Alex Kaduk - Academia.edu (original) (raw)
Papers by Alex Kaduk
Journal of Materials Chemistry, 1991
Page 1. J. MATER. CHEM., 1992, 2(8), 785-792 785 lsomorphous Substitution in Non-linear Optical K... more Page 1. J. MATER. CHEM., 1992, 2(8), 785-792 785 lsomorphous Substitution in Non-linear Optical KTiOPO,: Powder Diffraction Studies of Ko~5Rbo~,SnOP04, Ko~5Nao~5Tiom,Sno~, 0P0,, Na0.5Rb0.5Ti0.5Sn0.50P04 and K0.5Rb0.5Ti0.5Sn0S0p04 ...
The synthesis of ternary acetylides Li 2 TeC 2 and Na 2 TeC 2 is presented as the first example o... more The synthesis of ternary acetylides Li 2 TeC 2 and Na 2 TeC 2 is presented as the first example of ternary acetylides with metalloid elements instead of transition metals. The synthesis was carried out by the direct reaction of the corresponding bialkali acetylides with tellurium powder in liquid ammonia. Alternatively, the synthesis of Na 2 TeC 2 was also carried out by the direct reaction of tellurium powder and two equivalents of NaC 2 H in liquid ammonia leading to Na 2 TeC 2 and acetylene gas through an equilibrium containing the assumed NaTeC 2 H molecules besides the reactants and the products. The resulting crystalline materials were characterized by x-ray diffraction. Implications of these new syntheses on the synthesis of other ternary acetylides with metalloid elements and transition metals are also discussed.
Purpose À Most research on the work conditions and family responsibilities associated with work-f... more Purpose À Most research on the work conditions and family responsibilities associated with work-family conflict and other measures of mental health uses the individual employee as the unit of analysis. We argue that work conditions are both individual psychosocial assessments and objective characteristics of the proximal work environment, necessitating
Powder Diffraction, 2013
A series of iron-doped lead titanate PbTi(1−x)FexO(3−δ) samples in the x = 0–1 composition range ... more A series of iron-doped lead titanate PbTi(1−x)FexO(3−δ) samples in the x = 0–1 composition range was prepared using sol–gel synthesis at a calcination temperature of 700 °C. The room temperature CuKα powder diffraction data collected from x = 0, 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, and 0.3 samples were analyzed using the Rietveld method. Magnetoplumbite (PbFe12O19) secondary phase formation was observed at compositions x = 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. Fe-composition dependent decrease of tetragonal distortion has been observed. According to Vegard's law, the B-site iron solubility limit in the lead titanate host was found to be approximately 10 mol% (x = 0.1). Homogeneous distribution of dopants below the solubility limit was evidenced by the linear behavior of unit-cell parameters. The absence of a cubic phase and the persistence of distorted oxygen octahedra indicated the existence of ferroelectric properties even at the x = 0.3 composition. B...
Powder Diffraction, 2010
The crystal structure of Sb(C2O4)OH has been solved by charge flipping in combination with differ... more The crystal structure of Sb(C2O4)OH has been solved by charge flipping in combination with difference Fourier techniques using laboratory X-ray powder data exhibiting significant preferred orientation and refined by the Rietveld method. The compound crystallizes in Pnma with a=5.827 13(3), b=11.294 48 (10), c=6.313 77(3) Å, V=415.537(5) Å3, and Z=4. The crystal structure contains pentagonal pyramidal Sb3+ cations, which are bridged by hydroxyl groups to form zigzag chains along the a axis. Each oxalate anion chelates to two Sb in approximately the ab plane, linking the chains into a three-dimensional framework. The H of the hydroxyl group is probably disordered in order to form stronger more-linear hydrogen bonds. The highest energy occupied molecular orbitals are the Sb3+ lone pairs. The structure is chemically reasonable compared to other antimony oxalates and to Bi(C2O4)OH.
