Silicon Oxide Nitride Research Articles

Minimizing Risk of Failure from Ceramic-on-Ceramic Total Hip Prosthesis by Selecting Ceramic Materials Based on Tresca Stress

The choice of ceramic-on-ceramic coupling in total hip prosthesis has advantages over couplings with other combinations of materials that use polyethylene and metal materials in terms of high hardness, scratch resistance, low wear rate, and increased lubrication performance. To reduce the risk of primary postoperative failure, the selection of ceramic materials for ceramic-on-ceramic coupling is a strategic step that needs to be taken. The current study aims to analyze ceramic-on-ceramic coupling with commonly used ceramic materials, namely zirconium dioxide (ZrO2), silicon nitride (Si3N4), and aluminium oxide (Al2O3), according to Tressa failure criterion for the investigation of the stress distribution. A two-dimensional axisymmetric finite element-based computational model has been used to evaluate the Tresca stress on ceramic-on-ceramic coupling under gait cycle. The results show that the use of ZrO2-on-ZrO2 couplings can reduce Tresca stress by about 17.34% and 27.23% for Si3N4-on-Si3N4 and Al2O3-on-Al2O3 couplings, respectively.

Composition, structure, and magnetic properties of SiCxNyFez films produced by the PECVD method from a gas mixture of 1,1,1,3,3,3-hexamethyldisilazane, ferrocene, and helium

Composite SiCxNy:Fez films with magnetic properties were obtained by plasma-enhanced chemical vapor deposition from gas mixtures of hexamethyldisilazane, ferrocene, and helium. In the work, the ratio of elements of the initial gas phase was varied at a constant synthesis temperature of 873 K, which made it possible to obtain films that differ significantly in the content of elements, but are similar in structure. Using a complex of modern research methods: infrared spectroscopy, Raman spectroscopy, energy-dispersive X-ray spectroscopy, the relationship between changes in the concentration of elements of the initial gas mixture and changes in the composition of SiCxNy:Fez films was established. The structure of the obtained samples was studied by X-ray photoelectron spectroscopy, extended X-ray absorption fine structure, and X-ray phase analysis. Based on the data obtained, it is assumed that, in the studied range of conditions, the obtained films can be attributed to two different materials. Films containing less than 13% iron consist of an amorphous SiCxNy matrix with inclusions of disordered carbon and iron silicides. Films containing more than 27% iron are composite. The composite includes disordered carbon, iron silicides, and iron carbides. As well as inclusions of silicon nitride, silicon oxide and carbon nitride. It is assumed that the magnetic properties of the films are due to the content of iron silicides and iron carbides in them. Films containing more than 27 at% iron have ferromagnetic properties with a Curie temperature above room temperature.

Enhanced sensitivity of surface plasmon resonance biosensor for the selective detection of immunoglobin (IgG)

In this work, we propose a surface plasmon resonance (SPR) biosensor based on a hybrid structure of silicon nitride (Si3N4), molybdenum trioxide (MoO3), and graphene oxide (GO) in the Kretschmann configuration. To investigate the performance parameters of the SPR biosensor, we calculate, theoretically, the reflectance spectra of the proposed model and analysed it. The investigation of various performance parameters i.e., sensitivity, detection accuracy, and quality factor, of sensor configuration are theoretically done with the optimized thickness of silver (55 nm), silicon nitride (5 nm), molybdenum trioxide (10 nm), and graphene oxide (2.55 nm) respectively. The sensitivity, detection accuracy, and figure of merit for the proposed SPR structure are found at 301 deg./RIU, 4.01, and 133 RIU−1 respectively for the detection of IgG. Furthermore, the present SPR biosensor shows improved sensitivity as compared to the other reported works. The refractive index of the analyte changes from 1.33 to 1.37 due to adsorption of the analyte at the GO surface. The proposed sensor design can detect the small change in the refractive index of the sensing media doped with the analyte.

