and various maxillofacial applications [12,13]. One Eurasian Chemico-Technological Journal 26 (2024) 43-52 approach to enhance the strength of the glasses is by incorporating nitrogen into the silicate framework [14,15]. It has been demonstrated that as nitrogen substitutes oxygen in silicate glasses, the glass transition temperature, elastic modulus, and hardness rise progressively with the nitrogen proportion [16,17].…”

Review: Elaboration, structure, and mechanical properties of oxynitride glasses

“…107 Therefore, there should be less metallic micro-particles in the glasses when using AlN, meaning they should be more transparent. However, the consequences of using AlN over Si 3 N 4 changes with the synthesis conditions of the glass: it may provide a clearer glass, 103 have no effect on the transparency, 90 or oppositely remain undissolved in the glass 72,110 as its melting temperature is higher, making the choice of the nitride more complicated than expected.…”