Search NASA⌕ Search

SEARCH · Search NASA

Results for “powder diffraction”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Effect of reductant and PVP on morphology and magnetic property of ultrafine Ni powders prepared via hydrothermal route

Graphical abstract: The ultrafine Ni powders with the shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using different reductants. Their saturation magnetization, remanent magnetization and coercivity sequentially increase, and the coercivity of hexagonal sheet-like Ni powders increases by 25% compared with the Ni bulk counterpart. - Highlights: • The ultrafine Ni powders with various shapes of sphere, fish-bone, hexagonal sheet, etc. • Facile and one-step hydrothermal reduction using three reductants and PVP additive was developed. • Magnetic properties of the ultrafine Ni powders with different shapes were measured. • Compared with bulk Ni material, coercivity of hexagonal sheet Ni increases by 25%. • The formation mechanism of the shapes was suggested. - Abstract: The ultrafine nickel particles with different shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using hydrazine hydrate, sodium hypophosphite and ethylene glycol as reductants, polyvinylpyrrolidone as structure-directing agent. It has been verified with the characterization of X-ray powder diffraction and transmission/scanning electronic microscopy that as-prepared products belong to face-centered cubic structure of nickel microcrystals with high purity and fine dispersity. The magnetic hysteresis loops measured at room temperature reveal that the values of saturation magnetization, remanent magnetization and coercivity rise sequentially from silknet, sphere to hexagonal sheet. In comparison with nickel bulk counterpart, the coercivity of the hexagonal sheet nickel powders increases by 25%.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Luminescent properties of phosphor converted LED using an orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor

Graphical abstract: Display Omitted Highlights: ► Phase-pure Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} powders were synthesized by a solid state reaction process. ► The optimum emission intensity was observed at the Eu{sup 2+} ion concentration of 0.006. ► The dipole–dipole interaction was the major concentration quenching mechanism. ► The pc-LED coated with Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} had higher CRI than commercial red phosphor. -- Abstract: A series of orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphors were synthesized by a conventional solid-state reaction method. The as-prepared phosphors were characterized by X-ray powder diffraction (XRD), fluorescence spectroscopy, and spectroradiometry. XRD showed that all prepared samples exhibited a monoclinic Rb{sub 2}CaP{sub 2}O{sub 7} phase. Fluorescence spectroscopy showed that the photoluminescence efficiency of Rb{sub 2}Ca{sub 1−x}P{sub 2}O{sub 7}:Eu{sub x}{sup 2+} phosphors increased with increasing Eu{sup 2+} concentration until x = 0.006, then decreased at higher concentrations, due to a concentration quenching effect. The thermal activation energy was also measured to be 0.40 eV. Furthermore, a phosphor-converted LED (pc-LED) coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was fabricated, which exhibited bright orange emission under a forward bias, from 200 to 300 mA. The color rendering index (CRI) of pc-LED coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was higher than the CRI of pc-LED coated with commercial red phosphor, due to the broad emission band of Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor. In applying with three-band pc-LEDs, moreover, white pc-LED using Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor had a higher CRI, than using commercial phosphor. These results indicated that Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor could be a good candidate for a near-UV based w-LED.

36 MATERIALS SCIENCE↗
DOE OSTI2016

In cellulo serial crystallography of alcohol oxidase crystals inside yeast cells

The possibility of using femtosecond pulses from an X-ray free-electron laser to collect diffraction data from protein crystals formed in their native cellular organelle has been explored. X-ray diffraction of submicrometre-sized alcohol oxidase crystals formed in peroxisomes within cells of genetically modified variants of the methylotrophic yeast Hansenula polymorpha is reported and characterized. Furthermore, the observations are supported by synchrotron radiation-based powder diffraction data and electron microscopy. Based on these findings, the concept of in cellulo serial crystallography on protein targets imported into yeast peroxisomes without the need for protein purification as a requirement for subsequent crystallization is outlined.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Commissioning of Angle Dispersive X-ray Diffraction Beamline on Indus-2

An Angle dispersive x-ray diffraction (ADXRD) beamline on bending magnet source of Indus-2 synchrotron (2.5 GeV, 300 mA) has been commissioned, for the study of single and polycrystalline samples. The beamline optics is based on vertically focusing Pt-coated pre and post mirrors and sagittal focusing Si (311) based double crystal monochromator. Experimental station consists of a six circle diffractometer equipped with scintillation detector and an image plate area detector for powder diffraction. XRD experiments have been performed to study single crystal and polycrystalline samples.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Hydrogen bonds in crystalline D -alanine: diffraction and spectroscopic evidence for differences between enantiomers

