heeelp please * clear answer please :) Most real-world ceramics and metals are p
ID: 821869 • Letter: H
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heeelp please
* clear answer please :)
Most real-world ceramics and metals are polycrystalline rather than monocrystalline. Briefly explain the difference using what you have learned in class and from the textbook. Ferric oxide, Fe2O3 has partial solid solubility in MgO. Explain briefly what this means. The cations (Fe3+) in Fe2C>3 have a charge of +3, while MgO's cations are +2 (Mg2+). To maintain charge neutrality in the solid, only two Fe3+ ions can fill in for every three Mg2+ sites, leaving vacancies. These unequal cation charges are one reason solubility is limited. Calculate the percent difference between cation sizes for these two ceramics and comment how the size difference may also affect solubility.Explanation / Answer
1. Some of the crystal is composed of many small grains, if the arrangement between the grains are no rules, this is called polycrystalline crystal, such as copper and iron. But there are also the crystal itself is a complete large grains, the crystal is called monocrystalline
Monocrystalline cells with a cell conversion efficiency, good stability, but the cost is high. whereas Low-cost polycrystalline cells, the conversion efficiency slightly lower than the materials in a variety of defects such as grain boundaries, dislocations, micro-defects, and material impurities carbon and oxygen, as well as the stained process transition metals
2. Doping MgO with Fe2O3 enhanced the viscous contributions to creep and inhibited the nonviscous ones. Creep rates in these specimens increased with increasing Fe2O3additions. The occurrence of simultaneous grain growth during the high-temperature creep of magnesiowustite (i.e. MgO-Fe2O3 solid solutions) was used in establishing the strain rate vs grain size dependence. The results of this study are consistent with a transition between grain boundary and lattice diffusion mechanisms as the grain size increases (4 to 44 ?an). The creep of polycrystalline MgO is a mixed process in that viscous and nonviscous (dislocation) contributions are present
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