17 KB344 KB16 KB200020242000Drofenik, MihaelMakovec, DarkoUle, Ninaletnik:344 straništevilka:5str. 275-278ISSN:1580-2949COBISSID:236458URN:URN:NBN:SI:doc-JCD6QBVSslInštitut za kovinske materiale in tehnologijeMateriali in tehnologijebarijev titanatceramicelektrične lastnostikeramikamikrostrukturaEfekt PTKU v močno donorsko dopirani keramiki BaTiO3| PTCR effect in highly donor-doped BaTiO3 ceramics|PTC resistors are normally produced by sintering donor-doped ?$BaTiO_3$? in air. The concentration of donor must be lower than a critical value (0,3 mol.%in air), which blocks the grain growth during sintering. The critical donor concentration can be significantly increased by sintering in a reducing atmosphere.In this way, a coarse-grained, highly donor-doped ?$BaTiO_3$? may be obtained. In such ceramics the PTCR effect can be developed by annealing in air. In the present work the PTCR effect in ?$BaTiO_3$? ceramics, doped with La from 0 to 20 mol.% has been studied. The samples were sintered in a reducing mixture of ?$N_2$? containing 1 % of ?$H_2$? and subsequently reoxidized by annealing in airNavadno izdelujejo upore s pozitivnim temperaturnim koeficientom upornosti (PTK-upore) s sintranjem nizko donorsko dopiranega ?$BaTiO_3$? na zraku. Koncentracija donorja ne sme preseči kritične velikosti (-0,3 mol.% med sintranjem na zraku), ki povzroči zaustavitev pretirane rasti zrn med sintranjem. S sintranjem v redukcijski atmosferi lahko povišamo kritično koncentracijo donorja, in tako dobimo močno donorsko dopiran ?$BaTiO_3$? z grobo zrnato mikrostrukturo. V grobo zrnatem ?$BaTiO_3$? lahko s poznejšo reoksidacijo z žganjem na zraku uravnavamo PTKU-efekt. V tem delu so predstavljeni rezultati raziskave PTKU-efekta v keramikah ?$BaTiO_3$?, dopiranih s koncentracijami La od o do 20 ml.%. Vzorci so bili sintrani v redukcijski mešanici ?$N_2$? z 1 % ?$H_2$? in pozneje reoksidirani z žganjem na zrakuTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije