Search NASA⌕ Search

SEARCH · Search NASA

Results for “quantum 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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Spin–phonon interactions in silicon carbide addressed by Gaussian acoustics [Probing spin-phonon interactions in silicon carbide with Gaussian acoustics]

Hybrid spin-mechanical systems provide a platform for integrating quantum registers and transducers. Efficient creation and control of such systems require a comprehensive understanding of the individual spin and mechanical components as well as their mutual interactions. Point defects in silicon carbide (SiC) offer long-lived, optically addressable spin registers in a wafer-scale material with low acoustic losses, making them natural candidates for integration with high quality factor mechanical resonators. Here, we show Gaussian focusing of a surface acoustic wave in SiC, characterized by a novel stroboscopic X-ray diffraction imaging technique, which delivers direct, strain amplitude information at nanoscale spatial resolution. Using ab initio calculations, we provide a more complete picture of spin-strain coupling for various defects in SiC with C 3v symmetry. This reveals the importance of shear for future device engineering and enhanced spin-mechanical coupling. We demonstrate all-optical detection of acoustic paramagnetic resonance without microwave magnetic fields, relevant to sensing applications. Lastly, we show mechanically driven Autler-Townes splittings and magnetically forbidden Rabi oscillations. These results offer a basis for full strain control of three-level spin systems.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Revealing long- and short-range structural modifications within phosphorus-treated HZSM-5 zeolites by atom probe tomography, nuclear magnetic resonance and powder X-ray diffraction

In this study, the average and the local structure of phosphorus-treated HZSM-5 zeolites were investigated by means of atom probe tomography, powder X-ray diffraction (at ambient and cryogenic temperatures) and 1 H, 29 Si, 27 Al, and 31 P magic angle spinning (MAS) solid state nuclear magnetic resonance (NMR) spectroscopy. Phosphatation to yield a product with P/Al ≤ 1 followed by thermal treatment leads to breaking of the Si–OH–Al bridging groups, and subsequent partial dealumination of the zeolite framework, as shown by the contraction of the orthorhombic unit-cell volume and by the loss of tetrahedral framework Al, as observed in the 27 Al Multiple Quantum (MQ) MAS NMR spectrum. Most of the framework Al is present in an electronic environment distorted by the presence of phosphorus and appears not to be involved in classic Si–OH–Al Brønsted acid sites. The 31 P MAS NMR signals indicate that phosphorus interacts with the zeolitic framework to locally form silico-aluminophosphate (SAPO) domains and the presence of a new kind of acidic site was confirmed by the resonance at ~8.6 ppm in the 1 H MAS NMR spectra, attributed to P–OH groups. Increasing the phosphorus loading (P/Al >> 1) promotes further dealumination of the framework and cross-dehydroxylation between P–OH and Si–OH species, leading to the formation of a crystalline silicon orthophosphate phase. With decreasing Al content, the monoclinic HZSM-5 structure becomes preferred, especially at 85 K where the strain relaxation is higher. Nevertheless, the presence of a higher amount of silicophosphate impurities hinders the low-temperature strain release of the framework, indicating that some of these species are localized in the zeolite pores and contribute to the strain build up.

36 MATERIALS SCIENCE↗
DOE OSTI2024

First-principles calculation of Hubbard U for Terbium metal under high pressure

Abstract Using density functional theory (DFT) and linear response approaches, we compute the on-site Hubbard interaction U of elemental Terbium (Tb) metal in the pressure range ∼ 0–65 GPa. The resulting first-principles U values with experimental crystal structures enable us to examine the magnetic properties of Tb using a DFT+U method. The lowest-energy magnetic states in our calculations for different high-pressure Tb phases—including hcp, α -Sm, and dhcp—are found to be compatible with the corresponding magnetic ordering vectors reported in experiments. The result shows that the inclusion of Hubbard U substantially improves the accuracy and efficiency in modeling correlated rare-earth materials. Our study also provides the necessary U information for other quantum many-body techniques to study Tb under extreme pressure conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Imaging beyond the surface region: Probing hidden materials via atomic force microscopy

