Thermodynamic properties of magnesium orthovanadate Mg3(VO4)2 at high temperatures (298.15–1473 K)

Pei, Guishang; Xiang, Junyi; Yang, Lilian; Lv, Xuewei

doi:10.1016/j.calphad.2021.102295

Cited by 8 publications

(6 citation statements)

References 23 publications

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“…The enthalpy increments of CaMgV 2 O 7 at high temperatures were measured accurately using isothermal drop calorimetry. The average sensitivity of the drop calorimetry for each test was established and described elsewhere 28,29 . The sensitivity increased remarkably at high temperatures, consistently with the results of Beneš et al 30 .…”

Section: Resultssupporting

confidence: 71%

“…The average sensitivity of the drop calorimetry for each test was established and described elsewhere. 28,29 The sensitivity increased remarkably at high temperatures, consistently with the results of Beneš et al 30 In each experimental run, at least four drops of sample pellets and four drops of the sapphires were prepared to limit the experimental errors as soon as possible. The typical heat flow curves for the eight-drop tests at 773 K are presented in Figure 9, in which the blue line denotes the endothermic peaks for the sapphire reference pellets, whereas the green lines show the endothermic peaks for the CaMgV 2 O 7 pellets.…”

Section: Thermodynamic Propertysupporting

confidence: 78%

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Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

et al. 2022

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A double pyrovanadate CaMgV 2 O 7 sample was synthesized via a facile solidstate route under an air atmosphere. The nonequilibrium formation pathways of the CaMgV 2 O 7 were investigated via powder X-ray diffraction. A multistep reactions path (metavanadates-pyrovanadates-double pyrovanadate CaMgV 2 O 7 ) was proposed to describe the formation of the CaMgV 2 O 7 considering the thermodynamic and kinetic factors. The cell unit parameters of the CaMgV 2 O 7 sample indicated the crystallization according to a monoclinic system with space group P12/c1( 14), and the lattice parameters of a = 6.756 Å, b = 14.495 Å, c = 11.253 Å, β = 99.12, and V = 108.806 Å 3 . X-ray photoelectron spectroscopy also confirmed the +5 oxidation state vanadium in CaMgV 2 O 7 . The endothermic effects at 1033 and 1143 K were related to the incongruent melting and liquidus temperatures of CaMgV 2 O 7 , respectively. The comprehensive thermodynamic properties of CaMgV 2 O 7 were established in both low-and high-temperature regions, utilizing a physical property measurement system and multi-hightemperature calorimetry (96 lines). The heat capacity (200 J mol K −1 ) and entropy (198 J mol K −1 ) at 298.15 K were computed based on the low-temperature heat capacity values, and the enthalpy of formation at 298.15 K was also estimated. The fitted high-temperature capacity can be used to obtain the changes in the enthalpy, entropy, and Gibbs free energy. This study is part of building a reliable thermodynamic database of the CaO-MgO-V 2 O 5 system.

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Section: Resultssupporting

confidence: 71%

Section: Thermodynamic Propertysupporting

confidence: 78%

Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

et al. 2022

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“…Therefore, two heating cycles were taken, and the second cycle during the heating process was used in this study. The maximum uncertainties on the instrument of temperature measurements were equal to ±1 K and enthalpy change ±2.0%, which was calibrated using standard materials, such as aluminum, zinc, tin and indium, silver, nickel, respectively 24–26 …”

Section: Methodsmentioning

confidence: 99%

“…The maximum uncertainties on the instrument of temperature measurements were equal to ±1 K and enthalpy change ±2.0%, which was calibrated using standard materials, such as aluminum, zinc, tin and indium, silver, nickel, respectively. [24][25][26] The molar heat capacity of Ca 5 Mg 4 V 6 O 24 sample at high temperature was measured using a classic "three steps" method based on the DSC technique (NETZSCH STA 404 F3 Pegasus). Measurements were operated in a dynamic model with a heating rate of 10 K min −1 in the argon atmosphere (99.998%, 50 ml min −1 ), and the isothermal intervals of 15 and 10 min before and after the dynamic temperature profile were designed to stabilize the heat flow curve, respectively.…”

