Binary System 4MnO·Nb_2O_5-SiO_2—One of the Binary Sections in the Ternary System MnO-Nb_2O_5-SiO_2

摘要

The phase diagram of the binary systemMnO-Nb2O5 was studied by means of the differentialthermal analysis（DTA）,X-ray diffraction analysis andscanning electron microscopy（SEM）.Thermodynamic da-ta of the new compounds 4MnO·Nb2O5 andMnO·Nb2O5were found as follows:4MnO·Nb2O5:tm=1398±2℃△Hm=129000（J/mol）△Sm=77（J/mol,K）△Gmo=129000-77T（J/mol）MnO·Nb2O5:tm=1499±2℃△Hm=86940（J/mol）△Sm=49.6（J/mol,K）△Gmo=86940-49.6T（J/mol）The eutectic parameters for the system are given below:tE1=1383±3℃ NE1（MnO）=0.896tE2=1312±2℃ NE2（MoO）=0.713tE3=1400±4℃ NE3（MnO）=0.