Average Particle Crystallite Size Research Articles

Impregnated layer combustion synthesis of co doped ZnO green nanopigments: Using nature-based cellulosic templates

In this research, nanostructured green pigments of ZnO and Co (CoxZn1-xO) were synthesized using impregnated layer combustion synthesis under microwave radiation. Taguchi design of experiments was employed to systematically investigate the influence of variables including the type of fuel, cobalt percentage, fuel to oxidizer ratio and type of template (impregnated active layer) to minimize the average crystallite size of particles. Three different types of fuels such as xylitol, mannitol and sorbitol as well as three templates containing filter paper, cotton and sterile gauze were used for the first time for synthesizing CoxZn1-xO nanopigments. The optimum sample with the average crystallite size of 35 nm was synthesized in specific conditions including mannitol as a fuel, filter paper as a template, cobalt percentage of 7%, fuel to oxidizer ratio of 1.3× stoichiometry. XRD analysis demonstrated that whole samples have followed ZnO pattern representative pure phases in the final structure and well-doped Co2+. FESEM images revealed the homogeneity of the nanoparticles, with average particle size of 90 nm. As a result of colorimetric studies on the optimum sample a broad reflectance band nearby 520 nm demonstrates green region with L* = 58.19, a* = −13.65, C* = 14.35 and h° = 162.07. Results showed that the pigment calcination influences the reflectance intensity effectively (∼40%). Co percentage and template type are the most important factors affecting the final green product colorimetric properties.

Influence of Mg and Ni substitution on structural, microstructural and magnetic properties of Sr2Co2−xMgx/2Nix/2Fe12O22 (Co2Y) hexaferrite

In this study, Mg and Ni substituted Y-type hexaferrite particles with narrow size distribution have been prepared by using a sol–gel auto combustion method. The effects on structural, microstructure and magnetic properties have been investigated by substituting Mg2+ and Ni2+ at Co2+ sites. XRD patterns showed that Y-type hexaferrite phase formation has not been affected by substituting magnesium and nickel with cobalt in the range of 0.0≤x≤0.75. Various parameters such as lattice constants, cell volume and crystallite size have been calculated based on XRD data. The morphology and size distribution of the particles have been studied using high resolution field emission scanning electron microscopy (FESEM). It was also understood that the average crystallite size of particles increased from 45 to 63nm with an increase of x content at Co2Y compound. Magnetic properties were determined using a vibrating sample magnetometer (VSM). The magnetic results revealed that by increasing the Mg and Ni in octahedral and tetrahedral sites, the coercivity was also increased from 949 to 1066Oe, whereas saturation magnetization and Remnant magnetization were decreased from 47.98 to 40.78emu/g and 23.05 to 20.99emu/g, respectively.