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The electrolytic cell is the main equipment for electrolytic aluminum production. The visual electrolytic cell can observe and study the production process and mechanism of aluminum electrolysis. The effects of Y2O3 addition and sample thickness on the densification behavior and transmittance of Magnesium-aluminate spinel (MAS) were studied. The relative density, porosity, phase composition, microstructure, Vickers hardness, and transmittance of the sintered samples were characterized using the Archimedes method, x-ray diffraction analysis, scanning electron microscopy, Vickers hardness tester, and UV-visible near-infrared diffuse reflection. The results show that the appropriate amount of Y2O3 can enhance the transmittance of MgAl2O4 and the optimum Y2O3 content is 2 wt.%. At this time, the relative density of Magnesium-aluminate spinel (MAS), the maximum hardness, and the maximum transmittance are 96.19%, 18.18 GPa, and 36.3%, respectively. Under the optimum conditions, when the mass of the sample is 0.2 g, the relative density and maximum hardness of the Magnesium-aluminate spinel (MAS) sample are 97.28% and 18.18 GPa, respectively. Although the transmittance is not the highest, it is only lower than the transmittance of 0.15 g sample. The optimum sintering additive content and sample thickness jointly promote the densification, hardness, and transmittance of Magnesium-aluminate spinel (MAS). [ABSTRACT FROM AUTHOR]

This work investigated the influence of microwave sintering on the BaCe 0.2 Zr 0.7 Y 0.1 O 3-δ phase, incorporating 2 mol% or 4 mol% NiO as sintering aid. X-ray diffraction analysis of perovskite phase detected a rhombohedral structure under both sintering heating rates (280 and 500 °C/min), also exhibiting the presence of a second phase deficient in Ba with Ni incorporated into the structure, replacing part of the Zr. Raman analysis indicated no distortions in the perovskite structure, independent of the rates and NiO concentrations. The efficacy of NiO addition as a sintering aid was demonstrated by high densification of the samples, exceeding 97 % relative density. Detailed analysis of structural, microstructural, and conductivity properties revealed that microwave sintering, particularly using a heating rate of 500 °C/min, yielded superior results compared to conventional sintering. The enhanced electrical response was attributed to a higher concentration of structural defects, oxygen vacancies, in the microwave-sintered samples, evidenced by the band at 630 cm−1 in the Raman spectrum. Among these, the BCZY sample with 2 mol% NiO, sintered under these conditions, stood out as the most promising, showcasing not only high density but also a uniform microstructure and appreciable electrical conductivity. [ABSTRACT FROM AUTHOR]

For the first time, Ni 25 Co 20 Cu 10 Fe 25 Mn 20 high entropy alloy (HEA) was employed as a sintering aid for fabrication of ZrB 2 -based ceramics using spark plasma sintering (SPS) process. The mechanical properties, phase evolution, microstructural changes, and the densification mechanisms of ZrB 2 -5 wt% HEA ceramics during the SPS step were scrutinized. The ZrB 2 -5 wt% HEA ceramic, manufactured at 1900 °C, yielded interesting combination of properties, counting a relative density of 96%, a fracture toughness of 6.4 MPa m1/2, and a hardness of 12.6 GPa. According to XRD patterns, there were ZrC and ZrO 2 phases with ZrB 2 matrix in the sintered samples. An unknown phase was also observed in the XRD patterns. Based on the history of the NiCoCuFeMn alloy and separation of Cu within the temperature range of 650–850 °C, that phase was related to CuB. [ABSTRACT FROM AUTHOR]

