Novel Routes to Europium Sulfide

Abstract

Europium chalcogenide nanocrystals exhibit significant changes in their magnetic and luminescent properties as compared to bulk. The magneto-optical properties of these materials are strongly dependent on their shape, size, and surface conditions. O’Brien et al., have pioneered the preparation of many single source precursors as efficient routes to high quality, crystalline and monodispersed nanoparticles with semiconducting properties. This work in the second chapter presents the synthesis of nine novel europium compounds: [Eu(C6H5COS)3(phen)2] (1), [Eu(C6H5COS)3(phen)].CHCl3 (2s), and [Eu(C6H5COS)3(bipy)(MeOH)] (3s). tris(methyhexyldithio-carbamato)europium(III) -1,10phenanthroline [Eu(S2CN(CH3)(C6H13))3(phen)](4), tris(dihexyldithio- carbamato)europium(III)-1,10phenanthroline [Eu(S2CN(C6H13)2)3(phen)](5), teraphenylphosphonium tetrakis (ethylxanthato)-europium(III) (Ph4P)[Eu(S2COCH2CH3)4] (6), teraphenylphosphonium tetrakis (diethyldithio- carbamato)europium(III) (Ph4P)[Eu(S2CN(CH2CH3)2)4] (7) and tris- (dithiophosphato)europium(III) complexes: [Eu(S2P(OCH2CH3)2)3(phen)] (8), [Eu(S2P(OCH2CH3)2)3(bipy)] (9), followed by their characterisation by micro- elemental analysis, 1H NMR, infra-red spectroscopy and X-ray crystallography. Eu2O2S and EuS nanoparticles have been synthesized by the thermolysis and colloidal route as reported in the third chapter and decomposition of single source precursors. The nanoparticles were characterised by powder X-ray diffraction, transmission electron microscopy and scanning electron microscopy. In the fourth chapter the nanoparticles were characterised by UV-Visible spectroscopy and the band gaps were determined and magnetic measurements revealed that EuS nanoparticles show ferromagnetic behaviour at 10 K from compounds (2s), (3s), (4), (6) and (7), the exception is EuS nanoparticles from compound (5), which shows paramagnetic behaviour at the same temperatures. Reported studies of EuS nanoparticles from precursors (2s), (3s), (4), (5) and (7) show paramagnetic behaviour at 300 K with very small ferromagnetic contribution. In contrast, EuS nanoparticles from precursor (6), show no sign of formation of magnetic nanoparticles.

Date of Award	31 Dec 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Collison (Supervisor), Paul O'Brien (Supervisor) & Stephen Yeates (Supervisor)