Electrochemical Behaviour of Gd(Ⅲ) on Bi Electrode and Thermodynamic Data of BixGdy Intermetallic Compounds in LiCl-KCl Molten Salts†

doi:10.7503/cjcu20170820

Abstract

Abstract:

Electrochemical behaviours of Gd(Ⅲ) were investigated on liquid Bi pool electrode and Bi film electrode in eutectic LiCl-KCl molten salts in the temperature range of 723—823 K by a series of electrochemical techniques. Moreover, the thermodynamic data, such as activities and relative partial molar Gibbs energies of Gd in the Bi-Gd alloys as well as the Gibbs energies, enthalpies and entropies of formation for Bi₂Gd, BiGd, Bi₃Gd₄ and Bi₃Gd₅ were calculated using open circuit chronopotentiometry. Galvanostatic and potentiostatic electrolysis were performed to prepare the Bi-Gd alloy on liquid Bi electrode. The alloy samples were characterized by X-ray diffraction(XRD) and scanning electronic microscopy-energy dispersive spectrometry(SEM-EDS). The results indicate that Bi-Gd alloys are comprised of BiGd and Bi₃Gd₅ phase, respectively.

Key words: Electrochemical behaviour, Bi electrode, Thermodynamic property, Bi-Gd alloy, Molten chloride

CLC Number:

O641
O643

TrendMD:

JIANG Tao, WANG Ning, PENG Shuming, LI Mei, HAN Wei, CHEN Yitung. Electrochemical Behaviour of Gd(Ⅲ) on Bi Electrode and Thermodynamic Data of Bi_xGd_y Intermetallic Compounds in LiCl-KCl Molten Salts^†[J]. Chem. J. Chinese Universities, 2018, 39(8): 1759.

Figures/Tables 11

Fig.1 Cyclic voltammograms under different conditionsa. LiCl-KCl melts on W electrode; b. LiCl-KCl-GdCl3(5.2×10-5 mol/mL) melts on W electrode; c. LiCl-KCl melts on liquid Bi electrode; d. LiCl-KCl-GdCl3(5.2×10-5 mol/mL) melts on liquid Bi pool electrode. Scan rate: 0.1 V/s, SW=0.314 cm2, SBi=0.2 cm2, T=773 K.

Fig.2 Cyclic voltammograms obtained in LiCl-KCl-GdCl3(5.2×10-5 mol/mL) melts on liquid Bi pool electrode at different scan rates(A) and relatioship between cathodic and anodic peak potentials with logarithm of scan rates(B)SBi=0.2 cm2, T=773 K.

Fig.3 Cyclic voltammograms under different conditions(A) LiCl-KCl-BiCl3(3.37×10-6 mol/mL) melts on W electrode(dotted curve); LiCl-KCl-BiCl3(3.37×10-6 mol/mL)-GdCl3(8.67×10-5 mol/mL) melts on pre-deposited Bi film electrode(solid line); (B) LiCl-KCl-BiCl3(3.37×10-6 mol/mL)-GdCl3(8.67×10-5 mol/mL) melts on pre-deposited Bi film electrode at different terminal potentials. Terminal potential/V: a. -2.25; b. -2.00; c. -1.80; d. 1.75. Scan rate=0.1 V/s, S=0.314 cm2, T=773 K.

Fig.4 Square wave voltammogram obtained in LiCl-KCl-BiCl3(3.37×10-6 mol/mL)-GdCl3(8.67×10-5 mol/mL) melts on pre-deposited Bi film electrodePotential step=1 mV, frequency=20 Hz, S=0.314 cm2, T=773 K.

