Differential thermal analysis (DTA) measures the temperature difference between a sample and an inert reference material as they are heated or cooled under identical conditions. DTA can detect physical or chemical changes in materials by identifying endothermic or exothermic reactions as peaks on a thermogram. The technique is used to determine phase changes, melting points, heat capacity, and decomposition temperatures of materials. Common applications of DTA include identification of materials, pharmaceutical analysis, and studying reactions in cement, minerals, foods, bones, and archaeological samples.

1. DIFFERENTIAL THERMAL
ANALYSIS (DTA)
Presented
By;Sushil kumar
1205068

3. Thermal Analysis Techniques
 It is a group of techniques in which
a physical property is measured as
a function of temperature, while
the sample is subjected to a
controlled temperature
programme (heating, cooling or
isothermal).

4. Thermal Analysis Techniques
& Types of thermal analysis :
Differential Thermal Analysis (DTA) –
temperature difference
Differential Scanning Calorimetry (DSC) –
heat difference
Thermogravimetric analysis(TGA)-change
in weight

5. What is DTA ?
• Involves the technique of recording the difference in
temperature between the Test and Reference material
time being constant for both.
• Hence the Differential Thermogram consists record of
difference in Temperatures.

6. DTA Principle:
DTA is a technique in which the difference
between the sample and reference
material is measured as a sample of
furnace temp(t) while sample and ref.
materials are subjected to a controlled
programme.
Usually a tempr programme involves
heating the sample and ref. material in
such a way that tempr of sample (ts)
increases linerally with time.

7. • In Differential Thermal Analysis, the
temperature difference that develops
between a sample and an inert reference
material is measured, when both are subjected
to identical heat - treatments.
• The related technique of Differential Scanning
Calorimetry relies on differences in energy
required to maintain the sample and reference
at an identical temperature.

8. INTRODUCTION(DTA)
• This is a comparison method
• Analytical method for recording the
difference in temperature (∆T) b/w a
substance and an inert reference material as
a function of temperature or time
• Any transformation – change in specific heat
or an enthaply of transition can be detected
by DTA

9. • In DTA both test sample & an inert reference
material (alumina) – controlled heating or
cooling programming
• If zero temperature difference b/w sample &
reference material – sample does not
undergo any chemical or physical change.
• If any reaction takes place temperature
difference (∆T) will occur b/w sample &
reference material

10. Thermogram
A differential thermogram consists of a record of the
difference in sample and reference themperature(∆T)
plotted as a function of time t, sample
temperature(Ts), reference temperature(Tr) or furnace
temperature(Tf).
In most of the cases,
physical changes give
rise to endothermic
curves,
whereas chemical
reactions give rise to
exothermic peaks.

11. DTA CURVE
• A DTA curve can be used as a finger print
for identification purposes, for example,
• in the study of clays where the structural
similarity of different forms renders
diffraction experiments difficult to interpret.

12. Factors affecting DTA curve
A] Environmental factors
B] Instrumental factors
i] Sample holder
ii] Differential temperature sensing device
iii] Furnace characteristics
iv] Temperature- programmer controller
v] Thermal Regime
vi] Recorder
C] Sample factors
1] Physical
2] Chemical

13. ∆T VS Temp.
Sharp Endothermic – changes in crystallanity or fusion
Broad endotherms - dehydration reaction
Physical changes usually result in endothermic curves
Chemical reactions are exothermic

14. Instrumentation
• A differential thermal analysis is composed of five
basic components, namely :
1} Furnace
2} Sample holder
3} temperature programmer/sensors
4} Recorders
5}Atmosphere control and Amplifiers
• .

16. 1} Furnace Assembly
The furnace is of high temperature electric tube,max
temperature upto 1000 ºc can be provided.

17. It is a tube containing sample ,a similar tube
containing reference material such as alumina or
silicon carbide which are inert substances .This tube
are inserted into a metallic heater
block.Thermocouple are inserted in sample &
reference tube.
In low temp range termocouple are used & other
detector such as prt and thermistor can also be
used.

18. It provides smooth heating or cooling at a linear
rate by changing the voltage through heating
component.
Modern DTA instruments incorporate electronic
temp controller in which the signal from
thermocouple in furnace is compared
electically against ref.potential which can be
programmed to corresponds to a variety of
heating modes & heating rates.

19. It is a dual pen strip chart recorder usually ∆t
change in temperature is recorded at y-axis & Tz
furnace temp is x-axis.

20. 5} Atmosphere control and Amplifiers
For some type of samples the
atmosphere must be controlled to
suppress and undesirable reaction such
as oxidation by flowing an inert gas.
• AMPLIFIERS;It is used for amplification of signals
obtained from (T) c.It is gain and low noise circuit.

21. Differential Thermal Analysis
advantages:
• instruments can be used at very high
temperatures
• instruments are highly sensitive
• characteristic transition or reaction
temperatures can be accurately
determined
disadvantages:
• uncertainty of heats of fusion, transition,
or reaction estimations is 20-50%
DTA

22.  Physical Chemistry
1. Heat of a Reaction
2. Specific Heat of substance like Naphthalene.
3. Thermal Diffusivity of samples
 Analytical Chemistry
1. Identification of Products since no two
products have identical curves.
2. Determination of Melting point.

23. Applications Of DTA;
1.A DTA curve can be used only as a finger
print for identification purpose but usually
the applications of this method are the
determination of phase diagrams,heat
change measurements & decomposition in

24. Applications of DTA……….
2.DTA is widely used in
medical(pharmaceutical)and food
industries.
3.DTA may be used in cement
chemistry,mineralogical research and
enviromental studies.
4.DTA curves may also be used to
date bone remains or to study
archaeological materials.