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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.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Iron and aluminum interaction with amyloid-beta peptides associated with Alzheimer’s disease

An elevation in the concentration of heavy metal ions in Alzheimer’s disease (AD) brain has been demonstrated in many studies. Aβ precipitation and toxicity in AD brains seem to be caused by abnormal interactions with neocortical metal ions, especially iron, copper, zinc, and aluminum [1–3]. There is increasing evidence that iron and aluminum ions are involved in the mechanisms that underlie the neurodegenerative diseases [4,5]. However, evidence was brought to demonstrate that some Aβ fragments, at physiological pH, are not able to form binary complexes with Fe(III) ions of sufficient stability to compete with metal hydroxide precipitation [6]. On the contrary, multiple metal ions are known to interact with Aβ peptides [7]. Consequently, we investigated here the interaction of Fe(II/III) and Al(III) ions with some amyloid-β peptides and fragments that results in peptide aggregation and fibrillation [8,9]. Infrared spectroscopy, atomic force microscopy, scanning electron microscopy, electrophoresis and mass spectrometry demonstrated conformational changes of peptides in the presence of such metals.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Electronic cigarette aerosols and copper nanoparticles induce mitochondrial stress and promote DNA fragmentation in lung fibroblasts

Oxidants or nanoparticles have recently been identified as constituents of aerosols released from various styles of electronic cigarettes (E-cigs). Cells in the lung may be directly exposed to these constituents and harbor reactive properties capable of incurring acute cell injury. Our results show mitochondria are sensitive to both E-cig aerosols and aerosol containing copper nanoparticles when exposed to human lung fibroblasts (HFL-1) using an Air-Liquid Interface culture system, evident by elevated levels of mitochondrial ROS (mtROS). Increased mtROS after aerosol exposure is associated with reduced stability of OxPhos electron transport chain (ETC) complex IV subunit and nuclear DNA fragmentation. Increased levels of IL-8 and IL-6 in HFL-1 conditioned media were also observed. These findings reveal both mitochondrial, genotoxic, and inflammatory stresses are features of direct cell exposure to E-cig aerosols which are ensued by inflammatory duress, raising a concern on deleterious effect of vaping. - Graphical abstract: Oxidants and possibly reactive properties of metal particles in E-cig aerosols impart mitochondrial oxidative stress and DNA damage. These biological effects accompany inflammatory response which may raise concern regarding long term E-cig use. Mitochondria may be particularly sensitive to reactive properties of E-cig aerosols in addition to the potential for them to induce genotoxic stress by generating increased ROS. - Highlights: • Mitochondria are sensitive to both E-cig aerosols and metal nanoparticles. • Increased mtROS by E-cig aerosol is associated with disrupted mitochondrial energy. • E-cig causes nuclear DNA fragmentation. • E-cig aerosols induce pro-inflammatory response in human fibroblasts.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Effect of amine type on acidic toxic gas adsorption at ambient conditions on modified CuBTC

We report two amine-modified copper-based Metal Organic Frameworks (MOF (CuBTC)) of different surface chemical and textural features were synthesized and used as adsorbents of acidic toxic gases (NO 2 and H 2 S) in both moist (71% relative humidity (R.H.)) and dry conditions. The initial and exhausted samples were characterized by nitrogen adsorption, powder X-ray diffraction, scanning electron microscopy, thermal gravimetric analysis and Fourier transform infrared spectroscopy. The addition of melamine prevented full growth of CuBTC crystals and resulted in amorphous-like particles with sizes less than 200 nm. The material was non-porous with a small surface area. When urea was used as an amine source, the resulting particles maintained the overall octahedral shape of the parent CuBTC MOF and the material was more porous than the parent MOF. While the urea-modified CuBTC sample performed well as an NO 2 adsorbent in the presence of moisture, the reactivity of the melamine-modified sample and its physical properties provided a favorable environment for the removal of H 2 S. The incorporation of amines into the MOF structure also resulted in surface defects /open copper sites that favored the removal of toxic gases in dry conditions. The reactivity of the adsorbents with toxic gases was demonstrated by the changes in the adsorbent colors, in texture, and in surface chemistry (organic salts, complexes, sulfides and nitrates were formed).