In the past decades, Zirconia (ZrO 2) has emerged as a promising technical ceramic, both as high temperature structural material and electrolyte for fuel cells, etc. The traditional synthesis of ZrO 2 with spark plasma sintering (SPS) usually requires a sintering temperature as high as 1200 °C. General interest in lowering the sintering temperature to reduce energy consumption and thermal stresses has led to research on two promising routes – cold sintering via temperature-dependent chemical reactivity and sintering aids, which facilitates mass transport and improves densification. Here we combine both by developing a single-step sintering process benefitting from both water vapor through the in-situ conversion of Zr(OH) 4 to ZrO 2 and liquid phase Bi 2 O 3 as a sintering aid. The resultant ZrO 2 has a relative density above 80% with a sintering temperature as low as 900 °C, significantly higher than that of ZrO 2 without sintering aids, which had a relative density of 54%, both sintered at 50 MPa. The dependence of porosity of sintered samples as a function of sintering pressure (range: 50 MPa–300 MPa) and temperature (range 400 °C–1200 °C) is mapped out as guidance for further material property design. A linear relationship between hardness and relative density was found, with a maximal hardness of 6.6 GPa achieved in samples with 30% porosity. In addition to sintered density, phase stabilization of tetragonal ZrO 2 is enhanced at sintering temperature of 900 °C with water vapor and Bi 2 O 3 , respectively. [ABSTRACT FROM AUTHOR]

In this study, it is executed to obtain Zr 2 - x Ti x WP 2 O 12 (x = 0. 0 5 , 0.10, 0.15, 0.20) ceramics with high relative density, 0–0.9 wt% MgO was added as a sintering aid. The influence of MgO amount and relative density on the coefficient of thermal expansion for Zr 2 - x Ti x WP 2 O 12 was also investigated. Pure and monophase of Zr 1. 8 Ti 0. 2 WP2O 1 2 with MgO has been obtained and MgO used sintering aid was doped in the crystal. The coefficients of thermal expansion of the 0.9 wt% MgO-doped sample and MgO-free sample were − 2. 2 4 ppm/K and − 2. 2 5 ppm/K, respectively. This result suggests that doping of MgO does not have an influence on the coefficient of thermal expansion. In other words, adding MgO increases sintering properties without change in the coefficient of thermal expansion. [ABSTRACT FROM AUTHOR]

The reduction of sintering time and temperature using an unconventional route and sintering aid for the densification of BaCe 0.2 Zr 0.7 Y 0.1 O 3-δ were investigated. The effects of ZnO addition and microwave sintering were explored on the structure, sinterability, microstructure, and electrical conductivity. BaCe 0.2 Zr 0.7 Y 0.1 O 3-δ powders were synthesized by solid-state reaction. The addition of 2 and 4 mol% ZnO was beneficial to obtain a single perovskite structure and improved sinterability producing dense samples. Relative densities of 99% at 1300 °C by conventional sintering and 98% at 1400 °C by microwave sintering were reached. A total conductivity of 1.20 mS cm−1 for the sample with 2 mol% ZnO by conventional sintering (relative density 99%) was obtained at 550 °C in a wet nitrogen atmosphere. Additionally, a high conductivity was also obtained for this compound produced by microwave sintering (relative density 98%) even with its microstructure exhibiting the smallest average grain size. In conventional sintering, the presence of the eutectic liquid phase responsible for the densification, was prejudicial to the total conductivity, being more evident in the samples with 4 mol% ZnO addition. The results indicate that microwave sintering was a rapid alternative for sintering, capable of reducing or inhibiting the appearance of the liquid phase producing dense, uniform samples, and with high conductivity. [ABSTRACT FROM AUTHOR]

In this work, MgAl 2 O 4 : Cr3+ transparent ceramics have been synthesized by the hot press sintering techniques, and the effect of the sintering aid Gd 2 O 3 and its content on the densification, microstructure, and optical, photoluminescence was studied and discussed. The relative density reached 99.29% with 0.8 wt% Gd 2 O 3 as a sintering aid, and the optical transmittance at 686 nm and 1446 nm were approximately 76%. As Gd 2 O 3 content continued to increase, the grain size of the ceramics became smaller and uniform, accompanied by some pores with the size of ～1 μm. The ceramics with 4.0 wt% Gd 2 O 3 showed a higher transmittance, of 82% at 1446 nm. Additionally, Gd 2 O 3 was helpful for Cr3+ in the sites of octahedral symmetry, which increased the quantum yield. The quantum yield of MgAl 2 O 4 : Cr3+ with 0.8 wt% Gd 2 O 3 was about 0.175, which was 36% higher than that of ceramic without Gd 2 O 3. In short, the sintering aid Gd 2 O 3 not only contributed to improving the densification, homogenizing the grain size, and heightening the optical transmittance but also enhanced the quantum yield of Cr3+. [ABSTRACT FROM AUTHOR]

