0000000000311384
AUTHOR
Artūrs Zariņš
showing 7 related works from this author
Thermokinetic Investigation of the Drying Conditions on Amorphous Calcium Phosphate
2017
The present work investigated dried calcium phosphate powders which still retain an amorphous or poorly crystalline structure under a variety of conditions. In previous studies, freeze-drying was found to be the optimum drying condition. However, several publications, as well as our previous studies, have shown that calcium phosphate amorphous, or a poorly crystalline structure, can retain their structure even if the samples are dried immediately after synthesis up to 200°C. In our study, we used the thermokinetic studies FTIR and XRD and showed that the samples are amorphous, or poorly crystalline, but were unable to answer the questions: Is there a difference between the differently dried…
Characterisation and radiolysis of modified lithium orthosilicate pebbles with noble metal impurities
2017
Modified lithium orthosilicate (Li4SiO4) pebbles with additions of titanium dioxide (TiO2) are suggested as an alternative tritium breeding ceramic for the European solid breeder test blanket module. The noble metals – platinum (Pt), gold (Au) and rhodium (Rh), can be introduced into the modified Li4SiO4 pebbles during the melt-based process, due to the corrosion of Pt-Rh and Pt-Au alloy crucible components. In this study, the surface microstructure, chemical and phase composition of the modified Li4SiO4 pebbles with different contents of the noble metals was analysed. The influence of the noble metals on the radiolysis was evaluated after irradiation with accelerated electrons (E = 5 MeV),…
FTIR Analysis of Electron Irradiated Single and Multilayer Si<sub>3</sub>N<sub>4</sub> Coatings
2018
Silicon nitride (Si3N4) due to its good mechanical and electrical properties is a promising material for wide range of applications, including exploitation under action of ionizing radiation. For estimating the changes of chemical bonds in silicon nitride nanolayers under action of ionizing radiation single and multi-layer silicon nitride nanolayered coatings on prepared Si subtrate were investigated by means of Fourier transform infrared spectrometry. Three main groups of signals were identified in both types of nanolayers, at 510 and 820 cm-1 and group of broad signals at 1000-1200 cm-1. Irradiation with accelerated electrons up to absorbed doses 36 MGy causes minor changes of signal inte…
Behaviour of neutron irradiated beryllium during temperature excursions up to and beyond its melting temperature
2015
Abstract Beryllium pebble behaviour has been studied regarding the accidental operation conditions of tritium breeding blanket of fusion reactors. Structure evolution, oxidation and thermal properties have been compared for nonirradiated and neutron irradiated beryllium pebbles during thermal treatment in a temperature range from ambient temperature to 1600 K. For neutron irradiated pebbles tritium release process was studied. Methods of temperature programmed tritium desorption (TPD) in combination with thermogravimetry (TG) and temperature differential analysis (TDA), scanning electron microscopy (SEM) in combination with Energy Dispersive X-ray analysis (EDX) have been used. It was found…
Formation, accumulation and annihilation of radiation-induced defects and radiolysis products in advanced two-phase ceramic tritium breeder pebbles
2018
Modificētās litija ortosilikāta (Li4SiO4) minilodītes ar litija metatitanāta (Li2TiO3) piedevām ir izvirzītas kā alternatīvs materiāls tritija ģenerēšanai nākotnes kodoltermiskās sintēzes reaktoros. Promocijas darbā pirmo reizi ir analizēta un aprakstīta radiācijas defektu (RD) un radiolīzes produktu (RP) veidošanās, uzkrāšanās un rekombinācija Li4SiO4 minilodītēs ar dažādu Li2TiO3 daudzumu 5 MeV paātrināto elektronu un augstas temperatūras vienlaicīgā iedarbībā. Izpētīta un novērtēta cēlmetālu, minilodīšu diametra, graudu izmēra un hemosorbcijas produktu ietekme uz Li4SiO4 minilodīšu radiolīzi, lai izslēgtu tehnoloģisko faktoru ietekmi uz RD un RP veidošanos un uzkrāšanos apstarošanas laik…
Silīcija dioksīda un termiskās apstrādes ietekme uz fizikāli ķīmiskajiem procesiem litiju saturošā keramikā inertā un gaisa atmosfērā
2012
Darbā pētīta tritiju ģenerēšanai paredzētā keramika - Li4SiO4 minilodītes ar 2,5±0,1% SiO2 piedevu (Ø=250-630 Ām). Noteikts, ka SiO2 piedeva 2,0±0,5% apmērā praktiski neietekmē vai pat palielina Li4SiO4 keramikas radiācijas stabilitāti. Pierādīts, ka kodoltermiskās sintēzes reaktoram „līdzīgos” darbības apstākļos, t.i., paātrināto elektronu starojuma ietekmē (D=10,6 GGy) un paaugstinātā temperatūrā (T=300±10oC), inertā atmosfērā, Li4SiO4 minilodītēs ar 2,5±0,1% SiO2 piedevu, praktiski neuzkrājas radiācijas defekti (0,4±0,1•1016 radik.•g-1) un radiolīzes produkti (α=0,15%). Noteikts, ka termiski apstrādātām „nestandarta” Li4SiO4 minilodītēm (Ø<50 μm) ir praktiski vienāda radiācijas stabilitā…
Litija ortosilikāta nanopulveru un minilodīšu radiolīze
2010
Litija ortosilikāts ir viens no perspektīvākajiem materiāliem tritija atražošanai blanketa zonā nākamās paaudzes kodolsintēzes reaktoros (ITER, DEMO u.c.). Darbā mērķis ir noteikt radiācijas stabilitāti, pamatojoties uz struktūras, sastāva izmaiņu, radiācijas defektu un radiolīzes produktu veidošanos 3 veidu Li4SiO4 minilodītēm, kas ir ražotas ar kausējuma izsmidzināšanas metodi, un 2 veidu plazmā sintezētiem nanopulveriem. Litija ortosilikata paraugus apstaro ar paātrinātajiem 5 MeV elektroniem istabas un paaugstinātā temperatūrā gaisa un argona atmosfērā. Jonizējošā starojuma iedarbībā minilodītēs un nanopuveros veidojas un uzkrājas lokalizēto elektronu (F+, F), elektronu (E’–SiO33-) un c…