Enantiomeric amino acids have specific physiological functions in complex biological systems. Systematic studies focusing on the solid-state properties of D-amino acids are, however, still limited. To shed light on this field, structural and spectroscopic studies of D-alanine using neutron powder diffraction, polarized Raman scattering and ab initio calculations of harmonic vibrational frequencies were carried out. Clear changes in the number of vibrational modes are observed as a function of temperature, which can be directly connected to variations of the N—D bond lengths. These results reveal dissimilarities in the structural properties of D-alanine compared with L-alanine.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Neutron diffraction study and superparamagnetic behavior of ZnFe{sub 2}O{sub 4} nanoparticles obtained with different conditions

Spinel-type (S.G.= Fd3-bar m) ZnFe{sub 2}O{sub 4} fine particles with sizes from 4 to 19 nm prepared by solvothermal and microwave-assisted solvothermal methods have been studied by neutron powder diffraction at room temperature. The cation distribution corresponding to mixed spinel structure (Zn{sup 2+}{sub 1-x}Fe{sup 3+}{sub x})[Fe{sup 3+}{sub 2-x}Zn{sup 2+}{sub x}]O{sub 4} along with the unit cell parameter has been estimated after Rietveld refinement of the obtained neutron diffraction data for all the samples. It has been found that the inversion degree parameter (x) takes values between 0.11 and 0.20 depending not only on the particle size but also on the synthesis conditions as well. All the samples behave as superparamagnetic with an effective magnetic moment per particle ({mu}{sub SP}) from 7.0x10{sup 2} to 7.7x10{sup 3} {mu}{sub B}. The sample obtained by microwave assistance displays a different magnetic behavior as the ZFC and FC magnetic susceptibility and the magnetization versus applied field hysteresis loop measured at 5 K suggest. This is related with the dipole interactions that are a consequence of the higher inversion degree and {mu}{sub SP}. - Graphical abstract: ZnFe{sub 2}O{sub 4} nanoparticles of 19 nm obtained by the solvotermal method together with its Rietveld refined pattern. Highlights: > Solvothermally prepared ZnFe{sub 2}O{sub 4} nanoparticles.{yields} Inversion degree obtained after Rietveld refinement of neutron data.{yields} Superparamagnetic behavior.{yields} Dependence with the synthesis conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Magnetic order and ice rules in the multiferroic spinel FeV 2 O 4

We present a neutron-diffraction study of FeV2O4, which is rare in exhibiting spin and orbital degrees of freedom on both cation sublattices of the spinel structure. Our data confirm the existence of three structural phase transitions previously identified with x-ray powder diffraction and reveal that the lower two transitions are associated with sequential collinear and canted ferrimagnetic transitions involving both cation sites. Through consideration of local crystal and spin symmetry, we further conclude that Fe2+ cations are ferro-orbitally ordered below 135 K and V3+ orbitals order at 60 K, in accordance with predictions for vanadium spinels with large trigonal distortions and strong spin-orbit coupling. Intriguingly, the direction of ordered vanadium spins at low temperature obey ice rules more commonly associated with the frustrated rare-earth pyrochlore systems.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Powder X-ray diffraction of nintedanib esylate hemihydrate, (C 31 H 33 N 5 O 4 )(C 2 H 5 O 3 S)(H 2 O) 0.5

The crystal structure of nintedanib esylate hemihydrate was refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Nintedanib esylate hemihydrate crystallizes in space groupP-1(#2) witha= 11.5137(1),b= 16.3208(4),c= 19.1780(5) Å,α= 69.0259(12),β= 84.4955(8),γ= 89.8319(6)°,V= 3347.57(3) Å 3 , andZ= 4 at 295 K. Hydrogen bonds are prominent in the crystal structure. The water molecule forms two medium-strength O–H⋯O hydrogen bonds to one of the esylate anions. The protonated nitrogen atom in each cation forms a N–H⋯O hydrogen bond to an esylate anion. The ring N–H groups form strong intramolecular N–H⋯O hydrogen bonds to carbonyl groups. The ring N–H groups form intramolecular N–H⋯O hydrogen bonds to esylate anions. Many C–H⋅⋅⋅O hydrogen bonds (and one C–H⋯N hydrogen bond), with aromatic C–H, methylene groups and methyl groups as donors, are present. The hydrogen bonding patterns of the two cations differ considerably. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®)

Materials Science↗
DOE OSTI2023

Neutron diffraction and DFT studies of oxygen defect and transport in higher-order Ruddlesden–Popper phase materials

