Transcript
Page 1: Zeolites  and Negative Thermal Expansion

Zeolites and Negative Thermal ExpansionRachel Pallant, Josie Paton,

Alen Akhabaev, Ross Davies

Page 2: Zeolites  and Negative Thermal Expansion

Zeolites Microporous Minerals

› Microporous – Contains pores with diameters <2nm

› Mineral – Naturally occurring substance that is a stable solid rtp

206 structures identified Base SinO2n, other molecules can be

included

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Negative Thermal Expansion

•Caused by decrease in bond angles•With no/little energy bond angle is 180°•Energy provided by heat overcomes electrostatic forces of electron groups mutually repelling•Molecule bends, Si-Si distance now smaller although bonds are longer

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Zeolites chosen Control – MEP Positive thermal expansion – DON Negative thermal expansion – EDI, YUG Detail - STI

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MEP (1104 atoms) Already proven to have negative

thermal expansion

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DON (1152 atoms) Was modelled to have positive thermal

expansion

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EDI (1872 atoms) Was modelled to have negative

thermal expansion

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YUG (2160 atoms) Was modelled to have negative

thermal expansion

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STI (2592 atoms) Showed an unusual shift

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STI Detail (1728 atoms) Using smaller temperature steps still

just showed a sudden shift Only two of the side lengths changed,

not all three

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STI Structure Animation Structure of STI at 90K

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Thank You!


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