Influence of Zn-Nb on the magnetic properties of barium hexaferrite

In the present study, BaFe12-2x Zn x Nb x O19 (x=0. 2, 0.4, 0.6 and 0.8) hexaferrites were prepared by the sol-gel technique and subsequent thermal treatment. The crystal structure, grain size, and magnetic properties were studied by means of X-ray diffraction (XRD), high-resolution scanning electron microscope (HR-SEM) and vibrating sample magnetometer (VSM). The X-ray diffraction analysis showed that the barium hexaferrite with small substitutions still maintained a hexagonal magneto-plumbite phase. It was found that the mean size of the grains increased with increasing substitution. The saturation magnetization increased slightly with increasing x, which was attributed to different preferential site occupation of Zn-Nb at low and high concentration ranges. The coercivity decreased with increasing x. Structural and magnetic characterizations of these ferrites provide significant information about their reactive physical properties

Dielectric properties of Zr doped CaCu3Ti4O12 synthesized by sol-gel route

Zr substituted CaCu3Ti4−xZrxO12 (CCTZO) with x = 0.00, 0.02, 0.10, 0.20 and 0.50 mol% were prepared by sol–gel route from the metal nitrate solutions, Titanium isoproxide, and zirconium oxy chloride. XRD analysis confirmed the formation of a single phase material in the samples calcinated at 800 °C for 3 h. The crystal structure did not change on doping with zirconium and it remained cubic in all the four studied compositions. The permittivity and dielectric loss of 0.1 mol% Zr doped CaCu3Ti4O12 were improved for K ≈ 6020 and tan δ ≈ 0.52 at 1 kHz after the sample had been sintered at 1040 °C for 4 h. AFM studies showed that the particle size of the CCTZO powder ranged from 47 to 85 nm. FE-SEM micrographs of the CaCu3Ti4−xZrxO12 samples showed that the grain size was in the range of 250 nm to 5 μm for these samples. EDX studies showed the presence of calcium, copper, titanium, oxygen and zirconium. Remarkably, the dielectric constant increased and dielectric loss had lower values compared to the undoped CCTO

Influence of Er on microstructural and dielectric properties of CaCu3Ti4O12

Erbium-doped CaCu3Ti(4−x)ErxO12 (x = 0, 0.02, 0.1, 0.2, 0.5, 1.0)—(CCTEO) samples were synthesized by using the sol–gel method. The crystal structure did not change on doping with erbium; and it remained cubic when all the six compositions were studied. It was found that lattice parameter increased slightly with Erbium doping. AFM studies showed that the particle size of the CCTEO powder ranged from 52 to 97 nm. The surface morphology of the samples sintered at 1,040 °C in air for 3 h was observed using a high resolution scanning electron microscope. It showed that the grain size was in the range of 0.7–5 µm for these samples. Er doping has been shown to reduce the dielectric loss remarkably while maintaining a high dielectric constant. This result indicates that 0.02 mol% of Er dopant can be used to improve the dielectric properties (dielectric constant- 164,000) of CaCu3Ti4O12

Particle morphology and magnetic properties of Ba0.5Sr0.5Fe12O19 powder calcined conventionally and by microwave heating

Barium strontium hexaferrite (Ba0.5Sr0.5Fe12O19-BSF) has been prepared by sol–gel process involving use of d-Fructose as a fuel. The prepared precursor was calcined in two different calcinations techniques conventional and microwave furnace. X-ray powder diffraction studies confirmed the formation of single phase Ba0.5Sr0.5Fe12O19. HR-SEM results show the morphology of the particles is hexagonal structures in platelet form. The average particle size of conventionally calcined BSF powder is 100–250 nm and that of microwave calcined powder is 30–100 nm. The broad hysteresis loop reveals that powder is well crystallized and exhibits hard magnetic properties

Influence of ER doping on the microstructural and dielectric properties of microwave sintered calcium copper titanate

The present work reports synthesis, as well as a detailed characterization of structural, morphological and dielectric properties of Er doped CaCu3Ti4-xErxO12 (CCTEO) with x = 0.00, 0.02, 0.10, 0.20 and 0.50 mol% ceramics were prepared by sol-gel route. The prepared samples were sintered by using microwave sintering. The phase composition and microstructure were studied by means of X-ray diffraction (XRD) and high resolution scanning electron microscopy (HRSEM). The crystal structure did not change on doping with erbium; and it remained cubic when all the six compositions were studied. At lower frequencies, it was found that the dielectric constants had a maximum value at 0.5 mol% of Er. This result indicates that a certain amount of Er dopant can be improve the dielectric properties of CaCu3Ti4O12

Microwave sintering of Zn-Nb doped barium hexaferrite synthesized via sol-gel method

A series of polycrystalline M-type hexagonal ferrites with the formula BaFe12-2xZnx NbxO19 (x = 0.2, 0.4, 0.6, 0.8 mol%) have been synthesized by the sol-gel method. The composition and microstructure govern the magnetic properties of ferrites. The XRD analysis shows the formation of pure magneto plumbite phase without any other impurity phases. The Zn-Nb substitutions in barium hexaferrite have been confirmed through magnetic measurements. The results show that the magnetic properties are closely related to the distributions of Zn-Nb ions on the five crystallographic sites. The saturation magnetization and coercivity increase with increasing Zn-Nb concentration

Microstructural and dielectric properties of Zr doped microwave sintered CaCu3Ti4O12 synthesized by sol-gel route

Polycrystalline samples with the chemical formula CaCu3 Ti 4 - x Zrx O12 (x = 0, 0.02, 0.1, 0.2, 0.5, and 0.1) CCTZO were synthesized from metal nitrate solutions by the sol-gel method, followed by conventional and microwave heat treatments. The X-ray diffraction pattern of powder calcined at 800°C in conventional furnace for 3 h showed formation of a single phase. The crystal structure did not change on doping with zirconium and it remained cubic in the five studied compositions. The surface morphology of samples sintered at 1000°C in microwave furnace for 10 min was observed using a high resolution scanning electron microscope (HR-SEM). The grain sizes were in the range of 250 nm-5 m for these samples. HRSEM results show that doping with Zr enhanced grain growth or densification. Energy dispersive X-ray spectroscopy (EDX) confirmed the presence of Zr. The dielectric characteristics of Zr doped CCTO were studied with an LCR meter in the frequency range of 50 Hz-1 MHz. A very high dielectric constant 21,500 was observed for the sample doped with Zr (0.02 mol%) at 50 Hz

Effect of microwave sintering on microstructural and magnetic properties of strontium hexaferrite using sol-gel technique

The sol–gel method is used to prepared hexaferrite using d-Fructose as a fuel. The effect of sintering temperature on the microstructure of SrFe12O19 ceramics is analyzed. The observed XRD results indicate a well-formed crystalline phase of dense hexagonal SrFe12O19 ceramics. From this analysis, no secondary phases are identified. The microstructure of the sintered single phase M-type ferrites ceramics displays a hexagonal-platelet like morphology. Sintering temperature can markedly affect the grains in sintered ferrite. The sintered product is shown to be dense microstructure with relatively small grains. The maximum sintered density 95 % was obtained at lower temperature of 1,150 °C. In addition, saturation magnetization (50.43 emu/g) and the coercivity (Hc) 5,594.53 Gauss were observed