Controlling structural complexity and dynamics in dicyanometallates

热电材料将热直接转化为电。这些材料可以彻底提高能源效率，并解决与世界不断增长的能源消耗相关的问题。它们的可靠性、可扩展性和长寿命提供了巨大的潜力。它们的低效率阻碍了它们的广泛使用。好的热电材料导电性好，但导热性差。不幸的是，这种属性组合是罕见的。这项研究旨在通过探索降低热（或热）导电性的方法来进一步设计热电材料，同时不影响材料的其他性能。因此，这项研究关注的是改变材料的原子振动。固体中的原子不断地振动。这些振动在原子之间协调一致。科学家可以计算出振动的能量和与之相关的原子运动。声子可以用不同的技术来测量，比如用红外光或中子照射材料。声子是理解材料热特性的关键。材料在受热时的膨胀或导热性等特性都依赖于声子。声子是固体材料的热载体，破坏它们会导致导热性降低。降低导热系数的一种直观方法是在材料中引入缺陷。缺陷是材料内部的缺陷——这通常是材料中应该有原子的地方的间隙。甚至是一个原子在错误的位置。缺陷会破坏原子振动，使声子“散射”。不幸的是，缺陷也倾向于散射电子，降低材料的导电性。然而，从理论上讲，人们可以在材料中引入无序性，这种无序性对导热性的影响远大于对导电性的影响。要做到这一点，紊乱必须不是随机的，而是相互关联的。无序和声子之间的相互作用是本研究的主题。这项研究旨在回答一个基本问题：能否以系统的方式引入无序来影响某些声子？双氰金属酸盐被用来回答这个问题。它们形成大晶体，用中子可以很容易地测量它们的声子。它们还允许一种直接的机制来可控地引入无序。希望研究能通过一个迭代的过程进行。无序对声子性质的影响将通过实验测量。这些结果将被用来用计算方法预测无序对声子性质的影响。这有可能极大地帮助热电设计。这项研究属于EPSRC物理科学研究领域。工作将由古德温和德林格小组进行。

Thermoelectric materials transform heat into electricity directly. These materials could revolutionise energy efficiency and solve problems associated with the world's growing energy consumption. Their reliability, scalability and long lifespan offer huge potential. It is their low efficiency that has prevented their widespread use. A good thermoelectric material conducts electricity well but heat poorly. Unfortunately, this combination of properties is rare.This research aims to further design of thermoelectrics by probing ways of reducing thermal (or heat) conductivity whilst not affecting other properties of the material. This research is therefore concerned with altering the atomic vibrations of a material. Atoms in solids are constantly vibrating. These vibrations are concerted between atoms. Scientists can calculate the energy of the vibration and the associated movement of atoms. Phonons can be measured using different techniques such as shining infrared light or neutrons on a material. Phonons are critical to understand the thermal properties of a material. Properties such as the expansion of a material as it is heated or its thermal conductivity all rely on phonons. Phonons are the heat carriers for solid materials, and disrupting them leads to lower thermal conductivity.An intuitive way of reducing the thermal conductivity is to introduce defects into the material. Defects are imperfections within the material - this can often be a gap where there should be an atom in the material. Or even an atom of the material in the wrong position. Defects break up the atomic vibrations and can 'scatter' the phonons. Unfortunately, defects also tend to scatter electrons reducing the electrical conductivity of the material. Yet theoretically, one could introduce disorder into a material that can affect the thermal conductivity much more than the electrical conductivity. For this to occur, the disorder must be not be random but correlated. The interplay between disorder and phonons is the subject of this research. This research aims to answer the fundamental question: can one introduce disorder in a systematic manner to affect certain phonons?Dicyanometallates are used to answer this question. These form large crystals and can have their phonons measured easily using neutrons. They also allow a straightforward mechanism for controllably introducing disorder. The hope is that the research proceeds via an iterative process. The effect of disorder on phonon properties will be measured experimentally. These results will then be used to predict the effects of disorder on phonon properties using computational methods. This has the potential to greatly aid thermoelectric design.This research falls in the EPSRC Physical Sciences Research Area. Work will be carried out from the Goodwin and Deringer groups.