Influence of the Addition of Sialon and Aluminum Nitride Fillers on the Photocuring Process of Polymer Coatings

This article presents the results of a study on polymer coatings containing poly ethoxylated bisphenol A diacrylate (Bis-AEA10) with aluminum silicon nitride oxide (Sialon) and aluminum nitride (AlN). The polymer coatings were obtained by the photopolymerization technique. Investigations were carried out to determine the effect of the AlN and Sialon content on the UV-curing kinetics, as well as on the mechanical (hardness), thermal (Tg, thermal stability), physicochemical (water contact angle), and structural properties of the polymer coatings. Polymerization rates were characterized as functions of double-bond conversion using the photo-Differential Scanning Calorymetry technique (photo-DSC). The results obtained showed that a small addition of sialon filler (3–5 wt.%) to Bis-AEA10 increases the photopolymerization rate of the varnish, while the addition of more Sialon decreases the rate of photopolymerization. However, for the systems containing AlN filler, the maximum polymerization rate was observed for samples containing 10 wt.% filler. In the case of a varnish composition containing AlN, the maximum polymerization rate is characterized by the system containing 10 wt.% of AlN. This shows that the AlN filler has a good influence on the polymerization process. In either case, the final double bond conversion was high (80%–95%). Mechanical tests have shown that introducing the filler into the polymer matrix increases its hardness. The content of Sialon and AlN in the coatings causes an increase (up to 4–5 wt.%) and a decrease (>4–5 wt.%) in the glass transition temperature. The effect of the addition of fillers on the physicochemical properties of the coating surface has also been investigated and characterized by the water contact angle method. The addition of 20 wt.% Sialon and AlN increased the contact angle of the samples by approximately 40% and 31%, respectively, resulting in coatings with hydrophobic surface properties.

Chip platforms with synthetic lipid bilayers for electrophysiological analyses of pore proteins and extracellular vesicles

In this paper, we present microfluidic chip platforms to enable electrophysiological measurements of nanometer-sized extracellular vesicles. The basis of the chip platform is the realization of a synthetic free-standing lipid bilayer spanned within a microfabricated aperture. To allow ion channel current measurements, the background current noise level should be reduced to a minimum. This can be realized by coating microfabricated apertures from silicon, silicon oxide, or silicon nitride with PTFE or Parylene. Three promising chip platform designs are presented. Electrophysiological measurements conducted with these microfluidic systems show gating events of membrane proteins fused into synthetic lipid bilayers.

Modification strategies for improving antibacterial properties of polyetheretherketone

AbstractPolyetheretherketone (PEEK) is a semi‐crystalline thermoplastic polymer that has been gradually used in the repair of bone defects because of its well chemical stability, reliable biocompatibility, excellent X‐ray radiolucency, and low modulus. However, PEEK is a biologically inert material, and planktonic bacteria can adhere to its surface and eventually form biofilms, allowing for the rapid development of implant‐related infections. This review mainly introduces two important antibacterial modification strategies: antibacterial coating and surface morphology modification. Antibacterial coating include antibiotics, natural extracts, antimicrobial peptides, polymers, metals and metal oxides, selenium, fluoride, silicon nitride, and graphene oxide. These coatings can exert their antibacterial effect by inhibiting bacterial adhesion, killing bacteria by contact, or actively releasing antimicrobial substances. In terms of antibacterial surface topography, different surface microstructures have their respective antibacterial functions. Conical or cylindrical structures can exert stress on the bacterial surface causing the rupture of the cell membrane to kill bacteria. Nano protrusions or particles smaller than the size of bacteria can inhibit the adhesion of bacteria by reducing the contact area of bacteria and PEEK. The pit structure close to the size of bacteria can prevent the contact between adjacent bacteria and delay or prevent the formation of biofilm.

Synchronously improved thermal conductivity and dielectric constant for epoxy composites by introducing functionalized silicon carbide nanoparticles and boron nitride microspheres

Polymer-based dielectrics with high thermal conductivity and superb dielectric properties hold great promising for advanced electronic packaging and thermal management application. However, integrating these properties into a single material remains challenging due to their mutually exclusive physical connotations. Here, an ideal dielectric thermally conductive epoxy composite is successfully prepared by incorporating multiscale hybrid fillers of boron nitride microsphere (BNMS) and silicon dioxide coated silicon carbide nanoparticles (SiC@SiO2). In the resultant composites, the microscale BNMS serve as the principal building blocks to establish the thermally conductive network, while the nanoscale SiC@SiO2 as bridges to optimize the heat transfer and suppress the interfacial phonon scattering. In addition, the special core–shell nanoarchitecture of SiC@SiO2 can significantly impede the leakage current and generate a great deal of minicapacitors in the composites. Consequently, favorable thermal conductivity (0.76 W/mK) and dielectric constant (∼8.19) are simultaneously achieved in the BNMS/SiC@SiO2/Epoxy composites without compromising the dielectric loss (∼0.022). The strategy described in this study provides important insights into the design of high-performance dielectric composites by capitalizing on the merits of different particles.

