Measurement of liquidus in metal-rich region of lanthanoid-oxygen binary systems and the thermodynamic evaluation

IF 1.9 3区材料科学 Q4 CHEMISTRY, PHYSICAL

Calphad-computer Coupling of Phase Diagrams and Thermochemistry Pub Date : 2023-11-26 DOI:10.1016/j.calphad.2023.102636

Ryota Nakazawa , Ayumi Itoh , Shintaro Yasui , Masaki Kurata , Yoshinao Kobayashi

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Abstract

In this study, the solubilities of oxygen in molten La, Gd, Tb, Ho, and Er metals were measured and the oxide phases in equilibrium with each of these lanthanoid metals were identified to systematically determine the liquidus of lanthanoid-oxygen systems in the metal-rich region. The molten lanthanoid metal and lanthanoid oxide pellets were equilibrated at 1573–1873 K and then quenched. The oxygen concentration in the quenched metals was measured using inert gas fusion infrared absorption spectroscopy to determine the oxygen solubilities of molten lanthanoid metals. The crystal structures of the quenched lanthanoid oxide pellets were analyzed using XRD to identify the equilibrium oxide phases, which were identified as the sesquioxides of each lanthanoid element. Furthermore, the Gibbs free energies of the liquid phases of the Ln-O (Ln = La, Pr, Gd, Tb, Dy, Ho, Er) systems were evaluated using the CALPHAD method and thermodynamic software Pandat based on the oxygen solubilities of molten La, Gd, Tb, Ho, and Er metals measured in this study and those of Pr and Dy reported in previous studies.

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类镧-氧二元体系富金属区液相线的测定及热力学评价

在本研究中，测量了熔融La、Gd、Tb、Ho和Er金属中氧的溶解度，并确定了与这些类镧金属平衡的氧化相，以系统地确定富金属区类镧-氧体系的液相。在1573 ~ 1873 K的温度下，将熔融的镧系金属和氧化镧球团进行平衡，然后进行淬火。采用惰性气体熔合红外吸收光谱法测定淬火金属中的氧浓度，以测定熔融镧系金属的氧溶解度。用XRD分析了淬火后的类镧氧化物球团的晶体结构，确定了平衡氧化物相，确定了各类镧元素的倍半氧化物。此外，基于本研究测量的熔融La、Gd、Tb、Ho和Er金属的氧溶解度以及之前报道的Pr和Dy金属的氧溶解度，利用calphhad方法和热力学软件Pandat对Ln- o (Ln = La、Pr、Gd、Tb、Dy、Ho、Er)体系液相的Gibbs自由能进行了评估。

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来源期刊

Calphad-computer Coupling of Phase Diagrams and Thermochemistry 化学-热力学

CiteScore

4.00

自引率

16.70%

发文量

审稿时长

2.5 months

期刊介绍： The design of industrial processes requires reliable thermodynamic data. CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) aims to promote computational thermodynamics through development of models to represent thermodynamic properties for various phases which permit prediction of properties of multicomponent systems from those of binary and ternary subsystems, critical assessment of data and their incorporation into self-consistent databases, development of software to optimize and derive thermodynamic parameters and the development and use of databanks for calculations to improve understanding of various industrial and technological processes. This work is disseminated through the CALPHAD journal and its annual conference.