BaZr 0.8 Y 0.2 O 3-δ proton conductor has the characteristics of excellent chemical stability, but its impoverished sinterability and low conductivity hinder its applications in fuel cell and hydrogen separation. Hf doping in Zr site improves BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ sinterability and conductivity. To further enhance BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ properties, three kinds of sintering aids ZnO, NiO or Li 2 O were introduced and their effect on the sinterability, microstructure and conductivity of BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ were studied. The experimental results display that 4 mol% ZnO can enhance the sinterability and conductivity of BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ sample sintered at 1400 °C. Compared with BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ sintered at 1600 °C, BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ with 4 mol% ZnO is of larger grain size, higher relative density (95.5%) and lower sintering temperature (reducing by 200 °C). Meanwhile, the conductivity of BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ with 4 mol% ZnO reaches 4.17 × 10−3 S cm−1 in wet 5% H 2 /Ar at 700 °C, due to the reduction of the grain boundary resistance of sample. BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ with 4 mol% ZnO membrane for hydrogen separation via external short circuit was developed. The membrane with a thickness of 1.08 mm gives a hydrogen permeation flux of 0.098 mL min−1cm−2 at 800 °C with 50% H 2 /He as feed gas. The presence of water vapor significantly promotes the hydrogen permeability of the membrane. In addition, introduction of 3% CO 2 or 100 ppm H 2 S into feed gas does not decrease the hydrogen permeation flux of the membrane. [Display omitted] • ZnO improves the sinterability and conductivity of BaZr 0.6 Hf 0.2 Y 0.2 O 3-δ. • The conductivity of BZHY-Z4 is 4.17 × 10−3 S cm−1 in wet 5% H 2 /Ar at 700 °C. • A hydrogen permeation flux of 0.098 mL min−1cm−2 is acquired at 800 °C. [ABSTRACT FROM AUTHOR]

Magnesium–aluminum spinel (MAS) precursor powder was synthesized through a microwave hydrothermal method. The synergistic effects of sintering process and sintering aids on the densification, hardness and corrosion resistance of MAS were revealed. X-ray diffraction analysis (XRD), Archimedes' drainage method, fully automatic micro-Vickers hardness test and scanning electron microscopy (SEM) were performed to analyze the phase composition, bulk density, hardness microstructure and corrosion depth of the samples, respectively. Results revealed that the best two-step sintering condition is 1650 °C/3 min/1550 °C/20 h. The MAS products obtained under the best condition have clear grain boundaries, uniform particle size distribution, and few pores. When the amount of Y 2 O 3 added is 4 wt.%, Y 2 O 3 and Al 2 O 3 form the second-phase solid solution Al 5 Y 3 O 12 , which activates the crystal lattice and benefits the sintering densification of MAS. Under these conditions, the relative density of the MAS composite ceramics prepared is relatively large (95.94 %), the grain size is relatively uniform, the hardness is relatively large (1264 HV), and the corrosion depth is relatively small (94.58 μm). [ABSTRACT FROM AUTHOR]

BaZrO 3 -based materials doped with a trivalent cation have excellent chemical stability and relatively high proton conductivity which makes them potential proton conducting oxide materials for various electrochemical device applications such as hydrogen processing, high-temperature electrolysis, and solid electrolyte in fuel cells. However, BaZrO 3 showed poor sinterability, requiring high sintering temperatures (1700–2100 °C) with longtime sintering (20–100 h) to achieve the desired microstructure and grain growth. This sintering problem can be solved by slightly doping BaZrO 3 with a sintering aid element. Therefore, in this study, two different zirconate proton conductors: BaZr 0·9 Y 0·1 O 3-α (BZY) and BaZr 0·955 Y 0·03 Co 0·015 O 3-α (BZYC) were sintered in an air atmosphere and an oxygen atmosphere for 20 h in the temperature range of 1500–1640 °C. The sinterability was evaluated by analyzing the XRD diffraction patterns, lattice constant, lattice strain, crystallite size, relative density, open porosity, closed porosity, surface morphology, grain size, and grain boundary distribution, using the XRD, SEM, EDX, and Archimedes density measurement methods. It is concluded that in an oxygen atmosphere, sintering aid Co not only improves the relative density but also produces highly dense fine particles with clear grain boundaries which are promising for electrochemical hydrogen device applications. [ABSTRACT FROM AUTHOR]

