Sinteza i Strukturna Karakterizacija Mikroporoznih Arsenata i Fosfata

Abstract

Predmet rada i istraživanja ove doktorske disertacije su sinteza i strukturne karakteristike novih kristalnih arsenata i fosfata koji sadrže Mg, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ba i druge katjone. U strukturama arsenata i fosfata, AsO_4- i PO_4-tetraedri najčešće se vezuju sa tetraedarski ili oktaedarski koordinisanim katjonima prelaznih metala formirajući otvorene strukture (slojeve ili 3D mreže) sa širokim opsegom različitih topologija. U šupljinama ili porama u obliku povezanih ili nepovezanih kanala, tunela, kaveza i međuslojnog prostora mogu se ugraditi različiti vanmrežni joni (obično alkalni i zemnoalkalni katjoni) ili molekuli (najčešće mali organski molekuli), što čini ova jedinjenja veoma interesantnim zbog njihovih fizičkih i hemijskih osobina i potencijalne primene.

U okviru ispitivanja sistema T1O–T2O–X2O5–(H2O)–Y, gde je T1 dvovalentni ili jednovalentni (K⁺, Ca²⁺, Zn²⁺, Sr²⁺, Ba²⁺), T2 dvovalentni ili trovalentni (Mg²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Fe³⁺, Co³⁺), X petovalentni (P⁵⁺, As⁵⁺) katjon, a Y je vanmrežni katjon H₂(C₂H₈N₂)²⁺ ili NH₄ ⁺sintetisana su nova jedinjenja metodom niskotemperaturne hidrotermalne sinteze i određene njihove kristalne strukture. Cilj je bio da se u okviru ovog sistema sintetišu monokristali koji u mikroporama ili međuslojnom prostoru sadrže različite jone i molekule kao što je etilendiamin, C2H4(NH2)2, ili odgovarajuća protonovana forma.

Kvalitet dobijenih monokristala proveravan je pomoću optičkog mikroskopa ili binokularne lupe i strukture kristala određene su metodom rendgenske difrakcije na monokristalu. Za morfološku i hemijsku karakterizaciju korišćena je metoda skenirajuće elektronske mikroskopije (SEM) dopunjena energetsko-disperzivnim sistemom (EDS). Kod kristala koji su zahtevali preciznu kvantitativnu hemijsku analizu korišćena je elektronska mikrosonda, a metoda ramanske spektroskopije korišćena je za određivanje prisustva H2O, (OH)−, (NH4)+ i NH3.

Pokazano je da četiri sintetisana kristala imaju zeolitski DFT-tip strukture. To su (H₂en)[ZnAsO₄]2 (ZnAs), (H₂en)[Co0,1Zn0,9AsO₄]2 (ZnCoAs).

Alternate abstract:

The doctoral dissertation research subjects are the synthesis and structural investigation of new arsenate and phosphate containing Mg, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ba and other cations. In the structures of arsenates and phosphates, AsO4- and PO4-tetrahedra are usually linked with tetrahedrally and octahedrally coordinated cations of transition metals forming open structures (layers or 3D frameworks) with a wide range of different topologies. In the holes, or pores, which are in the form of a connected or unconnected channels, tunnels, cages and the interlayered space, various non-framework ions (usually alkaline and earth alkaline cations) or molecules (usually small organic molecules) can be incorporated. Therefore these compounds are very interesting due to their physical and chemical properties and potential applications.

In the course of the investigation of the T1O–T2O–X2O5–(H2O)–Y system, where T1 is a divalent or monovalent (K⁺, Ca²⁺, Zn²⁺, Sr²⁺, Ba²⁺), T2 divalent or trivalent (Mg²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Fe³⁺, Co³⁺), X pentavalent (P⁵⁺, As⁵⁺) cation, and Y is non-framework cation H₂(C₂H₈N₂)²⁺ or NH₄ ⁺, several novel compounds have been synthesized using the low temperature hydrothermal synthesis method, and their crystal structures have been determined. The aim was to synthesize single crystals with micropores or interlayer space containing different ions and molecules like the ethylenediamine, C2H4(NH2)2, or the corresponding protonated forms.

The quality of the obtained single crystals was evaluated using an optical or binocular microscope, and the crystal structure was solved using single-crystal X-ray diffraction data. For the morphological and chemical characterization the scanning electron microscopy (SEM), coupled with energy-dispersive system (EDS) was used. The electron microprobe provide precise quantitative chemical analysis, and the Raman spectroscopy method was used for the determination of the presence of H2O, (OH)−, (NH4)+ and NH3.