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ABSTRACT: The volatile scandium-β-diketonates are synthesised using acetylacetone (acac) and tetramethylheptanedione (tmhd) as coordinative
ligands for CVD application. The X-ray powder patterns are indexed and analysed and found to be orthorhombic and monoclinic
phases for Sc(acac)3(1) and Sc(tmhd)3(2) respectively. The sublimation and evaporation kinetics have been analyzed using three calculating techniques. The non-isothermal
based activation energy values are found to be 38±2 and 73±2kJmol−1 by Flynn–Wall technique for (1) and (2) respectively. The measured Ea values are close to the value obtained using Kissinger method.
KeywordsPowder X-ray diffraction-Scandium-β-diketonate-Sublimation kinetics
Journal of Thermal Analysis and Calorimetry 04/2012; 100(1):155-161. · 1.60 Impact Factor
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ABSTRACT: The congruent vaporization of La(tmhd)3, Sr(tmhd)2 and Mn(tmhd)3 were verified from the molar mass of the vapor species obtained using FABmass spectra (MS), thermogravimetry (TG) and vacuum sublimation techniques. The sublimed product was found to have the same XRD and FT-IR as the initial product taken. The equilibrium vapor pressures over a temperature span of 395542 K was determined by adapting a calibrated horizontal dual arm single furnace thermo-analyzer as a transpiration apparatus. The temperature dependence of pe/Pa could be represented as Clausius – Clapeyron equation by the least squares expression are,
La(tmhd)3:
Sr(tmhd)2:
Mn(tmhd)3:
The equilibrium vapor pressure data yielded a straight line when ln pe¬ was plotted against reciprocal temperature, leading to standard enthalpy of sublimation (subH°) values of 114±3, 84±3 and 79±4 kJ mol1 for La, Sr and Mn tmhd complexes, respectively. The activation energy of the complexes was calculated from non-isothermal TG studies using model fitting and isoconversional techniques. Thin films were grown at 773 K on alumina and Si substrates using a single solution source of La, Sr and Mn tmhd complexes dissolved in triglyme. These films were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray for their composition and morphology. The surface morphology analysis using scanning electron microscopy (SEM) revealed a grainy and densely packed agglomerates structure for films. Chemical analyses by energy dispersive X-ray (EDX) analysis showed the presence of lanthanum and strontium in the films, due to lower percentage of Mn added in the process, could not be identified from EDX analysis. Complete evaporation as single step at lower temperature of the synthesized precursors is identified themselves as an ideal precursor for CVD applications.
6th Coating Science International 2010, Noordwijk, The Netherlands; 01/2010
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ABSTRACT: Nanocrystalline cubic Y2O3 film deposition by PA-LICVD was studied at 773 K in a N2/O2 plasma environment with methanol and triglyme solution of aquatris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium(III) and its polyether adduct complexes as precursors. The X-ray powder patterns are analyzed and found to be triclinic and monoclinic for Y(tmhd)3·H2O(1) and Y2(tmhd)6·triglyme (2). Y2O3 film with (111) plane as the dominant orientation was obtained on graphite under a deposition pressure of 0.8–1.2 mbar.
Materials Letters. 12/2009; 63:2710-2713.
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ABSTRACT: Thin films of magnesia were deposited on various substrates using plasma-assisted liquid injection chemical vapor deposition with volatile Mg(tmhd)2·2H2O (1) (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedione). The precursor complexes, Mg2(tmhd)4·(2), and Mg(tmhd)2·pmdien (3) (pmdien; N,N,N′,N″,N″-pentamethyldiethylenetriamine) were prepared from Mg(tmhd)2·2H2O (1). The temperature dependence equilibrium vapor pressure (pe)T data yielded a straight line when log pe was plotted against reciprocal temperature in the range of 360–475 K, leading to standard enthalpy of vaporization (ΔvapH°) values of 59 ± 1 and 67 ± 2 kJ mol− 1 for (2) and (3) respectively. Thin films of magnesium oxide were grown at 773 K using complex (1) on various substrate materials. These films were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray for their composition and morphology.
Surface and Coatings Technology. 09/2009; 204:222-227.
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ABSTRACT: The plasma assisted liquid injection chemical vapor deposition of silicon carbide was studied by varying plasma gas composition, plasma current, and precursor, solvent composition using organosilane as precursor. The film composition and particle size were varied, when film was deposited in hydrogen plasma. The characterization of the films was carried out using scanning electron microscope equipped with energy dispersive X-ray spectrometer. Analysis indicated that the SiC films consisted of oxygen. The particle size decreased on increasing the plasma current and hydrogen composition in carrier gas flow (Ar/H2).
First Asian Carbon Conference (FACC 2009), New Delhi; 01/2009
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ABSTRACT: Nanocrystalline cubic scandium oxide thin film deposition by plasma-assisted (PA) liquid injection (LI) CVD is studied at 773 K in a N2/O2 plasma environment with a triglyme solution of tris(2,4-pentanedionato)scandium(III) (Sc(acac)3) as the precursor. The vapor pressure of the precursor is measured by employing a horizontal, dual-arm, single-furnace, thermogravimetric analyzer as a transpiration apparatus. The standard enthalpy of sublimation (79 ± 1 kJ mol−1) of Sc(acac)3 was measured from the Clausius–Clapeyron plot [ln(pe/Pa)T versus 1/T]. A nanocrystalline film of Sc2O3 with the (222) plane as the dominant orientation is obtained on glass under a deposition pressure of 0.8–1.2 mbar.
Chemical Vapor Deposition. 01/2009; 15:262.