(Invited, Digital Presentation) Interface Charge Trapping and Scattering in SiC MOSFET Channels

The channel conductivity of SiC MOSFETs is severely limited by charge trapping at interface states and mobility limiting scattering processes. In this talk, the status of interface state passivation for both n- and p-channel 4H-SiC MOSFETs will be presented. First, results from capacitance-based methods to extract interface state density (Dit) across the entire 4H-SiC band gap for thermally grown nitrided silicon dioxide gate dielectrics will be presented, emphasizing the critical importance of the SiO2(N)/SiC interface composition and nitrogen bonding. Next, the scattering mechanisms for channel electrons and holes in these devices will be analyzed and contrasted by Hall measurements. [1] The transport will be characterized as a function of temperature and substrate-bias within an effective transverse electric field model. The final part of the talk will focus on latest development on deposited dielectrics for 4H-SiC. Deposited dielectrics are an attractive alternative to thermal oxidation as it minimizes the release of carbon and the perturbation of surface crystal structure and opens the possibility of ‘high-k’ dielectrics with higher permittivity than SiO2. Herein, the key importance of 4H-SiC surface control prior to dielectric deposition will highlighted using results obtained for atomic layer deposition (ALD) of Aluminum Oxide (Al2O3) [2]. To this end, a systematic variation of SiC surface termination with processes involving oxygen, hydrogen and nitrogen will be presented. The composition of the deposited films and the interfacial bonding will be characterized for various deposition processes and correleated with electrical measurements . It will be demonstrated that surface nitridation followed by H2 annealing prior to ALD results in a factor of 2 higher channel mobility than typical NO annealed thermal SiO2. This is due to the formation of stable sub-nm SiON layers that passivates the surface and enables the formation of high-quality interfaces between SiC and deposited dielectric. In addition, the results indicate that clean Si-H terminated surfaces formed by hydrogen etching and annealing, prior to dielectric deposition leads to uniform nucleation of Al2O3. The reduction of Dit is also accompanied by improvements in oxide charge trapping and bias instability, but dielectric leakage current is significantly higher for Al2O3 compared to SiO2 due to bulk trap-assisted tunneling in Al2O3. The reliability is a significant challenge that need to be overcome to exploit the enhanced mobilities and make deposited dielectrics competitive with traditional nitrided SiO2.Acknowledgments: The authors acknowledge support from the US Army Research Laboratory (grant ARMY-W911NF-18-2-0160) and US Department of Energy (subcontracted to National Renewable Energy Laboratory, grant NREL-AHL-9-92632-01). The authors also acknowledge the support Dr. Leonard C. Feldman (Auburn, Rutgers) and Mr. Hengfei Gu (Rutgers) for help with XPS measurements. The authors also deeply thank Ms. T Isaacs-Smith, Ms. Lu Wang (Auburn), Dr. K. Ramadoss and Dr. D. Morisette (Purdue Univ.) for useful discussions and help with fabrication.[1] S. Das et al., J. Appl. Phys. 130, 225701, (2021).[2] I. U. Jayawardhena et al., J. Appl. Phys. 129, 75702, (2021) Figure 1

Stress engineered SU-8 dielectric-microbridge based polymer MEMS Pirani gauge for broad range hermetic characterization

The paper introduces a SU-8 dielectric µ-bridge based polymer microelectromechanical systems (MEMS) Pirani gauge which can be employed for hermetic characterization of packaged electronic sensors. The µ-bridge structure is adopted due to its simplicity in fabrication and lower footprint, which makes it feasible for heterogeneous integration. Further, the integration of SU-8 polymer with the active thermistor offers superior thermal isolation from the substrate and extends the dynamic range. Before fabricating the actual device, the SU-8 based µ-bridge is optimized for stress-free release. A stress engineering is performed and thermal processing of SU-8 is optimized. The measurement results reveal that the removal of quenching from the baking steps leads to the successful fabrication of freely suspended µ-bridge with SU-8 polymer as a structural layer. A quantitative comparison of the proposed gauge is established by comparing the gauge performance with conventional dielectric materials like silicon dioxide (SiO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3). The fabricated SU-8 polymer-based MEMS Pirani gauge with a 40 µm × 7 µm footprint can be used for hermetic characterization from 30 Pa to 105 Pa and is an ideal candidate for heterogeneous integration.

