DTA - Mixing and phase separation mechanisms in perovskite materials and geological solid-solutions

Perovskite (ABO₃) compounds form the basis for numerous functional materials with applications in solar-cells, piezoelectric transducers, thermoelectrics, solid electrolytes and superconductors. The tendency for phase separation in perovskite solid solutions is a controlling factor in the microstructural development and consequent functional properties of ferroelectric ceramics such as BiFeO₃-BaTiO₃ (BF-BT), which are being developed for applications in high temperature piezoelectric transducers and dielectric energy storage.

The most abundant mineral in the Earth is bridgmanite, (Mg,Fe)(Si,Al)O₃, another perovskite solid solution which is stable between 660 km depth and the core-mantle boundary. A co-existing perovskite, Ca(Ti,Si)O₃, is said to be immiscible with bridgmanite but recent calculations suggest that the mutual solubilities of the two components are strongly dependent on the presence of minor impurities such as Ti.

Despite their importance, both industrially and in Earth Sciences, the mixing of perovskite solid-solutions is poorly understood. The project will focus on the temperature-dependent immiscibility in perovskite solid solutions and investigate the influence of minor dopants or impurities on both the equilibrium solubilities and microstructural evolution. Specific case studies based on Bridgmanite and ferroelectric BF-BT ceramics will be used as the basis for a systematic experimental programme to investigate the driving forces for phase separation and microstructure development during heat treatment. Depending on the background and interests of the student, the project will progress to high pressure studies, characterisation of mechanical and functional properties, and/or a wider range of perovskite compounds. Experimental methods will include the use of scanning & transmission electron microscopy (SEM & TEM), electron microprobe analysis (EPMA), and nanoscale secondary ion mass spectrometry (nano-SIMS) for quantification of micro-chemical heterogeneity. Crystallographic studies will be conducted using conventional x-ray diffraction (XRD), complemented by high energy synchrotron XRD and neutron diffraction methods at central facilities such as the Diamond light source and ISIS respectively. The influence of crystal point defects and chemical segregation at grain boundaries on conduction mechanisms will be monitored using electrical impedance spectroscopy.

We are looking for a strongly motivated student with a background in Earth Sciences, Materials Science, or a related physical science discipline to join our research group. Some knowledge or previous experience in electron microscopy, XRD, materials processing, coding, data manipulation, experimental petrology and measurement of mechanical or functional properties would be beneficial but not necessary, since you will receive training in all the relevant experimental and analytical methods. You will be encouraged to attend national and international conferences to share your research.

Academic background of candidates

Applicants should have or expect to achieve at least a 2.1 honours degree in Materials Science, Geology, Earth Sciences, Engineering, or related disciplines.

Equality, diversity and inclusion is fundamental to the success of The University of Manchester, and is at the heart of all of our activities. We know that diversity strengthens our research community, leading to enhanced research creativity, productivity and quality, and societal and economic impact. We actively encourage applicants from diverse career paths and backgrounds and from all sections of the community, regardless of age, disability, ethnicity, gender, gender expression, sexual orientation and transgender status.

We also support applications from those returning from a career break or other roles. We consider offering flexible study arrangements (including part-time: 50%, 60% or 80%, depending on the project/funder). 

To apply please follow the link below:

https://www.manchester.ac.uk/study/postgraduate-research/admissions/how-to-apply/