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Open Access Research Article Issue
Realizing translucency in aluminosilicate glass at ultralow temperature via cold sintering process
Journal of Advanced Ceramics 2022, 11 (11): 1714-1724
Published: 18 October 2022
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Glass with high visible-light transparency is widely considered as the most important optical material, which typically requires a processing temperature higher than 1000 ℃. Here, we report a translucent aluminosilicate glass that can be prepared by cold sintering process (CSP) at merely 300 ℃. After eliminating structural pores in hexagonal faujasite (EMT)-type zeolite by heat treatment, the obtained highly active nanoparticles are consolidated to have nearly full density by adding NaOH solution as liquid aids. However, direct densification of EMT powder cannot remove the structural pores of zeolite completely, leading to an opaque compact after the CSP. It is proved that the chemical reaction between the NaOH- and zeolite-derived powders is highly beneficial to dissolution–precipitation process during sintering, leading to the ultra-low activation energy of 27.13 kJ/mol. Although the addition of 5 M NaOH solution greatly promotes the densification via the reaction with aluminosilicate powder, lower or higher concentration of solvent can deteriorate the transmittance of glass. Additionally, the CSP-prepared glass exhibits a Vickers hardness of 4.3 GPa, reaching 60% of the reported value for spark plasma sintering (SPS)-prepared sample.

Open Access Research paper Issue
Mechanically exfoliated MoS2 nanoflakes for optimizing the thermoelectric performance of SrTiO3-based ceramic composites
Journal of Materiomics 2022, 8 (4): 790-798
Published: 12 February 2022

As a semiconducting material with relatively low thermal conductivity, MoS2 nanoflake has the potential to serve as a modulator for optimizing the performance of thermoelectric (TE) materials. However, the low yield of MoS2 nanoflakes prepared by conventional methods has constrained the development of MoS2 optimized TE materials. We propose a mechanical exfoliation method for mass production of MoS2 nanoflakes using attrition mill. After mixed with La and Nb co-doped SrTiO3 (SLNT) powder, the MoS2/SLNT composites are fabricated by spark plasma sintering. It is found that the heterojunctions formed at MoS2/SLNT interfaces with proper band offset can effectively scatter the low-energy electrons, resulting in enhanced Seebeck coefficient without significantly undermining the electrical conductivity. The power factor of composites is improved when the MoS2 content is lower than 1.5 vol%. Meanwhile, the thermal conductivity of composites is significantly decreased due to the phonon scattering induced large thermal resistance at MoS2/SLNT interfaces, which is much higher than that in graphene embedded SrTiO3 composites. Consequently, a maximum ZT = 0.24 is obtained at 800 K in 1.5 vol% MoS2/SLNT composite, which is ~26 % higher compared with pristine matrix. This work paves the way for application of TE materials modulated by transition metal dichalcogenides.

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