A series of higher-order Ruddlesden–Popper phase materials – La 3 PrNi 3 O 10-δ , La 2 Pr 2 Ni 3 O 10-δ and LaPr 3 Ni 3 O 10-δ – were synthesised and investigated by neutron powder diffraction to understand the oxygen defect structure and propose possible pathways for oxygen transport in these materials. Further complimentary DFT calculations of the materials were performed to support the experimental analysis. All of the phases were hypostoichiometric and it was observed that the majority of the oxygen vacancies were confined to the perovskite layers, with a preference for equatorial oxygen sites. A particular preference for vacancies in O(1) and O(5) sites at high temperatures was observed from neutron diffraction measurements which were further complimented by DFT calculations wherein the vacancy formation energy was found to be lowest at the O(1) site. Also, a preference for a curved oxygen transport pathway around the NiO 6 octahedra was observed which agrees with the published literature for Ruddlesden–Popper phase materials. Lattice parameters for all three compositions showed a linear increase with increasing temperature, but the increase was greatest in the c parameter while the b parameter showed only a slight increase when compared to the a parameter. The thermal expansion coefficient was calculated for all compositions and was found to be in the range 13.0–13.4 × 10 -6 °C -1 , which is compatible with the commonly used electrolyte materials for solid oxide fuel cells.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Characterization of Oxygen Storage and Structural Properties of Oxygen-Loaded Hexagonal R MnO 3+δ ( R = Ho, Er, and Y)

Single-phase polycrystalline samples of stoichiometric RMnO3+delta (R = Er, Y, and Ho) were achieved in the hexagonal P6(3)cm structure through solid state reaction at, similar to 1300 degrees C. Thermogravimetric measurements in oxygen atmospheres demonstrated that samples with the larger Ho and Y show rapid and reversible incorporation of large amounts of excess oxygen (0.3 > delta> 0) at an unusually low temperature range of similar to 190-325 degrees C, indicating the industrial usefulness of RMnO3+delta materials for lower cost thermal swing adsorption processes for oxygen separation from air. Further increase of the excess oxygen intake to delta similar to 0.38 was achieved for all the investigated materials when annealed under high pressures of oxygen. The formation of three oxygen stable phases with 6 = 0, 0.28, and 0.38 was confirmed by thermogravimetric measurements, synchrotron X-rays, and neutron diffraction. In situ synchrotron diffraction proved the thermal stability of these single phases and the regions of their creation and coexistence, and demonstrated that the stability of the delta = 0.28 phase increases with the ionic size of the R ion. Structural modeling using neutron powder diffraction for oxygen excess phases describes the formation and details of a large R3c superstructure observed for HoMnO3.28 by tripling the c-axis of the original parent unit cell. Modeling of the RMnO3.38 (R = Y and Er) oxygen-loaded phase converged on a structural model consistent with the symmetry of Pca2(1).

Abughayada, C.↗
DOE OSTI2014

Photocatalytic degradation of diethyl phthalate using TiO{sub 2} nanoparticles

TiO{sub 2} nanoparticles predominantly in rutile phase are synthesized by ultrasonication assisted sol-gel method. TiO{sub 2} powder is characterized using X-ray powder diffraction and UV-vis diffuse reflectance. TiO{sub 2} is used as catalyst in photocatalytic degradation of Diethyl Phthalate. TiO{sub 2} exhibits good photocatalytic activity for the degradation of diethyl phthalate.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRSDate not supplied

In-Situ Alloying of GRCop-42 via Additive Manufacturing: Precipitate Analysis

GRCop-42, a Cu-4at% Cr-2at% Nb alloy, was designed as a high temperature, high strength, high heat flux material for rocket engine combustion chamber liners by NASA Glenn Research Center. In situ alloying of GRCop-42 (ISGRCop-42) using powder bed fusion (PBF) additive manufacturing (AM) takes elemental powders of Cu, Cr, and Nb to be introduced into the PBF environment and develop the GRCop alloy while simultaneously building an AM component. Elemental powders were milled together prior to printing in an effort to facilitate the alloying process. Success of the in situ alloying process may provide lower cost, faster lead times, alloying optimization, and more design freedom in the development of regeneratively-cooled rocket propulsion systems. Evaluation of the ISGRCop-42 was conducted using a phase extraction procedure to isolate the Cr2Nb precipitates from the pure Cu matrix. The isolated precipitates were then examined using x-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS). It was found that ISGRCop-42 successfully and repeatedly formed Cr2Nb at a yield as high as 89% of potential Cr2Nb. Further, it was identified that the preparation of the powder was the most influential factor in alloying success, and the second most influential factor was the laser power.