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ABSTRACT: The present subject matter relates to a plasma-assisted liquid injection chemical vapour deposition process and apparatus for yttria-stabilised zirconia formation by using completely non-toxic, low melting and volatile metallorganic precursors.
Ref. No: Indian Patent Application No. 141/CHE/2009, Year: 01/2009
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ABSTRACT: The congruent vaporization of Sc(tmhd)3 was verified from the molar mass of the vapor species obtained using ESI-mass spectra and thermogravimetry. On the basis of the molar mass so obtained, the equilibrium vapor pressures over a temperature span of 375−465 K, determined by adapting a tested horizontal dual arm single furnace thermoanalyzer as a transpiration apparatus, gave values of 97 ± 1 and 77 ± 2 kJ mol−1 for the standard molar enthalpies of sublimation and vaporization, respectively, for Sc(tmhd)3.. The vapor pressure and enthalpy results of benzoic acid were found to be in good agreement with the reported data. A hybrid chemical vapor deposition process is described for reproducible solid electrolyte thin films of scandia-stabilized zirconia or alumina-doped ScSZ. The process uses a single solution source of Sc, Zr, and Al β-diketonates dissolved in triglyme. Experimental details of this process are described, and the effects of different process parameters are studied in order to improve the quality of the deposited layers.
Journal of Physical Chemistry C. 01/2009; 113:19011.
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ABSTRACT: Zirconia ceramics are remarkable materials, due to excellent mechanical and electrical properties. The high operating temperature of 1273 K limits the expansion of applications due to thermal stresses and rapid degradation of materials. Extensive researches have been conducted to reduce electrolyte resistance at reduced temperatures and the replacing YSZ with other suitable material or by reducing the thickness of the electrolyte to lower ohmic losses. The present study was made to solve these problems by a novel process of plasma assisted MO and LICVD technique on different surfaces. The completely volatile and non-toxic precursors of scandium have been developed and temperature dependence equilibrium vapour pressure using TG based transpiration technique has been measured. The films of ScSZ and Al2O3 doped ScSZ depositions by modified CVD technique along with surface characterisation have been carried out.
International Conference on Electrochemical Power Systems (ICEPS–2008), Thiruvanandapuram, Kerala; 01/2008
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ABSTRACT: The reaction between the magnesium β-diketonate complex Mg(tmhd)2(H2O)2 and 1 equiv. of N,N,N′,N′-tetramethylethylenediamine (tmeda = Me2NCH2CH2NMe2) in hexane at room temperature yielded Mg(tmhd)2(tmeda). The standard enthalpy of sublimation (83.2 ± 2.3 kJ mol−1) and entropy of sublimation (263 ± 6.3 J mol−1 K−1) of Mg(tmhd)2(tmeda) were obtained from the temperature dependence vapour pressure, determined by adopting a horizontal dual arm single furnace thermogravimetric analyser as a transpiration apparatus. From the observed melting point depression DTA, the standard enthalpy of fusion (58.3 ± 5.2 kJ mol−1) was evaluated, using the ideal eutectic behaviour of Mg(tmhd)2(tmeda) as a solvent with bis(2,4-pentanedionato)magnesium(II), Mg(acac)2 as a non-volatile solute.
Thermochimica Acta. 01/2008; 474:87.
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ABSTRACT: Total equilibrium vapour pressure, sublimation and vaporization enthalpies of scandium -diketonate, Sc(C5H8O2)3(cr) and Sc(C11H19O2)3(cr) were measured in the temperature range 375 to 445K and 365 to 455 by adapting a horizontal dual arm single furnace thermal analyzer as a transpiration apparatus, and their temperature dependence were found to fit the following equations: Sc(acac)¬3, log pe/Pa = 16.1391(±0.110) – 5437(±44)K/T, Sc(tmhd)3(cr) log pe/Pa = 15.8201(±0.172) – 5272(±67)K/T and Sc(tmhd)3(liq), log pe/Pa = 13.0788(±0.272) – 4222(±119)K/T. The sublimation and vaporization enthalpies of each scandium -diketonates are calculated by using Clausius – Clapeyron equation.
Thermal Analysis (Thermans 16), IGCAR, Kalpakkam; 01/2008
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ABSTRACT: The MOCVD precursors of magnesium, Mg(tmhd)2.2H2O(1), Mg2(tmhd)4(2), Mg(tmhd)2(dien)(3), Mg(tmhd)2(tmeda)(4) and Mg(tmhd)2(pmdien)(5) were prepared and characterized. Precise vapour pressure measurements were carried out for these complexes by adapting a horizontal dual arm single furnace thermal analyzer as a transpiration apparatus. The equilibrium vapour pressure data yielded a straight line when log pe¬ was plotted vs. reciprocal temperature range from 353 – 473K, leading to standard enthalpies of vaporization (lgH°vap) values 65.70(±1.84), 76.63(±3.3), 74.14(±1.50), 64.12(±1.12)kJ/mol for 2 - 5. The corresponding R2 values found to be 0.9981, 0.9988, 0.9992 and 0.9953.
Thermal Analysis (Thermans 16), IGCAR, Kalpakkam; 01/2008
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Frontiers in Chemical Sciences (ICFCS), Madras Christian College, Chennai; 01/2008
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ABSTRACT: The structure of the title compound, C19H22N2O2, shows two intramolecular O-HN hydrogen-bonding interactions. The packing is stabilized through van der Waals contacts and two C-H interactions.
Acta Crystallographica Section E. 01/2007; 63:1924.
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Acta Crystallographica Section E. 01/2007; 63(4):o1924-o1925.
