Influence of crystallite size and composition on the formation of polarons in nanocrystalline tungstates (2020. - 2022.)

Project leader Georgijs Bakradze

Agreement No 1.1.1.2/16/I/001

Research application No. 1.1.1.2/VIAA/3/19/444

 

Tungstates represent a large class of materials with a wide range of applications, including but not limited to scintillators, solid-state laser hosts, photocatalysis, supercapacitors, lithium-ion batteries and sensors. Many properties of tungstates are governed by the physics of lattice defects. Among them, the formation of polarons in tungstates has been rarely studied but is important for tailoring their optical and electrical properties. Within this project we intend to conduct systematic investigations of the local atomic and electronic structure in nanocrystalline tungstates with a particular emphasis on the local lattice deformations induced by the formation of the polaronic centres and their dependence on the crystallite size, dimensionality and chemical composition. This challenging task will be addressed using state-of-the-art experimental synchrotron-based techniques such as X-ray absorption spectroscopy (XAS) and resonant X-ray emission spectroscopy (RXES) in combination with theoretical analysis based on the first principles and atomistic simulations. A comprehensive understanding of the interconnection between the properties and defect physics in nanocrystalline tungstates will contribute substantially to the improvement of their functional properties in demanding applications.

 

The project will be implemented at the Institute of Solid State Physics, University of Latvia from 01.01.2020 until 31.12.2022. The total cost of the project is 133’805.88 EUR.


Project news

01.01.2021.

A paper entitled “X-ray absorption and Raman spectroscopy studies of tungstates solid solutions ZncNi1-cWO4 (c=0.0-1.0)” has been published in the journal “Low Temperature Physics”: Bakradze et al, Low Temperature Physics 46 (2020) 1412.

Measurements of scheelite samples using resonant X-ray emission spectroscopy and  X-ray absorption spectroscopy have been performed at the HASYLAB/DESY PETRA-III synchrotron centre at P64 and P65 work station, respectively.

Two online workshops have been attended. The first one was a three-days workshop entitled "PETRA-IV: Technical Challenges and Scientific Computing" was organised by the HASYLAB/DESY PETRA-III synchrotron centre in Hamburg. The second one was a four-days workshop entitled “Advanced XAS Data Analysis and Modeling Workshop” was organized by the Canadian Light Source in Saskatchewan.


01.10.2020.

A paper entitled “X-ray absorption and Raman spectroscopy studies of tungstates solid solutions ZncNi1-cWO4 (c=0.0-1.0)” has been accepted for publication in the journal “Low Temperature Physics”.

Nd2(WO4)3, CaWO4, SrWO4, BaWO4, and PbWO4 samples were synthesized and analyzed: their purity was confirmed by X-ray diffraction analysis and X-ray photoelectron spectroscopy.  Their X-ray absorption spectroscopy measurements have been performed between 09.09.2020. and 14.09.2020. at the HASYLAB/DESY PETRA-III synchrotron centre at PETRA-III P65 work station.

An online seminar - organised by the ESRF synchrotron in Grenoble - "X-ray absorption spectroscopy for solving chemical problems" (September 18) has been attended.

A research project for synchrotron measurements for Spring 2021 at the HASYLAB/DESY PETRA-III synchrotron centre has been written and submitted.


01.07.2020.

Based on the inhouse and synchrotron characterisation of NiWO4 and ZnWO4 solid solutions, a paper entitled “X-ray absorption and Raman spectroscopy studies of tungstates solid solutions ZncNi1-cWO4 (c=0.0-1.0)” has been submitted to the journal of Low Temperature Physics.

Crystal computing code has been used to simulate polaron intercalation into the tungstate structure.

Two online workshops - organised by the DESY synchrotron in Hamburg - "X-ray Powder Diffraction - new opportunities for research and industry" (June 22-25) and "Perspectives and new opportunities for X-ray absorption spectroscopy" (June 29-30) have been attended.


01.04.2020.

A review of the scientific literature has been done. Practical training on the analytical methods available at the institute has been performed. NiWO4, ZnWO4 and CuMo1-xWxO4 samples were synthesized and analyzed: their purity was confirmed by X-ray diffraction analysis and X-ray photoelectron spectroscopy. A research project for synchrotron measurements has been written and submitted. The preliminary acquaintance with Crystal computing code has begun.