Papers by Keyword: Powders-Chemical Preparation

Abstract: The influence in optimization of processing, calcinations and sintering parameter on the physical properties and characteristic of CaCu₃Mn₄O₁₂ were investigated. The stoichiometric CaCu₃Mn₄O₁₂ powders were successfully prepared by the citric gel method. Dried gel with three dimension network consisted of molar ratio of [citrates/metallic ion]; 1:2 was formed. The precursor gel formed was calcined and sintered at range 400 °C to 800 °C. A single-phase CaCu₃Mn₄O₁₂ fairly well densified at relative low temperature under atmospheric sintering condition. FESEM results turned out that CaCu₃Mn₄O₁₂ powder particle is submicron in size and highly agglomerates due to high calcinations temperature. The smaller particle size with higher grain boundary and less of porosity were found for the sample sintered at 700 °C to 800 °C. The samples show the ‘superparamagnetism’ behavior where the M-H curves are linear with the field and have a smaller value of coercivity at room temperature. Sintering at 800 °C produced the sample with lowest Hc value due to the phenomenon of over grown magnetocrystallites, grain size and grain boundaries.

Abstract: Due to the disadvantageous of solid state in CaCu₃Mn₄O₁₂ ceramic processing, the sol gel synthesis has been extensively studied to produce fine size of powder and better homogeneity at low processing temperature. This paper provides a summary to prove that the single phase of CaCu₃Mn₄O₁₂ ceramic with high purity and characteristic is actually can be produced via sol gel synthesis at relative low temperature under pressureless sintering process. The stoichiometric CaCu₃Mn₄O₁₂ powders were successfully prepared by the citric gel method with molar ratio of [citrates/metallic io; 1:2. The precursor gel formed was calcined and sintered at range 400 °C to 800 °C. A single-phase CaCu₃Mn₄O₁₂ fairly well densified at relative low temperature under atmospheric sintering condition. Analysis has been done under XRD and FESEM. Result shown formation of CaCu₃Mn₄O₁₂ started at 500 °C and was formed completely at 700 °C for 18h. FESEM results turned out that CaCu₃Mn₄O₁₂ powder particle is submicron in size and highly agglomerates due to high calcinations temperature. Varying in sintering parameter is actually exhibit differences in phase formation, grain size and magnetic behavior.

Abstract: The present research compares properties and behaviour of co-precipitated 3Y-PSZ powders submitted, after co-precipitation, to different milling treatments. The characteristics of the different products were evaluated by measurement of particle size distribution, thermogravimetric analysis, X-ray diffraction, specific surface area and scanning electron microscopy analysis. It has been demonstrated that 1h of attrition milling enables the production of powders with micrometric particles: the dispersing liquid used on milling has little influence. Crystallization of the amorphous powder is achieved after 1h of high energetic milling, without any thermal treatment.