Y2O3 MgO Nanocomposites Research Articles

Physiochemical etching characteristics and surface analysis of Y2O3-MgO nanocomposite under different CF4/Ar/O2 plasma atmospheres

During plasma etching in the semiconductor manufacturing process, not only the wafers but also the ceramic components that make up the interior of the chamber are influenced by the highly reactive plasma. Because chemical and physical etching work concurrently, and selective etching is possible by controlling the plasma gas composition, it is essential to develop novel ceramics with outstanding resistance to various plasma environments that do not produce contamination particles; this will allow us to elevate production yield of chips and overall equipment effectiveness (OEE). Herein, we report the plasma etching behavior of 50:50 vol% Y2O3-MgO nanocomposite ceramics under different CF4/Ar gas ratios conditions. It was found that the erosion depths and surface roughness changes of this material were much lower than those values of reference materials under both chemical and physical etching. Effects of plasma environment on the penetration depth of fluorine on the nanocomposite surface and of physical sputtering attack were also investigated. The results indicate that a nanocomposite with fine grains and high density can decrease particle generation and improve its life cycle under strong bias voltage and various plasma gas conditions, thereby showing itself a promising material for next-generation ceramic components in the semiconductor manufacturing process.

Fluorination behavior of Y2O3-MgO nanocomposite films irradiated by CF4/O2 plasma

In this study, the Y2O3-MgO (YM) nanocomposite film was prepared using radio frequency magnetron sputtering. The microstructures, chemical compositions, and fluorination behavior of YM films were systematically investigated and compared to those of Y2O3 and MgO films. After exposure to CF4/O2 etching plasma, the surface morphology of the YM nanocomposite film exhibited uniform etching behavior and preserved its original smooth surface. Energy dispersive X-ray spectroscopy mapping and transmission electron microscopy revealed that fluorine atoms present near surface region of the YM nanocomposite film and formed a thin homogeneous fluorinated layer having an average thickness of approximately 20 nm. Furthermore, the fluorinated layer of the YM nanocomposite film did not expand with prolonged plasma exposure. These results demonstrate that the chemical stability of the fine-grained YM nanocomposite film against damage due to the suppression of surface fluorination during CF4/O2 plasma etching.

Microstructural characterization, mechanical properties and erosion behavior of Y2O3–MgO nanocomposite films by magnetron sputtering

The effect of Y2O3: MgO ratio on the microstructures, mechanical properties, and plasma erosion behaviors of Y2O3–MgO (YM) nanocomposite films were investigated. The columnar growth structure of the YM nanocomposite film is disrupted as the MgO content increases, resulting in the refinement of the Y2O3 grains. When the Y2O3: MgO ratio is 40 : 60, the columnar crystal structure of the YM nanocomposite film can be refinement effectively due to thermodynamic incompatibility of Y2O3 and MgO. As a result, YM nanocomposite film is strengthened significantly with the maximum hardness and elastic modulus of 16.78 ± 0.8 GPa and 149.24 ± 4.7 GPa, respectively. X-ray photoelectron spectroscopy revealed few changes in the elemental and chemical compositions of the surface layer after fluorination in the YM nanocomposite film, confirming the chemical stability of the YM nanocomposite samples. The etching depth is ∼48% lower on the YM nanocomposite film (with a MgO content of 60%) than on the commercial Y2O3 film. The findings show that the strengthened YM nanocomposite film is more erosion resistant than the commercial Y2O3 coating.

Effects of Ho3+ concentration on the fabrication and properties of Ho: Y2O3-MgO nanocomposite for Mid-infrared laser applications