Fig.5 Open circuit chronopotentiograms of different conditions(A) a. LiCl-KCl-GdCl3(8.67×10-5 mol/mL) melts on W electrode; b. LiCl-KCl-BiCl3(3.37×10-6 mol/mL) melts on W electrode; c. LiCl-KCl-BiCl3(3.37×10-6 mol/mL)-GdCl3(8.67×10-5 mol/mL) melts on pre-deposited Bi film electrode; (B) LiCl-KCl-BiCl3(3.37×10-6 mol/mL)-GdCl3(8.67×10-5 mol/mL) melts on pre-deposited Bi film electrode at different temperatures. Deposition potential=-2.5 V, deposition time=60 s, S=0.314 cm2, T=773 K.

Table 1 Thermodynamic properties of Gd in two-phase coexisting states at different temperatures

Plateau^*	T/K	E_eq/V(vs. Ag/AgCl)	ΔE/V[vs. Gd(Ⅲ)/Gd]	Δ $G ˉ Gd$ /[kJ·(mol Gd)^-1]	a_Gd
Ⅱ	723	-1.933±0.002	—	—	—
	748	-1.918±0.004	—	—	—
	773	-1.903±0.002	—	—	—
	798	-1.888±0.003	—	—	—
	823	-1.881±0.002	—	—	—
A	723	-1.106±0.003	0.827±0.005	-239.42±1.44	5.04×10^-18
	748	-1.093±0.002	0.825±0.006	-238.84±1.74	2.09×10^-17
	773	-1.081±0.002	0.822±0.004	-237.97±1.16	8.30×10^-17
	798	-1.071±0.003	0.817±0.006	-236.52±1.74	3.29×10^-16
	823	-1.067±0.003	0.814±0.005	-235.65±1.45	1.10×10^-15
B	723	-1.226±0.001	0.707±0.003	-204.68±0.87	1.63×10^-15
	748	-1.219±0.002	0.699±0.006	-202.36±1.74	7.38×10^-15
	773	-1.209±0.003	0.694±0.005	-200.91±1.45	2.65×10^-14
	798	-1.201±0.003	0.687±0.006	-198.89±1.74	9.57×10^-14
	823	-1.197±0.001	0.684±0.003	-198.02±0.87	2.70×10^-13
C	723	-1.441±0.001	0.492±0.003	-142.43±0.869	5.12×10^-11
	748	-1.439±0.001	0.479±0.005	-138.67±1.448	2.07×10^-11
	773	-1.438±0.002	0.465±0.004	-134.62±1.158	8.00×10^-10
	798	-1.436±0.002	0.452±0.005	-130.85±1.448	2.72×10^-9
	823	-1.433±0.001	0.448±0.003	-129.70±0.869	5.86×10^-9
D	723	-1.667±0.001	0.266±0.003	-77.00±0.869	2.73×10^-6
	748	-1.664±0.002	0.254±0.006	-73.53±1.74	7.32×10^-6
	773	-1.662±0.003	0.241±0.005	-69.77±1.45	1.93×10^-5
	798	-1.659±0.002	0.229±0.005	-66.30±1.45	4.57×10^-5
	823	-1.657±0.003	0.224±0.005	-64.85±1.45	7.66×10^-5

Table 1 Thermodynamic properties of Gd in two-phase coexisting states at different temperatures

