2
38
B.-P. Liu et al. / Thermochimica Acta 401 (2003) 233–238
ꢀ
Hm
fus
[
Gd4/3Y2/3(Gly) (H2O)4](ClO4) · 5H2O
6
6
ꢀ
fusSm =
(4)
Tm
◦
9
3–320 C
→
[Gd4/3Y2/3(Gly) (H2O)4](ClO4)6
6
9
.5% (10.96%)
where T is the temperature a few degrees lower than
the initial melting temperature, Tm the melting peak
temperature, T the temperature slightly higher than
i
◦
386–776 C
4
3
2
→
GdCl3 + YCl3
3
f
57.9% (56.8%)
the final melting temperature, Q the total energy in-
troduced into the sample cell from T to T , H0 the
i
f
[
ErY(Gly) (H2O)4](ClO4) · 5H2O
6
6
heat capacity of the sample cell from T to T , Cp,1
i
f
◦
1
12–189 C
the heat capacity of the sample in solid phase from Ti
to Tm, Cp,2 the heat capacity of the sample in liquid
→
[ErY(Gly)6(H2O)4](ClO4)6
6
.0% (6.1%)
◦
3
04–746 C
phase from Tm to T , and n the molar amount of the
→
ErCl + YCl3
f
3
61.9% (61.9%)
sample. The molar enthalpies and molar entropies of
fusion for the two coordination compounds were de-
The mass-loss percentages in the brackets are the cal-
culated theoretical values of the corresponding ther-
mal decomposition reaction.
−
1
−1
−1
termined to be 18.48 kJ mol and 53.9 J K mol
for [Gd4/3Y2/3(Gly) (H2O)4](ClO4) ·5H2O, and 1.82
6
6
−1
−1
−1
kJ mol and 5.5 J K mol for [ErY(Gly) (H2O)4]-
6
(
ClO4) ·5H2O, respectively.
6
Acknowledgements
3
.3. TG analysis
The authors gratefully acknowledge the National
Natural Science Foundation of China for financial sup-
port to this work under Grant No. 20073047.
The TG curve of [Gd4/3Y2/3(Gly) (H2O)4](ClO4) ·
6
6
5
H2O is shown in Fig. 2. It can be seen clearly
from the mass-loss curve that the most of the activ-
◦
ities occur in the temperature range of 263–750 C.
References
The solid-state coordination compound was stable
◦
◦
below 90 C, and started decomposition at 93 C.
The total mass-loss (%) is 57.9%. We consider that
the residue should be 4/3 GdCl3 and 2/3 YCl3 be-
cause the theoretically calculated mass-loss (%) is
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[2] B.S. Guo, J. Chin. Rare Earth Soc. 20 (1999) 64.
[3] T.Z. Jin, C.Q. Yang, Q.C. Yang, J.G. Wu, G.X. Xu, Chem.
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5
6.8% if the final residues are 4/3 GdCl3 and 2/3
YCl3.
Fig. 3 shows that the structure of [ErY(Gly) -
[4] L.Y. Wang, F. Gao, T.Z. Jin, Chin. Chem. Bull. 10 (1996) 14.
[5] P.Y. Wei, T.Z. Jin, G.X. Xu, J. Chin. Rare Earth Soc. 10
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6
◦
[6] J.R. Li, X. Wang, T.Z. Jin, in: Proceedings of the Third
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X.K. Wang, Sci. China Ser. B 25 (1983) 1014.
(
H2O)4](ClO4) ·5H2O is stable below 100 C, it
6
◦
started mass-loss at 112 C. The experiment result of
final mass-loss was 61.9%, which suggested that the
residual products should be ErCl3 and YCl3, because
the theoretical mass-loss (%) of the decomposition is
[8] Z.-C. Tan, G.Y. Sun, Y. Sun, A.X. Yin, W.B. Wang, J.C. Ye,
L.X. Zhou, J. Therm. Anal. 45 (1995) 59.
6
1.9% when the final residues are ErCl3 and YCl3.
[9] Z.-C. Tan, G.Y. Sun, Y.J. Song, L. Wang, J.R. Han, Y.S. Liu,
M. Wang, Thermochim. Acta 352–353 (2000) 247.
According to the mass-loss in each step, the possible
mechanisms of the thermal decompositions may be
deduced as follows:
[10] D.A. Ditmars, S. Ishihara, S.S. Chang, G. Bernstein, E.D.
West, J. Res. Nat. Bur. Stand. 87 (1982) 159.
Liu, Bei-Ping