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

Frontier methods in coherent X-ray diffraction for high-resolution structure determination

Abstract In 1912, Max von Laue and collaborators first observed diffraction spots from a millimeter-sized crystal of copper sulfate using an X-ray tube. Crystallography was born of this experiment, and since then, diffraction by both X-rays and electrons has revealed a myriad of inorganic and organic structures, including structures of complex protein assemblies. Advancements in X-ray sources have spurred a revolution in structure determination, facilitated by the development of new methods. This review explores some of the frontier methods that are shaping the future of X-ray diffraction, including coherent diffractive imaging, serial femtosecond X-ray crystallography and small-angle X-ray scattering. Collectively, these methods expand the current limits of structure determination in biological systems across multiple length and time scales.

Biophysics↗
DOE OSTI2017

Hybrid-Functional Calculations of the Copper Impurity in Silicon

We calculate formation energies and transition levels for copper-related defects in silicon using the screened hybrid functional of Heyd, Scuseria, and Ernzerhof HSE06. We consider Cu siting on interstitial sites ( Cu i ), a substitutional site ( Cu Si ), a Cu Si - Cu i pair, a complex formed from substitutional Cu and interstitial hydrogen ( Cu Si - H i ), and a complex formed from a substitutional Cu and three interstitial Cu atoms ( Cu Si - 3 Cu i ). We find that Cu i is a fast diffuser, with a migration barrier of only 0.19 eV, in good agreement with experimental values. Cu i is a shallow donor and its formation energy is lower than that of Cu Si for all Fermi-level positions in the band gap. Cu Si , on the other hand, induces levels in the gap which are related to the occupation of antibonding states originating from the coupling between the Cu 3 d states ( t 2 ( d ) ), resonant in the valence band, and the vacancy-induced gap states ( t 2 ( p ) ). The stable charge states of Cu Si in the gap are + 1 , 0, - 1 , and - 2 . The transition levels of Cu Si - Cu i and Cu Si - H i are closely related to the levels of isolated Cu Si : a donor level ( + / 0 ) near the valence band, an acceptor level near midgap, and a double-acceptor level in the upper part of the gap. Overall, the calculated transition levels are in good agreement with experimental results, and the formation energies explain the observed solubility.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

In-situ angle-resolved photoemission spectroscopy of copper-oxide thin films synthesized by molecular beam epitaxy

We present that angle-resolved photoemission spectroscopy (ARPES) is the key momentum-resolved technique for direct probing of the electronic structure of a material. However, since it is highly surface-sensitive, it has been applied to a relatively small set of complex oxides that can be easily cleaved in ultra-high vacuum. Here we describe a new multi-module system at Brookhaven National Laboratory (BNL) in which an oxide molecular beam epitaxy (OMBE) is interconnected with an ARPES and a spectroscopic-imaging scanning tunneling microscopy (SI-STM) module. This new capability largely expands the range of complex-oxide materials and artificial heterostructures accessible to these two most powerful and complementary techniques for studies of electronic structure of materials. Lastly, we also present the first experimental results obtained using this system — the ARPES studies of electronic band structure of a La 2-x Sr x CuO 4 (LSCO) thin film grown by OMBE.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Carbon Redistribution and Carbide Precipitation in a High-Strength Low-Carbon HSLA-115 Steel Studied on a Nanoscale by Atom Probe Tomography

