Influence of Ho–Ni–Mn substitution on the structural and magnetic behavior of Ba–Sr Co2Z-type nanohexaferrites extension up to Mossbauer investigations

• Published in: Applied physics. A, Materials science & processing Vol. 125; no. 12; pp. 1 - 11
• Main Authors: Singha, Kirti, Singh, Virender Pratap, Chandel, Monika, Negi, Nain Jeet Singh, Kalia, Susheel, Kotnala, R. K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2019; Springer Nature B.V
• Subjects: Applied physics; Barium; Characterization and Evaluation of Materials; Coercivity; Combustion synthesis; Condensed Matter Physics; Crystal structure; Crystallites; Crystallography; Electronic devices; Machines; Magnetic measurement; Magnetic properties; Magnetic saturation; Magnetic storage; Magnetism; Manganese; Manufacturing; Materials science; Materials substitution; Microstructural analysis; Microwave absorption; Miniaturization; Mossbauer spectroscopy; Nanotechnology; Nickel; Optical and Electronic Materials; Permanent magnets; Physics; Physics and Astronomy; Porosity; Processes; Room temperature; Sol-gel processes; Spectrum analysis; Strontium; Surfaces and Interfaces; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-019-3097-4

A series of Co
2
Z-type Ba–Sr nanohexaferrites Ba
1.5
Sr
1.5
Co
2−
z
Ho
z
Mn
x
Ni
y
Fe
24−
x
−
y
O
41
(
z
 = 0.0, 0.05, 0.10, 0.15, 0.20,
x
 = 
y
 = 0.0, 0.25, 0.5, 0.75, 1.00) have been synthesized using sol–gel auto-combustion synthesis route. The effect of Ho–Ni–Mn substitutions on crystallographic and magnetic properties of synthesized nanohexaferrites was investigated using XRD, VSM, and Mössbauer spectroscopy. Microstructural analysis showed single-phase crystal structures without any impurities and hexagonal with the space group
P63/mmc
. The average variation in crystallite size ranges from 43 to 60 nm with a slight increase in X-ray density and appreciable decrease in porosity was observed for different dopants. FE-SEM (Nova Nano SEM-450) substantiates the hexagonal structure and HR-TEM images assisted with SAED pattern confirm the crystalline quality and FWHM of the material, which significantly support the XRD results. FTIR spectra showed two characteristic metal stretching peaks in the range of 400–600 cm
−1
 due to the substitution of Ho–Ni–Mn. Magnetic measurements show maximum magnetic saturation (
M
s
) at 44.04 emu g
−1
and elevated value of coercivity (
H
c
) 224O
e
imparting typical characteristics of soft ferrite with high coercivity. Mössbauer analysis with least squares fit sextets of six distinguishable sites at room temperature for all samples substantially supports the results of VSM. The materials with large coercivity are useful in permanent magnet applications. The prepared composites could be useful for applications in microwave absorbing materials, magnetic storage, and the miniaturization of antennas for wireless communication devices.