Probing material properties at surfaces down to the single-particle scale of atoms and molecules has been achieved, but high-resolution subsurface imaging remains a nanometrology challenge due to electromagnetic and acoustic dispersion and diffraction. The atomically sharp probe used in scanning probe microscopy (SPM) has broken these limits at surfaces. Subsurface imaging is possible under certain physical, chemical, electrical, and thermal gradients present in the material. Of all the SPM techniques, atomic force microscopy has entertained unique opportunities for nondestructive and label-free measurements. Here, we explore the physics of the subsurface imaging problem and the emerging solutions that offer exceptional potential for visualization. We discuss materials science, electronics, biology, polymer and composite sciences, and emerging quantum sensing and quantum bio-imaging applications. The perspectives and prospects of subsurface techniques are presented to stimulate further work toward enabling noninvasive high spatial and spectral resolution investigation of materials including meta- and quantum materials.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2023

CMOS-Compatible Ultrathin Superconducting NbN Thin Films Deposited by Reactive Ion Sputtering on 300 mm Si Wafer

We report a milestone in achieving large-scale, ultrathin (~5 nm) superconducting NbN thin films on 300 mm Si wafers using a high-volume manufacturing (HVM) industrial physical vapor deposition (PVD) system. The NbN thin films possess remarkable structural uniformity and consistently high superconducting quality across the entire 300 mm Si wafer, by incorporating an AlN buffer layer. High-resolution X-ray diffraction and transmission electron microscopy analyses unveiled enhanced crystallinity of (111)-oriented δ-phase NbN with the AlN buffer layer. Notably, NbN films deposited on AlN-buffered Si substrates exhibited a significantly elevated superconducting critical temperature (~2 K higher for the 10 nm NbN) and a higher upper critical magnetic field or H c2 (34.06 T boost in H c2 for the 50 nm NbN) in comparison with those without AlN. These findings present a promising pathway for the integration of quantum-grade superconducting NbN films with the existing 300 mm CMOS Si platform for quantum information applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Experimental evidence for nonspherical magnetic form factor in Ru 3 +

The Mott insulator ..alpha..-RuCl3 has generated great interest in the community due to its possible field-induced Kitaev quantum spin liquid state. Despite enormous effort spent trying to obtain the form of the low-energy Hamiltonian, there is currently no agreed upon set of parameters which is able to explain all of the data. A key piece of missing information lies in the determination of the magnetic form factor of Ru3+, particularly for a true quantitative treatment of inelastic neutron scattering data. Here we present the experimentally derived magnetic form factor of Ru3+ in the low spin 4d5 state using polarized neutron diffraction within the paramagnetic regime on high-quality single crystals of ..alpha..-RuCl3. We observe strong evidence of an anisotropic form factor, expected of the spin-orbit coupled jeff=12 ground state. We model the static magnetization density in increasing complexity from simple isotropic cases, to a multipolar expansion, and, finally, ab initio calculations of the generalized jeff=12 ground state. Comparison of both single ion models and inclusion of Cl- anions support the presence of hybridization of Ru3+ with the surrounding Cl- ligands.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Evolution of magnetic field induced ordering in the layered quantum Heisenberg triangular-lattice antiferromagnet Ba 3 CoSb 2 O 9

