| Nano-titanate powder of barium (lead) titanate and its solid solution is an important electronic ceramic material. It has been focused on the theory and technical application in recent years. During the preparation processes of barium titanate, the fundamental characteristic is that polycrystalline ceramics were prepared from powder, followed by molding and sintering. The quality of ceramic powder has direct influence on the resultant products. So the preparation of powder which meets the requirements of product' properties is the key problem for preparing electronic ceramic devices such as barium titanate. Therefore, it has great theoretical and practical significance in studying the problems such as new method of synthesizing, the mechanism of reaction, and the rule of phase transformation for nano-powder of barium titanate.The research status of electronic ceramic powder such as barium (lead) titanate etc. was reviewed detailedly in this study. And the applied fundamental researches of the synthesis method, phase transformation & reaction mechanism and doping modification etc. were carried out systematacially with BaTiO3, PbTiO3, Ba(ZrTi)O3 and Pb(ZrTi)O3 as the research objects.1. The reaction process (mechanism) of preparing nano-barium titanate by using peroxide precursor thermal decomposition method was studied and presented. Taking H2TiO3, ammonia water, hydrogen peroxide and water-soluble barium salts as raw materials, nano-barium titanate powder was prepared using peroxide precursor thermal decomposition method, in which cubic phase barium titanate with grain sizes between 20 and 40 nm were obtained by calcining at 600℃for 1 hour, and tetragonal phase barium titanate with grain sizes between 60 and 100 nm was obtained by calcining at 1000℃for 1 hour. Meanwhile, oxygen was produced when heating the peroxide precursors of barium (calcium and strontium) titanate. By combining experimental analysis of TG-DSC and electron spectrum etc., the reaction process (mechanism) of preparing nano-barium titanate using peroxide precursor thermal decomposition method was proved to be:H2TiO3+2H2O+2NH3→(NH4)2Ti(H2O2)2O3 (NH4)2Ti(H2O2)2O3+Ba2+→BaTi(H2O2)2O3↓+2NH4+BaTi(H2O2)2O3→(BaTiO5+2H2O)→BaTiO3↓+2H2O↑+O2↑2. The phase transformation law of (strontium) doping induced barium titanate was studied. Nano-barium titanate powder was prepared by using peroxide precursor thermal decomposition method. A small amount of strontium was added during preparation process, and the strontium ions were allowed to enter into the crystal lattice of mother substance evenly which obviously caused the phase transformation temperature to be reduced. After adding molar ratio of strontium ions less than 2% among the total cation, the phase transformation temperature was changed from 900℃-1000℃to 800℃-900℃. After adding molar ratio of strontium ions more than 5%, phase transformation was hard to occur even if the temperature was increased, and the powder would be decomposed at high temperature. This was related to the steric hindrance of titanium ions in the crystal structure. When the barium ions were replaced partially by ions with smaller radius, the crystal structure of the barium titanate would change, and the steric hindrance of titanium ion became smaller, the vibration became easier, and the phase transformation temperature of barium titanate crystal from cubic phase to tetragonal phase would be reduced; However, when more barium ions were replaced by ions with smaller radius, the steric hindrance of titanium ion became even smaller, and the up & down vibration of titanium ion was very easy. Therefore, the transformation of tetragonal phase was hard to occur. When the calcination temperature was changed, the structure of barium titanate crystal was transformed. Therefore, the Ti ions in the octahedral structure became eccentric (off-centering) and formed a pentacoordinate rearranged structure with stable Ti-O bond, where Ti-O bond length was longer than that in hexacoordinate structure, and so that the Ti ions would exist stably. Eventually, barium titanate would transform from the stable cubic structure to the metastable tetragonal structure.Meanwhile, the grain sizes that phase transformation of barium titanate occurred were reduced greatly by mixing an amount of strontium ions. The experiment results indicated that, the grain sizes which barium titanate transformed from cubic phase to tetragonal phase were around 33nm (calculated value from experiments).3. This study explored and proposed a preparation method of nano powder of BaTiO3 and BaZr0.1Ti0.9O3 by a gel-combustion method for the first time. Nano-BaTiO3 powder was prepared by taking the metatitanic acid, hydrogen peroxide, ammonia water and barium nitrate etc. as raw materials and using organic coordination compound combustion method. And nano-barium titanate powder with cubic phase or tetragonal phase was prepared respectively by controlling the calcining temperature of the precursor. Cubic phase nano-BaTiO3 powder with little BaCO3 impurity was prepared by calcining the precursor of barium titanate at 800℃for 4 hours; while calcining temperature increased to 1000℃, tetragonal phase nano-BaTiO3 powder would be prepared. The grain sizes of the prepared tetragonal phase nano-powder of BaTiO3 were between 60 and 120 nm with average grain size of approx.80nm. By changing the raw materials, nano-powder of barium zirconate titanate (BaZr0.1Ti0.9O3) was prepared by using the same method, with the grain sizes between 30 and 80 nm and the average grain size at approx 50 nm.4. A new combustion preparation method for nano-powder of PbTiO3 and PbZr0.52Ti0.48O3 was studied and presented for the first time. Taking the H2TiO3, H2O2 and Pb(CH3COO)2·3H2O etc. as raw materials, and EDTA and citric acid as complexing agent and fuel agent, precursor powder of PbTiO3 was prepared firstly, then by calcining the powder at 700℃for 1 hour, nano-powder of PbTiO3 was prepared with the grain sizes between 50 and 80 nm and average grain size at approx.70 nm. By changing raw materials, cubic phase powder of PZT (PbZr0.52Ti0.48O3) was prepared by using the same method, with the grain sizes between 100 and 200 nm and average grain size at approx.100 nm. This method, with extensive sources of raw materials, simple process, low cost and easy control of production conditions, is a good reference for preparation of other titanates nano-powder.5. PZNT and PMNT nano-powders were prapared by a gel-combustion method using meta-titanic acid, hydrogen peroxide, ammonia, zinc acetate, lead acetate and magnesium nitrate as raw materials, EDTA and citric acid as complexing agent and incendiary agent seprarately. The results showed that PZNT and PMNT were prapared through the obtained jelly being calcined at 488-527℃and 514-545℃, and the obtained jelly being calcined at 700℃for 2h, the grain sizes of obtained nano-powder of PZNT was 50-150nm, the average diameter of the particles was about 100nm, and the obtained jelly being calcined at 800℃for 2h, the grain sizes of obtained nano-powder of PMNT was 100-300nm, the average diameter of the particles was about 200nm.6. Li4Ti5O12 submicron-powders were prepared through Gel-combustion method with Citric acid as Complexing and fueling agent, and Titanic hydroxide, hydrogen peroxide, ammonia and lithium nitrate as the starting materials. Firstly, H2Ti03 was dissolved in the mixture of H2O2 and NH3·H2O at certain molar ratio, and some citric acid was added to obtain a orange-red transparent solution which then was added with identical mole of Li+solution.The obtained mixture was heated and condensed into jelly before calcined at different temperatures, and micro-powder of Li4Ti5O12 was fabricated. Investigations based on XRD, TG-DTA, TEM and IR show that LTO was fabricated at about 450℃. With the obtained jelly being calcined at 800℃for 2h, the grain sizes of obtained submicro-powder of Li4Ti5O12 was in the range of 200-300nm, respectively.
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