Solid-state Thermal Decomposition Research Articles

Synthesis, structure, solid-state thermal decomposition and magnetic properties of binuclear Nd, Gd and Eu cymantrenecarboxylates

New rare-earth cymantrenecarboxylates [Nd 2(μ 2-OOCCym) 4(OOCCym) 2(THF) 4] ( 1) and [Ln 2(μ 2-OOCCym) 4(OOCCym) 2(THF) 4]·THF (Ln = Gd ( 2), Eu ( 3); Cym = (η 5-C 5H 4)Mn(CO) 3) were synthesized starting from carboxycymantrene and lanthanide nitrates, and characterized by X-ray diffraction. The crystals of 1– 3 consist of isolated binuclear molecules; the Ln atoms are eight-coordinate. The magnetic properties of 2 are indicative of antiferromagnetic coupling between the Gd atoms at liquid helium temperature. The thermal decomposition of complexes 1– 3 was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). According to the X-ray powder diffraction patterns, the thermal decomposition of the complexes in air affords a mixture of LnMn 2O 5 and Mn 2O 3 as the final products.

Kinetic analysis for non-isothermal decomposition of unirradiated and γ-irradiated indium acetyl acetonate

Kinetic studies for the non-isothermal decomposition of un-irradiated and γ-irradiated indium acetyl acetonate In(acac)3 with 102 kGy total γ-ray dose were carried out in static air. The results showed that the decomposition proceeds in one major step in the temperature range of 150-250 °C with the formation of In2O3 as solid residue. The non-isothermal data for un-irradiated and γ-irradiated In(acac)3 were analysed using linear Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ) iso-conversional methods. The results of application of these free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes were observed in both decomposition behaviour and (Eα-α) dependency between unirradiated and γ-irradiated In(acac)3. Calcination of In(acac)3 at 400 °C for 5 hours led to the formation of In2O3 monodispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesised nanoparticles. This is the first attempt to prepare In2O3 nanoparticles by solid state thermal decomposition of In(acac)3.

Simple and low-temperature synthesis of NiO nanoparticles through solid-state thermal decomposition of the hexa(ammine)Ni(II) nitrate, [Ni(NH 3) 6](NO 3) 2, complex

NiO nanoparticles with an average size of about 12 nm were easily prepared via the thermal decomposition of hexa(ammine)Ni(II) nitrate complex, [Ni(NH 3) 6](NO 3) 2, at low temperature of 250 °C. The product was characterized by thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), UV–Vis spectroscopy, BET specific surface area measurement, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and magnetic measurement. The magnetic measurement revealed a small hysteresis loop at room temperature, confirming a superparamagnetic (weak ferromagnetic) nature of the synthesized NiO nanoparticles. Indeed, the NiO nanoparticles prepared by this method could be an appropriate semiconductor material due to the optical band gap of 3.35 eV which shows a red shift in comparison with the previous reports. This method is simple, fast, safe, low-cost and also suitable for industrial production of high purity NiO nanoparticles for applied purposes.

Characterization of The Lithium−Manganese Ferrite LiFeMnO4 Prepared by Two Different Methods

Lithium−manganese ferrite LiFeMnO4 was prepared using two different methods: a conventional ceramic high-temperature solid-state reaction technique (Cer) and thermal decomposition of metal nitrate salts (NTD). The characterization of the compounds was carried out by SEM/EDX, XRD, XPS, Fe K- and Mn K-edge XANES, and Mossbauer spectroscopy. Both Cer and NTD LiFeMnO4 samples have the nominal expected Fe/Mn atomic ratio and show a homogeneous morphology, but they exhibit different particle sizes. Fe K-edge XANES and Mossbauer spectroscopy results show that the oxidation state of Fe ions is +3 in both samples, whereas the Mn K-edge XANES data indicate that the bulk average Mn oxidation state is +3 for the NTD sample and close to +4 for the Cer one. Thus, to maintain the charge neutrality, the NTD sample has to be nonstoichiometric in oxygen with a composition close to LiFeMnO3.5. The Mn 3s XPS data indicate that the average surface oxidation state of Mn is also lower in the NTD sample. The results suggest the ...