Quantum fluctuations in the effective spin-12 layered triangular-lattice quantum Heisenberg antiferromagnet Ba 3 CoSb 2 O 9 lift the classical degeneracy of the antiferromagnetic ground state in magnetic field, producing a series of novel spin structures for magnetic fields applied within the crystallographic ab plane, including a celebrated collinear “up-up-down” spin ordering with magnetization equal to 1/3 of the saturation magnetization over an extended field range. Theoretically unresolved, however, are the effects of interlayer antiferromagnetic coupling and transverse magnetic fields on the ground states of this system. Additional magnetic field induced phase transitions are theoretically expected and in some cases have been experimentally observed, but details regarding their number, location, and physical character appear inconsistent with the predictions of existing models. Conversely, an absence of experimental measurements as a function of magnetic-field orientation has left other key predictions of these models untested. To address these issues, in this study we have used specific heat, neutron diffraction, thermal conductivity, and magnetic torque measurements to map out the phase diagram as a function of magnetic field intensity and orientation relative to the crystallographic ab plane. For H||ab, we have discovered an additional magnetic field induced phase transition at low temperature and an unexpected tetracritical point in the high-field phase diagram, which coupled with the apparent second-order nature of the phase transitions eliminates several theoretically proposed spin structures for the high-field phases. Our calorimetric measurements as a function of magnetic field orientation are in general agreement with theory for field-orientation angles close to plane parallel (H||a) but diverge at angles near plane perpendicular; a predicted convergence of two phase boundaries at finite angle and a corresponding change in the order of the field induced phase transition are not observed experimentally. Our results emphasize the role of interlayer coupling in selecting and stabilizing field induced phases, provide guidance on the nature of the magnetic order in each phase, and reveal the need for new physics to account for the nature of magnetic ordering in this archetypal two-dimensional spin-12 triangular-lattice quantum Heisenberg antiferromagnet.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Structural complexity in ramp-compressed sodium to 480 GPa

Abstract The properties of all materials at one atmosphere of pressure are controlled by the configurations of their valence electrons. At extreme pressures, neighboring atoms approach so close that core-electron orbitals overlap, and theory predicts the emergence of unusual quantum behavior. We ramp-compress monovalent elemental sodium, a prototypical metal at ambient conditions, to nearly 500 GPa (5 million atmospheres). The 7-fold increase of density brings the interatomic distance to 1.74 Å well within the initial 2.03 Å of the Na + ionic diameter, and squeezes the valence electrons into the interstitial voids suggesting the formation of an electride phase. The laser-driven compression results in pressure-driven melting and recrystallization in a billionth of a second. In situ x-ray diffraction reveals a series of unexpected phase transitions upon recrystallization, and optical reflectivity measurements show a precipitous decrease throughout the liquid and solid phases, where the liquid is predicted to have electronic localization. These data reveal the presence of a rich, temperature-driven polymorphism where core electron overlap is thought to stabilize the formation of peculiar electride states.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effective Electrochemical Charge Storage in the High-Lithium Compound Li8ZrO6

Li8ZrO6 is a pseudolamellar compound with high lithium content. Even though it is intrinsically a poor conductor and does not contain a transition metal with easily variable oxidation states, a new synthetic approach to preparing it in nanocomposite form with intimate contact to a conductive carbon by mechanical delamination enabled galvanostatic cycling of coin half-cells containing Li8ZrO6/C as the cathode and Li-metal as the anode at 221 mAh/g (which corresponds to extracting 2 Li per formula unit) over at least 140 cycles. With a higher capacity limit, a discharge capacity of 331 mAh/g (which corresponds to extracting 3 Li per formula unit) was maintained over 15–20 cycles. Ex-situ and operando X-ray diffraction (XRD) studies of galvanostatically cycled cells showed that at these levels of charge, delithiation follows a reversible, topotactic path with only small distortions around Zr atoms. During this process, crystalline grain sizes decrease continuously, shortening diffusion lengths within grains but increasing the number of grain boundaries and electrode/electrolyte interfaces. Charge storage in Li8ZrO6 appears to involve partial oxidation of oxygen atoms and production of small-polaron holes, as supported by XRD, X-ray photoelectron spectroscopy, and pair-distribution function studies and predicted by quantum mechanical calculations. At higher depths of charge, delithiation results in amorphization of the active electrode material. The charge storage mechanism in Li8ZrO6 is unusual among lithium-ion battery electrode materials and involves a combination of mechanisms that resemble intercalation and conversion reactions. With further refinement, Li8ZrO6/C based materials open up opportunities to develop new cathode materials for lithium-ion batteries that may improve on currently existing capacity barriers.

