Papers by Keyword: Templated Grain Growth

Abstract: It is proposed a parallel Monte Carlo algorithm to simulate templated grain growth in sintering ceramics materials. The algorithm applies the general Potts model to treat the matrix as the discrete lattices for simulating the grain growth and there will be a number of lattices to be computed synchronously. The scheme is performed by CUDA GPU parallelization programming framework which is of much more feasibility and low cost comparing with the former conventional program. The most key point is that the parallel algorithm is of great temporal performance which means it takes less time to complete a simulation. The results of comparative experiments show that the algorithm is unquestionable effective while the other statistic numerical features of simulations are almost the same.

Abstract: Micro-scale plake-like SrTO3 particles were synthesized by two routes of topochemical conversion. One is by growing on Sr3Ti2O7 (S3T2) core particles in molten salt condition, and the other is from the layer-structured SrBi4Ti4O15 (SBT) precursor in a KCl medium. The effects of the morphology and size of the precursor to platelet SrTiO3 crystals were studied. X-ray diffraction analysis revealed that the crystallographic {010} plane of SBT was converted into the pseudo-cubic {001} plane of SrTiO3. The polycrystalline SrTiO3 particles from BST precursor exhibited a plate-like shape with 10-15μm in length and a high aspect ratio, and were more suitable for preparing textured ceramics by templated grain growth process than the platelets from the S3T2 precursors.

Abstract: The development of texture was studied during electrophoretic deposition in alumina suspensions containing plate shaped alumina particles. The mechanism of platelet orientation during EPD was examined with respect to the influence of the electric field, gravity and hydrodynamic forces. This was realized by using two different deposition cells, with vertically or horizontally positioned deposition electrode. The texture of the green deposit was further enhanced during sintering by templated grain growth in which the platelet shaped alumina particles were growing at the expense of the fine grained matrix. The sharp ‘fiber texture’ obtained after templated grain growth during sintering of the deposit was characterized by means of x-ray diffraction and Electron Backscatter Diffraction (EBSD).

Abstract: The spark plasma sintering technique was used to fabricate ceramics from Pb(Mg1/3Nb2/3)O3– PbTiO3 ceramic layers which were prepared by tape casting and TGG method used BaTiO3 templates as seeds. During heat treatment, epitaxial grain growth occurred on the BaTiO3 surfaces and formed <001> textured lead magnesium niobate-lead titanate, Pb(Mg1/3Nb2/3)O3-0.325PbTiO3 (PMN-32.5PT) ceramics. The phase compositions and microstructure were investigated. The results indicated that this method was an alternative sintering technology to synthesize dense lead-based relaxor ferroelectric ceramics.

Abstract: <001> textured 0.675Pb(Mg1/3Nb2/3)O3-0.325PbTiO3 (PMN-32.5PT) ceramics were prepared by templated grain growth with micron scale BaTiO3 platelet templates. 0%~7% excess PbO was added to form liquid phase. The influence of liquid phase concentration on the growth of matrix and templated grains was investigated. The growth process was controlled by a dissolution-precipitation mechanism. The templated grain growth was accelerated by the formed liquid phase and resulted in highly textured PMN-32.5PT ceramics.

Abstract: Textured SrBi2Nb2O9 (SBN) ceramics were fabricated by templated grain growth (TGG) method. The plated-like SBN particles with shape anisotropy prepared by molten salt method were used as the templates. The SBN powders prepared by conventional solid (CS) reaction were used as matrix powders. It was found that the textured SBN ceramics can be obtained by TGG method. The grain orientation (Lotgering factor, f) increased with the increase of sintering temperature and content of the templates. The textured SBN ceramics with f=0.86 could then be obtained after sintering at 1300 °C for 3 h with 20wt.% templates. The relative density keeps rising with increasing temperature until it reaches a peak value 91.22% at the sintering temperature 1300°C, after which it decreases.

Abstract: High <001>-textured Na1/2Bi1/2TiO3-BaTiO3 (6mol%BaTiO3) ceramics were fabricated by reactive-templated grain growth (RTGG), using plate-like Bi4Ti3O14 particles prepared by a molten salt method as the templates. The effect of template concentration on the texture development and microstructure evolution was studied, and the mechanisms of grain orientation and densification were also discussed. The design of Bi element reaction has important impact on the texture development.

Abstract: Fiber textured 0.70PMN-0.30PT ceramics was fabricated using the Templated Grain Growth (TGG) process. Tabular SrTiO3 particles synthesized in molten NaCl-KCl salts were used as templates and oriented in fine 0.70PMN-0.30PT matrix during rolling. Tabular SrTiO3 particles can stabilize in sintering by SPS technique and annealing. A degree of [001] texture (Lotgering factor ~ 0.38) was obtained by heteroepitaxial growth of oriented single PMN-PT on the SrTiO3 template particles.

Abstract: Spinel (MgAl2O4) formation from stoichiometric MgO and Al2O3 is strongly mineralized by B-containing compounds such as boron oxide (B2O3), lithium tetraborate (Li2B4O7) and sodium tetraborate (Na2B4O7) at 1000°C. TEM confirms that the mineralization with each compound involves borate glass which is presumably formed on cooling from liquid at 1000°C. EDS shows the boron-containing liquids formed from B2O3 and Na2B4O7-mineralized samples contain little alumina suggesting a templated grain growth whereas those in Li2B4O7-mineralized samples dissolve sufficient alumina to suggest dissolution-precipitation is occurring at this temperature. XRD shows that Li2B4O7 is the most effective mineralizer producing single- phase spinel with 3 wt% addition at 1000°C whereas B2O3 produces Mg3B2O6 at
1.5 wt% addition and both B2O3 and Na2B4O7- mineralized samples show incomplete spinelisation which may be explained by the composition of the liquids formed with these two mineralizers.

Abstract: The oriented 0.67Pb (Mg1/3Nb2/3)O3-0.33PbTiO3 (PMNT) polycrystals were prepared by the conventional ceramic technique and the templated grain growth method adding excess PbO in the matrix. Kinetics of the development of oriented structure was investigated systemically. In the presence of PbO liquid phase, the oriented PMNT polycrystals mainly grow by the dissolution-precipitation mechanism. The diffusion is determined by the sintering temperature and the PbO-excess content in the matrix. The thickness of oriented PMNT polycrystals displays a t1/3 dependence, which is characteristic of diffusion-controlled growth. For the thicker oriented structure, 20% excess PbO in the PMNT matrix and 1150oC for 10h are the proper experimental conditions. Moreover, the addition of PbO in the matrix hardly affects the final composition of ceramic matrix.