The influence of microstructure and phase composition of glass ceramics in the VO_2-V_2O_5-P_2O_5-Cu_2O-SNO_2 system on the electrical properties related to the metal-semiconductor phase transition

摘要

Phase composition, microstructure and electrical conductivity of glass ceramics in the VO_2-V_2O_5-P_2O_5-SNO_2 and VO_2-V_2O_5-P_2O_5-Cu_2O-SNO_2 systems have been studied. Only crystalline phases VO_2, SNO_2 and vanadium phosphate glass of the V_2O_5-P_2O_5 system have been found in glass ceramic compositions in the VO_2-V_2O_5-P_2O_5-SnO_2 system. Besides the above-mentioned phases, probably the X-ray lines of V_3O_5, V_4O_7, V_5O_9, V_6O_(11), V_7O_(13), V_4O_9, V_6O_(13), V_2O_5, SNO_2, SnO, Sn_2O_3, Sn_3O_4 and CuO phases are observed in the X-ray spectra of glass ceramics in the VO_2-V_2O_5-P_2O_5-Cu_2O-SnO_2 system. According to SEM/EDS data, these phases were observed as submicrometer fine-crystalline inclusions in glass on the surface of VO_2 crystallites and between them. The formation of these phases was caused by the redox processes in the liquid phase during glass ceramics synthesis. The important role of tin oxides possessing high electrical conductivity and vanadium oxides exhibiting a low temperature of metal-semiconductor phase transition in the stabilization of glass ceramics electrical properties related to the phase transition in VO_2 has been established.