doktorska disertacija
Boštjan Denac (Avtor), Matjaž Kristl (Mentor), Mihael Drofenik (Komentor)

Povzetek

Polprevodni materiali kot CdSe, CdTe, in CdSexTe1-x so osnova modernih elektronskih naprav. Znano je, da se polprevodni teluridi uporabljajo za senzorje, laserje, optične filtre, solarne celice in za mnoge druge naprave. Prav tako obetajoča za uporabo v solarnih celicah, fotoprevodnikih in tankoplastnih tranzistorih je mešanica binarnih halkogenidov s sestavo CdSexTe1-x. Ternarni kadmijevi halkogenidi so bili pripravljeni z uporabo različnih sinteznih metod: hidrotermalno, z mikrovalovi in s sonificiranjem v etilendiaminu in različnih razmerjih diamin/voda. Prav tako sem pripravil CdSexTe1-x nanodelce z direktno reakcijo segrevanja na zraku in v N2 atmosferi iz elementarnih delcev kadmija ter selena in telurja visoke čistoče ter iz binarnih delcev CdSe in CdTe. Dobljene ternarne nanodelce s sestavo CdSexTe1-x (x = 0.1 in x = 0.6) sem karakteriziral z uporabo rentgenske praškovne difrakcije (XRD) in presevnega elektronskega mikroskopa (TEM). Nastajanje in transformacijo ternarne faze sem spremljal s termično analizo (TGA). Pripravljeni halkogenidi so nanodelci med 6 in 35 nm, različnih kristalnih oblik, odvisno od izbrane metode priprave. Velikost delcev sem izračunal iz povprečja treh najmočneje izraženih vrhov za posamezne delce iz difraktograma s pomočjo Scherrerjeve enačbe. Izračunana velikost delcev s Scherrerjevo enačbo ustreza velikosti delcev določenih iz TEM posnetkov. Pri metodah priprave z uporabo topila imata izbira topila in reakcijska temperatura ključno vlogo pri nukleaciji in rasti binarnih CdE (E= Se, Te) in ternarnih CdSexTe1-x (x = 0.1 in x = 0.6) nanodelcev. Mešanica binarnih halkogenidov potrebuje višjo temperature in podaljšan čas segrevanja za tvorbo ternarnih halkogenidov s sestavo CdSexTe1-x kot mešanica elementarnih delcev. Prav tako ni zaznati večje razlike v produktih dobljenih s segrevanjem na zraku in v N2 atmosferi, nikjer ne nastajajo oksidi.

Ključne besede

halkogenidi;polprevodne ternarne spojine;nanomateriali;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.08 - Doktorska disertacija
Organizacija: UM FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik: B. Denac]
UDK: 549.31:620.3(043.3)
COBISS: 17436182 Povezava se bo odprla v novem oknu
Št. ogledov: 1724
Št. prenosov: 131
Ocena: 0 (0 glasov)
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Ostali podatki

Sekundarni jezik: Angleški jezik
Sekundarni naslov: PREPARATION AND CHARACTERIZATION OF NANOCRYSTALINE TERNARY CADMIUM CHALCOGENIDES
Sekundarni povzetek: Semiconductor materials such as CdSe, CdTe, and CdSexTe1-x are the bases of modern electronic devices. It is already known that semiconducting tellurides have found applications as sensors or laser materials, optical filters, solar cells, and in many other devices. The mixed pseudobinary compounds CdSexTe1-x are also a group of promising semiconductor materials used for various applications like solar cells, photoconductors and thin – film transistors. Ternary cadmium chalcogenides were prepared using different methods: hydrothermal, microwave, and sonochemical synthesis in ethylenediamine and different diamine/water solutions. CdSexTe1-x nanoparticles of different compositions were also synthesized by the direct reactions of high – purity elemental cadmium, selenium, and tellurium, as well as from CdSe and CdTe, heated in air or within a N2 atmosphere. The obtained ternary nanoparticles CdSexTe1-x (x = 0.1 and x = 0.6) were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The formation and transformation of ternary phases was studied by thermal analysis (TGA). The as – prepared chalcogenides were nanosized with different shapes and crystallite sizes between 6 and 35 nm, depending on the preparation method. All the particle sizes were calculated, using the Scherrer formula, from the averages of three strongest peaks from diffractograms for each material. Particle sizes calculated by the Scherrer formula are close to the particle size determined from TEM images. Solvent and reaction temperatures played a crucial role in controlling the nucleation and growth of binary CdE (E= Se, Te) and ternary CdSexTe1-x (x = 0.1 and x = 0.6) nanoparticles within the solvent using methods. The mixture of binary chalcogenides required higher temperatures and longer reaction times to form pseudobinary chalcogenides CdSexTe1-x than mixture of elementary particles. There is no significant difference in the product prepared by heating in air or within a N2 atmosphere. In both cases, no presence of oxides could be observed.
Sekundarne ključne besede: Ternarni kadmijevi halkogenidi;Disertacije;Nanomateriali;
URN: URN:SI:UM:
Vrsta dela (COBISS): Doktorska disertacija
Komentar na gradivo: Univ. Maribor, Fak. za kemijo in kemijsko tehnologijo
Strani: VII, 120 str.
ID: 8726146