Solid-State Electrochemical Sensor for Monitoring Mg in Al Refining Process

Kale, Girish M.; Jacob, Κ. T.; Hong, Yan

doi:10.1149/1.2214592

Cited by 5 publications

(8 citation statements)

References 7 publications

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“…The emf of the cell corrected for thermo-emf is given by: Figure 11(a) suggests that the solid electrolyte is chemically stable in molten Al at 700±5 o C. Meanwhile, instability in the sensor signal at 0.005 wt.% Mg in molten Al could in part be due to the possibility of reaching a limiting value for the measurement of Mg in molten Al using MgZr4P6O24 as solid electrolyte. 59,60 Figure 11(b) shows sensor voltage variation of the solid-state Mg-sensor in molten Al at 700±5 o C. The measured voltage variation of this solid-state Mg-sensor as a function of concentration of Mg in molten Al at 700±5 o C is in general agreement with the earlier findings. 59,60 The activity of Mg is relatively high at the alloy electrode and very low at the ceramic electrode exposed to air.…”

Section: Sensor For Mg In Liquid Al -Sensor Testing -supporting

confidence: 86%

“…The measured voltage variation of this solid-state Mg-sensor as a function of concentration of Mg in molten Al at 700 ± 5 °C is in general agreement with the earlier findings. 59,60 The activity of Mg is relatively high at the alloy electrode and very low at the ceramic electrode exposed to air. The electrochemical reaction at the alloy electrode on the right-hand side of the cell is:…”

Section: Resultsmentioning

confidence: 99%

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Assessment of MgZr₄P₆O₂₄as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Adamu

Jacob

Kale

2020

J. Electrochem. Soc.

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The potential solid electrolyte, MgZr4P6O24 was prepared using a modified sol-gel method. Both structural and electrical properties of the solid electrolyte were determined. DSC-TGA analysis indicated that pure dried xerogel when calcined at 900 o C converts to single phase MgZr4P6O24 nanopowder with good crystallinity. Pellets of 13mm diameter and 3.8mm thickness made by uniaxial compression were sintered at 1300 o C for 24h. XRD and HR-TEM indicated that the crystalline phase is monoclinic having crystallite size of approximately 40nm. The sintered pellets were stable in the temperature range from 1000 to 1300 o C, with minor extraneous peaks indicating traces of a coexistent second phase (Zr2P2O9) at the higher temperature. Using impedance spectroscopy, the electrical conductivity of MgZr4P6O24 was determined as 7.23 x 10-3 Scm-1 at 725 o C. MgZr4P6O24 pellet was successfully used for fabrication of a solid-state Mg-sensor for measuring Mg concentration in molten Al at 700±5 o C, with biphasic powder mixture of MgCr2O4+Cr2O3 as ceramic reference electrode in air. A linear dependence of emf on logarithm of Mg concentration was obtained. The results indicate that the transport number of Mg 2+-cation in MgZr4P6O24 is 0.85±0.03 at 700 o C. The solid electrolyte has likely applications in high-temperature electrochemical sensors.

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Section: Sensor For Mg In Liquid Al -Sensor Testing -supporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Assessment of MgZr₄P₆O₂₄as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Adamu

Jacob

Kale

2020

J. Electrochem. Soc.

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“…Furthermore, in magnesium containing phosphates such as Mg 0.5 M 2 (PO 4 ) 3 (M = Ti, Zr, Hf), − the coordination number of magnesium cations is either 4 or 6. MZP as a solid electrolyte was first investigated by Ikeda et al and was successfully used to develop CO 2 potentiometric sensors. , Kale et al , furthered the research and employed MZP for the development of Mg sensor for aluminum alloying and refining process. Wang and Kumar investigated a SO 2 gas sensor based on MZP as a solid electrolyte and Na 2 SO 4 as auxiliary electrode.…”

Section: Introductionmentioning

confidence: 99%

Novel Sol–Gel Synthesis of MgZr₄P₆O₂₄ Composite Solid Electrolyte and Newer Insight into the Mg²⁺-Ion Conducting Properties Using Impedance Spectroscopy