Optimal Design of Ceramic Based Hip Implant Composites Using Hybrid AHP-MOORA Approach.

Designing excellent hip implant composite material with optimal physical, mechanical and wear properties is challenging. Improper hip implant composite design may result in a premature component and product failure. Therefore, a hybrid decision-making tool was proposed to select the optimal hip implant composite according to several criteria that are probably conflicting. In varying weight proportions, a series of hip implant composite materials containing different ceramics (magnesium oxide, zirconium oxide, chromium oxide, silicon nitride and aluminium oxide) were fabricated and evaluated for wear and physicomechanical properties. The density, void content, hardness, indentation depth, elastic modulus, compressive strength, wear, and fracture toughness values were used to rank the hip implant composites. It was found that the density and void content of the biocomposites remain in the range of 3.920–4.307 g/cm3 and 0.0021–0.0089%, respectively. The composite without zirconium oxide exhibits the lowest density (3.920 g/cm3), while the void content remains lowest for the composite having no chromium oxide content. The highest values of hardness (28.81 GPa), elastic modulus (291 GPa) and fracture toughness (11.97 MPa.m1/2) with the lowest wear (0.0071 mm3/million cycles) were exhibited by the composites having 83 wt.% of aluminium oxide and 10 wt.% of zirconium oxide. The experimental results are compositional dependent and without any visible trend. As a result, selecting the best composites among a group of composite alternatives becomes challenging. Therefore, a hybrid AHP-MOORA based multi-criteria decision-making approach was adopted to choose the best composite alternative. The AHP (analytic hierarchy process) was used to calculate the criteria weight, and MOORA (multiple objective optimisation on the basis of ratio analysis) was used to rank the composites. The outcomes revealed that the hip implant composite with 83 wt.% aluminium oxide, 10 wt.% zirconium oxide, 5 wt.% silicon nitride, 3 wt.% magnesium oxide, and 1.5 wt.% chromium oxide had the best qualities. Finally, sensitivity analysis was conducted to determine the ranking’s robustness and stability concerning the criterion weight.

Physical Compact Model for Three‐Terminal SONOS Synaptic Circuit Element

A well‐posed physics‐based compact model for a three‐terminal silicon–oxide–nitride–oxide–silicon (SONOS) synaptic circuit element is presented for use by neuromorphic circuit/system engineers. Based on technology computer aided design (TCAD) simulations of a SONOS device, the model contains a nonvolatile memristor with the state variable QM representing the memristor charge under the gate of the three‐terminal element. By incorporating the exponential dependence of the memristance on QM and the applied bias V for the gate, the compact model agrees quantitatively with the results from TCAD simulations as well as experimental measurements for the drain current. The compact model is implemented through VerilogA in the circuit simulation package Cadence Spectre and reproduces the experimental training behavior for the source–drain conductance of a SONOS device after applying writing pulses ranging from −12 V to +11 V, with an accuracy higher than 90%.

Performance Analysis of Fully Depleted SOI (FD-SOI) MOSFET Incorporating Dielectric Engineering

This paper presents an efficacy of an FD SOI MOSFET structure in suppressing short channel effects is investigated through 2-Dimenional simulation on ATLAS Silvaco. The electrical comparison between Bulk MOSFET, FD-SOI MOSFET and FD-SOI MOSFET using high-k gate dielectric at 45nm technology has been carried out. The structures have been designed and study of threshold voltage, sub threshold slope, drain current (Ion), leakage current (Ioff), Ion/Ioff, transconductance has been done. The features offered by the new device structure are found to be better than the conventional bulk MOSFET. Aluminum Oxide (Al2O3) has been compared to SiO2 as dielectric material. As the dielectric constant of the materials increased, there is a reduction in the leakage current. It provides higher transconductance and better subthreshold slope, thus resulting in improvement of the device. A comparative analysis has been carried out among bulk MOSFET and SOI MOSFET using aluminum oxide, silicon oxide and silicon nitride as gate dielectric materials. Aluminum Oxide also provides higher drain current as compared to other dielectric materials presented in the paper. Thus, Aluminum Oxide is a good candidate as a dielectric for the future devices as compared to traditional oxides. The proposed device can be useful for low power applications.