Plateau^*	T/K	E_eq/V(vs. Ag/AgCl)	ΔE/V[vs. Gd(Ⅲ)/Gd]	Δ $G ˉ Gd$ /[kJ·(mol Gd)^-1]	a_Gd
Ⅱ	723	-1.933±0.002	—	—	—
	748	-1.918±0.004	—	—	—
	773	-1.903±0.002	—	—	—
	798	-1.888±0.003	—	—	—
	823	-1.881±0.002	—	—	—
A	723	-1.106±0.003	0.827±0.005	-239.42±1.44	5.04×10^-18
	748	-1.093±0.002	0.825±0.006	-238.84±1.74	2.09×10^-17
	773	-1.081±0.002	0.822±0.004	-237.97±1.16	8.30×10^-17
	798	-1.071±0.003	0.817±0.006	-236.52±1.74	3.29×10^-16
	823	-1.067±0.003	0.814±0.005	-235.65±1.45	1.10×10^-15
B	723	-1.226±0.001	0.707±0.003	-204.68±0.87	1.63×10^-15
	748	-1.219±0.002	0.699±0.006	-202.36±1.74	7.38×10^-15
	773	-1.209±0.003	0.694±0.005	-200.91±1.45	2.65×10^-14
	798	-1.201±0.003	0.687±0.006	-198.89±1.74	9.57×10^-14
	823	-1.197±0.001	0.684±0.003	-198.02±0.87	2.70×10^-13
C	723	-1.441±0.001	0.492±0.003	-142.43±0.869	5.12×10^-11
	748	-1.439±0.001	0.479±0.005	-138.67±1.448	2.07×10^-11
	773	-1.438±0.002	0.465±0.004	-134.62±1.158	8.00×10^-10
	798	-1.436±0.002	0.452±0.005	-130.85±1.448	2.72×10^-9
	823	-1.433±0.001	0.448±0.003	-129.70±0.869	5.86×10^-9
D	723	-1.667±0.001	0.266±0.003	-77.00±0.869	2.73×10^-6
	748	-1.664±0.002	0.254±0.006	-73.53±1.74	7.32×10^-6
	773	-1.662±0.003	0.241±0.005	-69.77±1.45	1.93×10^-5
	798	-1.659±0.002	0.229±0.005	-66.30±1.45	4.57×10^-5
	823	-1.657±0.003	0.224±0.005	-64.85±1.45	7.66×10^-5

Table 2 Formulas and results of calculated Gibbs free energies of formation for Bi-Gd intermetallic compounds

Intermetallic compound	Equation	T/K	Δ $G 0 — f$ /(kJ·mol^-1)
Bi₂Gd	Δ $G 0 — f$ (Bi₂Gd)=-3FΔE₁	723	-239.42±1.45
		748	-238.84±1.74
		773	-237.97±1.16
		798	-236.52±1.74
		823	-235.65±1.45
BiGd	Δ $G 0 — f$ (BiGd)=(1/2)[Δ $G 0 — f$ (Bi₂Gd)-3FΔE₂]	723	-222.05±1.16
		748	-220.60±1.74
		773	-219.44±1.30
		798	-217.70±1.74
		823	-216.84±1.16
Bi₃Gd₄	Δ $G 0 — f$ (Bi₃Gd₄)=3Δ $G 0 — f$ (BiGd)-3FΔE₃	723	-808.57±4.34
		748	-800.47±6.66
		773	-792.94±5.07
		798	-783.97±6.66
		823	-780.20±4.34
Bi₃Gd₅	Δ $G 0 — f$ (Bi₃Gd₅)=Δ $G 0 — f$ (Bi₃Gd₄)-3FΔE₄	723	-885.58±5.21
		748	-874.00±8.40
		773	-862.71±6.51
		798	-850.26±8.11
		823	-845.05±5.79

Table 2 Formulas and results of calculated Gibbs free energies of formation for Bi-Gd intermetallic compounds

Intermetallic compound	Equation	T/K	Δ $G 0 — f$ /(kJ·mol^-1)
Bi₂Gd	Δ $G 0 — f$ (Bi₂Gd)=-3FΔE₁	723	-239.42±1.45
		748	-238.84±1.74
		773	-237.97±1.16
		798	-236.52±1.74
		823	-235.65±1.45
BiGd	Δ $G 0 — f$ (BiGd)=(1/2)[Δ $G 0 — f$ (Bi₂Gd)-3FΔE₂]	723	-222.05±1.16
		748	-220.60±1.74
		773	-219.44±1.30
		798	-217.70±1.74
		823	-216.84±1.16
Bi₃Gd₄	Δ $G 0 — f$ (Bi₃Gd₄)=3Δ $G 0 — f$ (BiGd)-3FΔE₃	723	-808.57±4.34
		748	-800.47±6.66
		773	-792.94±5.07
		798	-783.97±6.66
		823	-780.20±4.34
Bi₃Gd₅	Δ $G 0 — f$ (Bi₃Gd₅)=Δ $G 0 — f$ (Bi₃Gd₄)-3FΔE₄	723	-885.58±5.21
		748	-874.00±8.40
		773	-862.71±6.51
		798	-850.26±8.11
		823	-845.05±5.79

