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Identifier 000445782
Title Study of spinel oxide alloys Mn3O4 based for printed temperature sensors
Alternative Title Μελέτη κραμάτων οξειδίων σπινελίου με βάση Mn3O4 το για εκτυπώσιμους αισθητήρες θερμοκρασίας
Author Κατερινοπούλου, Δήμητρα Η
Thesis advisor Κυριακίδης, Γεώργιος
Reviewer Ηλιόπουλος, Ελευθέριος
Ρεμεδιάκης, Ιωάννης
Γεωργακίλας, Αλέξανδρος
Κωνσταντινίδης, Γεώργιος
Gelinck, Gerwin
Lodziana, Zbigniew
Abstract Temperature is an important parameter in our daily life, monitoring and controlling of which can be achieved with corresponding sensors. Among the various types existing, negative temperature coefficient (NTC) thermistors, made by spinel oxides, hold a prominent position, due to the wide range they cover. The need for surfaces that can accurately monitor spatial and temporal changes in temperature are critical for many applications. Realizing such surfaces requires the deposition of hundreds of sensors over large areas, a task ideally accomplished by printing technologies. However, significant bottleneck obstructing their use are their complex and high temperature fabrication process and high stiffness, prohibiting their integration in large area or flexible applications combined with understanding of their conduction mechanism. In this study we investigate the transport mechanism of the ternary Zn0.5NixMn2.5-xO4 and ZnxNi0.5Mn2.5-xO4 spinel oxide alloys, with Ni and Zn content ranging between 0 ≤ x ≤ 1.25. Conductivity studies resulted to an unusual exponential dependence with the temperature associated with structural and vibrational analysis. In particular, for the system with Ni addition, theoretical calculations using density functional theory (DFT) oriented on structural and electronic properties were made. For intermediate Ni content, both experiment and theory revealed the coexistence of cubic and tetragonal phases, along with the presence of various metastable magnetic conformations at room temperature. Considering nearest-neighbor polaron transfer in such energetically inhomogeneous landscape, a new hopping mechanism model is proposed, which consistently describes the temperature dependence of conductivity in these ternary alloy spinel oxide systems. In addition, a printable NTC composite is demonstrated. It consists of a manganese-based spinel oxide powder dispersed in a benzocyclobutene resin. This printed sensor shown an excellent stability at different environmental temperature profiles and the choice of the binder led to a composite exhibiting less than 1°C change in resistance to humidity changes. Finally, sensors’ scalability was validated by demonstration of a hand placed on a mat consisting of over 400 sensors where the outline and temperature changes were clearly resolved
Language English
Subject Ceramic oxides
Flexible electronics
Thermistor
Transport mechanisms
Θερμιστόρ
Κεραμικά οξείδια
Μηχανισμός αγωγιμότητας
Σπινέλια
Issue date 2022-02-14
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/1/7/c/metadata-dlib-1644322068-872258-8721.tkl Bookmark and Share
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