Adamu

Kale

2016

J. Phys. Chem. C

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Magnesium zirconium phosphate, MgZr4P6O24 (MZP) is a magnesium ion conducting ceramic material with potential for application as solid electrolyte in high temperature electrochemical sensor in non-ferrous scrap metal refining and virgin metal alloying operations. In this work, MZP was synthesised using a simple but novel and economical solgel route at a significantly reduced temperature. An insight into the calcination process, and possible phase transformation at higher temperature was obtained using simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). Phase identification of the synthesised material was studied after calcining the powder at 900 o C for 3h using X-ray diffraction (XRD); a single monoclinic phase was observed at that temperature. However, a trace amount of possible minor second phase; zirconium oxide phosphate [Zr2(PO4)2O] was formed a T 1000 o C. Impedance spectroscopy measurement on platinised sintered-MZP pellets were carried out in the frequency range 100 mHz 32 MHz and in a temperature range of 30 -800 o C to determine the electrical properties of MZP. Ionic conductivity of MZP was found to be equal to 7.23x10 -3 -1 cm -1 at relatively lower, 725 o C. Furthermore, the Nyquist and modulus plots measured at 764 o C and 390 o C shows single semi-circles suggesting contribution from only grain interiors (GIs). The ionhopping rate was calculated by fitting the conductance spectra to the power law variation, ac dc A n . The ac and dc conductivity of MZP show Arrhenius-type of behaviour with activation energie Ea V SEM f the fractured MZP pellet sintered at 1300 o C for 24h revealed a highly dense microstructure with clearly visible grain boundaries and low porosity which is in good agreement with the relative density of ~99% determined A structure. EDS confirms the presence of Mg, Zr, P, O in appropriate atomic ratio to yield MgZr4P6O24. Finally, TEM on MZP particles with crystallite size of ~50nm also confirmed MZP as stable at 900 o C with no observable second phase, Zr2(PO4)2O.

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“…E/V (±0.003) = 2.1920 + 0.0754LogXMg (4) The response sequence of Mg-sensor designed and fabricated using MgZr4P6O24 as solid-state electrolyte and biphasic powder mixture of MgCr2O4 + Cr2O3 as reference electrode, varying the Mg concentration at 727±5 o C has been published [2,19]. The response sequences of solidstate Mg-sensor fabricated using MgHf4P6O24 solid-state electrolyte in this study as presented in Fig.…”

Section: Impedance Analysismentioning

confidence: 92%

Assessment of MgHf4P6O24 Electroceramic Oxide Electrolyte in High-Temperature Electrochemical Sensor for Sensing Mg in Non-Ferrous Alloys

Adamu¹

2020

Preprint

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In this paper, the electrochemical impedance analysis of MgHf4P6O24 electroceramic oxide electrolyte on platinised pellets of 13mm diameter (Ø) and 3.8mm thickness depicts the electrical properties of Mg 2+ -cation conducting species in the characterised solid-state electrolytes measured using the two-probe analysis at 182-764 o C, and from 100mHz to 32MHz, were evaluated. In this analysis, promising ionic conductivity of 4.52 x 10 -4 Scm -1 for MgHf4P6O24 electroceramic electrolyte was exhibited at 747 o C, thereby maintaining both materials and operational stability at 1000 o C ≤ T/ o C≤1300.In addition to this, the design, fabrication and testing of solid-state Mg-sensors using the electrochemical method have been achieved. The novel high-temperature Mg-sensors were designed using the highly conducting Mg 2+ -cation solid-state electrolyte by incorporating a biphasic powder mixture of MgCr2O4 + Cr2O3 as ceramic solid-state reference electrode in air, which has shown promising trend after successfully sensing the Mg dissolved in molten Al at 700±5 o C. A linear dependence of emf on logarithm of Mg concentration was achieved. The transport number, tmg2+ = 0.84±0.03 was achieved which indicates that the conducting specie in MgHf4P6O24 solid-state electrolyte is Mg 2+ -cation. The solid-state electrolyte has the potential for application in high-temperature electrochemical sensors and other devices.

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Solid-State Electrochemical Sensor for Monitoring Mg in Al Refining Process

Cited by 5 publications

References 7 publications

Assessment of MgZr₄P₆O₂₄as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Assessment of MgZr₄P₆O₂₄as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Novel Sol–Gel Synthesis of MgZr₄P₆O₂₄ Composite Solid Electrolyte and Newer Insight into the Mg²⁺-Ion Conducting Properties Using Impedance Spectroscopy

Assessment of MgHf4P6O24 Electroceramic Oxide Electrolyte in High-Temperature Electrochemical Sensor for Sensing Mg in Non-Ferrous Alloys

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Solid-State Electrochemical Sensor for Monitoring Mg in Al Refining Process

Cited by 5 publications

References 7 publications

Assessment of MgZr4P6O24as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Assessment of MgZr4P6O24as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Novel Sol–Gel Synthesis of MgZr4P6O24 Composite Solid Electrolyte and Newer Insight into the Mg2+-Ion Conducting Properties Using Impedance Spectroscopy

Assessment of MgHf4P6O24 Electroceramic Oxide Electrolyte in High-Temperature Electrochemical Sensor for Sensing Mg in Non-Ferrous Alloys

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Assessment of MgZr₄P₆O₂₄as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Assessment of MgZr₄P₆O₂₄as a Solid Electrolyte for Sensing Mg in Molten Non-Ferrous Alloys

Novel Sol–Gel Synthesis of MgZr₄P₆O₂₄ Composite Solid Electrolyte and Newer Insight into the Mg²⁺-Ion Conducting Properties Using Impedance Spectroscopy