A sample of dust from a failed fuel filter assembly on an electric generation turbine in a gas fi... more A sample of dust from a failed fuel filter assembly on an electric generation turbine in a gas field was subjected to a battery of tests, to determine the source of the contamination, and to see if it played any role in turbine blade erosion. The majority of the deposit was attracted to a magnet. Bulk chemical analysis indicated that the metal present in the largest concentration by far was Fe (43.0%). The sum of all the other metal concentrations was 1.68%; these other metals were those
Powder Diffraction - POWDER DIFFR, 2003
The Journal of Physical Chemistry C, 2013
ABSTRACT The recent discovery of a new class of negative ions called hyperhalogens allows us to c... more ABSTRACT The recent discovery of a new class of negative ions called hyperhalogens allows us to characterize this complex as belonging to a unique class of materials called hypersalts. Hyperhalogen materials are important while serving as the building blocks for the development of new materials having enhanced magnetic or oxidative properties. One prime example of a hydperhalogen is the Al(BH4)4– anion. Aluminum borohydride (17 wt % H) in itself is a volatile, pyrophoric compound that has a tendency to release diborane at room temperature, making its handling difficult and very undesirable for use in practical applications. Here we report that the combination of Al(BH4)3 with the alkaline metal borohydride KBH4 results in the formation of a new compound KAl(BH4)4 which is a white solid that exhibits remarkable thermal stability up to 154 °C and has the typical makeup of a hypersalt material. Using a variety of characterization tools and theoretical calculations, we study and analyze the physical characteristics of this compound and show its potential for stabilizing high hydrogen capacity, energetic materials.
Powder Diffraction - POWDER DIFFR, 2007
We know a lot about normal values of bond distances, bond angles, torsion angles, and other molec... more We know a lot about normal values of bond distances, bond angles, torsion angles, and other molecular parameters. This knowledge can be incorporated into the structure solution process and into Rietveld refinement through the use of restraints and rigid bodies. An important measure of the quality of the refined model is the chemical reasonableness of molecular geometry. Refinement of the structures of calcium tartrate tetrahydrate and guaifenesin is used to illustrate the importance of chemical reasonableness in determining the quality of a Rietveld refinement.
Organometallics, 1995
Some of the first examples of air stable y4-vinylallene-Fe(C0)3 complexes have been prepared by p... more Some of the first examples of air stable y4-vinylallene-Fe(C0)3 complexes have been prepared by photochemical reaction of Fe(C0)b and vinylallenes. A high degree of diastereofacial selectivity was observed for iron coordination and the mfacial preference confirmed by X-ray crystallography. Comparison of NMR data (lH and 13C) for y4vinylallene-Fe(C0)3 complexes and y4-isoprene-Fe(C0)3 revealed many similarities but some important differences that may be attributed to different polarization of these conjugated z-systems. Consistent with these differences the y4-vinylallene-Fe(C0)3 complexes showed significantly higher AG* for interconversion of the carbonyl ligands as compared to q4-isoprene-Fe(C0)3. The X-ray data rule out intra-or intermolecular contacts as the cause of the increased barrier to carbonyl isomerization. The data clearly indicate that the central allene carbon is strongly backbonding to the iron center, which may account for observed NMR and X-ray results.
Microporous and Mesoporous Materials, 2013
The crystal structure of dehydrated NaY zeolite (Na-FAU structure type) with and without adsorbed... more The crystal structure of dehydrated NaY zeolite (Na-FAU structure type) with and without adsorbed CO 2 has been determined at 4 K and at room temperature (RT) using neutron powder diffraction techniques. The CO 2-containing sample was prepared at 195 K and 0.1 MPa p CO2 (dry ice sublimation conditions). Neutron diffraction data provides direct evidence that adsorption of CO 2 results in significant migration of the extraframework Na cations in the zeolite structure. At 4 K, 45 of the apparent 76 CO 2 /cell were located in two crystallographically independent sites bonding to the Na cations (Na10) in the supercage site II. While the CO 2 molecule in the first site has a linear configuration interacting with Na10 via one terminal oxygen, the CO 2 molecule in the second site appears to have a bent O-CO configuration (148.3(3)°), with both oxygen atoms coordinating to two symmetry-related Na10. Using DFT total energy calculations we found that the Na-CO 2 interaction slightly facilitates the bending motion for CO 2 by decreasing the energy cost for the 148.3(3)°bond angle by %0.2 eV/CO 2. However, this Na-CO 2 interaction is not enough to cause a 32°bond angle distortion in CO 2 (the energy cost of %0.66 eV/CO 2). We propose that rotational disorder plays a significant role in the appearance of the bent CO 2 , while a small bending is possible. Our studies will help to provide a basis for interpreting CO 2 adsorption phenomena in NaY and related zeolites.
