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High-Temperature Ionic and Electronic Resistivity of MgO- and Ta2O5- doped Aluminum Nitride
유동수,이은실,이성민,김종영,박명하 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.1
In this work, using high-temperature impedance spectroscopy and microstructure analysis, we investigated the ionic and the electronic transport properties of aluminum nitride materials doped with MgO and Ta2O5 at temperatures up to 773 K. The electronic conductivity, due to the electron carrier, was greatly inhibited by addition of MgO, which might be due to the decreased electron carrier concentration via electronic compensation of MgO in the AlN matrix. The ionic conductivity due to grains of MgO-doped AlN increased by several orders of magnitude due to ionic defects generated by MgO substitution, whereas the ionic conductivity of the grain boundary of MgO-doped AlN decreased by one order of magnitude as a result of the formation of Mg′Al defects in the grain boundary, which elevated the Schottky barrier. The microstructural analysis showed that MgO addition promoted formation of an amorphous liquid phase including Mg, which is evidence of the selective precipitation of Mg in the grain boundary. Ta2O5-doped AlN also exhibited a decreased ionic conductivity of the grain boundary, which might have been due to the formation of an ionic pair of (ON·−V‴Al) caused by the dissolution of Ta in the AlN matrix.
劉東洙 大韓顎顔面 放射線學會 1983 Imaging Science in Dentistry Vol.13 No.1
The author analyzed the morphologic changes of bone structure from 848 radiographis(424 joints) of 212 patients with temporomandibular joint arthrosis, which were obtained by the oblque-lateral transcranial projection and orthopantomography. The interelation of the bone changes and condylar head positions the results were as follows: 1. In the 212 patients with TMJ arthrosis, 210 patients(99.05%) show the condylar positional changes. Among them. 187 patients 989.05%) show the bone changes. 2. In TMJ arthrosis patients with bone changes, 10% patients(57.75%) show both the condylar positional changes and bone changes. 66 patients( %) show the condylar psoitional changes bilaterally and bone changes unilaterally. On the other hand, 11 patients (5.88%) show the condylar positional changes unilaterally and bone change bilaterally. 3. The bone changes in the TMJ arthrosis patients with the condylar positional changes were as follows: There were the flatlenirg of articular surface in 103 cases (26.55%) the erosion in 99cases (925.52%), and the oresion in 88 cases (22.68%). There were not much differences among the three types of bone changes. And the deformity in 70 cases (18.04%), the sclerosis in 22 cases(5.67%), the marginal protiferation in 6 cases(1.55%) were seen. 4. The regions of bone changes in TMJ arthrosis patients with condylar positional changes were as follows: They occurred at the condyle head(51.04%), the articular eminence(39.20%) and the articular fossa(9.60%) in that order. The condylar positional changes and bone changes according to the regions were as follows: a) In the bone changes at the condyle head, the flatteming(34.63%) was a most frequent finding and the deformity(27.63%) the erosion(24.32%) in the order. In the condylar positional changes, the downward positioning of condyle(41.44%) was a most frequent finding in the mouth closed state and the restricted movement within the articular fossa(35.46%) in the mouth open state. b) In the bone changes at the articular eminence, the eburnation(33.26%) was a most frequent finding and the flatteming(31.16%), the erosion(28.37%) in that order. In the condylar positional changes, the downward positioning of condyle(39.81%) was a most frequent finding in the mouth closed state and the restricted movement within the articular fossa(24.77%) in the mouth open state. c) In the bone changes at the articular fossa, the eburnation(72.90%) was amost frequent findingnd theerosion(17.76%), the sclerosis(9.35%) in the arder. In the condylar positional changes, the downward positionirg of condyle(41.5%) was a most frequent finding in the mouth closed state and the mormal positioning of condyle(27.78%) in the mouth open state.