Complex sentence: For niobium this behavior was known since the beginning of the 20th century but the technical difficulty of the material with its high melting point of 2744 ° C hinder long times the realization of niobium electrolytic capacitors.
Split into simpler sentences: For niobium this behavior was known since the beginning of the 20th century. The high melting point of 2744 ° C hindered the development of niobium electrolytic capacitors.