Journal of Solid State Chemistry, 2010
interactions Structure of Ba2(G dx Y 1 À x)NbO 6 and (Gd x Y 3 À x)NbO 7 Reference X-ray powder p... more interactions Structure of Ba2(G dx Y 1 À x)NbO 6 and (Gd x Y 3 À x)NbO 7 Reference X-ray powder patterns a b s t r a c t A systematic study of the chemical interaction of Ba 2 YCu 3 O 6 + y and Gd 3 NbO 7 was conducted under two processing conditions: purified air (21% p o2), and 100 Pa p o2 (0.1% p o2). Phases present along the pseudobinary join Ba 2 YCu 3 O 6z and Gd 3 NbO 7 were found to be in two five-phase volumes within the BaOÀ 1 2 Y 2 O 3 À 1 2 Gd 2 O 3 ÀNb 2 O 5 ÀCuO y system. Three common phases that are present in all samples are (Y,Gd) 2 Cu 2 O 5 , Ba(Y,Gd) 2 CuO 5 and Cu 2 O or CuO (depending on the processing conditions). The assemblies of phases can be categorized in three regions, with Ba 2 YCu 3 O 6 + y : Gd 3 NbO 7 ratios of (I) o 5.5:4.5; (II) =5.5:4.5; and (III) 45.5:4.5. The lowest melting temperature of the system was determined to be E 938 1C in air, and 850 1C at 100 Pa p o2. Structure determinations of two selected phases, Ba 2 (Gd x Y 1 À x)NbO 6 (Fm3 m, No. 225), and (Gd x Y 3 À x)NbO 7 (C222 1 , No. 20 and Ccmm, No. 63), were completed using the X-ray Rietveld refinement technique. Reference X-ray powder diffraction patterns for selected phases of Ba 2 (Gd x Y 1 À x)NbO 6 (x= 0.2, 0.4, 0.6, and 0.8) and (Gd x Y 3 À x)NbO 7 (x= 0.6, 1.2, 1.8, 2.4 and 3) have been prepared for inclusion in the Powder Diffraction File (PDF).
Journal of Solid State Chemistry, 1995
The crystal structure of hydrated sodium aluminate, NaAlO2 · 5/4H2O, has been determined ab initi... more The crystal structure of hydrated sodium aluminate, NaAlO2 · 5/4H2O, has been determined ab initio from synchrotron powder diffraction data. The compound crystallizes in the acentric primitive tetragonal space group P4̄ 21m, with a = 10.53396(4) Å and c = 5.33635(3) Å at 27°C, and Z = 8. The structure consists of single layers parallel to (001) made of corner-sharing
Journal of Organometallic Chemistry, 1977
ABSTRACT
[
Journal of Organometallic Chemistry, 1977
The structure of (~3-allyl)carbonylchlorobis(dimethylphenylphosphine)iridium(II1) hexafluorophosp... more The structure of (~3-allyl)carbonylchlorobis(dimethylphenylphosphine)iridium(II1) hexafluorophosphate, [I~(~I~-C,H,)C~(CO)(P(CH&(C~H~)),IIPF& has been determined from three-dimensional X-ray data to add support for a proposed mechanism of the osidative addition of ally1 halides to IrX(CO)(PR,), (X = halide). The compound crystallizes in space group Czh-P2,/c with four formula units in a cell of dimensions a = 11.027(l), b = 12.230(2), c = 19.447(5) A, and p = 103.16(2)". Least-squares refinement of the structure has led to a value of the conventional R index (on F) of 0.066 for the 3018 independent reflections having Fg > 3 a(F2,). The crystal structure consists of discrete, monomeric ions. The hexafluorophosphate anion is disordered. The coordination geometry around the iridium atom may be described as octahedral, with the chloro ligand tram to the carbonyl group and each phosphorus atom trans to a terminal carbon of the ally1 group-Structural parameters: b-P = 2.366(4), 2.347(3); b-Cl = 2.389(3); Ir-C(ally1) = 2.28(l), 2.24(l), 2.25(l); 1r-C (carbonyl) = 1.85(l) A; P-B-P = 105.7(l); C(terminal)-Ir-C(terminal) = 66.2(8); CC -C = 125(2)"-The ally1 group makes an angle of 126" with the P-h-P plane. Correlations between geometric structure and number of d electrons are noted among several M-C3H5-complexes, and are interpreted in the light of theoretical models of the M-CBH5-bond.