A second phase of Y2O3‐stabilized Bi2O3 (Bi0.75Y0.25O1.5,YSB) is introduced into Y2O3‐doped CeO2 (Ce0.8Y0.2O1.9,YDC) as a sintering additive and the composite ceramics of YDC‐xYSB (x = 0, 5, 10, 20, 30, 40 wt%) are prepared through sintering at 1100°C for 6 h in air atmosphere. The YDC‐xYSB ceramics are composed of both YDC and YSB with cubic fluorite structure, and no other impurity phases are detected in XRD patterns. The relative density of YDC‐xYSB rises firstly for x ≤5 wt%, and then it declines with YSB addition from 5 to 40 wt%. The average grain size of YDC decreases from 270 nm to 85.7 nm with YSB addition from 0 to 40 wt%. The YSB phase segregates at the grain boundaries of YDC based on the TEM analysis result. The ionic conductivity of YDC‐xYSB (x ≥5 wt%) is lower than that of YDC in the test temperature of 200°C–500°C, while it gradually exceeds that of YDC in 500°C–750°C. At 750°C, the conductivity of YDC‐30%YSB (6.22 × 10−2 S/cm) is 1.35 times higher than that of YDC (4.6 × 10−2 S/cm). The YSB addition can improve the ionic conductivity of YDC in 500°C–750°C and decrease its sintering temperature. [ABSTRACT FROM AUTHOR]

• The addition of Li 2 CO 3 sintering aid significantly reduced the sintering densification temperature of ceramic specimen. • The addition of Li 2 CO 3 sintering aid did not have remarkable adversely affecting on the basic dielectric properties of the ceramic specimen. • The addition of lithium enhances the energy storage performance of the ceramic specimens. The low temperature sintering properties, structure and dielectric response behavior and AC impedance spectroscopy of Ba 0.95 Ca 0.05 Zr 0.3 Ti 0.7 O 3 + x wt.% Li 2 CO 3 (x = 0 and x = 1.0) ceramic specimens were investigated. On this basis, the polarization (P) vs. electric field (E) relation characteristics and energy storage performance of the ceramic specimens were studied. The addition of Li 2 CO 3 reduced the sintering densification temperature by 200 °C for the ceramic with x = 1.0, resulting in a relative density of 96.2 % after sintering at 1080 °C. Li+ incorporated into the B-site of the cubic perovskite-type and resulted in the formation of oxygen vacancy, which promoted the sintering densification process of ceramic samples with x = 1.0. The addition of lithium did not have remarkable adversely affecting on the basic dielectric properties, as the ceramic specimen with x = 1.0 sintered at 1080 °C exhibited a dielectric constant of 1950 and a loss of 0.4 % at 10 kHz. Additionally, the addition of lithium enhanced the energy storage performance of the specimens, with the maximum attainable electric field increasing by 50 % for the ceramic with x = 1.0 compared to the value for the ceramic with x = 0. The ceramic with x = 1.0 exhibited an energy storage density (ESD) of 1.0 J/cm3 and an efficiency of ∼80.0 % under 240 kV/cm, which was superior to the ceramic with x = 0. The enhanced energy storage performance of the ceramic with x = 1.0 (increased by ∼70 %) was tentatively explained with a strong restriction effect of the defect dipoles in the specimen to the electric field-driven motion of the oxygen vacancies in the specimen. Overall, these findings suggest that the addition of Li 2 CO 3 could significantly improve the sintering and energy storage performance of BT-based dielectric ceramics, while did not result in remarkable negative impact on dielectric properties. [Display omitted] [ABSTRACT FROM AUTHOR]

