Controlling structural complexity and dynamics in dicyanometallates

热电材料直接将热能转化为电能。这些材料可能会彻底提高能源效率，并解决与世界日益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。正是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，这种性能的组合是罕见的。这项研究的目的是通过探索在不影响材料其他性能的情况下降低热(或热)传导性的方法来进一步设计热电材料。因此，这项研究关注的是改变材料的原子振动。固体中的原子在不停地振动。这些振动是原子之间协调一致的。科学家可以计算出振动的能量和原子的相关运动。可以使用不同的技术来测量声子，例如在材料上照射红外光或中子。声子对于理解材料的热学性质至关重要。诸如材料受热时的膨胀或其导热系数等性质都依赖于声子。声子是固体材料的热载体，破坏声子会导致导热系数降低。降低导热系数的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空隙。甚至一个原子的物质处于错误的位置。缺陷会破坏原子的振动，并使声子“分散”。不幸的是，缺陷也往往会散射电子，降低材料的电导率。然而，从理论上讲，人们可以在材料中引入无序，这对导热系数的影响比对导电性的影响要大得多。要做到这一点，这种混乱不能是随机的，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：一个人能否以系统的方式引入无序来影响某些声子？双金属氰化物被用来回答这个问题。它们形成大晶体，可以很容易地用中子测量它们的声子。它们还为可控地引入混乱提供了一种直接的机制。希望这项研究能通过迭代过程进行。无序对声子性质的影响将在实验上测量。这些结果将被用来通过计算方法来预测无序对声子性质的影响。这将极大地帮助热电设计。这项研究属于EPSRC物理科学研究领域。古德温和德林格小组将开展工作。

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.