Physica C-superconductivity and Its Applications - PHYSICA C, 2003
The compounds BaR2CuO5 (R=Y and lanthanides) are well-known impurities that often coexist with th... more The compounds BaR2CuO5 (R=Y and lanthanides) are well-known impurities that often coexist with the high Tc superconductors, Ba2RCu3O6+x. With R=La and Nd, brown color solid solutions (Ba1+xR2−xCuO5−x) form instead of the “green phase”, BaR2CuO5 (lanthanides with ionic radii smaller than that of Sm). A complete solid solution of Ba(Nd2−xLax)CuO5 exists with the tetragonal space group P4/mbm. Crystallographic studies of selected members (x=0.2, 0.6, 1.2, and 1.6) by X-ray Rietveld refinement technique showed the structure consists of RO8 and BaO10 cages, and square planar CuO4 units. As x increases in Ba(Nd2−xLax)CuO5, the size of these RO8 and BaO10 cages increases. BaLa2CuO5 was confirmed to be ferromagnetic at ≈5 K; despite the isostructural property of BaLa2CuO5 and BaNd5CuO5, the Nd-analog was found to be antiferromagnetic. As x in Ba(Nd2−xLax)CuO5 increases between 0 and 2, the amount of ferromagnetism increases.
International Journal of Chemical Kinetics, 1977
The reaction between ozone and thiophene was studied from 30 to 125°C over a pressure range of 0.... more The reaction between ozone and thiophene was studied from 30 to 125°C over a pressure range of 0.005-0.3 torr ozone and 0.1-1 torr thiophene. The most abundant product was O2 with smaller amounts of CO2 and SO2. The mass balance was 100% for oxygen and approached 100% for sulfur at the higher values of [O3]0. The carbon balance, however, was only 25% and no H-containing products were found, suggesting that the missing product is a hydrocarbon which may be a polymer. The rate law found was -d[O3]/dt = k1[Th] [O3] + k2 [Th] [O3]2 where log k1(M−1 · sec−1) = 7.8 ± 0.5 - (8400 ± 700)/2.3RT, and log k2(M−2 · sec−1) = 12.4 ± 0.4 - (4700 ± 400)/2.3RT. Added O2 had no effect on k1 but reduced k2 to a limiting value. It is thus not possible to measure the primary rate constant in this system by measuring the overall rate in the presence of oxygen, and this restriction may also apply to other ozone systems. A mechanism is postulated involving two chain sequences, one of which is inhibited by added O2. A comparison with other ozone systems is made, and the chain lengths are far greater for ozone + thiophene than other systems, under the conditions employed. Possible intermediates in the mechanism are discussed.
Inorganic Chemistry, 1977
ABSTRACT
![Research paper thumbnail of Crystal and molecular structure of dinitrosylbis(triphenylphosphine)rhodium perchlorate, [Rh(NO)2(P(C6H5)3)2][ClO4]](https://attachments.academia-assets.com/76249312/thumbnails/1.jpg)
](Inorganic Chemistry, 1975
see discussion of spectra and metal-ligand distances for [RuCI-(CO)2(liNzPh)(PPh3)2] [ClO4] and P... more see discussion of spectra and metal-ligand distances for [RuCI-(CO)2(liNzPh)(PPh3)2] [ClO4] and PtCl(N2Ph)(PEt3)2. (41) This is the average for 12 four-(tetrahedral). five-and six-coordinate Ru and Os complexes conraining linear nitrosyl ligands.
