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Showing 3 results for Calcination

Sheikhi Moghaddam K., Ataie A.,
Volume 2, Issue 4 (12-2005)

Ultra-fine particles of barium hexaferrite have been synthesized by co-precipitation method using barium nitride and iron chloride precursors with a Fe/Ba molar ratio of 11. Co-precipitation was carried out at 25 and 80°C using NaOH as a precipitant. Effect of coprecipitation and annealing temperatures on the phase composition and morphology of the products have been investigated using XRD and SEM, respectively. XRD results indicated existence of BaFeO3-x as a major phase in co-precipitated samples. Analysis of the XRD results also revealed that barium hexaferrite starts to form at a relatively low temperature of 700°C for sample synthesized at 80°C. SEM micrographs exhibit plate-like hexagonal particles of barium hexaferrite for calcined samples. The SEM results showed that the mean particle size of co-precipitated sample at 25°C is smaller than that of 80°C after calcining.
M. Krishna, R. Nandini, A.v. Suresh, K. Narasimha Rao ,
Volume 15, Issue 2 (6-2018)

An efficient solid-state approach was established to synthesize (K0.5Na0.5) NbO3 ceramics using calcination kinetics and microwave assisted sintering. Milling of carbonate and oxide raw materials were carried out for 15h to obtain homogeneous nano particles. The crystallite size of 5.30 nm was obtained for the KNN system after calcination through optimized parameters and observed to be stoichiometric in nature. The obtained nano particles showed phase transition from orthorhombic to tetragonal crystal structure without any secondary phases. The high relative density and tetragonality ratio of KNN ceramics obtained through optimized sintering parameters yielded with significant piezoelectric and ferroelectric properties.

S.m. Moussavi Janbesarayi, M. Mohebi, S. Baghshahi, S.a. Ahmad Alem, E. Irom,
Volume 17, Issue 2 (6-2020)

Overusing nitrogen fertilizer causes some serious problems for water resources, soil, and agriculture products. Researchers have been trying to develop effective means which may use less amount of fertilizers containing nitrogen. In this work, cost-effective ceramic granule adsorbent was prepared to be used as a fertilizer carrier of controlled release behavior. A mixture of 70 wt.% domestic kaolin and 30 wt.% gibbsite was used to produce the granules. By utilizing thermal analysis of raw granule, the calcination temperatures were obtained and the effect of various calcination temperatures of 500, 600, and 700˚C on the water adsorption was studied. The characteristics of granules were investigated by XRD, BET, FTIR, and SEM analyses. The results showed that by increasing the calcination temperature, the crystal structure of the granules was transformed into a dehydrated form and by calcination at 600°C the specific surface area of granules increased from 7.50 to 53.45m2/g. The granules were soaked in a 500g/lit solution of urea, where they adsorbed about 10wt.% urea. The dried urea-loaded granules were placed in water where the release of urea was measured by UV-vis spectrophotometry. Finally, different portions of urea-loaded granules were evaluated as fertilizer in the growing bed of corn plant where the height and the stem diameter of samples were compared with a control sample as well as a sample fertilized by urea directly. The results showed that by using the loaded granules, the urea consumption can be reduced by 50%.

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