Influence of the nature of organic ligands on the character of thermal decomposition products of CoII and NiII pivalate complexes with amino derivatives of pyridine

The thermal stability and the solid-state thermal decomposition of the known mononuclear cobalt(II) and nickel(II) complexes [H2N(C5H3N)N(H)C(Me)=NH]M(OOCBut)2, [(NH2)2C6H2Me2]3M(OOCBut)2 and the new compounds L2M(OOCBut)2 (L = = (2-NH2)C5H3N, (2-NH2)(6-Me)C5H3N), and [(2,6-NH2)2C5H3N]2Ni(OOCBut)2 were studied by differential scanning calorimetry and thermogravimetric analysis. Efficient methods were developed for the synthesis of these complexes. The mononuclear complexes are thermally quite stable. The thermal stability of the complexes depends on the nature of the ligand and decreases in the series (2,6-NH2)2C5H3N > H2N(C5H3N)NHC(Me)=NH > (NH2)2C6H2Me2 > (2-NH2)C5H3N > (2-NH2)(6-Me)C5H3N. The nickel(II) complexes are thermally more stable than the related cobalt(II) complexes. The thermolysis (<500 °C) of Co and Ni pivalates is a destructive process. The phase composition of the decomposition products is determined by the nature of metal and coordinated ligands.

Carboxylate clusters with the M4O4 cubane-like core: pivalate cocrystal containing CoII and NiII

Joint thermolysis of the dinuclear pivalate complexes M2(μ-H2O)(μ-Piv)2(Piv)2(HPiv)4 (M = Co (1) and Ni (2), Piv- is the pivalate anion), in decane at 174 °C at the reactant ratio 1: 1 followed by treatment of the dry thermolysis product with methanol afforded crystals of a new cocrystallization product of the molecules containing the heterometallic cubane-like core M4(Co,Ni)O4. According to the X-ray diffraction data and the results of magnetic measurements, inductively coupled plasma atomic emission spectrometry (ICP-AES), and investigations of the solid-state thermal decomposition products, the isolated cocrystallization product has the general formula [Co1.6Ni2.4(μ3-OMe)4(μ2-Piv)2(pg2 -Piv)2(MeOH)4] ·4MeOH (3·4MeOH). Thermolysis of the crystals of the solvate 3·4MeOH is a destructive process accompanied by the intramolecular redox reaction. A mixture of metallic Ni and cobalt oxide (CoO) are the final solid decomposition products of 3 · 4MeOH in an argon atmosphere, whereas a mixture of the phases NiO, Co3O4, and NiCo2O4 is formed in air.

Influence of the nature of organic components in dinuclear copper(II) pivalates on the composition of thermal decomposition products

Tetrabridged dinuclear complexes ((2-NH 2)C 5H 4N) 2Cu 2(μ 2-OOCCMe 3) 4 ( 2·С 6Н 6) and ((3-NH 2)C 5H 4N) 2Cu 2(μ 2-OOCCMe 3) 4 ( 3) and the cocrystallization product ((4-NMe 2)C 5H 4N) 2Cu(η 2–OOCCMe 3) 2·2((4-NMe 2)C 5H 4N) 2Cu 2(μ 2-OOCCMe 3) 4 ( 4) were synthesized by the reaction of the polymer [Cu(OOCCMe 3) 2] n ( 1) with aminopyridine ligands (L) of different nature (Cu: L = 1:1) in С 6Н 6. The solid-state thermal decomposition of these compounds was studied by differential scanning calorimetry and thermogravimetry, and their electrochemical behavior was investigated by cyclic voltammetry. All newly synthesized complexes were studied by X-ray diffraction, the magnetic properties of the complexes were investigated, and ESR measurements were performed.

Can Na2[B12H12] be a decomposition product of NaBH4?

We synthesized Na(2)[B(12)H(12)] by a solid state procedure and thermal decomposition of Na[B(3)H(8)], and calculated from a first-principles approach the thermodynamic and structural properties. In particular, the calculated enthalpy of formation of the monoclinic structure, at T = 0 K, of -1086.196 kJ mol(-1) showed that it is a very stable compound. Therefore, in case it were formed during the thermal decomposition of NaBH(4), it would be rather considered a product, which, in addition, prevents the subsequent re-hydrogenation process because of its low reactivity to hydrogen. We reported the isotherms of absorption of H(2), O(2), and H(2)O, calculated both theoretically and experimentally.