Fig.6 Relatioship between standard Gibbs free energies of fomation for four Bi-Gd intermetallic compounds and temperatures

Table 3 Thermodynamic data of Bi-Gd intermetallic compounds in temperature range of 723—823 K

Intermetallic compound	Δ $H 0 — f$ / (kJ·mol^-1)	Δ $S 0 — f$ / (J·mol^-1·K^-1)
Bi₂Gd	-268.10±2.53	-39.39±3.27
BiGd	-387.34±3.74	-87.38±4.83
Bi₃Gd₄	-1400.22±19.96	-395.30±25.80
Bi₃Gd₅	-1568.07±27.40	-521.52±35.30

Table 3 Thermodynamic data of Bi-Gd intermetallic compounds in temperature range of 723—823 K

Intermetallic compound	Δ $H 0 — f$ / (kJ·mol^-1)	Δ $S 0 — f$ / (J·mol^-1·K^-1)
Bi₂Gd	-268.10±2.53	-39.39±3.27
BiGd	-387.34±3.74	-87.38±4.83
Bi₃Gd₄	-1400.22±19.96	-395.30±25.80
Bi₃Gd₅	-1568.07±27.40	-521.52±35.30

Fig.7 XRD pattern and SEM-EDS analysis of Bi-Gd alloy obtained in LiCl-KCl-GdCl3 melts by potentiostatic electrolysis(A) XRD pattern; (B) SEM image; (C) mapping analysis image of Bi; (D) mapping analysis image of Gd; (E) EDS spectrum of the framed area in (B). Electrolysis potential=-1.9 V, electrolysis time=4 h, Bi electrode, T=923 K.

Fig.8 XRD pattern and SEM-EDS analysis of Bi-Gd alloy obtained in LiCl-KCl-GdCl3 melts by galvanostatic electrolysis(A) XRD pattern; (B) SEM image; (C) mapping analysis image of Bi; (D) mapping analysis image of Gd; (E) EDS spectrum of the framed area in (B). Current intensity=-0.5 A, electrolysis time=5.5 h, Bi electrode, T=923 K.

