This book presents the physical, optical and microwave properties of the Bi1.5Zn1.0Nb1.5O7 and Bi2Zn2/3Nb4/3O7 ceramics and thin films in the Bi2O3-ZnO-Nb2O5 based pyrochlore system. The increasing demand for the microwave dielectric materials with improved properties suitable for modern integrated circuits was the major motivation for investigating these ceramics materials both in bulk and thin film forms. Bismuth zinc niobate based pyrochlore ceramics and thin films are being considered for many applications ranging from ceramic capacitors to frequency agile microwave devices. So this presents the study of the BZN ceramics and thin films in an inter disciplinary perspective which include aspects of physics, material science and microwave engineering.