Differential thermal analysis

1. DIFFERENTIAL
THERMAL
ANALYSIS

2. DIFFERENTIAL THERMAL ANALYSIS
• Differential Thermal Analysis (DTA) is a laboratory technique used to measure the changes in heat flow of
a sample as it's heated at a constant rate. It measures the difference in temperature between the sample
and an inert reference material (often alumina) as they are both subjected to the same heating program.
• DTA can be used to investigate various thermal events occurring in a sample, such as:
• Phase transitions: Melting, solidification, boiling, sublimation, etc.
• Chemical reactions: Decomposition, oxidation, hydration, etc.
• Physical changes: Adsorption, desorption, etc.
INTRODUCTION
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3. PRINCIPLE
• The basic principle involved in DTA is the temperature difference (AT) between the test
sample and an inert reference sample under controlled and identical (Abes of heating or
cooling is recorded continuously as a function of temperature of time thus, the heat
absorbed or emitted by a chemical system is determined.
• If any reaction takes place in the sample, then the temperature difference will occur between
the sample and the reference material. In an endothermic change (such as melting or
dehydration of the sample), the temperature of the sample is lower than that of the
reference material (i.e.) AT = -ve (for the endothermic process). In an exothermic change or
process, the sample temperature is higher than that of the reference material (i.e.) AT = + ve
(exothermic process).The shape and the size of the peak give information about the nature
of the test sample.
• (1) Sharp endothermic peaks indicate phase changes (such as; melting, fusion, etc.)
transition from one crystalline form to another crystalline form.
• (2) Broad endothermic peaks are obtained from dehydration reactions.
• (3) Chemical reactions like; oxidative reactions are exothermic reactions.
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4. DIFFERNTIAL
THERMAL
ANALYZER
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5. INSTRUMENTATION

6. INSTRUMENTATION
DTA Apparatus always prefered a tubelar furnace
This is constructed with an appropriate material wire
or ribbon wound on a refractory tube
This is fairly inexpensive
Furnance
Both metallic as well as nonmetallic are employed for fabrication
of sample holders
Metallic materials generally include stainless steel platinum and its
alloys
Non Metallic materials generally include glass vitreous silica
sintered ammonia
Sample Holder
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It is used for amplification of signal obtained from thermocouple
It gains a low by circuit
DC Amplifier

7. INSTRUMENTATION
In order to control temperature to three basic
elements are required these are sensor control
element and heater in this device if the sensor
signals indicate the temperature has become
greater than the set point the heater is immediately
cut off
Differential Temperature Detector
DTA instruments typically consist of a furnace, two thermocouples,
and a voltmeter. One thermocouple is placed in contact with the
sample, while the other is placed in contact with an inert reference
material. As the furnace heats up, the temperature of the sample and
the reference material will increase. However, if the sample
undergoes a phase transition, it will absorb or release heat, which
will cause its temperature to deviate from that of the reference
material. This difference in temperature is measured by the voltmeter
and plotted as a function of time or temperature.
Furance Temperature
Programmer
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In thermal analytical studies, the signal obtained from the sensor can be
recorded in which the signal trace is produced on paper or film hitting stylus
electric while writing or optical views
There are two types of recording devices similar to T G deflections type and null
point type
Recorder

8. WORKING
Sample and Reference:
•Two crucibles are placed in the furnace: one containing the
sample and another containing an inert reference material (e.g.,
alumina).
•Both materials are subjected to the same controlled heating
program.
2. Temperature Measurement:
•Thermocouples are attached to the sample and reference
crucibles to measure their respective temperatures.
•The difference in temperature between the sample and
reference (ΔT) is continuously monitored and recorded.
3. Endothermic and Exothermic Events:
•When an endothermic event (heat absorption) occurs in the
sample (e.g., melting), its temperature lags behind the
reference, resulting in a negative ΔT peak.
•Conversely, an exothermic event (heat release) in the sample
(e.g., oxidation) causes its temperature to rise faster than the
reference, leading to a positive ΔT peak.
4. DTA Curve:
•The ΔT is plotted against temperature or time, resulting in a
DTA curve.
•The peaks on the curve correspond to the thermal events
occurring in the sample, providing qualitative and quantitative
information.

9. ADVANTAGES & LIMITATIONS
• Instruments can be used at very high
temperature
• Instruments are highly sensitive
• Characteristic transition or reaction temperature
can be accurately determined
ADVANTAGES
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LIMITATIONS
• ΔT Determine by dta is not so accurate
(2-3) Celsius
• Small change in ΔT cannot be
determined and qualified
• Due to heat variation between sample
and reference makes it less sensitive

10. APPLICATIONS
• Qualitative and Quantitative Identification of Minerals: Detection of any minerals
in a sample.
•
• Polymeric Materials: DTA useful for the characterization of polymeric materials in the
light of identification of thermo physical, thermo chemical, thermo mechanical and
thermo elastic changes or transitions.
•
• Measurement of Crystalline: Measurement of the mass fraction of crystalline
material.
•
• Analysis of Biological Materials: DTA curves are used to date bone remains or to
study archaeological materials.
•
• DTA curves for two substances are not identical. Hence, they serve as finger prints for
various substances.
•
• This technique is used for testing the purity of the drug sample and also to test the
quality control of number of substances like; cement, soil, glass, etc.
•
• Used for the determination of heat of reaction, specific heat and energy change
occurring during melting, etc.

11. PRESENTED BY
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Firstname
Lastname
Firstname
Lastname
Bahalen Gagrai
20BPH015
Firstname
Lastname
Gungan Shashwat Kerketta
20BPH017
Harsh Kumar Sinha
20BPH019

12. REFERENCE
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A textbook of advanced Instrumentation techniques by Hitesh Vishwanat Shashare et.al Nirali publication
pg no. 3.6-3.10
A textbook of Advanced instrumentation techniques by Shital .S. Patil et.al PV publication pg no. 74-82