Li diffusion↗
DOE OSTI2025

Persistent short-range spin fluctuation in rare-earth substituted square lattice Sr 2 ⁢Ir 0.89 ⁢Tb 0.11⁢ O 4

Sr 2 ⁢IrO 4 , a prototypical 𝐽 eff = 1/2 square lattice system, is widely studied for novel physics. While transition metal substitution effects are well explored, rare-earth doping at the Ir 4+ site is less explored. Here we present a detailed magnetization and neutron diffraction study on Sr 2 ⁢Ir 1−𝑥 ⁢Tb 𝑥 ⁢O 4 (𝑥 = 0.11). The system tends to adopt an in-plane antiferromagnetic configuration with a “++++” stacking sequence. Strong spin fluctuations persist down to the lowest measured temperature, consistent with the concave shape order parameter. A pronounced magnetic diffuse scattering rod develops along the 𝐿 direction at low temperature, indicating the formation of short-range magnetic correlations with a characteristic length of ∼ 24⁢(2) ⁢Å. In conclusion, this work provides a new pathway to exotic quantum phases in the strongly spin-orbit-coupled iridates.

Iridates↗
DOE OSTI2022

Fluctuating Ru trimer precursor to a two-stage electronic transition in RuP

Superconductivity in binary ruthenium pnictides occurs proximal to and upon suppression of a non-magnetic ground state, preceded by a pseudogap phase associated with Fermi surface instability, and its critical temperature, T c , is maximized around the pseudogap quantum critical point. By analogy with isoelectronic iron based counterparts, antiferromagnetic fluctuations became ''usual suspects" as putative mediators of superconducting pairing. Here we report on a high temperature local symmetry breaking in RuP, nonsuperconducting parent of the maximum- T c branch of these novel superconductors, revealed by combined nanostructure-sensitive powder and single crystal X-ray total scattering analyses. Large local distortions of Ru chains associated with orbital-charge trimerization, further assembled into hexamers, exist above the two-stage electronic transition in RuP. In the pseudogap regime the precursors order with distortions retaining their strength, whereas they acquire spin-singlet characteristics which dramatically enhances the distortion as the nonmagnetic ground state establishes. The precursors enable the nonmagnetic ground state and presumed complex oligomerization, and the relevance of pseudogap fluctuations for superconductivity emerges as a distinct prospect. As a transition metal system in which partial d-manifold filling combined with high crystal symmetry promotes electronic instabilities, this represents a further example of local electronic precursors underpinning the macroscopic collective behavior of quantum materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Molecular beam epitaxy growth and characterization of GePb alloys

Pb based group-IV alloys such as GePb have been gaining interest as a potential alternative for infrared detectors, quantum materials, and high-speed electronic devices. Challenges remain in their growth due to the extremely low solid solubility of Pb in the Ge–Pb system. This paper reports molecular beam epitaxy growth of GePb alloy thin films on Ge(100) substrates. Effusion cells of Ge and Pb are used to control the flux ratio independently. The optimal substrate temperature is found to be near the thermocouple temperature of 300 °C based on the characterization of the grown films using high-resolution x-ray diffraction. A large change in the Ge:Pb beam equivalent pressure ratio from 10:1 to 1:1 results in only a minimal increase of the Pb composition from 0.74% to 2.84% as estimated from Raman spectroscopy and Rutherford backscattering spectrometry. Furthermore, scanning electron microscopy images show a large volume of Pb islands on the surface that form into either long trapezoidal rods or uniform droplets, with increasing Pb flux and growth time the density of Pb islands increased.

36 MATERIALS SCIENCE↗
DOE OSTI2025

High-resolution high-throughput spatiotemporal strain imaging reveals loss mechanisms in a surface acoustic wave device

Surface acoustic wave devices are key components for processing radio frequency signals in wireless communication because these devices offer simultaneously high performance, compact size and low cost. The optimization of the device structure requires a quantitative understanding of energy conversion and loss mechanisms. Here we use stroboscopic full-field diffraction x-ray microscopy to reveal an unanticipated acoustic loss in a prototypical one-port resonator device. A non-uniform acoustic excitation in the active area was responsible for the substantial end and side leakages observed at the design frequency. Quantitative analysis of the strain amplitude using a wave decomposition method allowed the determination of several key device parameters. This high-resolution high-throughput spatiotemporal strain imaging technique is more generally applicable to the study of dynamic strain modulation in nanoscale acoustic, electronic, optical and quantum devices. The high sensitivity allows precise measurement of the strain modulation with picometer-scale amplitude.

