Effect of magnesium on the phase equilibria in magnesio-thermic reduction of Nb2O5

Kyunsuk Choi; Hanshin Choi; Hyunwoong Na; Il Sohn

doi:10.1016/j.matlet.2016.07.058

Effect of magnesium on the phase equilibria in magnesio-thermic reduction of Nb₂O₅

Kyunsuk Choi, Hanshin Choi, Hyunwoong Na, Il Sohn

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

Nb powders were synthesized by magnesio-thermic reduction. Nb₂O₅ is reduced by Mg via an oxygen-metal cation exchange in a mixed powder bed. Although thermodynamics favor reduction of Nb₂O₅ with Mg, the final phase distributions can be affected by the Mg content and interaction between products and reactants. Mg/Nb₂O₅ molar ratio was changed from 5 to 7.5 in order to evaluate the reaction pathway and relevant phases. Due to premature Mg depletion, samples with Mg/Nb₂O₅=5 resulted in intermediate Mg-Nb-O oxides according to the phase equilibria. A time-series comparison of Mg/Nb₂O₅=5 at 700 °C and 800 °C resulted in faster Mg-Nb-O intermediate phase formation at higher temperatures. Depending on the average oxidation state, the face-centered cubic Mg-Nb-O and hexagonal Mg₃Nb₆O₁₁ phase were identified.

Original language	English
Pages (from-to)	151-155
Number of pages	5
Journal	Materials Letters
Volume	183
DOIs	https://doi.org/10.1016/j.matlet.2016.07.058
Publication status	Published - 2016 Nov 15

Bibliographical note

Funding Information:
This work was partially funded by the BK21PLUS Project in the Division of Eco-Humantronics Information Materials and partially sponsored by MOTIE No. 10052751 .

Publisher Copyright:
© 2016 Elsevier B.V.

All Science Journal Classification (ASJC) codes

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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@article{63cdd324c6fd4841b3879f32a4de598b,

title = "Effect of magnesium on the phase equilibria in magnesio-thermic reduction of Nb2O5",

abstract = "Nb powders were synthesized by magnesio-thermic reduction. Nb2O5 is reduced by Mg via an oxygen-metal cation exchange in a mixed powder bed. Although thermodynamics favor reduction of Nb2O5 with Mg, the final phase distributions can be affected by the Mg content and interaction between products and reactants. Mg/Nb2O5 molar ratio was changed from 5 to 7.5 in order to evaluate the reaction pathway and relevant phases. Due to premature Mg depletion, samples with Mg/Nb2O5=5 resulted in intermediate Mg-Nb-O oxides according to the phase equilibria. A time-series comparison of Mg/Nb2O5=5 at 700 °C and 800 °C resulted in faster Mg-Nb-O intermediate phase formation at higher temperatures. Depending on the average oxidation state, the face-centered cubic Mg-Nb-O and hexagonal Mg3Nb6O11 phase were identified.",

author = "Kyunsuk Choi and Hanshin Choi and Hyunwoong Na and Il Sohn",

note = "Funding Information: This work was partially funded by the BK21PLUS Project in the Division of Eco-Humantronics Information Materials and partially sponsored by MOTIE No. 10052751 . Publisher Copyright: {\textcopyright} 2016 Elsevier B.V.",

year = "2016",

month = nov,

day = "15",

doi = "10.1016/j.matlet.2016.07.058",

language = "English",

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journal = "Materials Letters",

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T1 - Effect of magnesium on the phase equilibria in magnesio-thermic reduction of Nb2O5

AU - Choi, Kyunsuk

AU - Choi, Hanshin

AU - Na, Hyunwoong

AU - Sohn, Il

N1 - Funding Information: This work was partially funded by the BK21PLUS Project in the Division of Eco-Humantronics Information Materials and partially sponsored by MOTIE No. 10052751 . Publisher Copyright: © 2016 Elsevier B.V.

PY - 2016/11/15

Y1 - 2016/11/15

N2 - Nb powders were synthesized by magnesio-thermic reduction. Nb2O5 is reduced by Mg via an oxygen-metal cation exchange in a mixed powder bed. Although thermodynamics favor reduction of Nb2O5 with Mg, the final phase distributions can be affected by the Mg content and interaction between products and reactants. Mg/Nb2O5 molar ratio was changed from 5 to 7.5 in order to evaluate the reaction pathway and relevant phases. Due to premature Mg depletion, samples with Mg/Nb2O5=5 resulted in intermediate Mg-Nb-O oxides according to the phase equilibria. A time-series comparison of Mg/Nb2O5=5 at 700 °C and 800 °C resulted in faster Mg-Nb-O intermediate phase formation at higher temperatures. Depending on the average oxidation state, the face-centered cubic Mg-Nb-O and hexagonal Mg3Nb6O11 phase were identified.

AB - Nb powders were synthesized by magnesio-thermic reduction. Nb2O5 is reduced by Mg via an oxygen-metal cation exchange in a mixed powder bed. Although thermodynamics favor reduction of Nb2O5 with Mg, the final phase distributions can be affected by the Mg content and interaction between products and reactants. Mg/Nb2O5 molar ratio was changed from 5 to 7.5 in order to evaluate the reaction pathway and relevant phases. Due to premature Mg depletion, samples with Mg/Nb2O5=5 resulted in intermediate Mg-Nb-O oxides according to the phase equilibria. A time-series comparison of Mg/Nb2O5=5 at 700 °C and 800 °C resulted in faster Mg-Nb-O intermediate phase formation at higher temperatures. Depending on the average oxidation state, the face-centered cubic Mg-Nb-O and hexagonal Mg3Nb6O11 phase were identified.

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