Lecture

Thermal Decomposition of Solids: Kinetics & Synthesis

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Description

This lecture covers the thermal decomposition of solids, focusing on the synthesis of powders through chemical methods. It explains the thermodynamics and kinetics involved in the decomposition process, highlighting factors affecting the production of powders. The lecture also delves into the kinetics of solid-solid reactions, discussing models like the shrinking core model and the mechanisms governing the reaction interfaces. Additionally, it explores the effects of size and mixing degree in solid-solid reactions, emphasizing the importance of particle size and initial mixing for successful reactions. The limitations of solid-solid reactions are also addressed, including the need for high temperatures and the risk of sintering and contamination.

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Related concepts (32)

Thermal analysis

Thermal analysis is a branch of materials science where the properties of materials are studied as they change with temperature.

Differential thermal analysis

Differential thermal analysis (DTA) is a thermoanalytic technique that is similar to differential scanning calorimetry. In DTA, the material under study and an inert reference are made to undergo identical thermal cycles, (i.e., same cooling or heating programme) while recording any temperature difference between sample and reference. This differential temperature is then plotted against time, or against temperature (DTA curve, or thermogram). Changes in the sample, either exothermic or endothermic, can be detected relative to the inert reference.

Thermogravimetric analysis

Thermogravimetric analysis or thermal gravimetric analysis (TGA) is a method of thermal analysis in which the mass of a sample is measured over time as the temperature changes. This measurement provides information about physical phenomena, such as phase transitions, absorption, adsorption and desorption; as well as chemical phenomena including chemisorptions, thermal decomposition, and solid-gas reactions (e.g., oxidation or reduction). Thermogravimetric analysis (TGA) is conducted on an instrument referred to as a thermogravimetric analyzer.

Chemical reaction

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

Reaction mechanism

In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs. A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction. The detailed steps of a reaction are not observable in most cases. The conjectured mechanism is chosen because it is thermodynamically feasible and has experimental support in isolated intermediates (see next section) or other quantitative and qualitative characteristics of the reaction.

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