HSLA-115 is a newly developed Cu-bearing high-strength low-carbon martensitic steel for use in Naval structural applications. This research provides, for the first time, a comprehensive compositional analysis of carbon redistribution and associated complex phase transformations in an isothermal aging study of HSLA-115 at 823 K (550 °C). Specifically, we characterize carbon segregation at lath boundaries, grain-refining niobium carbonitrides, cementite, and secondary hardening M2C carbides, in addition to copper precipitation, by 3D atom probe tomography (APT). Segregation of carbon (3 to 6 at. pct C) is observed at martensitic lath boundaries in the as-quenched and 0.12-hour aged microstructures. On further aging, carbon redistributes itself forming cementite and M2C carbides. Niobium carbonitride precipitates do not dissolve during the austenitizing treatment and are inherited in the as-quenched and aged microstructures; these are characterized along with cementite by synchrotron X-ray diffraction and APT. Sub-nanometer-sized M2C carbide precipitates are observed after the formation of Cu precipitates, co-located with the latter, indicating heterogeneous nucleation of M2C. The temporal evolution of the composition and morphology of M2C carbides at 823 K (550 °C) is described using APT; their precipitation kinetics is intertwined with Cu precipitates, affecting the bulk mechanical properties of HSLA-115. Phase compositions determined by APT are compared with computed compositions at thermodynamic equilibrium using ThermoCalc.

36 MATERIALS SCIENCE↗
NASA NTRS2000

Vacuum Plasma Spray of CuCrNb Alloy for Advanced Liquid - Fuel Combustion Chambers

The copper-8 atomic percent chromium-4 atomic percent niobium (CuCrNb) alloy was developed by Glenn Research Center (formally Lewis Research Center) as an improved alloy for combustion chamber liners. In comparison to NARloy-Z, the baseline (as in Space Shuttle Main Engine) alloy for such liners, CuCrNb demonstrates mechanical and thermophysical properties equivalent to NARloy-Z, but at temperatures 100 C to 150 C (180 F to 270 F) higher. Anticipated materials related benefits include decreasing the thrust cell liner weight 5% to 20%, increasing the service life at least two fold over current combustion chamber design, and increasing the safety margins available to designers. By adding an oxidation and thermal barrier coating to the liner, the combustion chamber can operate at even higher temperatures. For all these benefits, however, this alloy cannot be formed using conventional casting and forging methods because of the levels of chromium and niobium, which exceed their solubility limit in copper. Until recently, the only forming process that maintains the required microstructure of CrNb intermetallics is powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. Vacuum plasma spray (VPS) has been demonstrated as a method to form structural articles including small combustion chambers from the CuCrNb alloy. In addition, an oxidation and thermal barrier layer can be formed integrally on the hot wall of the liner that improve performance and extend service life. This paper discusses the metallurgy and thermomechanical properties of VPS formed CuCrNb versus the baseline powder metallurgy process, and the manufacturing of small combustion chamber liners at Marshall Space Flight Center using the VPS process. The benefits to advanced propulsion initiatives of using VPS to fabricate combustion chamber liners while maintaining the superior CuCrNb properties are also presented.

Zimmerman, Frank↗
NASA NTRS2003

Vacuum Plasma Spray Forming of Copper Alloy Liners for Regeneratively Cooled Liquid Rocket Combustion Chambers

Vacuum plasma spray (VPS) has been demonstrated as a method to form combustion chambers from copper alloys NARloy-Z and GRCop-84. Vacuum plasma spray forming is of particular interest in the forming of CuCrNb alloys such as GRCop-84, developed by NASA s Glenn Research Center, because the alloy cannot be formed using conventional casting and forging methods. This limitation is related to the levels of chromium and niobium in the alloy, which exceed the solubility limit in copper. Until recently, the only forming process that maintained the required microstructure of CrNb intermetallics was powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. This paper discusses the techniques used to form combustion chambers from CuCrNb and NARloy-Z, which will be used in regeneratively cooled liquid rocket combustion chambers.

Zimmerman, Frank↗
DOE OSTI2017

Copper coordination polymers constructed from thiazole-5-carboxylic acid: Synthesis, crystal structures, and structural transformation

