Solid solution materials

A solid solution is a crystal structure in which two (or more) atom types are arranged at random over the sites normally occupied by one atom type alone. For example, in the comndum structure solid solution formed by Cr2C>3 and AI2O3, a random mixture of Cr3+ and Al3+ ions occupy the cation sites that are only occupied by one of these in the parent phases. The formula of the solid solution materials is written (Al i JCCrJC)203. In this example, x can vary continuously between 0 and 1.0. In some cases, especially when the atoms involved have different sizes, only partial solid solutions are found, characterized by a composition range in which the span of x is smaller than 1.0. Solid solutions are widely exploited as both the chemical and physical properties of the solid can be varied sensitively by changing the relative amounts of the components of the solid solution. 

P. Greil, and J. Weiss, Evaluation of the Microstructure of b-SiAION solid-solution materials containing different amount of amorphous grain boundary phase. J. Mat. Sci. 17 (6), 1571-1578 (1992). 

The storage of hydrogen in solid-solution materials is characterized by endothermic and exothermic phase change reactions. The thermodynamic nature of these reactions requires the full characterization of influential material properties to enable the optimization of heat and mass transfer within the system. Additionally, the thermodynamic nature of the materials will define the containment technologies required to withstand the operational pressures and temperatures. 

The ablated vapors constitute an aerosol that can be examined using a secondary ionization source. Thus, passing the aerosol into a plasma torch provides an excellent means of ionization, and by such methods isotope patterns or ratios are readily measurable from otherwise intractable materials such as bone or ceramics. If the sample examined is dissolved as a solid solution in a matrix, the rapid expansion of the matrix, often an organic acid, covolatilizes the entrained sample. Proton transfer from the matrix occurs to give protonated molecular ions of the sample. Normally thermally unstable, polar biomolecules such as proteins give good yields of protonated ions. This is the basis of matrix-assisted laser desorption ionization (MALDI). 

Questions of the analytic control of maintenance of the bivalent metals cations to their joint presence in materials of diverse fixing always were actual. A simultaneous presence in their composition of two cations with like descriptions makes analysis by sufficiently complicated process. Determination of composition still more complicates, if analyzed object is a solid solution, in which side by side with pair of cations (for example, Mg " -Co ", Mn -Co, Zn -Co ) attends diphosphate anion. Their analysis demands for individual approach to working of methods using to each concrete cations pair. 

The addition of MgO leads to the formation of a naiTow range of solid solutions at high temperamre, which decompose to precipitate inclusions of tetragonal Zr02 dispersed in cubic zirconia. The material, which functions as a solid electrolyte, has the added advantage that the inclusions stop the propagation of any cracks which may arise from rapid temperature change. 

Strong materials either have a high intrinsic strength, /, (like diamond), or they rely on the superposition of. solid solution strengthening obstacles fo and work-hardening f i, (like high-tensile steels). But before we can use this information, one problem... 

The things that we have been talking about so far - metal crystals, amorphous metals, solid solutions, and solid compounds - are all phases. A phase is a region of material that has uniform physical and chemical properties. Water is a phase - any one drop of water is the same as the next. Ice is another phase - one splinter of ice is the same as any other. But the mixture of ice and water in your glass at dinner is not a single phase because its properties vary as you move from water to ice. Ice + water is a two-phase mixture. 

A phase is a region of material that has uniform physical and chemical properties. Phases are often given Greek symbols, like a or fi. But when a phase consists of a solid solution of an alloying element in a host metal, a clearer symbol can be used. As an example, the phases in the lead-tin system may be symbolised as (Pb) - for the solution of tin in lead, and (Sn) - for the solution of lead in tin. 

The alloy aluminium-4 wt% copper forms the basis of the 2000 series (Duralumin, or Dural for short). It melts at about 650°C. At 500°C, solid A1 dissolves as much as 4 wt% of Cu completely. At 20°C its equilibrium solubility is only 0.1 wt% Cu. If the material is slowly cooled from 500°C to 20°C, 4 wt% - 0.1 wt% = 3.9 wt% copper separates out from the aluminium as large lumps of a new phase not pure copper, but of the compound CuAlj. If, instead, the material is quenched (cooled very rapidly, often by dropping it into cold water) from 500°C to 20°C, there is not time for the dissolved copper atoms to move together, by diffusion, to form CuAlj, and the alloy remains a solid solution. 

The PTC materials already mentioned depend directly on the ferroelectric phase transition in solid solutions based on BaTi03, suitably doped to render them semiconducting. This is a typical example of the interrelations between different electrical phenomena in ceramics. 

Acetylene is passed for 1 hr through a mixture consisting of 0.5 g (72 mg-atoms) of lithium in 100 ml of ethylene-diamine. A solution prepared from 1 g (3.5 mmoles) of rac-3-methoxy-18-methylestra-l,3,5(10)-trien-I7-one and 30 ml of tetrahydrofuran is then added at room temperature with stirring over a period of 30 min. After an additional 2 hr during which time acetylene is passed through the solution the mixture is neutralized with 5 g of ammonium chloride, diluted with 50 ml water, and extracted with ether. The ether extracts are washed successively with 10% sulfuric acid, saturated sodium hydrogen carbonate and water. The extract is dried over sodium sulfate and concentrated to yield a solid crystalline material, which on recrystallization from methanol affords 0.95 g (87%) of rac-3-methoxy-18-methyl-17a-ethynyl-estra-l,3,5(10)-trien-17jB-ol as colorless needles mp 161°. 

To obtain the corresponding dihydrochloride, the base is dissolved in absolute alcohol (3 volumes) and to that solution is added 5N alcoholic hydrochloric acid. The dihydrochloride precipitates, is centrifuged and washed with alcohol. It is a solid white material, having a melting point of 134°C to 135°C. 

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