ALL libraries (COBIB.SI union bibliographic/catalogue database)
13.
Inversion boundaries in zinc oxide : dissertation = inverzne meje v cinkovem oksidu : doktorska disertacija
Daneu, Nina
Grain growth is one of the most important parameters in designing zinc oxide (Zn0) based varistor ceramics. Development of the Zn0 ceramic microstructure is commonly controlled by adding specific ...oxides. These oxides form spinel phase with Zn0 and in addition they trigger the formation of inversion boundaries in Zn0 grains. Most of the mechanisms describing the grain growth in Zn0 ceramics take into account only the influence of spinels while the role of inversion boundaries was completely overlooked. Investigating this phenomenon was one of the main challenges of my research. In the preliminary studies, I found a new dopant, tin oxide (Sn02) which triggers the formation of inversion boundaries in Zn0 grains, similarly as anti- mony oxide (Sb203) or titanium oxide (Ti02). While the influence of Sn02 on electrical proper- ties of varistor ceramics turned out to be highly unfavourable, further studies revealed that it is a perfect candidate for investigations of the role of inversion boundaries on microstructure devel- opment of Zn0-based ceramics. Using Zn0-Sn02 as a model system I was able to identify the IB-induced mechanism as the controlling mechanism of grain growth. According to this mechanism grains with inversion boundaries grow exaggeratedly and anisotropically in the direction of the inherent planar fault in the early stages of microstructure development. By controlling the number of nuclei it is possible to successfully control the grain size. The influence of secondary phases in Zn0 grain growth was found to be subordinate with respect to the role of inversion boundaries. To understand the nucleation and growth of inversion boundaries and their influ- ence on Zn0 grain growth I studied their atomic structure and chemistry. Atomic scale investi- gations have shown that inversion boundaries are basal plane faults with a head-to-head polarity reversal and involve a sphalerite shift in the plane of inversion. To precisely determine the che- mical composition of inversion boundary plane we developed a new analytical method. Using this method the composition of Sn- and Sb-rich inversion boundaries was determined to be one- half and one-third of the particular dopant element within the boundary layer, while the charge is balanced locally according to the Pauling's electroneutrality principle. Single Zn0 crystals were used to study the nucleation of inversion boundaries. The nucleation experiments proved the growth nature of inversion boundaries. Employing the IB-induced grain growth mechanism we are able to tailor microstructures for almost any desired varistor application.
Type of material - dissertation
; adult, serious
Publication and manufacture - Ljubljana : [N.Daneu], jun. 2003
It was not necessary to add the material to the shelf.
Bibliographic material was successfully added on shelf.
Adding bibliographical material on shelf was not successful.
Material is already on the shelf.
Permalink
URL:
Impact factor
Access to the JCR database is permitted only to users from Slovenia. Your current IP address is not on the list of IP addresses with access permission, and authentication with the relevant AAI accout is required.
Year
Impact factor
Edition
Category
Classification
JCR
SNIP
JCR
SNIP
JCR
SNIP
JCR
SNIP
Select the library membership card:
DRS,
in which the journal is indexed
Database name
Field
Year
Links to authors' personal bibliographies
Links to information on researchers in the SICRIS system
Subject headings in COBISS General List of Subject Headings
Select pickup location
The material from the parent unit is free. If the material is delivered to the pickup location from another unit, the library may charge you for this service.