Atomic layer deposition of CaB2O4 films using bis(tris(pyrazolyl)borate)calcium as a highly thermally stable boron and calcium source

The atomic layer deposition of CaB2O4 was carried out using bis(tris(pyrazolyl)borate)calcium (CaTp2) and water as precursors. CaTp2 melts at 280 °C, undergoes solid state thermal decomposition at 385 °C, and sublimed on a preparative scale at 180 °C/0.05 Torr in about 3 hours with 99.7% recovery and 0.2% non-volatile residue. Self-limited ALD growth was established at 350 °C with CaTp2 and water pulse lengths of ≥2.0 and ≥0.3 s, respectively. An ALD window was observed from 300 to 375 °C, in which the growth rate was between 0.34 and 0.36 A per cycle. The thin film compositions were assessed by elastic recoil detection analysis (ERDA) and X-ray photoelectron spectroscopy (XPS). The B/Ca ratios for CaB2O4 films deposited at 275, 325, 350, and 400 °C were 1.84(11), 1.85(11), 1.89(13), and 1.42(10), respectively, as determined by ERDA. Within the ALD window, hydrogen concentrations ranged from 0.22(2) to 0.35(4) atom% and the carbon and nitrogen concentrations were below the detection limits. XPS analyses on representative CaB2O4 thin films showed all expected ionizations. X-Ray diffraction experiments revealed that the as-deposited films were amorphous. The surface morphology was assessed by atomic force microscopy and scanning electron microscopy. The rms surface roughness of a typical 2 µm × 2 µm area for films deposited at 325 and 350 °C was 0.3 nm. Scanning electron micrographs of these films showed no cracks or pinholes.

Effect of CaCO3 Filler Component on Solid State Decomposition Kinetic of PP/LDPE/CaCO3 Composites

In this study, the effect of addition Calcium carbonate (CaCO3) filler component on solid state thermal decomposition procedures of Polypropylene-Low Density Polyethylene (PP-LDPE; 90/10 wt%) blends involving different amounts (5, 10, 20 wt%) Calcium carbonate (CaCO3) was investigated using thermogravimetry in dynamic nitrogen atmosphere at different heating rates. An integral composite procedure involving the integral iso-conversional methods such as the Tang (TM), the Kissinger-Akahira-Sunose method (KAS), the Flynn-Wall-Ozawa (FWO), an integral method such as Coats-Redfern (CR) and master plots method were employed to determine the kinetic model and kinetic parameters of the decomposition processes under non-isothermal conditions. The Iso-conversional methods indicated that the thermal decomposition reaction should conform to single reaction model. The results of the integral composite procedures of TG data at various heating rates suggested that thermal processes of PP-LDPE-CaCO3 composites involving different amounts of CaCO3 filler component (5, 10, 20 wt%) followed a single step with approximate activation energies of 226.7, 248.9, and 252.0 kJ.mol− 1 according to the FWO method, respectively and those of 231.3, 240.1 and 243.0 kJ mol− 1 at 5°C min− 1 according to the Coats-Redfern method, the reaction mechanisms of all the composites was described from the master plots methods and are Pn model for composite C-1, Rn model for composites C-2 and C-3, respectively. It was found that the thermal stability, activation energy and thermal decomposition process changed by the increasing CaCO3 filler weight in composite structure.

Pivalates with the MII 4O4 cubane core (M = Co, Ni): synthesis, structure, magnetic properties, and solid-state thermolysis

Methods were developed for the controlled thermal synthesis of high-spin cubane-like pivalates {MII4(μ3−OR)4} (M = Co or Ni; R = H or Me) starting from mono-and polynuclear complexes. The solid-state thermal decomposition of the known pivalate clusters [MII4(μ3−OMe)4−(μ2−OOCBut)2(η2−OOCBut)2(MeOH)4] and the new clusters [M4II(μ3)−OH4(η1−OOCBut)3−(μ−(NH2)2C6H2Me2)3(η1−(NH2)2C6H2Me2)3]+(OOCBut)− (M = Co or Ni) was studied by differential scanning calorimetry and thermogravimetry. The thermolysis of cubane-like CoII and NiII pivalates is a destructive process. The phase composition of the decomposition products is determined by the nature of coordinated ligands and the structural features of the metal core.

The Effects of Chemical Additives on the Induction Phase in Solid-State Thermal Decomposition of Ammonia Borane

The thermal decomposition of ammonia borane (AB) in the absence and presence of chemical additives was investigated to develop an approach for reducing the induction period for hydrogen release in the solid state. Gas chromatography techniques were used to measure the yield of hydrogen as a function of time under isothermal conditions between 75 and 90 °C to set the baseline. Solid-state 11B-NMR spectroscopy of the products produced after 1 mol equiv of hydrogen had been desorbed from AB (i.e., polyaminoborane) showed a complex mixture of sp3 boron species. Raman microscopy was used to follow the transformation of crystalline AB to amorphous AB upon heating and the subsequent formation of the diammoniate of diborane (DADB). A gas buret was used to monitor the time-dependent release of hydrogen from AB in the presence of chemical additives. The combination of these approaches provides insight into the mechanism of hydrogen release from solid AB. The release of molecular hydrogen is described by a process i...