We have successfully prepared crystals of thiazole-5-carboxylic acid (5-Htza) (L) and three new thiazole-5-carboxylate-based Cu{sup 2+} coordination polymers with different dimensionality, namely, 1D [Cu{sub 2}(5-tza){sub 2}(1,10-phenanthroline){sub 2}(NO{sub 3}){sub 2}] (1), 2D [Cu(5-tza){sub 2}(MeOH){sub 2}] (2), and 3D [Cu(5-tza){sub 2}]·H{sub 2}O (3). These have been characterized by single crystal X-ray diffraction and thermogravimetry. Interestingly, the 2D network structure of 2 can directly transform into the 3D framework of 3 upon removal of methanol molecules at room temperature. 2 can also undergo structural transformation to produce the same 2D network present in the known [Cu(5-tza){sub 2}]·1.5H{sub 2}O upon heat treatment for 2 h. This 2D network can adsorb water and convert to 3 upon exposure to air. - Highlights: • Rare examples of coordination polymers of thiazole-5-carboxylic acid were prepared. • Non-covalent interactions play a key role on the assembly of the complexes in solid state. • Structural transformation of a 2D framework to a 3D upon removal of methanol is observed.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Surface Induced Dissociation Coupled with High Resolution Mass Spectrometry Unveils Heterogeneity of a 211 kDa Multicopper Oxidase Protein Complex

Manganese oxidation is an important biogeochemical process that is largely regulated by bacteria through enzymatic reactions. However, the detailed mechanism is poorly understood due to challenges in isolating and characterizing these unknown enzymes. A manganese oxidase, Mnx, from Bacillus sp. PL-12 has been successfully overexpressed in active form as a protein complex with a molecular mass of 211 kDa. We have recently used surface induced dissociation (SID) and ion mobility-mass spectrometry (IM-MS) to release and detect folded subcomplexes for determining subunit connectivity and quaternary structure. The data from the native mass spectrometry experiments led to a plausible structural model of this multicopper oxidase, which has been difficult to study by conventional structural biology methods. It was also revealed that each Mnx subunit binds a variable number of copper ions. Becasue of the heterogeneity of the protein and limited mass resolution, ambiguities in assigning some of the observed peaks remained as a barrier to fully understanding the role of metals and potential unknown ligands in Mnx. In this study, we performed SID in a modified Fourier transform-ion cyclotron resonance (FTICR) mass spectrometer. The high mass accuracy and resolution offered by FTICR unveiled unexpected artificial modifications on the protein that had been previously thought to be iron bound species based on lower resolution spectra. Additionally, isotopically resolved spectra of the released subcomplexes revealed the metal binding stoichiometry at different structural levels. This method holds great potential for in-depth characterization of metalloproteins and protein–ligand complexes. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

An Historic Perspective of NPDES Individual Permit for Storm Water Discharges from Solid Waste Management Units at Los Alamos National Laboratory - 18667

