Preparing a compound: Heating two or more non-volatile solids which react to form the required product. The formed product depends on lot of factors such as initial concentration of precursors, temperature, time period, rate of heating and/or cooling, pressure, gas used.
Oxides generally are prepared in air, in some cases oxygen gas is passed for complete oxidation and sometimes inert gas is passed for partial oxidation. Carbon is prepared in absence of oxygen and therefore inert gas like argon or nitrogen in passed. Alloys are prepared in a sealed quartz tube since even a partial amount of gases like O2 or N2 will form byproducts.
Solid state preparation give micron sized morphology which may not be uniform. Chemical preparation like sol-gel, precipitation, etc give rise to uniform and lower size morphology down to nano-meter scale. The formation temperature in chemical method is lower than the solid state method, if the temperature is increased then the grain size increases.
Note: 1. Purity of sample is approximated to be 100%, if the sample are not pure then you may multiply with the resultant weight with the purity.
2. Calculator can also be used for alloys, In this case the precursor are the metals and the molecular weight is equal to atomic weight
After preparing compound, XRD pattern is taken for phase identification of the crystalline material.
After preparing compound, XRD pattern is taken for phase identification of the crystalline material.
very helpful
ReplyDelete