Journal of Materials Chemistry, 1991
Page 1. J. MATER. CHEM., 1992, 2(8), 785-792 785 lsomorphous Substitution in Non-linear Optical K... more Page 1. J. MATER. CHEM., 1992, 2(8), 785-792 785 lsomorphous Substitution in Non-linear Optical KTiOPO,: Powder Diffraction Studies of Ko~5Rbo~,SnOP04, Ko~5Nao~5Tiom,Sno~, 0P0,, Na0.5Rb0.5Ti0.5Sn0.50P04 and K0.5Rb0.5Ti0.5Sn0S0p04 ...
The synthesis of ternary acetylides Li 2 TeC 2 and Na 2 TeC 2 is presented as the first example o... more The synthesis of ternary acetylides Li 2 TeC 2 and Na 2 TeC 2 is presented as the first example of ternary acetylides with metalloid elements instead of transition metals. The synthesis was carried out by the direct reaction of the corresponding bialkali acetylides with tellurium powder in liquid ammonia. Alternatively, the synthesis of Na 2 TeC 2 was also carried out by the direct reaction of tellurium powder and two equivalents of NaC 2 H in liquid ammonia leading to Na 2 TeC 2 and acetylene gas through an equilibrium containing the assumed NaTeC 2 H molecules besides the reactants and the products. The resulting crystalline materials were characterized by x-ray diffraction. Implications of these new syntheses on the synthesis of other ternary acetylides with metalloid elements and transition metals are also discussed.
Purpose À Most research on the work conditions and family responsibilities associated with work-f... more Purpose À Most research on the work conditions and family responsibilities associated with work-family conflict and other measures of mental health uses the individual employee as the unit of analysis. We argue that work conditions are both individual psychosocial assessments and objective characteristics of the proximal work environment, necessitating
Powder Diffraction, 2013
A series of iron-doped lead titanate PbTi(1−x)FexO(3−δ) samples in the x = 0–1 composition range ... more A series of iron-doped lead titanate PbTi(1−x)FexO(3−δ) samples in the x = 0–1 composition range was prepared using sol–gel synthesis at a calcination temperature of 700 °C. The room temperature CuKα powder diffraction data collected from x = 0, 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, and 0.3 samples were analyzed using the Rietveld method. Magnetoplumbite (PbFe12O19) secondary phase formation was observed at compositions x = 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. Fe-composition dependent decrease of tetragonal distortion has been observed. According to Vegard's law, the B-site iron solubility limit in the lead titanate host was found to be approximately 10 mol% (x = 0.1). Homogeneous distribution of dopants below the solubility limit was evidenced by the linear behavior of unit-cell parameters. The absence of a cubic phase and the persistence of distorted oxygen octahedra indicated the existence of ferroelectric properties even at the x = 0.3 composition. B...
Powder Diffraction, 2010
The crystal structure of Sb(C2O4)OH has been solved by charge flipping in combination with differ... more The crystal structure of Sb(C2O4)OH has been solved by charge flipping in combination with difference Fourier techniques using laboratory X-ray powder data exhibiting significant preferred orientation and refined by the Rietveld method. The compound crystallizes in Pnma with a=5.827 13(3), b=11.294 48 (10), c=6.313 77(3) Å, V=415.537(5) Å3, and Z=4. The crystal structure contains pentagonal pyramidal Sb3+ cations, which are bridged by hydroxyl groups to form zigzag chains along the a axis. Each oxalate anion chelates to two Sb in approximately the ab plane, linking the chains into a three-dimensional framework. The H of the hydroxyl group is probably disordered in order to form stronger more-linear hydrogen bonds. The highest energy occupied molecular orbitals are the Sb3+ lone pairs. The structure is chemically reasonable compared to other antimony oxalates and to Bi(C2O4)OH.