Zhou, Tao [ESRF - The European Synchrotron, Grenob↗
DOE OSTI2018

Phase separation at the dimer-superconductor transition in Ir 1-x Rh x Te 2

The detailed evolution of the local atomic structure across the (x, T) phase diagram of transition metal dichalcogenide superconductor Ir 1–x Rh x Te 2 (0≤x≤0.3, 10 K≤T≤300 K) is obtained from high quality x-ray diffraction data using the atomic pair distribution function (PDF) method. Observed hysteretic thermal structural phase transition from trigonal (P3¯m1) to triclinic (P1¯) dimer phase for low Rh content emphasizes intimate connection between the lattice and electronic properties. For superconducting samples away from the dimer/superconductor phase boundary structural transition is absent and the local structure remains trigonal down to 10 K. In the narrow range of compositions close to the boundary PDF analysis reveals structural phase separation, suggestive of weak first order character of the Rh-doping induced dimer-superconductor quantum phase transition. Samples from this narrow range show weak anomalies in electronic transport and magnetization, hallmarks of the dimer phase, as well as superconductivity albeit with incomplete diamagnetic screening. Furthermore, results suggest that the dimer and superconducting orders exist in the mutually exclusive spatial regions

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2010

NASA Tech Briefs, September 2010

Topics covered include: Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures; Multi-Axis Accelerometer Calibration System; Pupil Alignment Measuring Technique and Alignment Reference for Instruments or Optical Systems; Autonomous System for Monitoring the Integrity of Composite Fan Housings; A Safe, Self-Calibrating, Wireless System for Measuring Volume of Any Fuel at Non-Horizontal Orientation; Adaptation of the Camera Link Interface for Flight-Instrument Applications; High-Performance CCSDS Encapsulation Service Implementation in FPGA; High-Performance CCSDS AOS Protocol Implementation in FPGA; Advanced Flip Chips in Extreme Temperature Environments; Diffuse-Illumination Systems for Growing Plants; Microwave Plasma Hydrogen Recovery System; Producing Hydrogen by Plasma Pyrolysis of Methane; Self-Deployable Membrane Structures; Reactivation of a Tin-Oxide-Containing Catalys; Functionalization of Single-Wall Carbon Nanotubes by Photo-Oxidation; Miniature Piezoelectric Macro-Mass Balance; Acoustic Liner for Turbomachinery Applications; Metering Gas Strut for Separating Rocket Stages; Large-Flow-Area Flow-Selective Liquid/Gas Separator; Counterflowing Jet Subsystem Design; Water Tank with Capillary Air/Liquid Separation; True Shear Parallel Plate Viscometer; Focusing Diffraction Grating Element with Aberration Control; Universal Millimeter-Wave Radar Front End; Mode Selection for a Single-Frequency Fiber Laser; Qualification and Selection of Flight Diode Lasers for Space Applications; Plenoptic Imager for Automated Surface Navigation; Maglev Facility for Simulating Variable Gravity; Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection; High-Speed Operation of Interband Cascade Lasers; 3D GeoWall Analysis System for Shuttle External Tank Foreign Object Debris Events; Charge-Spot Model for Electrostatic Forces in Simulation of Fine Particulates; Hidden Statistics Approach to Quantum Simulations; Reconstituted Three-Dimensional Interactive Imaging; Determining Atmospheric-Density Profile of Titan; Digital Microfluidics Sample Analyzer; Radiation Protection Using Carbon Nanotube Derivatives; Process to Selectively Distinguish Viable from Non-Viable Bacterial Cells; and TEAMS Model Analyzer.