Infrared transparent Ho: Y2O3-MgO nanocomposite ceramics with a volume ratio of 50:50 (RE2O3: MgO) were prepared by combining sol-gel powder synthesis and hot-pressing sintering techniques. In order to obtain Ho: Y2O3-MgO nanocomposite ceramics with fine grain size, dense microstructure and homogeneous phase domains, the effect of sintering temperature and Ho3+ doping concentration were studied. Transmittance and SEM measurement revealed that the grain size of 3 at.% Ho: Y2O3-MgO ceramic sintered at 1250 °C is 141 nm, and the transmission is up to 85.2% at 5 μm. The detailed spectroscopic investigation of x at.% Ho: Y2O3-MgO (x = 1, 3, 5, 7, 9, 15) ceramics was performed. The nanocomposites exhibited photoluminescence properties similar to that of Ho: Y2O3 crystals and ceramics. In addition, the thermal conductivity of 3 at.% Ho: Y2O3-MgO ceramic is 13.04 W/m·K, which is superior to that of Ho:Y2O3 ceramics. The high transmission, excellent thermal conductivity, and outstanding optical characteristics indicated that Ho: Y2O3-MgO ceramics is a promising material for efficient infrared solid-state laser.

Enhanced near-infrared transmission of ZnO-doped Y2O3–MgO nanocomposites with reduced light scattering due to decreased refractive index difference

Y2O3–MgO nanocomposites have received attention owing to their high optical and mechanical properties. However, the inevitable light scattering stemming from the refractive index difference between the two phases limits their applications in the near-infrared region. In this study, the grain boundary light scattering was reduced by doping ZnO into MgO. Y2O3–Mg1−xZnxO nanocomposites were fabricated by hot-press sintered nanopowders synthesized via the sol-gel combustion process. The addition of ZnO reduced the sintering temperature by almost 300 °C and reduced the average grain size by more than 50 nm. Transmittance of 75%–85% was maintained for all samples in the wavelength range of 2–6 µm. The near-infrared cut-on wavelength shifted from 1222 to 843 nm when the ZnO concentration was up to 25 mol%. This work demonstrates the potential of ZnO-doped Y2O3–MgO nanocomposites as infrared transparent ceramics over a wide infrared transmission range.

A novel IR-transparent Ho3+:Y2O3–MgO nanocomposite ceramics for potential laser applications

The work is devoted to obtaining of transparent nanocomposite materials as low loss, highly thermally conductive materials for potential laser applications. We report Ho3+:Y2O3–MgO nanocomposite ceramics with excellent mechanical and optical properties by combining glycine-nitrate process and spark plasma sintering. Morphology, structural-phase state, infrared transmittance and luminescence depending on the holmium concentration (0–12 at.%) were studied for the first time. It was found that optical transmittance reaches 75%@6000 nm for 3 at.% Ho3+:Y2O3–MgO ceramics. The absorption cross-section at 1931 nm and the emission cross-section at 2118 nm were determined to be σabs = 0.51 × 10−20 cm2 and σem = 0.29 × 10−20 cm2, respectively. Based on the testing results of luminescent characteristics it was demonstrated that Ho3+:Y2O3–MgO nanocomposite is a promising material for high-power eye-safe lasers operating in the 2 μm wavelength range.

Evolution of microstructure, mechanical, and optical properties of Y2O3-MgO nanocomposites fabricated by high pressure spark plasma sintering

A high-pressure spark plasma sintering (SPS) process was applied for consolidating Y2O3–MgO nanocomposites. This approach enabled to fabricate a fully dense infrared (IR) transparent nanocomposites, which possess an average grain size of ∼70 nm and high hardness, at a relatively low sintering temperature of 1130 °C under a high pressure of 300 MPa. The light transmittance was improved with increasing pressure and reached to the maximum transmittance of 64.5% at a wavelength of 0.2–1.6 μm owing to the fine-grained microstructure. The Vickers hardness exhibited 16.6 ± 0.7 GPa for the grain size of 74 nm, which is significantly higher than that of the sub-micro grains obtained at a conventional sintering pressure of 70 MPa (11.9 ± 0.8 GPa). The hardness rigorously followed the Hall–Petch relationship, that is, it is enhanced with a reduction of the grain size. Successful fabrication of the high-performance Y2O3–MgO nanocomposites indicates that the nanopowder processing followed by the high-pressure sintering process can be applied for fabricating fully dense fine-grained nanocomposites with excellent optical and mechanical properties.

