Volatile Iridium and Platinum MOCVD Precursors: Chemistry, Thermal Properties, Materials and Prospects for Their Application in Medicine

Abstract

Interest in iridium and platinum has been steadily encouraged due to such unique properties as exceptional chemical inertia and corrosion resistance, high biological compatibility, and mechanical strength, which are the basis for their application in medical practice. Metal-organic chemical vapor deposition (MOCVD) is a promising method to fabricate Ir and Pt nanomaterials, multilayers, and heterostructures. Its advantages include precise control of the material composition and microstructure in deposition processes at relatively low temperatures onto non-planar substrates. The development of MOCVD processes is inextricably linked with the development of the chemistry of volatile precursors, viz., specially designed coordination and organometallic compounds. This review describes the synthesis methods of various iridium and platinum precursors, their thermal properties, and examples of the use of MOCVD, including formation of films for medical application and bimetallics. Although metal acetylacetonates are currently the most widely used precursors, the recently developed heteroligand Ir(I) and Pt(IV) complexes appear to be more promising in both synthetic and thermochemical aspects. Their main advantage is their ability to control thermal properties by modifying several types of ligands, making them tunable to deposit films onto different types of materials and to select a combination of compatible compounds for obtaining the bimetallic materials.

Noble Metals for Modern Implant Materials: MOCVD of Film Structures and Cytotoxical, Antibacterial, and Histological Studies

“…Ir coatings were obtained at a deposition temperature of 310 °C, evaporator temperature of 110 °C (partial pressure of [Ir(cod)(acac)] was 0.02 Torr according to the equation ln(p, atm) = 23.4 − 14,136/T(K) [ 25 ]), and flow rates of 2 L/h for both carrier gas (argon) and reactant gas (oxygen). Pt coatings were obtained at a deposition temperature of 310 °C, evaporator temperature of 150 °C (partial pressure of [Pt(acac) 2 ] was 0.03 Torr according to the equation ln(p, atm) = 23.03 − 12,817/T(K) [ 25 ]), and argon and oxygen flow rates of 2 L/h and 1 L/h, respectively. PtIr coatings were obtained at a deposition temperature of 310 °C and argon and oxygen flow rates of 1.5 L/h and 1 L/h.…”

“…PtIr coatings were obtained at a deposition temperature of 310 °C and argon and oxygen flow rates of 1.5 L/h and 1 L/h. To obtain a stoichiometric metal ratio (1:1) in the coatings, the evaporation temperatures were set to provide the same precursor partial vapor pressure of 0.11 Torr, specifically, 165 °C for [Pt(acac) 2 ] and 131 °C for [Ir(cod)(acac)] [ 25 ].…”

“…Metal–organic complexes of platinum, iridium, and gold with beta-diketonate and cyclooctadiene ligands were used as precursors, for which synthetic approaches were developed and the thermal properties were studied in detail [ 25 ]. During the deposition process, metal coatings were formed as a result of a thermally activated chemical reaction of precursor vapors with a reactant gas on the substrate surface, with further removal of gaseous byproducts from the reaction zone.…”

The Theoretical and Experimental Investigation of the Fluorinated Palladium β-Diketonate Derivatives: Structure and Physicochemical Properties

“…Examples of the use of DFT calculations for the estimation of the volatility of fluorinated metal complexes with various combinations of CF 3 groups in ligands are known [ 21 , 35 , 36 ]. An increase in volatility in a series of Pd diketonates ([Pd(CH 3 COCHCOCH 3 ) 2 ] vs. [Pd(tfa) 2 ] (complex 1) vs. [Pd(hfa) 2 ]) is interpreted, first of all, by their structural features (weakening of intermolecular interactions between neighboring stacks of molecules), leading to a decrease in the values of E latt (|∆ sub H|) with an increase in the number of fluorinated groups in ligands [ 37 ].…”

Towards Understanding the Cathode Process Mechanism and Kinetics in Molten LiF–AlF3 during the Treatment of Spent Pt/Al2O3 Catalysts

“…The platinum group metals (PGMs) are extensively used in various fields such as the petroleum industry for improving gasoline quality [1], organic synthesis for cycloisomerization, in the hydrogen evolution reaction [2] and medicine [3]. Platinum coated alumina substrate is used as a catalyst in the reforming and isomerization process to create higher octane components for gasoline.…”