Section: Thermodynamic Property Measurementsmentioning

confidence: 99%

The phase structure, thermodynamic properties, and dissolution behavior of Ca₅Mg₄V₆O₂₄

et al. 2022

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A Ca5Mg4V6O24 compound was synthesized through solid‐state roasting routes under an air atmosphere, and its crystal structure and thermodynamic properties were determined using various methods. The cell parameters of Ca5Mg4V6O24 indicate that it crystallizes in cubic space group Ia3d with the unit cell parameters a = 12.442 ± 0.001 Å. X‐ray photoelectron spectroscopy also confirmed that the vanadium element in the Ca5Mg4V6O24 sample is present in the +5 state. The melting of Ca5Mg4V6O24 was detected at 1442 K. The molar heat capacity (374 J mol K−1) and entropy (688.2 J mol K−1) of Ca5Mg4V6O24 at 298.15 K were determined using physical properties measurement system, and simultaneous thermal analyzer for the first time. The solubility of Ca5Mg4V6O24 in water at different temperatures was measured and its dissolution behavior in sulfuric acid and kinetics was experimentally established.

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“…To accelerate in situ research and further clarify the thermodynamic conditions for the fabrication of Ca 3 (VO 4 ) 2 and its service performance when applied as a ferroelectric material, laser host material, and optical candidates, a comprehensive knowledge of its structural information, phase transformation, and thermodynamic properties, such as heat capacity, entropy, enthalpy, and Gibbs free energy, is indispensable. 14,15 Existing experimental studies and theoretical calculations aimed to characterize the structure and properties of Ca 3 (VO 4 ) 2 . Ca 3 (VO 4 ) 2 was originally believed to exhibit a monoclinic symmetry.…”

Section: Introductionmentioning

confidence: 99%

High‐temperature phase transformation and thermodynamic properties of Ca₃(VO₄)₂

Pei,

Jiao,

et al. 2024

J Am Ceram Soc.

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Ca3(VO4)2 is a promising candidate for applications in ferroelectric, laser host, and optical materials owing to its unique whitlockite structure and excellent physicochemical properties. In this study, the Ca3(VO4)2 powder was fabricated via a conventional solid‐phase route in air, using V2O5 and CaO as precursors. The trigonal Ca3(VO4)2 belongs to the space group R3c, having unit cell parameters of a = 10.8074 Å, b = 10.8074 Å, and c = 37.98871 Å, respectively. Ca3(VO4)2 melts congruently at 1680 K, as determined from differential scanning calorimetry measurements of the thermal profile of the second heating test. Enthalpy changes in Ca3(VO4)2 were experimentally determined for the first time across temperatures between 573 and 1623 K by drop calorimetry. The temperature‐dependent molar heat capacity of Ca3(VO4)2 was calculated from the enthalpy changes at elevated temperatures. Thermodynamic properties (entropy, enthalpy, and Gibbs free energy changes) were also calculated. The thermodynamic properties measured in this study were further applied to evaluate the appropriate precursors for fabricating Ca3(VO4)2 via solid‐state calcination. The results strongly recommend the use of V2O5 and Ca(OH)2 precursors for preparing the Ca3(VO4)2 samples because of their thermodynamic advantages.

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Thermodynamic properties of magnesium orthovanadate Mg3(VO4)2 at high temperatures (298.15–1473 K)

Cited by 8 publications

References 23 publications

Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

The phase structure, thermodynamic properties, and dissolution behavior of Ca₅Mg₄V₆O₂₄

High‐temperature phase transformation and thermodynamic properties of Ca₃(VO₄)₂

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Thermodynamic properties of magnesium orthovanadate Mg3(VO4)2 at high temperatures (298.15–1473 K)

Cited by 8 publications

References 23 publications

Double pyrovanadates CaMgV2O7: Formation mechanism, phase structure, and thermodynamic properties

Double pyrovanadates CaMgV2O7: Formation mechanism, phase structure, and thermodynamic properties

The phase structure, thermodynamic properties, and dissolution behavior of Ca5Mg4V6O24

High‐temperature phase transformation and thermodynamic properties of Ca3(VO4)2

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Product

Resources

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Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

Double pyrovanadates CaMgV₂O₇: Formation mechanism, phase structure, and thermodynamic properties

The phase structure, thermodynamic properties, and dissolution behavior of Ca₅Mg₄V₆O₂₄

High‐temperature phase transformation and thermodynamic properties of Ca₃(VO₄)₂