N. B. Morozova

Investigation of thermal properties of ruthenium(III) Β-diketonate precursors for preparation of RuO2 films by CVD

By means of a tensimetric flow method and a static method with a silica-membrane zero gauge, the dependence of vapour pressure on temperature was obtained for tris(2,4-pentanedionato)ruthenium(III), Ru(aa)3, and tris(1,1,1-trifluoropentane-2,4-dionato)ruthenium(III), Ru(tfa)3. The thermodynamic characteristics of vaporization and sublimation of these complexes were determined. The processes of thermal decomposition of the vapour of the compounds in vacuum, hydrogen and oxygen were investigated by using mass spectrometry in the temperature range 170–550‡C for Ru(aa)3 and 150–620‡C for Ru(tfa)3. The threshold temperatures of the stability of the vapour of the complexes and the rate constants of the thermolysis processes were determined. The main gaseous products of the thermal decomposition and the dependences of their composition on the presence of hydrogen and oxygen were established.

Saturated Vapor Pressure of Iridium(III) Acetylacetonate

The temperature dependency of the saturated vapor pressure of Ir(acac)3 has been measured by the method of calibrated volume (MCV), the Knudsen method, the flow transpiration method, and the membrane method. The thermodynamic parameters of phase transition of a crystal to gas were calculated using each of these methods, and the following values of ΔHT0 (kJ mol−1) and ΔST0 (J mol−1K−1), respectively, were obtained: MCV: 101.59, 156.70; Knudsen: 130.54, 224.40; Flow transpiration: 129.34, 212.23; Membrane: 95.45, 149.44Coprocessing of obtaining data (MCV, flow transportation method and Knudsen method) at temperature ranges 110−200°C as also conducted:ΔHT0 =127.9±2.1 (kJ mol−1 ); ΔST0 =215.2±5.0 (J mol−1 K−1 ).

Study of temperature dependence of saturated vapour pressure of zirconium(IV) β-diketonates

By means of a tensiometric flow method and a static method with a silica-membrane zero gauge, the dependences of saturated vapour pressure on temperature were obtained for the complexes of zirconium(IV) with acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, dipivaloylmethane and pivaloyltrifluoroacetone. The thermodynamic characteristics of the evaporation and sublimation of these complexes were determined.

Chemical vapour deposition of Ir-based coatings: chemistry, processes and applications

Chemical and materials science aspects of iridium-containing thin film formation by Chemical Vapor Deposition (CVD) methods for modern high-precision technology applications are considered. Chemical approaches to the synthesis of the main precursors used in CVD techniques, thin film growth processes and mechanisms as well as the main structure, composition and properties of iridium-containing thin films are analyzed, and modern thin film application examples are outlined. Numerical characterization of iridium-based thin film growth in 3D objects is presented.

Preparation of thin films of platinum group metals by pulsed MOCVD. II. Deposition of Ru layers

In situ high-temperature mass spectrometry is used to analyze the thermal decomposition of Ru(acac)3 and Ru(nbd)(allyl)2 vapor and possible schemes of thermal transformations on the heated surface. By pulsed MOCVD with in situ mass spectrometric control of deposition processes ultrathin Ru layers with a thickness of several nanometers are obtained. The role of the reaction medium, precursor nature, and deposition temperature in the formation of a nanocrystalline structure of the films is revealed. Ruthenium films with a compact continuous structure are formed from Ru(acac)3 and hydrogen at a deposition temperature of 340°C and below; an increase in the temperature results in the growth of nanogranular Ru layers. Regardless of deposition conditions, from Ru(nbd)(allyl)2 granular nanocrystalline Ru layers are formed

Chemical vapor deposition of electrolyte thin films based on yttria-stabilized zirconia

Gas-tight electrolyte films are obtained by chemical vapor deposition for solid oxide fuel cells from yttria-stabilized zirconia (YSZ) with a thickness of 4–15 μm on supporting porous ceramic anodes (YSZ/NiO). Volatile metal complexes with dipivaloylmethane Zr(dpm)4 and Y(dpm)3 are used as precursors. On the basis of an analysis of thermal properties of the starting compounds, parameter ranges in deposition processes are determined. Dependences of the structure, composition, and electrical characteristics on deposition conditions are found for YSZ electrolyte films. Electrochemical solid oxide fuel cells that operate at low temperatures with an open circuit voltage of 0.98–1.08 V and specific power up to 440 mW/cm2 at 1073 K and 1200 mW/cm2 at 1173 K are constructed.

