Sonication method synergism with rare earth based nanocatalyst: preparation of NiFe2-xEuxO4 nanostructures and its catalytic applications for the synthesis of benzimidazoles, benzoxazoles, and benzothiazoles under ultrasonic irradiation

NiFe2-xEuxO4 as an efficient rare-earth based nanocatalyst for the synthesis of benzimidazoles, benzoxazoles, and benzothiazoles under ultrasonic irradiation