Synthesis of highly-infrared transparent Y2O3–MgO nanocomposites by colloidal technique and SPS

Infrared (IR) transparent Y2O3–MgO nanocomposites with a volume ratio of 50:50 were synthesized by combining colloidal and spark-plasma-sintering (SPS) techniques. In order to attain well-dispersed and homogeneous starting Y2O3–MgO nanopowder mixture, the effects of the pH value and the amount of polyetherimide (PEI) dispersant on the suspension stability were studied. Rheological measurement reveals that highly-dispersed and stable suspension was obtained at 7 wt% of PEI dispersant under pH = 10.6. The obtained nanopowders with particle size of 20–30 nm were densified using SPS at several sintering temperatures. The sintered composites show fine grains, narrow grain size distribution and uniform microstructure. The nanocomposite sintered at 1250 °C showed the maximum IR transmittance of 84% at a wavelength range of 2.5–6 μm. The Vickers hardness of the nanocomposite was about 11.9 ± 0.3 GPa, which is significantly higher than those of single phase MgO or Y2O3. Successful fabrication of the high-performance Y2O3–MgO nanocomposite indicates that i) the colloidal technique is an effect method to obtain highly dispersed and homogeneous nanopowders and ii) the SPS technique is a powerful tool to fabricate fine-grained dense transparent ceramics, which are suitable for fabricating IR transparent Y2O3–MgO composite ceramics from commercial starting powders.

Influence of sintering temperature on structural and optical properties of Y2O3–MgO composite SPS ceramics

The paper studies infrared-transparent 50:50 vol% Y2O3–MgO fine-grained composite ceramics produced via glycine-nitrate process and spark plasma sintering (SPS). Effect of SPS temperature (T = 1100, 1200, 1250 and 1300 °С) on consolidation processes of Y2O3–MgO nanopowders and on ceramics properties has been investigated. Morphology, structural-phase state, density, Vickers microhardness and infrared transmittance of Y2O3–MgO nanocomposites have been studied. Transmittance has been found to increase with the SPS temperature reaching 71%@6000 nm wavelength at T = 1300 °C. Maximal Vickers hardness of 10.9 GPa has been achieved at T = 1200 °C. The correlation between processing conditions of ceramics and indicated characteristics was investigated.

Study on carbon contamination and carboxylate group formation in Y2O3-MgO nanocomposites fabricated by spark plasma sintering

For Y2O3-MgO nanocomposites fabricated by spark plasma sintering (SPS), the strong absorption peaks, which are assigned to the stretching vibrations of carboxylate group (OCO), are commonly observed in IR spectra. These absorption peaks can negatively affect military applications such as IR windows or domes. In order to suppress the formation of these absorption peaks, therefore, it is important to understand how the carboxylate group in the SPSed Y2O3-MgO nanocomposite originated. In this study, it is demonstrated that the formation of the carboxylate group is related to the carbon contamination during SPS processing. The carbon phase transforms into CO2 gas by annealing and this leads to a reaction with metal oxide phases, resulting in the formation of carbonate phase. This carbonate phase contributes to the absorption peaks of the carboxylate group.

Microstructural freezing of highly NIR transparent Y2O3-MgO nanocomposite via pressure-assisted two-step sintering

Y2O3-MgO nanocomposite has attracted attention for use in infrared windows and domes. However, the large difference in refractive index between the two phases of this materials phases induces inevitable grain boundary scattering. To overcome this drawback, it is indispensable to greatly reduce the grain size and eliminate residual pores. Two-step sintering has been extensively used to produce fine-grained ceramics, but long incubation time and an additional process are required. As a robust approach, pressure-assisted two-step consolidation of Y2O3-MgO nanocomposite ceramics is investigated to achieve full density while retaining domain size. A sintering path for pressure-assisted two-step sintering and related kinetic window are obtained for the first time. By effectively suppressing grain growth and eliminating residual pores via two-step hot-pressing, outstanding mid- and near-infrared transmittance were achieved. The results indicate that pressure-assisted two-step sintering is a promising alternative strategy that can decrease the domain size and achieve full density of ceramics.

