magistrsko delo
Valerija Danč (Author), Irena Ban (Mentor), Mihael Drofenik (Co-mentor)

Abstract

Sonokemija je področje kemije, kjer na potek kemijskih reakcij odločilno vpliva zvočna energija v obliki ultrazvoka. Ultrazvok in z njimi povezani pojavi so že znani več kot sto let, njegova uporaba v kemiji pa dosega razcvetv današnjem času. Naše raziskave so temeljile na sintezah nanodelcev kadmijevih sulfidov (CdS) in kadmijevih selenidov (CdSe) s sonokemijsko metodo. Ta metoda se je pri sintezah pokazala kot zelo uporabna, saj so končni produkti nanokristalinični materiali. Namen raziskave je bil sintetizirati polprevodniške nanodelce kadmijevega sulfida (CdS) in kadmijevega selenida (CdSe) v vodnem mediju. Kot izhodne snovi smo uporabili kadmijev sulfat hidrat (CdSO4 8/3 H2O), elementarno žveplo (S) in selen (Se) vprahu. Za topila smo uporabili vodne raztopine natrijevega hidroksida (NaOH),1.1 M vodno raztopino natrijevega sulfita (Na2SO3) in 0.05 M raztopino etilen diamin tetraetanojske kisline (EDTA). Pri sintezah smo uporabili direktno imerzijsko ultrazvočno sondo proizvajalca Vibracell. Pripravljene produkte smo karakterizirali z rentgensko praškovno difrakcijo (XRD), termično analizo (TA) in s transmisijsko elektronsko mikroskopijo (TEM). Zanimanje za uporabo anorganskih nanodelcev kadmijevih halkogenidov se v zadnjih letih povečuje zaradi njihovih polprevodniških lastnosti, kar omogoča uporabo pri izdelavi fotoprevodniških materialov, optičnih filtrov in predvsem pri izdelavi fotocelic. Kadmijev sulfid in selenid spadata med tipične polprevodnike tipa II-VI s širino prepovedanega pasu 2.42 oz. 1.74 eV pri sobni temperaturi. Hiter razvoj nanotehnologije je omogočil tudi velik napredek na področju razvoja fotocelic, saj je znano, da imajo kristali nanodimenzij bistveno drugačne kemijske, optične, elektronske in mehanske lastnosti kot makrokristaliničen material. Za CdS je znano, da se širina prepovedanega pasu v odvisnosti od velikosti delcev lahko spreminja med 2.4 in4 eV. CdS in CdSe imata odlične lastnosti kot polprevodnika tipa n najpogosteje v kombinaciji s polprevodnikom CdTe tipa p. Učinkovitost fotocelic CdS/CdTe presega 16% in narašča z uporabo nanokristaliničnega CdS. Raziskave polprevodniških sulfidov in selenidov dokazujejo njihovo uporabo v senzorjih, laserjih, optični filtrih in solarnih celicah. Sinteza halkogenidov je v zadnjih letih precej v razvoju in dosega vedno večje zanimanje na področju optike, elektronike, fotovoltaike, medicine ter na drugih področjih.

Keywords

kadmijev sulfid;nanodelci;sonokemija;rentgenska praškovna difrakcija;termična analiza;transmisijska elektronska mikroskopija;

Data

Language: Slovenian
Year of publishing:
Source: Maribor
Typology: 2.09 - Master's Thesis
Organization: UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher: [V. Danč]
UDC: 544.576
COBISS: 14690070 Link will open in a new window
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Other data

Secondary language: English
Secondary title: Synthesis and characterization of CdS and CdSe nanoparticles by sonochemical method in aqueous solution
Secondary abstract: Sonochemistry is a field of chemistry in which chemical reactions are critically influenced by sound energy in form of ultrasound. Ultrasound and related phenomena have been known for more than hundred years, while their usein chemistry has prospered only in recent times. Our research was based on synthesis of cadmium sulphide nanoparticles (CdS) and cadmium selenide (CdSe),by using the sonochemistry method. This method proved to be a very useful way of synthesis because of its final products - nanocrystal materials.The aim of the research was to synthesize semiconductor cadmium sulphide (CdS) and cadmium selenide (CdSe) nanoparticles in aqueous solution. As precursors we used cadmium sulphate hydrate (CdSO4 8/3 H2O), elementary sulphur (S) and selenium (Se) powder. As solvents we used aqueous solution ofnatrium hydroxide (NaOH), 1.1 M aqueous solution Na2SO3 and 0.05 M EDTA solution. For the synthesis we used direct immersion ultrasound probe made by Vibracell. The prepared products were characterized by X-Ray diffraction (XRD), thermal analysis (TA) and transmission electron microscopy. In recent years, the interest in using inorganic nanoparticles of cadmium chalcogenides is increasing due to their semiconductor properties, allowing the use in the manufacture of photoconductive materials, optical filters and especially in the manufacture of solar cells. Cadmium sulphide and selenide are among the typical type of II-VI semiconductors with the band-gap between 2,4 eV and 4 eVat room temperature. The rapid development of nanotechnology has also enabled significant progress in the development of solar cells, since it is known that the crystals in nanodimensions have significantly different chemical, optical, electronic and mechanical properties as macrocrystalline material. CdS can be band-gap tuned between 2,4 eV and 4 eV by adjusting its particles size. CdS and CdSe have excellent properties such as n-type semiconductor, usually in combination with p-type CdTe. The efficiency of solar cells CdS/CdTe exceed 16% and increase by using nanocrystalline CdS. Recearches of semiconductor cadmium sulphides and selenides confirmed their applicability in sensors, lasers, optical filters and solar cells. Recent syntheses of chalcogenides are in the process of development and achieves moreinterests in optical and electronic devices, photovoltaics, medicine and many other devices.
Secondary keywords: cadmium sulphide;nanoparticles;sonochemistry;thermal analysis;transmission electron microscopy;
URN: URN:SI:UM:
Type (COBISS): Master's thesis
Thesis comment: Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages: XIV, 82 f.
Keywords (UDC): mathematics;natural sciences;naravoslovne vede;matematika;chemistry;crystallography;mineralogy;kemija;physical chemistry;fizikalna kemija;chemistry of high energy processes;
ID: 1002512