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Figure 1. Thermogravimetric (TG) and differential thermogravimetric (DTG) curves of
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Figure 1. Thermogravimetric (TG) and differential thermogravimetric (DTG) curves of
thermolysis of the initial mixture containing (1-х)K
2
CO
3
-хNa
2
CO
3
-Sb
2
O
3
-WO
3
The phase composition was observed in filtered CuKα
1
-irradiation using an X-ray analysis method
performed on a D8 ADVANCE diffractometer (Brooker, Germany). Parameter a of the elementary cell was
determined by reflex 10.6.2. The error in determining parameter a was ± 0.003 Å.
X-rays of the obtained samples are a complex set of diffraction maxima characterized by two
concentration fields (Fig. 2, a, b, c, d). In the first field (0≤x≤0.6) the diffraction pattern does not change
significantly. A certain set of diffraction maxima is observed, the number of which does not change within a
certain angle of inclination (Fig. 2, a, b, c). In the second field (0.6≤x≤1.0) this group of reflexes disappears
and maxima appear at other diffraction angles (Fig. 2, d).
X-rays of 0≤ x≤0.6 (first field) of the purified mixtures contain a certain set of diffraction maxima
satisfactorily described for cubic syngonium crystals, and the loss of reflexes indicates that the phases differ
in composition in this concentration range with the pyrochlor-type structure Fd3m spatial symmetry groups
are formed (Table 1).
The observation of additional reflexes in the second area (0.6≤x≤1.0) is associated with the formation
of phases with a different type of symmetry (Fig. 1, d).
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