Source record↗
DOE OSTI2019

Low-Temperature Rotational Tunneling of Tetrahydroborate Anions in Lithium Benzimidazolate-Borohydride Li 2 (bIm)BH 4

To investigate the dynamical properties of the novel hybrid compound, lithium benzimidazolate-borohydride Li 2 (bIm)BH 4 (where bIm denotes a benzimidazolate anion, C 7 N 2 H 5 - ), we have used a set of complementary techniques: neutron powder diffraction, ab initio density functional theory calculations, neutron vibrational spectroscopy, nuclear magnetic resonance, neutron spin echo, and quasi-elastic neutron scattering. Our measurements performed over the temperature range from 1.5 to 385 K have revealed the exceptionally fast low-temperature reorientational motion of BH 4 - anions. This motion is facilitated by the unusual coordination of tetrahedral BH 4 - anions in Li2(bIm)BH4: each anion has one of its H atoms anchored within a nearly square hollow formed by four coplanar Li+ cations, while the remaining -BH 3 fragment extends into a relatively open space, being only loosely coordinated to other atoms. As a result, the energy barriers for reorientations of this fragment around the anchored B-H bond axis are very small, and at low temperatures, this motion can be described as rotational tunneling. The tunnel splitting derived from the neutron spin echo measurements at 3.6 K is 0.43(2) ueV. With increasing temperature, we have observed a gradual transition from the regime of low-temperature quantum dynamics to the regime of classical thermally activated jump reorientations. The jump rate of the uniaxial 3-fold reorientations reaches 5 x 10 11 s -1 at 80 K. Nearer room temperature and above, both nuclear magnetic resonance and quasi-elastic neutron scattering measurements have revealed the second process of BH4- reorientations characterized by the activation energy of 261 meV. This process is several orders of magnitude slower than the uniaxial 3-fold reorientations; the corresponding jump rate reaches ~7 x 10 8 s -1 at 300 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Plasmonic Nonlinear Energy Transfer Enhanced Second Harmonic Generation Nanoscopy

Nonlinear optical response is a fingerprint of various physicochemical properties of materials related to symmetry, including crystallography, interfacial configuration, and carrier dynamics. However, the intrinsically weak nonlinear optical susceptibility and the diffraction limit of far-field optics restrict probing deep-subwavelength-scale nonlinear optics with measurable signal-to-noise ratio. Here, we propose an alternative approach toward efficient second harmonic generation (SHG) nanoscopy for SHG-active sample (zinc oxide nanowire; ZnO NW) using an SHG-active plasmonic nanotip. Our full-wave simulation suggests that the experimentally observed high near-field SHG contrast is possible when the nonlinear response of ZnO NW is enhanced and/or that of the tip is suppressed. Here, this result suggests possible evidence of quantum mechanical nonlinear energy transfer between the tip and the sample, modifying the nonlinear optical susceptibility. Further, this process probes the nanoscale corrosion of ZnO NW, demonstrating potential use in studying various physicochemical phenomena in nanoscale resolution.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Double-Layer Kagome Metals Pt 3 Tl 2 and Pt 3 In 2

The connectivity and inherent frustration of the kagome lattice can produce interesting electronic structures and behaviors in compounds containing this structural motif. Here we report the properties of Pt 3 X 2 (X = In and Tl) that adopt a double-layer kagome net structure related to that of the topologically nontrivial high-temperature ferromagnet Fe 3 Sn 2 and the density wave hosting compound V 3 Sb 2 . We examined the structural and physical properties of single crystal Pt 3 Tl 2 and polycrystalline Pt 3 In 2 using X-ray and neutron diffraction, magnetic susceptibility, heat capacity, and electrical transport measurements, along with density functional theory calculations of the electronic structure. Our calculations show that Fermi levels lie in pseudogaps in the densities of states with several bands contributing to transport, and this is consistent with our Hall effect, magnetic susceptibility, and heat capacity measurements. Although electronic dispersions, characteristic of simple kagome nets with nearest-neighbor hopping, are not clearly seen, likely due to the extended nature of the Pt 5d states, we do observe moderately large and non-saturating magnetoresistance values and quantum oscillations in the magnetoresistance and magnetization associated with the kagome nets of Pt.

36 MATERIALS SCIENCE↗