Structural changes in V2O5-P2O5 glasses: non-constant force field molecular dynamics and IR spectroscopy

Received: 27.04.2021. Revised: 07.06.2021. Accepted: 09.06.2021. Available online: 10.06.2021.Quasi-binary phosphate-vanadate glasses have been studied by both IR spectroscopy and a novel method of molecular dynamics with a non-constant force field. This method is used for the self-assembly of structural models of glasses. The obtained models and the glass network structure are analyzed quantitatively using element distribution by the number of R–O–R bonds (R is phosphorous or vanadium) and 4-, 6-, and 8-membered cycles. The bends on the concentration dependences of atoms distribution in the second coordination sphere agree well with changing the shape of IR spectra. Based on the cycle analysis, the formation of cycles is shown to be more characteristic for vanadate fragments that can form 4-membered cycles, which, according to Zachariasen’s rule, negatively affects glass-forming ability.The research was supported by the Russian Science Foundation (project no. 18-73-10205)

Formation of conductive oxide scale on 33NK and 47Nd interconnector alloys for solid oxide fuel cells

Two grades of chromium-free alloys were studied in order to apply them as interconnectors for solid oxide fuel cells. The surface modification methods were proposed for each alloy with the purpose of forming of oxide scales considering the required physicochemical properties. Investigations of the structure and properties of the obtained oxide scales were performed and the efficiency of the chosen surface modification methods was approved. The samples with the surface modification exhibited higher conductivity values in comparison with the nonmodified samples. A compatibility study of samples with surface modification and glass sealant of chosen composition was accomplished. The modified samples demonstrated good adhesion during testing and electrical resistance less than 40 mOhm/cm2 at 850 ◦C in air, which allowed us to recommend these alloys with respective modified oxide scales as interconnectors for SOFC. © 2019 by the authors.Russian Foundation for Basic Research, RFBR: 17-58-10006This research was funded by the Russian Foundation of Basic Research grant number 17-58-10006. The facilities of the shared access center "Composition of Compounds" of IHTE UB RAS were used in this work

Non-crystallising Glass Sealants for SOFC: Effect of Y2O3 Addition

The joining of ceramic and metal (interconnect) parts is one of the main challenges in the development of solid oxide fuel cells (SOFC). A promising approach to solving this problem is the use of glassy sealants. In this work, we investigated the effect of yttria additions on the properties of SiO2–Al2O3–CaO–Na2O–ZrO2–Y2O3 glass sealants. An increase in the concentration of yttria is shown to reduce the tendency of the glasses under study to crystallisation. A glass containing 4 wt% of Y2O3 is found to be amorphous, even after exposure at 850 °C for 100 h. Moreover, the defectiveness of the glass microstructure, after sealing, is found to decrease along with a growth in the Y2O3 concentration. The developed non-crystallising sealant was successfully applied for joining a YSZ ceramic and an Fe–Ni–Co alloy having the phase transition of around 500 °C. The use of the non-crystallising sealant allows us to join materials with very different thermal expansion coefficients and to avoid cracking under cooling, which might occur due to a large difference in thermal expansion coefficients. © 2019 Elsevier Ltd and Techna Group S.r.l.This study was financially supported by the RFBR project no. 17-58-10006. The research was partially performed using the facilities of the Shared Access Centre “Composition of Compounds” of IHTE UB RAS . The authors are grateful to Dr. S.V. Plaksin for XRD analysis, Dr. N. I. Moskalenko for AES analysis, A. S. Farlenkov for SEM analysis, and A. A. Solodyankin and V. A. Vorotnikov for their assistance in sample preparation

SYNTHESIS AND INVESTIGATION OF PROPERTIES Li2O-B2O3-V2O5 GLASS SYSTEM

Samples in 30Li2O-(70-x)B2O3-xV2O5 glass system (x = 30...47.5 mol. %) have been obtained. The influence of concentration of vanadium oxide on the characteristic temperatures of glasses, structure and electrical conductivity has been investigated. It was found that at the V2O5 concentration of 47.5 mol% the electrical conductivity increases. The maximum value of conductivity is 5.5·10-5 S/cm at room temperature for the composition 30.0Li2O-22.5B2O3-47.5V2O5.В данной работе получены и исследованы стекла системы 30Li2O-(70-x)B2O3-xV2O5 (x = 30…47,5 мол. %). Изучено влияние концентрации оксида ванадия на характеристические температуры стекол, структуру и электропроводность. Установлено, что при увеличении концентрации V2O5 до 47,5 мол. % происходит резкое увеличение электропроводности. Максимальное значение проводимости при комнатной температуре составляет 5,5·10-5 См/см для состава 30,0Li2O-22,5B2O3-47,5V2O5