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Projects / Programmes source: ARIS

Extended defects in natural and synthesized perovskite oxides: nanogeochemcial indicators and functional interfaces

Research activity

Code Science Field Subfield
1.06.00  Natural sciences and mathematics  Geology   

Code Science Field
1.05  Natural Sciences  Earth and related Environmental sciences 
Keywords
perovskite, loparite, chemical twinning, interfaces, extended defects, Ruddlesden-Popper phases, oxygen vacancies, brownmillerite phases, modulated phases, atomic structure, atomic chemical composition, quantitative scanning transmission electron microscopy (STEM), electron spectroscopy
Evaluation (rules)
source: COBISS
Points
8,327.61
A''
3,038.72
A'
5,353.01
A1/2
6,955.97
CI10
20,782
CImax
1,841
h10
61
A1
30.73
A3
5.92
Data for the last 5 years (citations for the last 10 years) on July 21, 2024; A3 for period 2018-2022
Data for ARIS tenders ( 04.04.2019 – Programme tender, archive )
Database Linked records Citations Pure citations Average pure citations
WoS  993  22,561  20,042  20.18 
Scopus  1,030  24,917  22,263  21.61 
Researchers (12)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  54684  Petruša Borštnar  Materials science and technology  Junior researcher  2021 - 2024  12 
2.  39207  PhD Alja Čontala  Materials science and technology  Junior researcher  2021 - 2024  24 
3.  19029  PhD Nina Daneu  Materials science and technology  Head  2021 - 2024  428 
4.  21372  PhD Matej Dolenec  Geology  Researcher  2021 - 2024  478 
5.  02556  PhD Goran Dražić  Materials science and technology  Researcher  2021 - 2024  1,047 
6.  13311  PhD Marjeta Maček Kržmanc  Materials science and technology  Researcher  2021 - 2024  183 
7.  53417  Tina Radošević    Technical associate  2021 - 2024  80 
8.  10083  PhD Aleksander Rečnik  Chemistry  Researcher  2021 - 2024  651 
9.  37779  PhD Francisco Ruiz Zepeda  Materials science and technology  Researcher  2021 - 2024  239 
10.  24273  PhD Matjaž Spreitzer  Materials science and technology  Researcher  2021 - 2024  369 
11.  11093  PhD Srečo Davor Škapin  Chemistry  Researcher  2021 - 2024  591 
12.  37470  PhD Urška Trstenjak  Materials science and technology  Researcher  2021 - 2024  49 
Organisations (3)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  91,961 
2.  0104  National Institute of Chemistry  Ljubljana  5051592000  21,271 
3.  1555  University of Ljubljana, Faculty of Natural Sciences and Engeneering  Ljubljana  1627074  19,946 
Abstract
Crystal growth in diverse geological environments is a complex process governed by a combination of physicochemical factors. Geochemical and geophysical changes during the growth are imprinted into crystal grains in the form of inclusions, crystallographic defects, intergrowths and other patterns. One of the most informative are growth-type extended defects, such as twin or antiphase boundaries. These 2D interfaces are characterized by locally different atomic structure and chemical composition. Atomic-scale analyses of such interfaces provide key information about mineral and rock crystallization history (nanogeochemcial indicators) and help mineralogists and petrologists to decipher the sequence of crystallization processes. Formation of growth-type defects occurs also during crystal growth in functional materials prepared under controlled synthesis conditions. Here, these complex interfaces exhibit a range of important effects, from influence on crystal/grain growth and overall microstructure development to quantum effects emerging from their local atomic structure. In this project we will focus our investigations on extended defects in perovskite oxides, which are one of the most intriguing groups of compounds in terms of structural and chemical diversity. They occur as natural minerals in a wide variety of parageneses and are being increasingly recognized as important geoenvironmental indicators. They are even more widespread as functional materials with a range of interesting properties. One of the main characteristics of perovskite oxides is their capacity to incorporate many elements in the form of solid solubility, point defects, extended defects, modulated phases and similar. For our studies we selected natural perovskite oxides with different geological background and chemical composition: perovskite (CaTiO3) crystals from Zlatoust, Ural; loparite ((Na,REE)Ti2O6) interpenetration twins from Mt. Khibiny, Kola peninsula (both Russia); and perovskite-magnetite intergrowths from alkaline basalts, East Eifel, Germany. All crystals are rich in different types of extended defects and contain many trace elements. The atomic structure of extended defects will be studied down to the atomic-scale using quantitative scanning transmission electron microscopy (STEM) in combination with spectroscopic techniques for determination of local chemical composition of the interfaces (EDS, EELS). Most challenging task will be detection of trace elements at different types of interfaces. Our primary objective will be related to the nanogeochemical aspect of extended defects in natural perovskites. Based on the nanoscale structure and chemical composition of different types of extended defects in natural samples, we will reconstruct their formation mechanism (via transformation or growth) and further, determine geochemical and geophysical conditions during crystallization. The studies on natural crystals will be complemented with synthesis of nature-mimicked compositions under controlled laboratory conditions. The influence of trace elements (detected in natural samples) on the formation of single perovskites and modulated phases from the perovskite-loparite-tausonite system and the formation mechanism of oxygen deficient brownmillerite phases in Fe-doped perovskite will be studied. Objectives related to the functionality of chemically induced interfaces will be to reveal the relationship between the local atomic structure of extended defects and modulated phases and functional properties of natural single crystals and polycrystalline samples. The local electrical properties of chemically-induced extended defects will be evaluated using in-situ measurements. The project team involves specialists from complementary research fields like mineralogy, petrology, chemistry and materials science and leading experts in advanced electron microscopy.
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