Dehydrogenation of LiAlH 4 in HMPA

In this study, hydrogen desorption from LiAlH 4 in HMPA solution was investigated. One equiv. H atom per LiAlH 4 was evolved from the solution at ambient temperature. Heating the solution to ∼90 °C led to the evolution of three more H atoms. Unlike the solid-state thermal decomposition, LiAlH 4 in solution does not decompose to the Li 3AlH 6 intermediate. In fact, Li 3AlH 6 was found to be unstable in HMPA. Two equiv. H atoms were found to detach from Li 3AlH 6 upon mixing it with HMPA at ambient temperature. Subsequent heating of the resulting solution to 90 °C resulted in the dehydrogenation of ca. 4 equiv. H atoms.

An investigation on the solid-state thermal decomposition of bimetallic oxalate and tartrate coordination precursors of lanthanum(III) and palladium(II) ions

The bimetallic oxalate and tartrate coordination precursors, palladium(II)tris(oxalato)lanthanate(III)heptahydrate (POL) and palladium(II)tris(tartrato)lanthanate(III)pentahydrate (PTL) have been synthesized and their thermal behaviors were explored. The precursors were characterized by elemental analysis, IR, electronic spectral and X-ray powder diffraction studies. The solid-state thermal decomposition studies (TG, DTG and DTA) in air revealed that the oxalate precursor led mainly to a mixed metal oxide, La 4PdO 7 along with a trace of oxides of palladium and lanthanum at 1000 °C. The generation of several unstable intermediate phases at different temperatures was attributed. The mixed metal oxides, La 4PdO 7 and La 2Pd 2O 5 along with oxycarbonate and oxide of lanthanum were identified at 1000 °C in case of tartrate precursor. The carbides of lanthanum and elemental carbon were also generated at the end in both the precursors. The ΔH# and ΔS# of all the steps up to 500 °C of the precursors are explored from DSC study in nitrogen.

A mechanistic and non-mechanistic approach on the solid state thermal decomposition of transition metal complexes of 3-(3-furan-2-yl-acryloyl)- 4-hydroxy-6-methyl-pyran-2-one

The thermal decomposition of Mn11, Fe111, Cu ΙΙ , Ni ΙΙ and Cu ΙΙ chelates of 3-(3-furan-2-yl-acryloyl)-4-hydroxy-6-methyl-pyran-2-one was studied by TG-DTA and X-ray powder diffraction methods. The thermal stability of the complexes was studied using thermogravimetry and the decomposition schemes of the complexes were given. The mechanism of the decomposition has been established from TG data. The kinetic parameters i.e. n (order of reaction), E (energy of activation), Z (pre-exponential factor), AS (entropy change) and AG (free energy change) were calculated from the TG curve using mechanistic (Sestak-Berggren and Satava) and non-mechanistic (Coats-Redfern, MacCallum-Tanner and Horowitz-Metzger) integral equations.

Thermal decomposition of dinuclear complexes LM(μ-OOCR)4ML (L is α-substituted pyridine)

The solid-state thermal decomposition of the tetrabridged dinuclear MnII, FeII, CoII, NiII, and CuII pivalate complexes with apical α-substituted pyridine ligands containing different substituents (2,3-dimethylpyridine or quinoline) was studied by differential scanning calorimetry and thermogravimetry. The decomposition of the CoII complexes is accompanied by the aggregation to form the volatile octanuclear complex Co8(μ4-O)2(μn-OOCCMe3)12, where n = 2 or 3, whereas the thermolysis of the MnII, FeII, NiII, and CuII complexes is accompanied by the degradation of the starting compounds, the phase composition of the decomposition products being substantially dependent on the nature of metal and the apical organic ligand.