The influence of copper addition (0.5–2 mol%) on the crystal structure, densification microstructure, and electrochemical properties of Ce0.8Gd0.2O1.9 synthesized in a one-step sol–gel combustion synthesis route has been studied. It has been found that Cu is very active as sintering aids, with a significative reduction of GDC firing temperature. A reduction of 500 °C with a small amount of copper (0.5 mol%) was observed achieving dense bodies with considerable ionic conductivities. Rietveld refined was used to investigate the crystal structure while relative density and microstructural examination were performed in the sintering temperature range of 1000–1200 °C after dilatometer analysis. High dense bodies were fabricated at the lowest sintering temperature, which promotes the formation of Ce0.8(1−x)Gd0.2(1−x)CuxO[1.9(1−x)+x] solid solution and the absence of secondary phase Cu-rich or the segregation or copper at the grain boundary. As compared to the pure GDC an improvement of total conductivity was achieved with a maximum for the highest copper content of 2.23·10−3–9.19·10−2 S cm−1 in the temperature range of 200–800 °C. [ABSTRACT FROM AUTHOR]

To promote the densification and therefore the mechanical properties of boride-based ceramics, MgO was added as sintering aid into Os 0.9 Re 0.1 B 2 powders for densification by using spark plasma sintering (SPS). The Os 0.9 Re 0.1 B 2 powders were synthesized by mechanochemical method from powder mixture of Os, Re and amorphous B. The role of MgO on densification, phase composition, microstructure and mechanical properties (hardness, fracture toughness and wear behavior) were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) with energy-dispersive spectroscopy (EDS), micro indentation and ball-on-disk tribometer. The results show that, with the introduction of MgO as sintering aid, the relative density of the Os 0.9 Re 0.1 B 2 ceramic samples increased. When the MgO content reached 9 wt%, the as-sintered sample is almost fully dense. No obvious regularity was found from the samples with the addition of different content of MgO. Vickers hardness values of the samples with 0, 3 wt% and 9 wt% MgO are found to be very close with each other within the experimental error (~30 GPa), while the sample with the addition of 6 wt% MgO exhibits the highest hardness of ~35 GPa. The fracture toughness of the samples is decreased slightly with the addition of MgO. The friction coefficient and wear rate of the sample with the addition of 6 wt% MgO was also found to be the lowest among all samples, which indicate best wear resistance. As a whole, with the addition content of 6 wt% MgO, the Os 0.9 Re 0.1 B 2 ceramic sample performs relatively excellent mechanical properties among four groups of samples. [ABSTRACT FROM AUTHOR]

The sintering mechanism and electrical conductivity of ZnO added BaCe 0.8 Zr 0.1 Y 0.1 O 3-δ (BCZY) proton conducting perovskites were investigated. The additions of 0.1 to 3 wt% ZnO to BCZY promoted the sintering of the BCZY pellet samples, and the samples with ZnO showed impermeable bodies with relative densities ≥90% after firing at 1400 °C for 6 h. First-principles calculations suggest that Ba in BaZnO 2 is more stable than in perovskites, and Zn is hardly soluble in BCZY. These theoretical results indicate that ZnO reacts with Ba in the BCZY perovskites. The melting points of the BaO and ZnO mixtures were approximately 1100 °C. Because their liquid phase should react with excess Y component in the perovskite, the liquid phase containing Y component enhances the densification of the doped perovskite by the liquid phase sintering. The electrical conductivities of BCZY perovskites with ZnO content ranging between 0.1 wt% and 3 wt% varied from 1.3 × 10−2 to 1.5 × 10−2 S/cm at 600 °C in an atmosphere of 3.0% H 2 O, 19.4% H 2 and 77.6% N 2. The electrical conductivities of BCZY perovskites with ZnO were comparable to those of the dense BCZY perovskite without ZnO. The present result suggests that addition of a small amount of ZnO is appropriate for enhancing the sintering and retaining the high electrical conductivity of BCZY. • Melted Ba-Zn-Y oxides promoted the sintering of ZnO added BaCe 0.8 Zr 0.1 Y 0.1 O 3-δ (BCZY). • Only 0.1 wt% ZnO dramatically improved the sintering characteristics of BCZY. • ZnO addition had a slight impact on the electrical conductivity of BCZY. [ABSTRACT FROM AUTHOR]