Structure and properties of films based on HfO2-Sc2O3 double oxide

The results of the investigation of the chemical constitution and structure of (HfO2)x(Sc2O3)1−x thin films are reported. The films are obtained by chemical vapor deposition (CVD) from hafnium 2,2,6,6-tetramethyl-3,5-heptandionate (Hf(thd)4) and scandium 2,2,6,6-tetramethyl-3,5-heptandionate (Sc(thd)3) coordination compounds. It is demonstrated by powder X-ray diffraction and infrared spectroscopy that depending on the scandium content in the films the structure is changed from monoclinic to cubic. Voltage-capacity dependences of test Al/(HfO2)x(Sc2O3)1−x/Si structures are used to calculate the dielectric constant of the films. For the films with the cubic structure it is found that k = 21, while for the films with the monoclinic structure k = 9.

Synthesis and crystal structure of dimethylgold(III) carboxylates

Three novel carboxylate complexes were synthesized: dimethylgold(III) trifluoroacetate [Me2Au(Tfa)]2 (I), trimethylacetate (pivalate) [Me2Au(Piv)]2 (II), and benzoate [Me2Au(OBz)]2 (III). The starting reagent was [Me2AuI]2. The procedure of its synthesis provides 60% product yield. Dimethylgold(III) carboxylates were identified from the IR and 1H NMR data. The title compounds were studied by X-ray diffraction. The unit cell parameters for I, C8H12Au2F6O4: a = 15.5522(13), b = 12.9398(11), c = 15.6555(14) Å, β = 104.308(2)°, Z = 8, ρ(calcd.) = 2.959 g/cm3, space group C2/c, R = 0.0779; for II, C14H30Au2O4: a = 10.3025(3), b = 15.5952(4), c = 12.6819(3) Å, β = 105.8270(10)°, Z = 4, ρ(calcd.) = 2.224 g/cm3, space group P21/c, R = 0.0229; for III, C18H22Au2O4: a = 12.8050(2), b = 19.7886(3), c = 7.60300(10) Å, Z = 4, ρ(calcd.) = 2.401 g/cm3, space group Pnma, R = 0.0144. Compounds I–III have the molecular structures; the structural units are the [(CH3)2Au(OOCR)]2 dimers (Au…Au 2.984–3.080 Å), R = CF3, tert-Bu, Ph. The gold atoms have the square coordination with two carbon atoms and two oxygen atoms (Au-O 2.120–2.173 Å). The molecules in compounds I–III are united into infinite unidimensional chains connected by van der Waals interactions.

Vapour Pressure and Thermoanalytical Study of Diethyldithiocarbamates of Platinum Metals

A thermoanalytical study of the diethyldithiocarbamates of the platinum metals Pt(II), Pd(II), Rh(III), Ir(III) and Ru(III) was carried out by means of DTA techniques in an inert atmosphere and in vacuum. Decomposition temperatures were determined and the mass loss curves were obtained for these compounds in helium and in vacuum. The X-ray diffraction patterns of the solid products of M(dtk)n thermolysis were studied. The temperature dependences of the saturated vapour pressures of the listed chelates were measured by flow and Knudsen methods, and the vaporization parameters were determined.

Structure of lanthanum(III) tris-dipivaloylmethanate

A series of Ln(III) dipivaloylmethanates of the composition Ln(dpm)3 (Ln = La, Tm, Yb) is obtained. It is established that Tm(dpm)3 and Yb(dpm)3 complexes are isostructural with Lu(dpm)3. The crystal structure of [La(dpm)3]2 at 150(2) K is determined (space group P21/n, a = 12.4412(5) Å, b = 28.0579(12) Å, с = 21.9533(8) Å, β = 105.796(2)°, V = 7373.9(5) Å3, Z = 4). The studied compound is isostructural with [Pr(dpm)3]2, [Eu(dpm)3]2, [Gd(dpm)3]2, and [Tb(dpm)3]2 complexes. The crystal structure of the complex is formed by dimeric [La(dpm)3]2 molecules. Thermogravimetric investigations show that the volatility of Ln(dpm)3 increases in the series from [La(dpm)3]2 to Yb(dpm)3. Melting points of the complexes are close to the known literature data.