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Unformatted text preview: t t e r n s . There was little or no evidence of intercalation as determined from the X-ray data on the group
C samples. T h e X RF a nalysis of the samples resulted in inconsistantly high and low values for the ratios of A g/Ti
w hich varied over different portions of the sample.
the X - r a y diffraction and X R F r e s u l t s , the Ag + Rased o n T iSZ s amples which were cooled slowly from 1 000 C w ere not intercalated to
any significant d e g r e e . It is possible that the silver was distributed over the surface of the T iSZ c rystalline powder
in such a way that very little or no crystalline silver was
present which is supported by the absence of pure silver
X-ray diffraction lines. P age - 3 3 - C HAPTER 4
D IFFERENTIAL SCANNING CALORIMETRY 4 -1 G eneral Discussion
Differential scanning calorimetry (DSC) is a technique whereby a sample material and a reference material are heated
or cooled while a quantity which is proportional to the
differential enthalpic change (or change in heat
capacity) between the sample and reference materials is
measured. The data are recorded as a function of time or temperature. Enthalpic changes are caused by fundamental
changes in s t a t e , chemical composition, molecular reactivity
of the materials, etc. The shape of the enthalpy change vs temperature or time is basically a function o f t he reaction
kinetics but is also influenced by sample packing, geometric
shape of the sample and reference, the heating r a t e ,
atmosphere, temperatures of the sample and reference, thermal
contacts at all interfaces, as well a s the time constants of
the electronics, etc. The sample and reference materials are placed in identical containers which may or may not be
hermetically sealed, then placed in thermal contact with a
heat source. A uniform linear rate of heating is usually desired because of the time dependence of the measured
quantity. Thermocouples are used to monitor the temperatures of the sample and reference. P age - 3 4 - 4-2 T wo Standard Methods of DSC...
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This note was uploaded on 10/08/2009 for the course CME MAT E 630 taught by Professor Dr. during the Fall '09 term at University of Alberta.
- Fall '09