Correlation Between Grain-Boundary Segregation and Grain-Boundary Plane Orientation in Nb-Doped TiO2
نویسنده
چکیده
Grain-boundary (GB) segregation has been measured in Nbdoped TiO2 (rutile) by Auger electron spectroscopy analyses of the two surfaces exposed by inter-granular fracture. In addition, the orientations of the exposed GB planes on both sides of the fracture surface have been determined. A strong anisotropy of GB composition is found. Measurements on 166 individual GB fracture surfaces show that boundary planes with low and high levels of segregation tend to be clustered along the (110)–(010) and (001)–(011) regions of the stereographic triangle, respectively. The matching halves of GB planes with either high or low segregation also tend to be terminated by planes in the same respective regions of orientation space. High and low levels of segregation occur in regions of GB plane orientation space estimated to correspond to high and low GB energy, respectively. This trend is consistent with qualitative arguments based on Gibbsian adsorption.
منابع مشابه
Effects of Nb-doping and Segregation on the Grain Boundary Plane Distribution in TiO2
Orientation imaging microscopy has been used to investigate the effects of Nb doping on the grain boundary plane distributions in TiO2 (rutile). By comparing the grain boundary plane distribution of the undoped material with theoretical estimates of grain boundary energy anisotropy of pure rutile, it is possible to show that the frequency of grain boundary planes is inversely correlated with gr...
متن کاملEvidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics
The (Nb + In) co-doped TiO2 ceramics were synthesized by conventional solid-state sintering (CSSS) and spark plasma sintering (SPS) methods. The phases and microstructures were studied by X-ray diffraction, Raman spectra, field-emission scanning electron microscopy and transmission electron microscopy, indicating that both samples were in pure rutile phase while showing significant difference i...
متن کاملSome aspects of the anisotropy of grain boundary segregation and wetting
A recently developed model of grain boundary (GB) segregation, in terms of the five macroscopic parameters of GB orientation, has been exercised to explore the anisotropy of GB segregation. The five macroscopic GB orientation parameters are defined by means of the orientations of the two crystallographic planes that terminate the crystals on either side of the GB, and a twist angle. Some import...
متن کاملInfluence of Y and La Additions on Grain Growth and the Grain-Boundary Character Distribution of Alumina
Grain-boundary character distributions (GBCDs) were determined for spark plasma sintered Yand La-doped aluminas prepared at temperatures between 1450°C and 1600°C. La doping leads to grain boundaries that adopt (0001) orientations 3.7 times more frequently than expected in a random distribution, whereas the Y-doped microstructures are more equiaxed. At 1500°C, some of the boundaries in the Y-do...
متن کاملThe Effects of Segregation on Grain Boundary Cohesive Energies in Ni3-xAIl+x 1L Najafahadi?,
The structure and properties of grain boundaries in the intermetallic alloy Ni3A1 have received considerable attention in the past several years due to their interesting mechanical properties. The aim in many of these studies [1-13] was to explain the increase in ductility that occurs when polycrystalline Ni3AI is doped with boron. Experimental observations [1-7] have shown that there is a stro...
متن کامل