The Los Alamos National Laboratory (LANL) and the associated communities of Los Alamos and White Rock are located in Los Alamos County in north-central New Mexico approximately 60 mi north-northeast of Albuquerque and 25 mi northwest of Santa Fe. The 36-mi{sup 2} facility is situated on the Pajarito Plateau, which consists of a series of fingerlike mesas separated by deep east-to-west oriented canyons cut by predominately ephemeral and intermittent streams. The mesa tops range in elevation from approximately 7800 ft. on the flanks of the Jemez Mountains to about 6200 ft. at their eastern termination above the Rio Grande Canyon. The land surrounding the Laboratory is largely undeveloped. Public access to much of the facility is limited for safety and security reasons. Large tracts of surrounding land are held by the U.S. Forest Service (Santa Fe National Forest), the Bureau of Land Management (Bandelier National Monument), the General Services Administration and San Ildefonso Pueblo. Storm water discharges from Solid Waste Management Units (SWMUs) have been regulated at the LANL since the early 1990's and have evolved into an Individual Stormwater Permit (IP) that may be one of the most complex in the nation. Historically, storm water discharges from SWMUs at LANL were regulated under a nationwide general permit using a watershed based approach requiring a Storm Water Pollution Prevention Plan (SWPPP), monitoring at sub-watershed scale 'USGS like' gage stations, and inspection and maintenance of erosion controls. In 2001, the Cerro Grande Fire destroyed many Laboratory structures, residential homes and over 80,000 acres of forested lands in the upper watershed above Los Alamos that significantly changed the local hydrology. Several years later, a Federal Facilities Compliance Agreement (FFCA) was issued by U.S. Environmental Protection Agency (USEPA) that was followed by a Clean Water Act lawsuit filed by concerned citizens, the result of which required more focus on stormwater discharges from individual SWMUs and an IP covering over 400 Sites. The IP contains non-numeric technology-based effluent limitations, coupled with a comprehensive, coordinated inspection and monitoring program, to minimize pollutants in LANL's storm water discharges associated with historical industrial activities from specified Sites. Non-numeric technology-based effluent limitations include minimizing pollutants in discharges through erosion and sedimentation controls, management of run-on and runoff, employee training, inspection and maintenance of controls, annual reporting and public involvement. The IP establishes Target Action Levels (TALs) that are equivalent to New Mexico State water-quality criteria. These TALs are used as benchmarks to determine the effectiveness of control measures implemented under the IP. That is, storm water quality sample results from SWMU discharges are compared with applicable TALs. If one or more sample results exceed a TAL, LANL must take additional corrective action. The TAL results are also confounded by high levels of naturally occurring constituents such as aluminum and gross alpha, and urban constituents such as copper, zinc and PCBs which may not be a source from the regulated SWMU. Due to the remote rugged terrain, security access issues, number of monitoring locations, stringent TALs, reporting requirements and public involvement requirements, this permit is likely one of the most stringent and complex in the country. The Laboratory has implemented this permit in a compliant manner for the past seven years and is anticipating the issuance of a new permit in the next few months. This paper will cover permit requirements related to control measure installations, monitoring, reporting and public involvement as well as process improvements and remaining water quality initiatives such as developing studies to address issues such as discriminating between natural background levels and LANL-related contaminants during the execution of this unique permit. (author)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Residue Specific Characterization of Electrostatics, Conformational Heterogeneity, and Dynamics of Electron Transfer Proteins with Linear and Nonlinear Infrared Spectroscopy. Final Report

The goal of this research project was to further our understanding of biological electron transfer through the development and application of new methods for studying proteins and their complexes with high spatial and temporal detail. The approach was based on incorporation of reporter bonds with distinct vibrational frequencies at specific locations in proteins and their characterization through the interaction of the bonds with pulses of infrared light. The project focused on the proteins plastocyanin (Pc) and cytochrome (cyt) f, two electron transfer partners in photosynthesis. The first thrust of the project was the incorporation of carbon deuterium bonds as non-perturbative probes at a ligand to the copper ion of Pc and their use to detect changes in the bonding due to the number of electrons at the metal and how the bonding changes upon association with cyt f. Toward developing more advanced approaches to characterize proteins, we incorporated a stronger reporter, the cyano group of cyanophenylalanine, at several locations in Pc and measured the frequency dynamics in the absence and presence of cyt f. The acquired data improved the current model for the protein complex. Notably, the data indicated that the majority of the population is involved in a loosely bound complex, providing insight into the nature of the ensembles formed by electron transfer protein complexes that is not available via other approaches. In addition to learning about the protein complex, we made strides toward developing and improving the new experimental approach to study highly dynamic behaviors of proteins.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Health Risk Assessment Associated with Abandoned Copper and Uranium Mine Tailings

This study aims to investigate the dose rate and pollution level of Ciudanovita, Lisava, Anina, and Moldova Noua mining tailing dumps. In order to accomplish this, soil samples were collected according to LUCAS 2009/2012, in the summer of 2017. To start with, these samples were measured in situ for dose rate and revealed some interesting aspects, following this, they were investigated in the laboratory using different physico-chemical methods for more complex data. Therefore, two techniques have been used for structural investigation that revealed some particularities in terms of morphology, color and shape (optical microscopy, scanning electron microscopy) and, two for chemical composition (Fourier transform infrared spectroscopy and inductive coupled plasma mass spectrometry), which provided the qualitative confirmation of chemical groups involved in soil composition along with the heavy and radioactive metals presence (i.e. Pb, U, Cu, Cr, Cd, Ni, Zn, and Mn), expressed also by contamination factor.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Advances in understanding vacuum break dynamics in liquid helium-cooled tubes for accelerator beamline applications