Well-dispersed Ceria-promoted Sulfated Zirconia Supported on Mesoporous Silica

Ceria-promoted sulfated zirconia (CeSZ) was supported on mesoporous molecular sieve of pure-silica MCM-41 (abbreviated as CeSZ/MCM-41). It was prepared by direct impregnation of metal sulfate onto the as-synthesized MCM-41, followed by solid state dispersion and thermal decomposition. The resultant catalysts were characterized by TG, XRD, nitrogen physisorption and TEM. It was showed that the hollow tubular structure of MCM-41 was retained, even with ZrO2 loading as high as 60 wt.%. Most of CeSZ was well dispersed on the interior surface of the ordered mesopores, following a slight twist of the channels. The catalytic activity of CeSZ/MCM-41 was studied in the octadecanol oxidation. The improved performance of CeO2-promoted catalysts was attributed to the high dispersion of sulfated zirconia (SZ) and the introduction of CeO2 enhancing the oxidation ability of catalysts by retarding the transformation of zirconia from highly catalytic active metastable tetragonal phase to monoclinic phase.

A mechanistic approach on the solid state thermal decomposition of bimetallic oxalate coordination compounds of Mn(II), Fe(II) and Cu(II) with cobalt

The mixed metal carboxylates, manganese(II)bis(oxalato)cobaltate(II)hydrate (MOC), iron(II)bis(oxalato)cobaltate(II)pentahydrate (IOC), and copper(II)bis(oxalato)cobaltate(II)trihydrate (COC) have been synthesized and characterized by elemental analysis, IR spectral and X-ray powder diffraction studies. Thermal decomposition studies (TG, DTG and DTA) in air showed that the compound MOC decomposed mainly to MnCoO 3 at 315 °C through the formation of a complete anhydrous compound. The species CoFeO 3 is generated at 274 °C from the compound IOC through the formation of a very transient anhydrous compound at around 218 °C. In case of the compound, COC the end product was found to be CuCoO 2 at ∼1000 °C through the existence of a quite stable mixture of CuO and CoO at ∼318 °C. DSC studies in nitrogen indicated the formation of a mixture of MnO and CoO in case of MOC, cobalt ferrite in case of IOC and a brown mixture of Cu 2O and CoO from COC as end products. The kinetic parameters have been evaluated for both the dehydration and decomposition steps of all the three compounds using four non-mechanistic equations. Using seven mechanistic equations, the rate controlling processes of the dehydration and decomposition mechanism are also inferred. The kinetic parameters, Δ H and Δ S obtained from DSC are presented. IR and X-ray powder diffraction studies identified some of the decomposition products.

ZnS and ZnSe Nanoparticles via Solid-State and Solution Thermolysis of Zinc Silylchalcogenolate Complexes

The thermolysis of the zinc trimethylsilylchalcogenolate complexes (N,N′-tmeda)Zn(ESiMe3)2 (E = S, 1; E = Se, 2) and (3,5-Me2-C5H3N)2Zn(ESiMe3)2 (E = S, 3; E = Se, 4) has been investigated. Solid-state thermal decomposition of complexes 1–4 above 250°C results in the formation of hexagonal ZnS and cubic ZnSe, respectively, via the liberation of TMEDA (1–2) or 3,5-lutidine (3–4) and E(SiMe3)2. Solid-state or solution thermolysis of these complexes up to 200°C produces nanocrystalline ZnS and ZnSe materials whose surface is protected by either coordinated TMEDA or 3,5-lutidine ligands. The progress of the step-wise solid-state decomposition of these complexes was monitored by thermogravimetric and single differential thermal analysis and volatile decomposition products in both solution and solid-state experiments were identified by GC/MS.

Synthesis of poly(dihalophenylene oxide)s by atom transfer radical rearrangement polymerization via Ce(IV)/Ce(III) complexes in solid state

Poly(dihalophenylene oxide)s by solid-state thermal decomposition of (trihalophenolato) cerium complexes with either N-methyl imidazole or pyridine as neutral ligands were synthesized at different temperatures (80–250°C) and different time intervals (3–48 h) via atom transfer rearrangement radical polymerization. The complexes were characterized by FT-IR, DSC, SEM, mass spectroscopy, magnetic susceptibility and elemental analyses. Structural analyses of polymers were performed by 1H- and 13C-NMR, SEM and FT-IR spectroscopic analyses, T g by DSC and the molecular weights by viscometry. 2,4,6-Trichlorophenolate displayed a slightly higher selectivity in favor of 1,2-addition, whereas 1,2- and 1,4-additions took place at equal rates in the case of 2,4,6-tribromophenolate. Pyridine complexes decomposed at lower temperatures and had lower polymer yield than the N-methyl imidazole complexes. Among the synthesized polymers in solid state, the highest intrinsic viscosity value of 0.058 dl/g (M w = 7.15 × 104) was achieved only with Ce(TCP)3(Py)2 complexes. All the polymers having high T g values (178–189°C) were rigid.