Processing of textured zinc oxide varistors via templated grain growth

FAST/SPS sintering of nanocrystalline zinc oxide—Part II: Abnormal grain growth, texture and grain anisotropy

“…Díaz-Chao et al [23] concluded that the crystallographic preferred orientation is a direct consequence of the needle-like morphology, which reoriented under the uniaxial pressure. Similar investigations about the sintering of needle-like ZnO particles also resulted into crystalline texture [20,43,57,68]. These particles may rotate under mechanical pressure into a direction perpendicular to it and finally align, which is an important mechanism for this formation of texture [69].…”

“…This isotropic morphology was found to be independent from sintering process (free sintering, hot pressing, FAST/SPS) or initial particle size (nano to macro scale). In contrast, anisotropic grain growth for polycrystalline ZnO is known to occur only for sintering of powders which originally contain a certain fraction of non-spherical particles [43]. Here, for pure ZnO no study exists that reports the development of grain anisotropy from isometric powder particles.…”

Hybrid processing and anisotropic sintering shrinkage in textured ZnO ceramics

“…They can be used in conjunction with texture-developing heat treatment processes such as oriented consolidation of anisometric particles (OCAP) [8][9][10], templated grain growth (TGG) [2,[11][12][13], reactive templated grain growth (RTGG) [14] and hetero-templated grain growth (HTGG) [15]. Applications of OCAP, TGG, RTGG and HTGG to the production of textured piezoelectric materials have been recently reviewed by Kimura [16].…”

c-axis oriented ZnO formed in a rotating magnetic field with various rotation speeds

“…[1][2][3][4][5][6][7] The use of a high magnetic field with a super conducting magnet has been reported for alignment crystal grains. 7 The feature of the use of magnetic field is to align crystal grains with no physical contact.…”