A sample of dust from a failed fuel filter assembly on an electric generation turbine in a gas fi... more A sample of dust from a failed fuel filter assembly on an electric generation turbine in a gas field was subjected to a battery of tests, to determine the source of the contamination, and to see if it played any role in turbine blade erosion. The majority of the deposit was attracted to a magnet. Bulk chemical analysis indicated that the metal present in the largest concentration by far was Fe (43.0%). The sum of all the other metal concentrations was 1.68%; these other metals were those
Powder Diffraction - POWDER DIFFR, 2003
The Journal of Physical Chemistry C, 2013
ABSTRACT The recent discovery of a new class of negative ions called hyperhalogens allows us to c... more ABSTRACT The recent discovery of a new class of negative ions called hyperhalogens allows us to characterize this complex as belonging to a unique class of materials called hypersalts. Hyperhalogen materials are important while serving as the building blocks for the development of new materials having enhanced magnetic or oxidative properties. One prime example of a hydperhalogen is the Al(BH4)4– anion. Aluminum borohydride (17 wt % H) in itself is a volatile, pyrophoric compound that has a tendency to release diborane at room temperature, making its handling difficult and very undesirable for use in practical applications. Here we report that the combination of Al(BH4)3 with the alkaline metal borohydride KBH4 results in the formation of a new compound KAl(BH4)4 which is a white solid that exhibits remarkable thermal stability up to 154 °C and has the typical makeup of a hypersalt material. Using a variety of characterization tools and theoretical calculations, we study and analyze the physical characteristics of this compound and show its potential for stabilizing high hydrogen capacity, energetic materials.
Powder Diffraction - POWDER DIFFR, 2007
We know a lot about normal values of bond distances, bond angles, torsion angles, and other molec... more We know a lot about normal values of bond distances, bond angles, torsion angles, and other molecular parameters. This knowledge can be incorporated into the structure solution process and into Rietveld refinement through the use of restraints and rigid bodies. An important measure of the quality of the refined model is the chemical reasonableness of molecular geometry. Refinement of the structures of calcium tartrate tetrahydrate and guaifenesin is used to illustrate the importance of chemical reasonableness in determining the quality of a Rietveld refinement.
Organometallics, 1995
Some of the first examples of air stable y4-vinylallene-Fe(C0)3 complexes have been prepared by p... more Some of the first examples of air stable y4-vinylallene-Fe(C0)3 complexes have been prepared by photochemical reaction of Fe(C0)b and vinylallenes. A high degree of diastereofacial selectivity was observed for iron coordination and the mfacial preference confirmed by X-ray crystallography. Comparison of NMR data (lH and 13C) for y4vinylallene-Fe(C0)3 complexes and y4-isoprene-Fe(C0)3 revealed many similarities but some important differences that may be attributed to different polarization of these conjugated z-systems. Consistent with these differences the y4-vinylallene-Fe(C0)3 complexes showed significantly higher AG* for interconversion of the carbonyl ligands as compared to q4-isoprene-Fe(C0)3. The X-ray data rule out intra-or intermolecular contacts as the cause of the increased barrier to carbonyl isomerization. The data clearly indicate that the central allene carbon is strongly backbonding to the iron center, which may account for observed NMR and X-ray results.
Microporous and Mesoporous Materials, 2013
The crystal structure of dehydrated NaY zeolite (Na-FAU structure type) with and without adsorbed... more The crystal structure of dehydrated NaY zeolite (Na-FAU structure type) with and without adsorbed CO 2 has been determined at 4 K and at room temperature (RT) using neutron powder diffraction techniques. The CO 2-containing sample was prepared at 195 K and 0.1 MPa p CO2 (dry ice sublimation conditions). Neutron diffraction data provides direct evidence that adsorption of CO 2 results in significant migration of the extraframework Na cations in the zeolite structure. At 4 K, 45 of the apparent 76 CO 2 /cell were located in two crystallographically independent sites bonding to the Na cations (Na10) in the supercage site II. While the CO 2 molecule in the first site has a linear configuration interacting with Na10 via one terminal oxygen, the CO 2 molecule in the second site appears to have a bent O-CO configuration (148.3(3)°), with both oxygen atoms coordinating to two symmetry-related Na10. Using DFT total energy calculations we found that the Na-CO 2 interaction slightly facilitates the bending motion for CO 2 by decreasing the energy cost for the 148.3(3)°bond angle by %0.2 eV/CO 2. However, this Na-CO 2 interaction is not enough to cause a 32°bond angle distortion in CO 2 (the energy cost of %0.66 eV/CO 2). We propose that rotational disorder plays a significant role in the appearance of the bent CO 2 , while a small bending is possible. Our studies will help to provide a basis for interpreting CO 2 adsorption phenomena in NaY and related zeolites.