Calcined powders of ZrV 1.2 P 0.8 O 7 (ZVP) and ZrV 2 O 7 (ZV) were synthesized by heating gels prepared from NH 4 H 2 PO 4 , NH 4 VO 3 , and ZrOCl 2 solutions at 500 and 400 °C, respectively. Dense ZV-added ZVP sintered bodies were subsequently fabricated through heating at 850 °C for 20 h, with the addition of ZrV 2 O 7 as a sintering additive. The resulting material had a relative density of ca. 92%, while the relative density of pure sintered ZVP was ca. 72%. NH 4 H 2 PO 4 (NHP) was also added to ZVP along with ZV to obtain a molar ratio of P in NHP for V in ZV = 1. Subsequently, a single phase (NHP, ZV)-added ZVP sintered body was obtained by heating at 850 °C. Thermomechanical analysis showed that the dense ZV-added ZVP sintered body exhibited a positive thermal expansion from 25 to 150 °C and a negative thermal expansion from 150 to 500 °C. [ABSTRACT FROM AUTHOR]

In this work, first, a systematic study has been done to optimize the rheological behavior of silicon carbide (SiC) slurries to produce 20 mm disc-shaped green bodies with the highest relative density by adding sintering aids and changing the most effective parameters of the slip casting process. In the second step, slip-casted SiC green bodies were sintered via spark plasma sintering (SPS) under the same conditions: at a heating rate of 200 °C/min and under a vacuum atmosphere (10−2 Torr), the temperature reached 1900 °C and was maintained for 15 min, then, a pressure of 50 MPa was applied, and sintering was performed for 15 min. Initial powders, as well as green bodies, were well characterized via different methods. Also, the microstructure, physical, and mechanical properties of sintered samples were investigated. Results showed that the optimal concentration of tetramethylammonium hydroxide (TMAH) as a dispersant agent for slurry with 60 wt% of SiC was 2 wt%. In addition, the optimal milling time for slurries containing sintering aids was 24 h. The sintered SiC samples containing a mixture of Al 2 O 3 and Y 2 O 3 powder as a liquid phase sintering aid in a range of 5–10 wt% showed low sinterability and as a result, their microstructures contained pores. In contrast, the use of B 4 C powder as a solid phase sintering aid in a range of 5–10 wt% resulted in forming of sintered SiC samples with completely uniform and dense structures without visible pores. The optimal percentage of B 4 C was 7 wt%, and the relative density and the hardness of the corresponding sintered sample were 99.5% and 3300 ± 20 Hv, respectively. • Fabrication of SiC ceramics by a combination of slip casting and SPS. • Producing 20 mm disc-shaped green bodies with the highest relative density. • Sintered samples with a relative density of 99.5% and hardness of 3300 Hv. [ABSTRACT FROM AUTHOR]

NASICON-type solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) has become an excellent substitute for organic liquid electrolytes due to its high ionic conductivity and exceptional air stability. However, its application is limited by its poor sintering characteristics and high grain boundary resistance. In this study, TeO 2 was introduced into LATP as a sintering aid to promote its sintering, and its properties were measured by XRD, SEM, XPS, EIS and dilatometry. The results show that the addition of TeO 2 can form eutectic liquid phase in LATP ceramic pellets during sintering, thus effectively promoting particle sintering. Not only the grain size was greatly increased, but also grain boundary and pore defects were reduced. With the help of TeO 2 , the performance of LATP is greatly improved when sintered at only 750 °C, the relative density and total ionic conductivity reached 90.64% and 0.207 mS/cm, respectively. The highest total ionic conductivity of 0.279 mS/cm and the highest relative density of 93.81% were obtained when sintered at 800 ℃ and 950 ℃, respectively. However, due to the volatilization of Li and Te at high temperature, the relative density and total ionic conductivity of LATP with TeO 2 added sintered at high temperature have only a small increase compared to that without addition. In conclusion, this study provides a feasible scheme for improving LATP performance. • LATP is prepared by solid-state reaction method with TeO 2 as sintering aid. • After adding TeO 2 , the performance of LATP is improved when sintered at only 750 °C. • The LATP-2 wt%TeO 2 sintered at 800 ℃ shows the highest ionic conductivity of 0.279 mS/cm. • Te produces a lot of evaporation loss when sintered at high temperature. [ABSTRACT FROM AUTHOR]

