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  Wolff, N.; Klimm, D.: Determination of the phase diagram Tb₂O₃-SiO₂ and crystal growth of the rare earth pyrosilicate Tb₂Si₂O₇ by the optical floating-zone (OFZ) technique. Journal of Solid State Chemistry 312 (2022), p. 123269/1-6

10.1016/j.jssc.2022.123269

Abstract:
By differential thermal analysis (DTA) is was shown that the pseudo-binary system Tb2O3–SiO2 contains intermediate compounds Tb2SiO5, Tb4Si3O12 and Tb2Si2O7. All three compounds melt congruently, a phase diagram was proposed, and from the latter compound single crystals could be grown for the first time. This was possible from stoichiometric feed rods by the optical floating-zone (OFZ) technique. X-ray powder analysis proved the Pna21 phase of the crystals. Melting temperature and heat of fusion were measured by DTA to be 1769◦C and  kJ/mol, respectively. The specific heat capacity of Tb2Si2O7 was measured by dynamic DSC to be cp ​= ​149.4982 ​+ ​0.2242 ⋅ T − 7.3913 ​× ​10−5 ⋅ T2 + 558449.3624 ⋅ T−2.