In Situ alloying↗
DOE OSTI2018

First Full Structural Characterization of Chloro Formamidinium Salts

While the synthesis of chloro formamidinium chloride has been known for over one century, no solid‐state structure of a chlorine‐substituted formamidinium compound has been reported up to now. Herein, we describe syntheses, solid‐state structures, and vibrational properties of four chloro formamidinium compounds, namely [ClC(NH 2 ) 2 ]Cl ( 1 ), [ClC(NH 2 ) 2 ](AuCl 4 ) ( 2 ), [ClC(NH 2 ) 2 ] 2 (PdCl 4 ) ( 3 ), and [ClC(NH 2 ) 2 ] 2 (PtCl 6 ) ( 4 ), as determined by single‐crystal X‐ray diffraction (SCXRD). 1 and 3 crystallize in the monoclinic space group P 2 1 / c , 2 in the orthorhombic space group Pbcn , whereas 4 adopts the triclinic space group P 1 . By using a combination of high‐resolution time‐of‐flight neutron powder diffraction, state‐of‐the‐art DFT calculations as well as IR spectroscopy, the prior SCXRD result was fully confirmed and augmented by determining the hydrogen‐bonded molecular networks. First‐principles electronic‐structure calculations corroborate the ionic nature of these salts by showing very flat, molecular‐like bands next to the Fermi level, in addition to indirect bandgaps. This study underlines the upmost importance of complementing diffraction data by ab initio calculations, as theory‐derived anisotropic displacement parameters served as fixed numerical entries.

Möller, Andreas↗
DOE OSTI2011

Static Compression of Tetramethylammonium Borohydride

Raman spectroscopy and synchrotron X-ray diffraction are used to examine the high-pressure behavior of tetramethylammonium borohydride (TMAB) to 40 GPa at room temperature. The measurements reveal weak pressure-induced structural transitions around 5 and 20 GPa. Rietveld analysis and Le Bail fits of the powder diffraction data based on known structures of tetramethylammonium salts indicate that the transitions are mediated by orientational ordering of the BH{sub 4}{sup -} tetrahedra followed by tilting of the (CH{sub 3}){sub 4}N{sup +} groups. X-ray diffraction patterns obtained during pressure release suggest reversibility with a degree of hysteresis. Changes in the Raman spectrum confirm that these transitions are not accompanied by bonding changes between the two ionic species. At ambient conditions, TMAB does not possess dihydrogen bonding, and Raman data confirms that this feature is not activated upon compression. The pressure-volume equation of state obtained from the diffraction data gives a bulk modulus [K{sub 0} = 5.9(6) GPa, K'{sub 0} = 9.6(4)] slightly lower than that observed for ammonia borane. Raman spectra obtained over the entire pressure range (spanning over 40% densification) indicate that the intramolecular vibrational modes are largely coupled.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

The system Ce-Zn-B at 800 deg. C

The isothermal section for the system Ce-Zn-B has been established at 800 deg. C using electron microprobe analysis and X-ray powder diffraction. No ternary compounds exist and mutual solid solubilities of binary phases are negligible. In the concentration range of 10.0-10.5 at% Ce two structural modifications have been confirmed: high temperature {beta}Ce{sub 2}Zn{sub 17} above {approx}750 deg. C with the Th{sub 2}Zn{sub 17} type (R3-bar m, a=0.90916(4) nm, c=1.3286(1) nm) and low temperature {alpha}CeZn{sub 7} (Ce{sub 1-x}Zn{sub 5+2x}; x{approx}0.33) up to 750 deg. C for which we attributed the TbCu{sub 7} type (P6/mmm, a=0.52424(2), c=0.44274(1) nm). The crystal structure of CeZn{sub 7} was derived from the Rietveld refinement of X-ray powder intensities. Precise data on atom site distribution and positional parameters have been furthermore provided from X-ray single crystal refinements for two compounds, for which crystal structures hitherto have only been derived from X-ray diffraction photographs: Ce{sub 3}Zn{sub 11} (Immm, a=0.45242(2) nm, b=0.88942(3) nm, c=1.34754(4) nm) and Ce{sub 3}Zn{sub 22} (I4{sub 1}/amd; a=0.89363(2) nm, c=2.1804(5) nm). - Graphical abstract: Existence of low temperature modification {alpha}CeZn{sub 7} (Ce{sub 1-x}Zn{sub 5+2x}; x{approx}0.33) of Ce{sub 2}Zn{sub 17} has been verified up to 750 deg. C that is attributed with the TbCu{sub 7} type. Highlights: > Isothermal section of system Ce-Zn-B at 800 deg. C. > In System Ce-Zn, X-ray single crystal intensity data refinement of Ce{sub 3}Zn{sub 11} and Ce{sub 3}Zn{sub 22} and Rietveld refinement of Ce{sub 13}Zn{sub 58}. > Two temperature modifications of Ce{sub 2}Zn{sub 17}, rhombohedral {beta}Ce{sub 2}Zn{sub 17} (hT) and of hexagonal {alpha}CeZn{sub 7} (lT). > No ternary compound in the System Ce-Zn-B (<50 at% Ce) at 800 deg. C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