Journal of Solid State Chemistry, 2010
interactions Structure of Ba2(G dx Y 1 À x)NbO 6 and (Gd x Y 3 À x)NbO 7 Reference X-ray powder p... more interactions Structure of Ba2(G dx Y 1 À x)NbO 6 and (Gd x Y 3 À x)NbO 7 Reference X-ray powder patterns a b s t r a c t A systematic study of the chemical interaction of Ba 2 YCu 3 O 6 + y and Gd 3 NbO 7 was conducted under two processing conditions: purified air (21% p o2), and 100 Pa p o2 (0.1% p o2). Phases present along the pseudobinary join Ba 2 YCu 3 O 6z and Gd 3 NbO 7 were found to be in two five-phase volumes within the BaOÀ 1 2 Y 2 O 3 À 1 2 Gd 2 O 3 ÀNb 2 O 5 ÀCuO y system. Three common phases that are present in all samples are (Y,Gd) 2 Cu 2 O 5 , Ba(Y,Gd) 2 CuO 5 and Cu 2 O or CuO (depending on the processing conditions). The assemblies of phases can be categorized in three regions, with Ba 2 YCu 3 O 6 + y : Gd 3 NbO 7 ratios of (I) o 5.5:4.5; (II) =5.5:4.5; and (III) 45.5:4.5. The lowest melting temperature of the system was determined to be E 938 1C in air, and 850 1C at 100 Pa p o2. Structure determinations of two selected phases, Ba 2 (Gd x Y 1 À x)NbO 6 (Fm3 m, No. 225), and (Gd x Y 3 À x)NbO 7 (C222 1 , No. 20 and Ccmm, No. 63), were completed using the X-ray Rietveld refinement technique. Reference X-ray powder diffraction patterns for selected phases of Ba 2 (Gd x Y 1 À x)NbO 6 (x= 0.2, 0.4, 0.6, and 0.8) and (Gd x Y 3 À x)NbO 7 (x= 0.6, 1.2, 1.8, 2.4 and 3) have been prepared for inclusion in the Powder Diffraction File (PDF).
Journal of Solid State Chemistry, 1995
The crystal structure of hydrated sodium aluminate, NaAlO2 · 5/4H2O, has been determined ab initi... more The crystal structure of hydrated sodium aluminate, NaAlO2 · 5/4H2O, has been determined ab initio from synchrotron powder diffraction data. The compound crystallizes in the acentric primitive tetragonal space group P4̄ 21m, with a = 10.53396(4) Å and c = 5.33635(3) Å at 27°C, and Z = 8. The structure consists of single layers parallel to (001) made of corner-sharing
Journal of Organometallic Chemistry, 1977
ABSTRACT
[
Journal of Organometallic Chemistry, 1977
The structure of (~3-allyl)carbonylchlorobis(dimethylphenylphosphine)iridium(II1) hexafluorophosp... more The structure of (~3-allyl)carbonylchlorobis(dimethylphenylphosphine)iridium(II1) hexafluorophosphate, [I~(~I~-C,H,)C~(CO)(P(CH&(C~H~)),IIPF& has been determined from three-dimensional X-ray data to add support for a proposed mechanism of the osidative addition of ally1 halides to IrX(CO)(PR,), (X = halide). The compound crystallizes in space group Czh-P2,/c with four formula units in a cell of dimensions a = 11.027(l), b = 12.230(2), c = 19.447(5) A, and p = 103.16(2)". Least-squares refinement of the structure has led to a value of the conventional R index (on F) of 0.066 for the 3018 independent reflections having Fg > 3 a(F2,). The crystal structure consists of discrete, monomeric ions. The hexafluorophosphate anion is disordered. The coordination geometry around the iridium atom may be described as octahedral, with the chloro ligand tram to the carbonyl group and each phosphorus atom trans to a terminal carbon of the ally1 group-Structural parameters: b-P = 2.366(4), 2.347(3); b-Cl = 2.389(3); Ir-C(ally1) = 2.28(l), 2.24(l), 2.25(l); 1r-C (carbonyl) = 1.85(l) A; P-B-P = 105.7(l); C(terminal)-Ir-C(terminal) = 66.2(8); CC -C = 125(2)"-The ally1 group makes an angle of 126" with the P-h-P plane. Correlations between geometric structure and number of d electrons are noted among several M-C3H5-complexes, and are interpreted in the light of theoretical models of the M-CBH5-bond.
