A Single Source CVD Precursor to MgAl2O4: [Mg{(Ot-Bu)2AlH2}2]

Abstract

The hydride-modified heterometal alkoxide [Mg{(O t Bu) 2 AlH 2 } 2 ] (1), a precursor with tailored composition for single-source chemical vapor deposition (CVD) synthesis of MgAl 2 O 4 , has been synthesized and characterized using spectroscopic methods and single-crystal X-ray diffraction analysis. Thermal decomposition of 1, in a CVD process, on an inductively heated (450 C) metal substrate (steel, Ni, Cu) gave crystalline deposits of high purity MgAl 2 O 4 with low carbon contamination (<0.5 %) and nano-sized crystallites (<10 nm). Analysis of the pyrolysis gases using on-line mass spectroscopy, and comparing the results obtained with the deuterated compound [Mg{(O t Bu) 2 AlD 2 } 2 ] (2), confirmed the gaseous products to be isobutylene (2-methylpropene) and dihydrogen (HD in the case of 2). The 27 Al magic angle spinning (MAS) NMR study of the obtained spinel shows a partly inverse structure with Al 3+ ions occupying both octahedral and tetrahedral sites. This distribution (octahedral/tetrahedral) remains unaltered even on heat treatment. The thin layers obtained were characterized using glow discharge mass spectrometry (GDMS), energy dispersive X-ray (EDX), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), solid-state NMR and C-H analysis.

The use of mixed-metal single source precursors for the synthesis of complex metal oxides

“…11,23,34,41,54,56 Low temperature synthetic routes can allow access to new phases or those with high dopant content, 12,30,59 and to materials that have high porosity and/or small particles sizes. 30,45,58,130 Examples demonstrate that synthesising CMOs from mixed-metal SSPs can improve their properties compared with those from mixtures of precursors. 43,44,46 Furthermore, many SSPs have good solubility, allowing for convenient processing and generating the potential for scale up of materials for practical applications using solution deposition techniques.…”

“…Please do not adjust margins Please do not adjust margins least reduce the diffusion distances required to assemble the CMO structure. 32 By using lower synthesis temperatures, CMOs can be produced with small particle sizes and large surface areas, 30,45 or deposited onto more delicate substrates. The large amount of heat released from the decomposition of organic molecules can also facilitate the crystallisation of purephased oxides at relatively low reaction temperatures, enabling formation of high surface-area nanoporous structures otherwise unobtainable at higher temperatures.…”

“…the hydrocarbons CH4 and CH2=CMe2 are eliminated as gases as the only by-products). 11,45 Replacing alkoxide or amido groups with tin containing − OSnR3 or − N(SnR3)2 moieties allows direct formation of heterobimetallic complexes, 103 an example being the [R3SnOZnR']4 (R = Me, Ph, R'=Me, Et, t Bu) cubanes which can be used for the production of Sn doped ZnO and/or Zn2SnO4 tested as field-effect or thin-film transistors (Fig. 7a).…”

Reactivity and catalytic activity of tert-butoxy-aluminium hydride reagents

“…Since the unsolvated Mg compound [Mg{( t BuO) 2 AlH 2 } 2 ] has been reported previously, having a ion-paired dimeric molecular arrangement composed of Mg 2+ cations and [( t BuO) 2 AlH 2 ] − anions, 12 we anticipated a similar composition for 3 and 4. However, surprisingly the X-ray structures of both complexes revealed that their true nature is highly sensitive to the Lewis base ligand present.…”

Cyclopentanolates of Aluminum Hydride/Aluminum Chloride forming Aluminum‐Oxygen‐Hetero‐Cages and Mixed Coordination Oligomers

“…Hydride metal alkoxides (homo and heterometal alkoxides) are attracting growing attention for their use to produce metal/ metal oxide thin films through chemical vapor deposition (CVD). [1,2] Further more, these compounds are versatile, as can be exemplified by the tert-butoxy alane, [H 2 Al(OtBu)] 2 : under CVD conditions at low temperatures the phase HAlO is formed, whereas with growing temperature either nano balls or nano wires of the biphasic composite Al/Al 2 O 3 are obtained. [2][3][4][5][6] The basic molecular structures of hydride/alkoxides of aluminum and gallium are often similar to that of metal alkoxides, varying from monomeric to polymeric.…”