References 30

[1]	Gibilaro M., Massot L., Chamelot P., Taxil P., Electrochim. Acta, 2009, 54(22), 5300—5306
[2]	Kinoshita K., Koyama T., Inoue T., Ougier M., Glatz J.P., J. Phys. Chem. Solids, 2005, 66(2—4), 619—624
[3]	SouČek P., Cassayre L., Malmbeck R., Mendes E., Jardin R., Glatz J. P., Radiochim. Acta, 2008, 96(4/5), 315—322
[4]	Shirai O., Iwai T., Shiozawa K., Suzuki Y., Sakamura Y., Inoue T., J. Nucl. Mater., 2000, 277(2), 226—230
[5]	McFarlane H. F., Lineberry M., J. Prog. Nucl. Energ., 1997, 31(1), 155—173
[6]	Chen L.J., Zhang M. L., Han W., Yan Y. D., Cao P., Chem. J. Chinese Universities, 2012, 33(2), 327—330
	(陈丽军, 张密林, 韩伟, 颜永得, 曹鹏. 高等学校化学学报, 2012, 33(2), 327—330)
[7]	Li M., Li W., Han W., Zhang M.L., Yan Y. D., Chem. J. Chinese Universities, 2014, 35(12), 2662—2667
	(李梅, 李炜, 韩伟, 张密林, 颜永得. 高等学校化学学报, 2014, 35(12), 2662—2667)
[8]	Li M., Gu Q.Q., Han W., Zhang X. M., Sun Y., Zhang M. L., Yan Y. D, RSC Adv., 2015, 5(100), 82471—82480
[9]	Castrillejo Y., Bermejo M.R., Diaz-Arocas P., Rosa F. D. L., Barrado E., Electrochemistry, 2005, 73(8), 636—643
[10]	Castrillejo Y., Bermejo M.R., Arocas P. D., Martínez A. M., Barrado E., J. Electroanal. Chem., 2005, 579(2), 343—358
[11]	Jiang T., Peng S.M., Li M., Pei T. T., Han W., Sun Y., Zhang M. L, Acta Phys.-Chim. Sin., 2016, 32(7), 1708—17140
	(姜涛, 彭述明, 李梅, 裴婷婷, 韩伟, 孙杨, 张密林. 物理化学学报, 2016, 32(7), 1708—1714)
[12]	Han W., Li Z.Y., Li M., Li W. L., Zhang X. M., Yang X. G., Zhang M. L., Sun Y. J., Electrochem. Soc., 2017, 164(4), E62—E70
[13]	Han W., Ji N., Wang J., Li M., Yang X., Sun Y., Zhang M., RSC Adv., 2017, 7(50), 31682—31690
[14]	Vandarkuzhali S., Chandra M., Ghosh S., Samanta N., Nedumaran S., Prabhakara Reddy B., Nagarajan K., Electrochim. Acta, 2014, 145, 86—98
[15]	Kato T., Inoue T., Iwai T., Arai Y., J. Nucl. Mater., 2006, 357(1), 105—114
[16]	Wang L., Liu Y.L., Liu K., Tang S. L., Yuan L. Y., Lu T., Chai Z. F., Shi W. Q., J. Electrochem. Soc., 2015, 162(9), E179—E184
[17]	Liu Y.L., Yuan L. Y., Kui L., Ye G. A., Zhang M. L., He H., Tang H. B., Lin R. S., Chai Z. F., Shi W. Q., Electrochim. Acta, 2014, 120, 369—378
[18]	Li M., Wang J., Han W., Yang X.G., Zhang M., Sun Y., Zhang M. L., Yan Y. D., Electrochim. Acta, 2017, 228, 299—307
[19]	Iizuka M., J. Electrochem. Soc., 1998, 145(1), 84—88
[20]	Caravaca C., de Córdoba G., Tomás M. J., Rosado M., J. Nucl. Mater., 2007, 360(1), 25—31
[21]	Tang H., Pesic B., J. Electrochem. Soc., 2014, 161(9), D429—D436
[22]	Bermejo M.R., Gómez J., Medina J., Martínez A. M., Castrillejo Y., J. Electroanal. Chem., 2006, 588(2), 253—266
[23]	Nourry C., Massot L., Chamelot P., Taxil P., Electrochim. Acta, 2008, 53(5), 2650—2655
[24]	Nourry C., Massot L., Chamelot P., Taxil P., J. Appl. Electrochem., 2009, 39(12), 2359—2367
[25]	Nourry C., Massot L., Chamelot P., Taxil P., J. Appl. Electrochem., 2009, 39(6), 927—933
[26]	Zhou W., Liu Y.L., Liu K., Liu Z. R., Yuan L. Y., Wang L., Feng Y. X., Chai Z. F., Shi W. Q., J. Electrochem. Soc., 2015, 162(10), D531—D539
[27]	Seon F., Picard G., Tremillon B., Electrochim. Acta, 1983, 28(2), 209—215
[28]	Shibata H., Hayashi H., Akabori M., Arai Y., Kurata M., J. Phys. Chem. Solids, 2014, 75(8), 972—976
[29]	Castrillejo Y., Vega A., Vega M., Hernández P., Rodriguez J.A., Barrado E., Electrochim. Acta, 2014, 118, 58—66
[30]	Wang J.S., Li C. R., Guo C. P., Du Z. M., Wu B, Calphad., 2013, 41, 1—5