title: Effect on the grain size of single-mode microwave sintered NiCuZn ferrite and zinc titanate dielectric resonator ceramics.
abstract: Microwave sintering of materials significantly depends on dielectric, magnetic and conductive Losses. Samples with high dielectric and magnetic loss such as ferrites could be sintered easily. But low dielectric loss material such as dielectric resonators (paraelectrics) finds difficulty in generation of heat during microwave interaction. Microwave sintering of materials of these two classes helps in understanding the variation in dielectric and magnetic characteristics with respect to the change in grain size. High-energy ball milled Ni0.6Cu0.2Zn0.2Fe1.98O4-delta and ZnTiO3 are sintered in conventional and microwave methods and characterized for respective dielectric and magnetic characteristics. The grain size variation with higher copper content is also observed with conventional and microwave sintering. The grain size in microwave sintered Ni0.6Cu0.2Zn0.2Fe1.98O4-delta is found to be much small and uniform in comparison with conventional sintered sample. However, the grain size of microwave sintered sample is almost equal to that of conventional sintered sample of Ni0.3Cu0.5Zn0.2Fe1.98O4-delta. In contrast to these high dielectric and magnetic loss ferrites, the paraelectric materials are observed to sinter in presence of microwaves. Although microwave sintered zinc titanate sample showed finer and uniform grains with respect to conventional samples, the dielectric characteristics of microwave sintered sample are found to be less than that of conventional sample. Low dielectric constant is attributed to the low density. Smaller grain size is found to be responsible for low quality factor and the presence of small percentage of TiO2 is observed to achieve the temperature stable resonant frequency.
authors.affiliation: Department of Physics, Indian Institute of Technology, Madras, Chennai 600036, India.
authors.forename: Roopas Kiran
authors.initials: RK
authors.lastname: Sirugudu
authors.affiliation: Department of Physics, Indian Institute of Technology, Madras, Chennai 600036, India.
authors.forename: Rama Krishna Murthy
authors.initials: RK
authors.lastname: Vemuri
authors.affiliation: Department of Physics, Indian Institute of Technology, Madras, Chennai 600036, India.
authors.forename: Subramanian
authors.initials: S
authors.lastname: Venkatachalam
authors.affiliation: Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras, Chennai 600036, India.
authors.forename: Anisha
authors.initials: A
authors.lastname: Gopalakrishnan
authors.affiliation: Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras, Chennai 600036, India.
authors.forename: Srinivasa Murty
authors.initials: SM
authors.lastname: Budaraju
mesh_terms: D002516:Ceramics / Q000737:chemistry* / Q000528:radiation effects*; D003300:Copper / Q000737:chemistry* / Q000528:radiation effects; D017097:Electric Impedance; D006361:Heating / Q000379:methods*; D008422:Materials Testing; D008872:Microwaves; D009532:Nickel / Q000737:chemistry* / Q000528:radiation effects; D010316:Particle Size; D011829:Radiation Dosage
chemical_list: C062136:nickel copper alloy; D003300:Copper; D009532:Nickel