Physica C-superconductivity and Its Applications - PHYSICA C, 2003
The compounds BaR2CuO5 (R=Y and lanthanides) are well-known impurities that often coexist with th... more The compounds BaR2CuO5 (R=Y and lanthanides) are well-known impurities that often coexist with the high Tc superconductors, Ba2RCu3O6+x. With R=La and Nd, brown color solid solutions (Ba1+xR2−xCuO5−x) form instead of the “green phase”, BaR2CuO5 (lanthanides with ionic radii smaller than that of Sm). A complete solid solution of Ba(Nd2−xLax)CuO5 exists with the tetragonal space group P4/mbm. Crystallographic studies of selected members (x=0.2, 0.6, 1.2, and 1.6) by X-ray Rietveld refinement technique showed the structure consists of RO8 and BaO10 cages, and square planar CuO4 units. As x increases in Ba(Nd2−xLax)CuO5, the size of these RO8 and BaO10 cages increases. BaLa2CuO5 was confirmed to be ferromagnetic at ≈5 K; despite the isostructural property of BaLa2CuO5 and BaNd5CuO5, the Nd-analog was found to be antiferromagnetic. As x in Ba(Nd2−xLax)CuO5 increases between 0 and 2, the amount of ferromagnetism increases.
International Journal of Chemical Kinetics, 1977
The reaction between ozone and thiophene was studied from 30 to 125°C over a pressure range of 0.... more The reaction between ozone and thiophene was studied from 30 to 125°C over a pressure range of 0.005-0.3 torr ozone and 0.1-1 torr thiophene. The most abundant product was O2 with smaller amounts of CO2 and SO2. The mass balance was 100% for oxygen and approached 100% for sulfur at the higher values of [O3]0. The carbon balance, however, was only 25% and no H-containing products were found, suggesting that the missing product is a hydrocarbon which may be a polymer. The rate law found was -d[O3]/dt = k1[Th] [O3] + k2 [Th] [O3]2 where log k1(M−1 · sec−1) = 7.8 ± 0.5 - (8400 ± 700)/2.3RT, and log k2(M−2 · sec−1) = 12.4 ± 0.4 - (4700 ± 400)/2.3RT. Added O2 had no effect on k1 but reduced k2 to a limiting value. It is thus not possible to measure the primary rate constant in this system by measuring the overall rate in the presence of oxygen, and this restriction may also apply to other ozone systems. A mechanism is postulated involving two chain sequences, one of which is inhibited by added O2. A comparison with other ozone systems is made, and the chain lengths are far greater for ozone + thiophene than other systems, under the conditions employed. Possible intermediates in the mechanism are discussed.
Inorganic Chemistry, 1977
ABSTRACT
Inorganic Chemistry, 1975
see discussion of spectra and metal-ligand distances for [RuCI-(CO)2(liNzPh)(PPh3)2] [ClO4] and P... more see discussion of spectra and metal-ligand distances for [RuCI-(CO)2(liNzPh)(PPh3)2] [ClO4] and PtCl(N2Ph)(PEt3)2. (41) This is the average for 12 four-(tetrahedral). five-and six-coordinate Ru and Os complexes conraining linear nitrosyl ligands.