Li2O has been evaluated as a sintering aid for Gd0.1Ce0.9O2−δ (GDC). Using 2.5 mol% ratio of Li2O to GDC (5LiGDC), dense samples with relative density of 99.3% were achieved at sintering temperature as low as 900 °C. A high total conductivity of 0.059 S cm−1 at 600 °C was obtained for the 5LiGDC samples sintered at 1000 °C (5LiGDC1000), while 5LiGDC samples sintered at 1400 °C showed a lower conductivity of 0.017 S cm−1 at 600 °C. It has been found that Li2O has the tendency to accumulate in the grain boundary region to form Li–Gd–Ce–O phases when the 5LiGDC sintering temperature is at 1000 °C or below, leading to an increase in the grain boundary conductivity. Increasing the 5LiGDC sintering temperature above 1000 °C will accelerate the vaporization of Li2O, association of the oxygen vacancy and formation of additional pores in the bulk, resulting in a decrease of both the grain boundary and grain interior conductivity. Secondary ion mass spectrometry (SIMS) results have confirmed the existence of Li ions for the 5LiGDC samples sintered at or below 1000 °C, while most of Li species has vaporized for the 5LiGDC samples sintered above 1000 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixing sintering aids to digest SiO 2 surface-layer of silicon kerf waste. • The addition range of sintering aids was designed by thermodynamic simulation. • The emerged liquid slag phase has a positive effect on the separation of B. • After a few sintering aids mixed, the removal efficiency of B reached 45.32%. • The mechanism of removing B in silicon kerf waste was discussed in detail. Removing the SiO 2 surface-layer and impurity boron in diamond wire saw silicon powder waste (DWSSP) are two difficulties in the field of photovoltaic waste recycling. Aiming at the two difficulties, this paper proposes a method of mixing sintering aids to digest the SiO 2 layer and remove impurity boron. Firstly, sintering aids Al 2 O 3 and CaO were mixed into DWSSP, and DWSSP-ceramics were prepared by pressure-less sintering. The mixed sintering aids reacted with the SiO 2 surface-layer of DWSSP, and the formed liquid slag phase plays a role in promoting the densification of DWSSP-ceramics (the relative density reached 85.97% when sintered at 1300 °C). Secondly, to obtain low-boron silicon, the slag phase was separated from DWSSP-ceramics by smelting treatment. The results showed that an optimal boron removal effect of 45.32% was reached after only 10.11 wt% sintering aids were mixed into DWSSP. The mechanism that the liquid slag phase gathered impurity boron during the sintering process, and then promoted boron to remove from silicon was reasonably deduced. The method of mixing sintering aids to remove the SiO 2 surface-layer and impurity boron provides a novel insight into purification and recovery of DWSSP. [ABSTRACT FROM AUTHOR]

Phosphors have wide applications in many industries, especially the automotive industry. Low efficiency and complex production methods are current challenges of phosphor packaging technology. In this study, M 2 Si 5 N 8 :Eu2+ (M = Ba, Sr) phosphor ceramics (PCs) were developed that exhibited excellent thermal quenching characteristics and a broad wavelength range—580 (yellow)–620 nm (amber)—for use as automotive amber light-emitting diode (LED) light sources. Phosphors— M 2 Si 5 N 8 :Eu2+ (M = Ba, Sr)— with various Ba:Sr compositions were synthesized at 1600 °C. These phosphors were, in turn, used to fabricate PCs; pressureless sintering was aided by the addition of a MgO/CaO—70:30—mixture. The density, microstructure, and optical properties of the phosphors and PCs were analyzed. When the molar concentration of Sr was 0.2 mol, the corresponding phosphor wavelength was 593 nm; these optical characteristics are suitable for amber LED applications. The PC containing 5 wt% sintering aid showed a density of 4.187 g/cm3 and relative density of more than 99%. These sintered PCs demonstrated excellent adaptive optical characteristics that can be used to great effect in automotive LED applications. • Eu2+ activated M2Si5N8:Eu2+ (M = Ba, Sr) phosphor ceramics were synthesized. • Pressureless sintering was performed with the addition of MgO/CaO sintering aid. • 0.2 mol of Sr showed the suitable optical characteristics for amber LED applications. [ABSTRACT FROM AUTHOR]