Understanding air propagation and condensation following a catastrophic vacuum break in particle accelerator beamlines cooled by liquid helium is essential for ensuring operational safety. This review summarizes experimental and theoretical work conducted in our cryogenics lab to address this issue. Systematic measurements were performed to study nitrogen gas propagation in uniform copper tubes cooled by both normal liquid helium (He I) and superfluid helium (He II). These experiments revealed a nearly exponential deceleration of the gas front, with stronger deceleration observed in He II-cooled tubes. To interpret these results, a one-dimensional (1D) theoretical model was developed, incorporating gas dynamics, heat transfer, and condensation mechanisms. The model successfully reproduced key experimental observations in the uniform tube system. However, recent experiments involving a bulky copper cavity designed to mimic the geometry of a superconducting radiofrequency (SRF) cavity revealed strong anisotropic flow patterns of nitrogen gas within the cavity, highlighting limitations in extrapolating results from simplified tube geometries to real accelerator beamlines. To address these complexities, we outline plans for systematic studies using tubes with multiple bulky cavities and the development of a two-dimensional (2D) model to simulate gas dynamics in these more intricate configurations. As a result, these efforts aim to provide a comprehensive understanding of vacuum breaks in particle accelerators and improve predictive capabilities for their operational safety.

Beamline tube↗
DOE OSTI2014

Syntheses, structures, molecular and cationic recognitions and catalytic properties of two lanthanide coordination polymers based on a flexible tricarboxylate

Two lanthanide coordination polymers, namely, ([La(TTTA)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (La-TTTA) and [Nd(TTTA)(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (Nd-TTTA) have been hydrothermally synthesized through the reaction of lanthanide ions (La{sup 3+} and Nd{sup 3+}) with the flexible tripodal ligand 2,2′,2″-[1,3,5-triazine-2,4,6-triyltris(thio)]tris-acetic acid (H{sub 3}TTTA). La-TTTA and Nd-TTTA are isostructural and both show three dimensional structures. La-TTTA and Nd-TTTA show good recognition of amine molecules via quenching the luminescent intensities in amines emulsions. They can also recognize Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Cr{sup 3+} and Co{sup 2+} ions with the quenching the peak around 361 nm when the compounds immersed in ionic solutions. The two compounds act as efficient Lewis acid catalysts for the cyanosilylation of benzaldehyde and derivatives in high yields shortly due to the strong Lewis acidity and the possible open sites of the lanthanide ions. - Graphical abstract: We have synthesized two isostructural 3D compounds based on H{sub 3}TTTA. They are chemical sensor of amine solvents and cations. They have higher yields and TOFs to catalyze cyanosilylation reactions. - Highlights: • The compounds show recognition of amine molecules via quenching luminescent intensities. • The compounds recognize Fe{sup 3+}, Cu{sup 2+}, Mg{sup 2+}, Cr{sup 3+} and Co{sup 2+} ions via quenching the peak around 361 nm. • They act as efficient Lewis acid catalysts for the cyanosilylation reactions in high yields.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Structural, Bulk Permittivity, and Magnetic Properties of Lead-Free Electronic Material: Ba{sub 1}Bi{sub 1}Cu{sub 1}Fe{sub 1}Ni{sub 1}Ti{sub 3}O{sub 12}

In this report, Ba{sub 1}Bi{sub 1}Cu{sub 1}Fe{sub 1}Ni{sub 1}Ti{sub 3}O{sub 12} (BBCFNTO termed further) ceramics were synthesized using a conventional ceramic processing route. The formation of multiple phases has been confirmed from by the XRD pattern at room temperature. The surface micrograph indicates the uniform distribution of grains with distinct grain boundary. The co-relation between the impedance and dielectric parameters was realized by using a phase sensitive meter over a good temperature and frequency range. The temperature- and frequency-dependent dielectric properties are linked to the conduction mechanism. The dielectric constant (K) and loss (tanδ) are increased sharply at high-temperature region, which is expected to be the onset of dipolar relaxation phenomena. The contribution of grain boundary (GBs) and grain (Gs) effects can be identified using the complex impedance spectroscopy. This synthesized material is investigated to model multifunctional devices.

36 MATERIALS SCIENCE↗