Influence of the SPS heating rate on the optical and mechanical properties of Y2O3-MgO nanocomposites

Influence of the SPS heating rate on the optical and mechanical properties of Y2O3-MgO nanocomposites

A novel approach of an infrared transparent Er:Y2O3–MgO nanocomposite for eye-safe laser ceramics

Photoluminescence spectrum and energy levels of an Er:Y2O3–MgO nanocomposite.

Influence of microstructure control on optical and mechanical properties of infrared transparent Y2O3-MgO nanocomposite

Among many kinds of infrared transparent ceramics, the Y2O3-MgO nanocomposite is one of the most promising candidates to meet the requirements of excellent IR transparency and strength. Since this nanocomposite has a large difference in refractive index between its two phases, minimizing the grain size is important to obtain transparency in the near-infrared region. The microstructure of a sintered body depends on the initial particles. We studied the effect of the microstructure of Y2O3-MgO nanocomposite on the optical and mechanical characteristics. Uniform and fine Y2O3-MgO nanoparticles can be synthesized via the glycine-nitrate process with optimum conditions. Grain coarsening was suppressed by using the hot-press method, through which small grains with enhanced transmittance and hardness was produced. The correlations between the optical properties and the sintering temperature were further investigated. The results indicate that optimized powder synthesis and sintering conditions are required to obtain Y2O3-MgO nanocomposites with outstanding mechanical and optical performance.

Influence of synthesis conditions on the properties of Y2O3–MgO nanopowders and sintered nanocomposites

In this study, a citrate–nitrate combustion method was applied to synthesize composite Y2O3–MgO nanopowders. In order to optimize the synthesis condition to support sufficient combustion, the molar ratio of citric acid to nitrate (c/n molar ratio) used in the reaction mixtures was varied between 0.17 and 0.34. Nanopowders with an average particle size of 17nm were achieved. The properties of these nanopowders indicated that the higher molar ratios decreased the unreacted organic components and increased the amount of carbide on the surface of the oxides, which helped to inhibit the formation of carbonate groups. The amount of carbonate groups was reduced with the increasing c/n molar ratio. Y2O3–MgO nanocomposites fabricated through hot-isostatic-pressing sintering showed a uniform distribution of Y2O3 and MgO grains, which had an average size of ∼180nm. In addition, the absorption peaks at 1410 and 1511cm−1 disappeared until the c/n molar ratio reached 0.28. A high average infrared transmittance of 83% in the range of 4000–1667cm−1 (2.5–6μm) was obtained in the nanocomposites.

Influence of moisture absorption on the synthesis and properties of Y2O3–MgO nanocomposites

Y2O3–MgO nanocomposites are appropriate materials for hypersonic infrared windows and domes because of their low emissivity and improved mechanical properties. In this study, the synthesized Y2O3–MgO nanopowders are investigated to evaluate the influence of moisture absorption on the manufacturing process and properties of the resulting nanocomposites. It is shown that MgO plays a more significant role than Y2O3 in the moisture absorption of the composite nanopowders, and the absorbed moisture leads to a lowering IR transmittance of the final Y2O3–MgO nanocomposites. A higher calcination temperature improves the resistance to moisture absorption of Y2O3–MgO nanopowders, which is beneficial for IR transmittance of the final nanocomposites. In addition, increasing the sintering temperature to 1100°C during spark plasma sintering (SPS) minimizes the influence of absorbed moisture on the IR transmittance of the final nanocomposites. In the water resistance test, the Y2O3–MgO nanocomposites demonstrate severely eroded surfaces and degraded IR transmittance after water erosion, suggesting the requirement for necessary water-proof treatments on such materials in practical applications.

Infrared‐Transparent Y2O3–MgO Nanocomposites Fabricated by the Glucose Sol–Gel Combustion and Hot‐Pressing Technique

A glucose sol–gel combustion method has been developed to synthesize composite nanopowders with equal volume fractions of Y2O3 and MgO. The synthesis involves the generation of precursor foam containing Y3+ and Mg2+ cations via the chemical and thermal degradation of glucose molecules in aqueous solutions. Subsequent calcination of the foam gave the composite nanopowders uniform composition and surface areas of 44–62 m2/g depending on the relative amount of glucose. Then the nanopowder with an average particle size of 19 nm was consolidated by the hot‐pressing technique with different sintering temperatures. The fabricated nanocomposite is mid‐infrared transparent as the result of fine grains, narrow grain size distribution, and uniform phase domains. The transmittance increases with increase in the sintering temperature and reaches 83.5% at 3–5 μm mid‐infrared wave range once the temperature reaches 1350°C, which is close to the theoretical value of 85%. And it is noteworthy that the cutoff wavelength reaches 9.6 μm, which is superior to those of spinel, AlON, and sapphire. And the Vickers hardness of the sample reaches 10.0 ± 0.1 GPa, which is significantly higher than those of the coarse grained single‐phase MgO and Y2O3. The results indicate that the glucose sol–gel combustion and hot‐pressing technique is an effective method to fabricate infrared transparent Y2O3–MgO nanocomposites.

Y2O3–MgO–ZrO2 Infrared Transparent Ceramic Nanocomposites

Increased strength and improved erosion resistance are required for future infrared windows working in harsher mechanical and thermal environments than those used today. In this study, Y2O3–MgO–ZrO2 composite nanopowders were synthesized using a sol–gel combustion process. The fully dense Y2O3–MgO–ZrO2 nanocomposites were prepared by pressureless sintering of the nanopowders at 1400°C for 2 h, followed by hot isostatic pressing at 1350°C for 1 h. The effects of ZrO2 concentration on the microstructure, infrared transmittance, and microhardness of the nanocomposites were studied. It is shown by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) that ZrO2 is selectively soluble in Y2O3 with the concentration up to 13.2 mol%, forming supersaturated solid solution. The microhardness of the Y2O3–MgO–ZrO2 nanocomposites scales linearly with the square root of the ZrO2 concentration (from 10.6 GPa without ZrO2 to 13.5 GPa with 13.2 mol% ZrO2 addition). Good mid‐infrared transmittance (53%–70%) over 3–7 μm wavelength was maintained with ZrO2 concentration up to 8.8 mol%, compared with that of Y2O3–MgO nanocomposites (62%–80%) at the same wavelength range. This work shows ZrO2 solid solution strengthened Y2O3 (ZSSY) nanocomposites for their potential to be used as infrared transparent materials with enhanced mechanical properties.

Phase Homogeneity in Y2O3–MgO Nanocomposites Synthesized by Thermal Decomposition of Nitrate Precursors with Ammonium Acetate Additions

Nanocomposite powders with equal volume fractions of Y2O3 and MgO have been produced by the thermal decomposition of precursor mixtures of yttrium nitrate and magnesium nitrate. Solutions of the precursor salts were mixed with ammonium acetate fuel, dried to form a gel‐like substance, and then calcined to give nanocrystalline ceramic powders. The amount of ammonium acetate added to the metal nitrate precursors was varied systematically, and the morphology and distribution of the component phases in consolidated compacts of the resultant ceramic powders were examined by a combination of focused ion beam sectioning, scanning, and transmission electron microscopy. The dispersion of the Y2O3 and MgO phases within the synthesized powders improved, and the sizes of the phase domains reduced, with increasing ammonium acetate content up to the quantity required for a stoichiometric redox reaction with the metal nitrates. The addition of excess ammonium acetate gave no further improvement in phase domain dispersion or reduction in phase domain sizes. These phenomena are related to the thermal characteristics for the decomposition of the precursors and their effect on phase separation during oxide crystallization.

The influence of oxygen vacancy on the optical transmission of an yttria–magnesia nanocomposite

A fully dense Y2O3–MgO nanocomposite with a grain size below 100 nm was successfully sintered using a sol–gel-processed nanopowder with a grain size below 30 nm. The nanocomposite has an excellent transmission (∼80%) in the infrared range. The nanocomposite is highly sensitive to the annealing environment in air or vacuum. The optical transmission is reversible by changing the annealing atmosphere from vacuum to air. Based on this combined with X-ray diffraction analysis, it is reasoned that oxygen vacancy is responsible for the optical properties of the composite.