Title Transportna i magnetska svojstva PANI-HCl organskog vodiča
Title (english) Transport and magnetic properties of PANI-HCl organic conductor
Author Mario Novak
Mentor Ivan Kokanović (mentor)
Committee member Antun Tonejc (predsjednik povjerenstva)
Committee member Ivan Kokanović (član povjerenstva)
Committee member Silvia Tomić (član povjerenstva)
Committee member Emil Babić (član povjerenstva)
Committee member Ivo Batistić (član povjerenstva)
Granter University of Zagreb Faculty of Science (Department of Physics) Zagreb
Defense date and country 2010-07-14, Croatia
Scientific / art field, discipline and subdiscipline NATURAL SCIENCES Physics
Universal decimal classification (UDC ) 53 - Physics
Abstract Proučavan je utjecaj stupnja dopiranja i nereda na temperaturno ovisna električna transportna te statička magnetska svojstva hidrokloriranog polianilina (PANI-HCl). Promatrani PANI-HCl sintetiziran je u vlastitom laboratoriju pomoću reakcije oksidacijske polimerizacije. Uzorci su istraživani nizom različitih eksperimentalnih metoda. Električna transportna mjerenja su pokazala da se ovisno o stupnju dopiranja električna vodljivost, a time i provodnost na sobnoj temperaturi promjeni preko deset redova veličine. Također je pronadeno da temperaturna ovisnost električne provodnosti σ (T) slijedi oblik ln σ α −(T0/T)α , gdje parametar α poprima vrijednosti 1, 1/4, 2/5 i 1/2, ovisno o vrsti uzorka (odnosno, stupnju dopiranja i količini nereda) te temperaturi (T). Za sve uzorke eksperimentalno određena σ (T) daje vrlo visok stupanj slaganja s Fogler-Teber-Shklovskii(FTS) modelom transporta naboja preskocima promjenjivog dosega. Dobro slaganje s FTS modelom transporta sugerira da u elektronskom podsistemu postoji nezasjenjena Coulombova interakcija koja snažno utječe na niskotemperaturnu σ (T). Niskotemperaturna σ (T) pokazuje vrijednosti α = 1/2 i 2/5 što je posljedica pojave mekog Coulombovog procjepa. Na višim temperaturama α prelazi u 1/4, odnosno 1 zbog toga što termalna energija nadvlada efekte Coulombove interakcije. Magnetska mjerenja su pokazala da se temperaturna ovisnost magnetske susceptibilnosti može opisati kao suma Curievog i Paulijevog tipa susceptibilnosti. Također je pronadeno da na T na kojima se mijenja vrijednost parametra α dolazi do promjena u magnetskoj susceptibilnosti uzoraka, što upućuje na povezanost nosioca naboja i spina u promatranim uzorcima PANI-HCl. Pomoću nuklearne spektroskopske metode raspršenja protona određen je stupanj dopiranja uzoraka. Rentgenskom difrakcijom dobiven je uvid u morfologiju uzoraka i kako se ona mijenja s promjenom stupnja dopiranja.
Abstract (english) We investigated the influence of the doping level (Y = [Cl]/[N]) on the electrical transport and static magnetic properties of the conducting polymer polyaniline (PANI). PANI was synthesized by an oxidative polymerization, and doped with hydrochloric acid (HCl). The investigated samples differ by the level of doping (from the fully doped (Y = 0.5) to the undoped one (Y = 0)), and were produced by pressing the PANI-HCl powder into pellets. The transport measurements show that the electrical conductivity follows the relation ln σ (T) α −(T0/T)α , for all samples. The exponent changes its value depending on Y and temperature (T). More precisely, α = 1/2 for the samples with Y < 0.3, and 2/5 for the samples with Y > 0.3, at low T. At high T the exponent α changes to 1/4 for the samples with Y < 0.4, and to ∼ 1 for all other samples. One of the samples (the most conductive one) also shows a transition α = 2/5 → 1/4 → 1, with increasing of T. All obtained values of α and the temperature induced transitions between them can be well described by the Fogler, Teber and Shklovskii variable-range-hopping model (FTS-VRH). According to the FTS-VRH model the low-T conductivity is governed by the Coulomb interaction which opens a ”soft” Coulomb gap at the Fermi energy, therefore, α = 2/5 and 1/2. At the high T the influence of the Coulomb gap is weakened due to the increase in temperature, and α goes to 1/4 and 1. Exponent α = 1 indicates transition from the VRH to the nearest- neighbour hopping. Static magnetic measurements give that the magnetic susceptibility Χ (T) can be described as the sum of the Curie-like and the Pauli-like susceptibility. Furthermore, a correspondence between σ (T) and Χ (T) was found. Namely, the parameters of (T) and Χ(T) change values around the same temperatures, which indicates the connection between the charge and spin carriers. The samples were also subjected to the elemental analysis and the X-ray diffraction.
Keywords
polianilin
sinteza
električna provodnost
magnetska susceptibilnost
Keywords (english)
polyaniline
synthesis
electrical conductivity
magnetic susceptibility
Language croatian
URN:NBN urn:nbn:hr:217:242493
Study programme Title: Physics Study programme type: university Study level: postgraduate Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
Type of resource Text
Extent 146 str.
File origin Born digital
Access conditions Open access
Terms of use
Created on 2017-08-24 07:24:00