Effect of milling duration on structural properties of polycrystalline bulk barium hexaferrite

• Main Authors: Nishkala, K.R., Radhakrishna Rao, Rajat, Mutalik, Srinivas, Murari, M.S., Daivajna, Mamatha D.
• Format: Conference Proceeding
• Language: English
• Subjects: Ball milling; Barium hexaferrite; Milling duration; M−type hexaferrites; Porosity; Resistivity
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2022.01.326

•Polycrystalline BaFe12O19 were synthesized by ball milling followed by sintering at high temperature.•Single phase barium hexaferrite structure was formed for milling time t > 4 hours.•12 hour milled sample show minimum crystallite size and maximum strain.•Formation of hexagonal plate like grains were observed in 8 hour milled sample.•16 hour milled sample show agglomeration of grains with different grain size.•Highest amount of porosity was observed for 8 hour milled sample.•Maximum electrical resistivity is found for 8 hour milled sample.•The electrical resistivity varies linearly with porosity.•Good quality, single phase, large resistive barium hexaferrite can be obtained from 8 hours of milling. Polycrystalline bulk Barium hexaferrite, BaFe12O19 were synthesised by ball milling for different milling duration followed by sintering at high temperature. Effect of milling duration on structural, morphological and dc electrical properties were studied for 4, 8, 12 and 16 h of milling using planetary ball mill. X-ray diffraction measurement data shows the formation of single phase barium hexaferrite which belongs to P63/mmc group for 8, 12 and 16 h milled samples. There is formation of intermediate phase along with M−phase of barium hexaferrite in 4 h milled sample. Inverse relation of the crystallite size and lattice strain was observed. The saturation value of crystallite size and maximum lattice strain were observed for 12 h milled sample. Morphological studies for 8 and 16 h milled samples reveals the formation of hexagonal plate like grains for the former and agglomerates with different grain size for the latter. High porosity for 8 h milled sample was observed by density measurements. Resistivity of the samples measured from I-V characteristics using 2 probe method exhibits maximum resistivity for 8 h milled sample and minimum resistivity for 12 h milled samples. Linear relationship was observed between electrical resistivity and porosity.