Thermal simulation of micro hotplate for multiple MEMS gas sensors

With the development of MEMS technologies, research on MEMS gas sensor has emerged recently, and micro hotplate (MHP) is designed to provide suitable temperature for MEMS gas sensor. Heat properties of MHP profoundly influence the sensing properties of MEMS gas sensor. With the tendency of down-sizing in MEMS gas sensors, traditional temperature measurements such as contact measure and infrared temperature detection are no longer available due to relatively low resolution. In this work we used finite element analysis (FEA) to realize cost- and time-saving heat property evaluations for MEMS gas sensor with different MHP structures, and two indexes were introduced to describe heat properties of MHPs, such as area factor Q to describe area of isotherm and roundness of isotherm % R to evaluate isotherm shape. It is found that silicon oxide and silicon nitride suspension structures have different tendency in heat properties. The size of working area has important impacts on the heat properties of the MHP, and MHP with different working area may be applied in different applications. For instance, larger MHP with 1643 μm 2 /K area factor Q is suitable for noble metal catalytic gas sensing application, which requires uniform temperature distribution, and smaller MHP, which could reach 609 °C peak temperature at 30 mW power-consumption, is applied to IoT applications with battery power supply. Furthermore, some special characteristics of the heat distribution of MHP are found with adjusting the width of suspension beams. This work provides guidance on how to design proper sensing material shapes to utilize the performance of MHP and reduce heat loss.

Effect of Ultrathin Silicon Oxide and Titanium Nitride Composite Layer on Photogenerated Electron Export

Effect of Ultrathin Silicon Oxide and Titanium Nitride Composite Layer on Photogenerated Electron Export

Gettering in silicon photovoltaics: A review

A key efficiency-limiting factor in silicon-based photovoltaic (PV) devices is the quality of the silicon material itself. With evolving cell architectures that better address other efficiency-loss channels in the device, the final device efficiency becomes increasingly sensitive to the contaminants in the silicon wafer bulk. However, due to cost constraints, silicon materials for PV are inherently less pure and further contamination during device fabrication is commonly found, especially in mass production environments. Metallic impurities are ubiquitous and abundant, and they are strong efficiency-loss channels in the device if not removed. Gettering is the process of removing metallic impurities to a less harmful region of the device, and is therefore an essential aspect of the cell fabrication process. This article presents an up-to-date review of the gettering techniques and processes in silicon solar cells, providing a complete picture of the possible gettering sinks and routes in various cell architectures. The article starts by explaining the common nomenclatures in gettering and summarising recent updates to the solubility and diffusivity data of the common 3d transition metals in silicon. Then the three-step gettering process (release, diffusion, capture) is explained, and its implications for solar-grade cast-grown silicon (in terms of release) and various cell architectures (in terms of diffusion) are discussed. The main focus of the article is to summarise and review the various capture approaches in the context of silicon PV. These include phosphorus diffusion, boron diffusion, selective doping via ion implantation, state-of-the-art polycrystalline-silicon/oxide passivating contact structures, dielectric films (silicon nitride and aluminium oxide), aluminium alloying, surface damaged regions including black silicon, and internal gettering in cast-grown silicon by existing crystallographic defects. Their gettering effects, current understanding of the gettering mechanisms, modelling, improvement strategies, implementation in processing and potential impacts on cell performance are reviewed.

Pre-metal dielectric PE TEOS oxide pitting in 3D NAND: mechanism and solutions

In 3D NAND, as the stack number increases, the process cost becomes higher and higher, and the stress problem becomes more and more serious. Therefore, the low cost and low stress plasma enhanced tetraethyl orthosilicate (PE TEOS), compared to high density plasma (HDP) oxide, shows its superiority as pre-metal dielectric (PMD) oxide layer in 3D NAND. This paper explores the challenges in the application of PE TEOS in 3D NAND PMD oxide layer. In our experiment both PE TEOS and HDP are employed as the PMD oxide for 3D NAND staircase protection. There is not any void found in the two oxide structures. However, oxide pitting is spotted in the subsequent diluted hydrofluoric acid wet etching in the PE TEOS split. Moreover, we observe that the top silicon nitride corrodes in hot phosphoric acid. We study the mechanism of PE TEOS oxide pitting and silicon nitride corroding, propose two solutions: (1) HDP oxide + PE TEOS, and (2) PE TEOS + dry etching. Experimental results demonstrate that our solutions can well address the issue of PE TEOS oxide pitting and effectively protect the staircase structure. This work extends the application of PE TEOS oxide of which the cost and the stress are both low in 3D NAND.

