Chemistry professor Andrea Sella joins the discussion on the various states of matter beyond solids, liquids, and gases, exploring plasma and exotic phases like glasses and liquid crystals. The podcast delves into the complexities of molecular structures, phase transitions, material evolution from pure elements to alloys like steel, and the impact of industrial revolution on material science.
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Quick takeaways
Plasma represents a fourth state of matter, constituting over 99% of the universe's visible matter.
Liquid crystals bridge the gap between ordered crystals and flowing liquids, finding applications in technologies like display screens.
Understanding phase transitions involves energy considerations, where heat drives molecular motion to surpass solid constraints.
Glass exhibits an amorphous structure, representing a frozen liquid state with random molecular arrangements.
Material composition manipulation allows control over crystal structures, highlighting the interplay between composition and material properties.
Deep dives
Variety of States of Matter
Scientists are exploring new and exotic states of matter beyond solids, liquids, and gases. Plasma, making up over 99% of the visible universe, represents a distinct fourth state of matter. Liquid crystals, intermediate between ordered crystals and fluids, find applications in modern technology like display screens. Understanding the phase states of matter involves energy considerations that lead to phase transitions, such as melting and boiling.
Molecular Differences in Solids and Liquids
At the molecular level, solids like ice have ordered structures where molecules are fixed, while liquids allow molecules to move more freely, resulting in fluidity. The transition from solid to liquid occurs as increased heat causes molecular motion to exceed solid constraints. In the gas phase, molecules move independently, illustrating distinct molecular behaviors across phases.
Complexities in Understanding Liquids
Liquids pose a unique challenge in understanding the molecular arrangement due to their intermediate nature between solids and gases. Predicting the temperature at which a material transitions to the liquid state remains complex due to varying factors like molecule size and bond strength. Research reveals that liquids exhibit mysterious behavior due to challenges in precisely determining their melting temperatures.
Glass's Amorphous Structure
Despite appearing solid, glass exhibits an amorphous structure where molecules lack a defined order. Glass represents a frozen liquid state, embodying random molecular arrangements like a snapshot of a liquid's disordered state. Understanding the composition of materials like steel allows researchers to manipulate phase transitions and create innovative materials with desired properties.
Prominence of Liquid Crystals
Liquid crystals, discovered in the 19th century, exhibit properties between ordered crystals and flowing liquids. These materials align molecules in specific directions, allowing for applications like in display screens. Liquid crystals can transition from ordered orientations to disordered ones based on external influences, demonstrating versatility for technological advancements.
Unique Host-Guest Structures
Materials can exhibit host-guest structures where crystal hosts contain structured guest molecules or atoms. Some substances, under high pressures, display behaviors where they simultaneously exist as both liquids and solids due to intricate composition interactions. Understanding such complex structures sheds light on the diverse and intriguing properties of matter.
Innovations in Material Transformations
By altering the composition and thermal processing of materials like steel, scientists can control crystal structures to achieve desired material properties. The ability to influence phase transitions through compositional changes highlights the intricate interplay between material composition and characteristics. Research in this area aims to unlock novel materials and enhance industrial applications.
Research Advances in High-Pressure Studies
Studying materials under extreme pressures provides insights into planetary compositions and material behaviors under unique conditions. The ability to simulate high-pressure environments using diamond anvils allows researchers to explore exotic states of matter and understand the complex transformations that occur under extreme conditions. Such studies have implications for planetary science and industrial applications.
Applications of Phase Diagrams and Material Composition
Analyzing phase diagrams and material compositions plays a crucial role in understanding the behaviors and transitions of matter. Steel, for example, demonstrates how varying compositions impact the crystalline structure and mechanical properties of materials. By manipulating material composition and thermal treatments, researchers can tailor materials for specific applications, highlighting the importance of composition control in material science.
Melvyn Bragg and his guests discuss the science of matter and the states in which it can exist. Most people are familiar with the idea that a substance like water can exist in solid, liquid and gaseous forms. But as much as 99% of the matter in the universe is now believed to exist in a fourth state, plasma. Today scientists recognise a number of other exotic states or phases, such as glasses, gels and liquid crystals - many of them with useful properties that can be exploited.
With:
Andrea Sella
Professor of Chemistry at University College London
Athene Donald
Professor of Experimental Physics at the University of Cambridge
Justin Wark
Professor of Physics and Fellow of Trinity College at the University of Oxford
Producer: Thomas Morris.
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