The Contribution of Lattice Vibrations to Switchable Spin-Crossover Crystals

Spin-crossover is a high-spin-to-low-spin transition at a transition metal centre, induced by temperature or pressure. It is common in iron chemistry, but also occurs in some compounds of other common metals. Spin-crossover switching changes the volume, hardness and magnetic properties of the sample, and may also affect its colour, electrical resistance or other properties depending on the material. These properties have been harnessed in materials applications such as thermochromic inks; stimuli-responsive polymers; and solid state refrigeration.<br /> <br /> Different materials can undergo spin-crossover abruptly or gradually with temperature, and with or without thermal hysteresis. This is governed by how strongly the individual switching centres in the material interact with each other, which in turn relates to its crystal packing. Designing a spin-crossover material with bespoke properties for a specific application is a challenging problem, which hinges on the structure, dynamics and cohesive forces within a crystal lattice. <br /> <br /> This project will address part of this question, by correlating the switching characteristics of spin-crossover materials with their internal lattice vibrations. The student will use Leeds&rsquo; world-leading facilities for terahertz spectroscopy (that is, low energy vibrational spectroscopy). THz data will be combined with IR and Raman spectroscopy measurements, to image the vibrational landscape of selected materials and how it changes during the spin-crossover event. <br /> <br /> A particular focus of the work is to identify collective lattice vibrations correlating with abrupt spin-crossover switching in these materials. This information will then be used to rationally design new materials to enhance the appropriate lattice dynamics and increase the cooperativity of their switching properties, to confirm the validity of that structure:function relationship.<br /> <br /> As part of these investigations, we will study why replacing the hydrogen atoms with deuterium atoms in spin-crossover crystals changes their switching temperature. That is a 40-year old conundrum, which was first noted in the 1980s but has never been explained in any detail. Since deuterating a molecule changes its vibrations but doesn't affect its electronic character, that observation must have a vibrational explanation. Thus, addressing this question is also relevant to the wider goals of the project. <br /> <br /> This project will involve organic and inorganic synthesis; crystallography and powder diffraction; solid state magnetic measurements; infrared, Raman and THz vibrational spectroscopy; and other physical techniques as appropriate. There will be opportunities to perform X-ray crystallography at the Diamond synchrotron.<br /> <br /> The project is available to start on October 1st 2024.

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University&#39;s website</a>. Please state clearly in the Planned Course of Study section that you are applying for <em><strong>PhD Chemistry,&nbsp;</strong></em>in the research information section&nbsp;that the research degree you wish to be considered for is <em><strong>THE CONTRIBUTION OF LATTICE VIBRATIONS TO SWITCHABLE SPIN-CROSSOVER CRYSTALS</strong></em><span style="font-size:11pt"><span style="line-height:normal"><span style="text-autospace:none"><span style="font-family:Calibri,sans-serif"> </span></span></span></span> as well as&nbsp;<a href="https://eps.leeds.ac.uk/chemistry/staff/4173/professor-malcolm-halcrow">Professor Malcolm Halcrow</a> as your proposed supervisor&nbsp;and&nbsp;<em><strong>in the Finance Section, the funding source that you are applying for is</strong></em>&nbsp;<em><strong>Leverhulme Trust Doctoral Training Studentship.</strong></em></p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p> <p class="MsoNoSpacing">Applications will be considered on an ongoing basis. &nbsp;Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application. &nbsp;We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p>Please note that you must provide the following documents in support of your application by the closing date of 13 May 2024:</p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> </ul>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<p>A Leverhulme Trust Doctoral Training Studentship consisting of the award of fees at the UK Fee rate with a tax-free maintenance grant of &pound;19,237 per year for 3 years. Some funding for conference travel is also available.<br /> <br /> This opportunity is open to UK applicants only. Please refer to the&nbsp;<a href="https://www.ukcisa.org.uk/">UKCISA</a>&nbsp;website for&nbsp;information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information about your application, please contact Doctoral College Admissions by email to&nbsp;<a href="mailto:maps.pgr.admissions@leeds.ac.uk">maps.pgr.admissions</a><a href="mailto:EMAIL@leeds.ac.uk">@leeds.ac.uk</a></p> <p>For further information about this project, please contact Professor Malcolm Halcrow by email to&nbsp;<a href="mailto:M.A.Halcrow@leeds.ac.uk">M.A.Halcrow@leeds.ac.uk</a></p>