Steep Subthreshold Swing and Enhanced Illumination Stability InGaZnO Thin-Film Transistor by Plasma Oxidation on Silicon Nitride Gate Dielectric.

In this paper, an InGaZnO thin-film transistor (TFT) based on plasma oxidation of silicon nitride (SiNx) gate dielectric with small subthreshold swing (SS) and enhanced stability under negative bias illumination stress (NBIS) have been investigated in detail. The mechanism of the high-performance InGaZnO TFT with plasma-oxidized SiNx gate dielectric was also explored. The X-ray photoelectron spectroscopy (XPS) results confirmed that an oxygen-rich layer formed on the surface of the SiNx layer and the amount of oxygen vacancy near the interface between SiNx and InGaZnO layer was suppressed via pre-implanted oxygen on SiNx gate dielectric before deposition of the InGaZnO channel layer. Moreover, the conductance method was employed to directly extract the density of the interface trap (Dit) in InGaZnO TFT to verify the reduction in oxygen vacancy after plasma oxidation. The proposed InGaZnO TFT with plasma oxidation exhibited a field-effect mobility of 16.46 cm2/V·s, threshold voltage (Vth) of −0.10 V, Ion/Ioff over 108, SS of 97 mV/decade, and Vth shift of −0.37 V after NBIS. The plasma oxidation on SiNx gate dielectric provides a novel approach for suppressing the interface trap for high-performance InGaZnO TFT.

Evaluation of dominant loss mechanisms of PERC cells for optimization of rear passivating stacks

In this paper a comprehensive theoretical analysis has been carried out for Passivated Emitter Rear Contact (PERC) solar cells with the help of numerical modeling using Sentaurus TCAD simulation software. For the rear passivation we have explored various dielectric layers, such as, Aluminium Oxide (Al2O3), Silicon Oxide (SiO2), Hafnium Oxide (HfO2) and Aluminium Nitride (AlN) along with the Silicon Nitride (SiNx) capping layer. Optical generation near the rear side the passivating stacks was analyzed. Recombination current densities were also evaluated for assorted defects with various concentration, hole and electron capture cross sections and position of quasi Fermi level for surface passivation. Thicknesses of the passivating and capping layers were optimized with respect to optical and electrical losses. Field effect passivation (FEP) property of the rear passivating stacks was also investigated. For simulated textured Al-BSF solar cell on silicon wafer of bulk lifetime 250µs, an efficiency of 19.5% was obtained. This solar cell has been used here for reference. We have achieved efficiency of 22.6% for PERC solar cells of rear contact area of 8% on similar type of wafer. It was noticed from few articles that industrial PERC solar cells were fabricated using rear metal contact less than 10% which is well validating our study. It was also perceived that employing Passivated Emitter Rear Totally Diffused (PERT) structure with optimized design parameters further improved the efficiency to ∼ 24%.

Selective wet etching and hydrolysis of polycrystalline AlN films grown by metal organic chemical vapor deposition

Polycrystalline AlN grown on Si3N4 by metal organic chemical vapor deposition is found to be wet etched by EKC265™ polymer strip solution, in which the active component is hydroxylamine (H3NO). The etch rate shows to be strongly dependent on surface oxides that can be dissolved in deionized water by hydrolysis. An etch rate of 1.2 nm/min was achieved for an AlN surface in optimal condition. The etching process appears to be mainly anisotropic, etching along the grain boundaries of the AlN layer, and being highly selective over silicon nitride, silicon dioxide and aluminum oxide.

Microstructure Evaluation and Impurities in La Containing Silicon Oxynitrides.

Oxynitride glasses are not yet commercialised primarily due to the impurities present in the network of these glasses. In this work, we investigated the microstructure and instinctive defects in nitrogen rich La−Si−O−N glasses. Glasses were prepared by heating a powder mixture of pure La metal, Si3N4, and SiO2 in a nitrogen atmosphere at 1650–1800 °C. The microstructure and impurities in the glasses were examined by optical microscopy, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy in conjunction with electron energy-loss spectroscopy. Analyses showed that the glasses contain a small amount of spherical metal silicide 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. The microstructure examination revealed that the opacity of these nitrogen rich glasses is due to the elemental Si arise from the decomposition reaction of silicon nitride and silicon oxide, at a high temperature above ~1600 °C and from the metallic silicide particles formed by the reduction of silicon oxide and silicon nitride at an early stage of reaction to form a silicide intermetallic with the La metal.