A neutron diffraction study and mode analysis of compounds of the system La{sub 1−x}Sr{sub x}FeO{sub 3−x}F{sub x} (x=1, 0.8, 0.5, 0.2) and an investigation of their magnetic properties

We report here a detailed study of the system La{sub 1−x}Sr{sub x}FeO{sub 3−x}F{sub x}, by neutron powder diffraction- and magnetic-measurements. All the compounds are robust antiferromagnetics with ordering temperatures well above room temperature. Magnetic moments are shown to align parallel to the c-axis. FC-ZFC measurements indicate a small canting of the magnetic moments, resulting in a ferromagnetic component with a maximum for La{sub 0.5}Sr{sub 0.5}FeO{sub 2.5}F{sub 0.5}. We show that the system exhibits a composition-driven transition from a phase, for low fluorination levels (x≤0.5), with Pnma symmetry and the usual system of octahedral tiltings, to a phase with space group Imma for higher fluorine contents, where a correlated distortion of the oxygen octahedra plays a significant role. The consistency of the structural models, with respect to the expected continuity of the amplitudes of the different distortion modes and the invariance of their internal form, was monitored through the symmetry mode decomposition of the structures. - Graphical abstract: The crystal and magnetic structure of La{sub 0.5}Sr{sub 0.5}FeO{sub 2.5}F{sub 0.5}. Display Omitted - Highlights: • The compounds La{sub 1−x}Sr{sub x}FeO{sub 3−x}F{sub x} (x=1, 0.8, 0.5, 0.2) were studied by neutron diffraction. • A mode analysis shows lower symmetry for Sr rich compounds than previously reported. • SrFeO{sub 2}F crystallizes in the orthorhombic space group Imma. • Magnetic moments resulting from canting depend on metric distortion. • The magnetic structure was determined for La{sub 0.5}Sr{sub 0.5}FeO{sub 2.5}F{sub 0.5}.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Crystal structure details of La- and Bi-substituted hydroxyapatites: Evidence for LaO{sup +} and BiO{sup +} with a very short metal–oxygen bond

Crystal structures of substituted apatites with general formula Ca{sub 10−x}M{sub x}(PO{sub 4}){sub 6}(OH{sub 1−δ}){sub 2−x}O{sub x}, where M=La, Bi, 0≤x<2, were refined using high-resolution X-ray powder diffraction patterns. Individual positions for Ca{sup 2+} and M{sup 3+}-ions localized near Ca2-site were determined. The M{sup 3+}-ion was found shifted toward the hexagonal channel center with respect to the Ca{sup 2+}-ion, forming very short bond with the intrachannel O{sup 2−}, while leaving considerably longer distances to other oxygen atoms, which suggested the existence of a MO{sup +} ion. Distinct bands of stretching M–O modes were observed in the Raman and FT-IR spectra of the compounds. The bond lengths for BiO{sup +} and LaO{sup +} were estimated to be 2.05(1) and 2.09(1) Å correspondingly. The latter was almost 0.3 Å lower than the shortest La–O bond in La{sub 2}O{sub 3}. The realization of such a strong lanthanide–oxygen bond in a crystal lattice could provide a very high axial ligand field and might be implemented to develop high-energy-barrier single-molecule magnets as well as to tune properties of lanthanide-based luminophores. - Graphical abstract: A fragment of the La-for-Ca substituted apatite crystal structure focusing on the La–O bond. - Highlights: • Individual positions in the apatite crystal lattice for a doping atom (La, Bi) and Ca. • The doping atom shifts toward the center of the hexagonal channel. • BiO{sup +} and LaO{sup +} with estimated short bond lengths of 2.05 and 2.09 Å respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Investigation of structural and electrical transport properties in Ti doped Sr{sub 2}IrO{sub 4}

Effects of Ti substitution at Ir-site on structural and electrical properties are studies in Sr{sub 2}IrO{sub 4}. Structural investigation has been done using x-ray powder diffraction and allied Rietveld analysis for all the samples. While there is no structural phase transition but the lattice parameters evolve with Ti doping. Resistivity measurements show an insulating behavior for all the samples. Data show resistivity increases drastically with Ti doping. The increase in resistivity is understood to arise due to dilution of Ir-O-Ir network as well as tuning of electronic correlation effect.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