A5005850270- Ferroelectric and Piezoelectric Materials
- Acoustic Wave Resonator Technologies
- Semiconductor materials and devices
- Electronic and Structural Properties of Oxides
- Microwave Dielectric Ceramics Synthesis
- High Entropy Alloys Studies
- Plasmonic and Surface Plasmon Research
- ZnO doping and properties
- GaN-based semiconductor devices and materials
- Multiferroics and related materials
- Thermal properties of materials
- High-Temperature Coating Behaviors
- Metal and Thin Film Mechanics
- Thermal Radiation and Cooling Technologies
- Advanced materials and composites
- Advanced ceramic materials synthesis
- Ferroelectric and Negative Capacitance Devices
- Magnetic and transport properties of perovskites and related materials
- Gold and Silver Nanoparticles Synthesis and Applications
- Ga2O3 and related materials
- Metamaterials and Metasurfaces Applications
- High-pressure geophysics and materials
- Dielectric properties of ceramics
- Advanced Materials Characterization Techniques
- Advancements in Semiconductor Devices and Circuit Design
Pennsylvania State University
2001-2025
Carnegie Mellon University
2024
MSSCORPS (Taiwan)
2024
Millennium Engineering and Integration (United States)
2023
The University of Texas at Dallas
2023
Center for Dielectrics & Piezoelectrics
2014-2022
Colorado School of Mines
2022
James Madison University
2022
University of Virginia
2022
North Carolina State University
2012-2021
Abstract Configurational disorder can be compositionally engineered into mixed oxide by populating a single sublattice with many distinct cations. The formulations promote novel and entropy-stabilized forms of crystalline matter where metal cations are incorporated in new ways. Here, through rigorous experiments, simple thermodynamic model, five-component formulation, we demonstrate beyond reasonable doubt that entropy predominates the landscape, drives reversible solid-state transformation...
Manipulating a crystalline material's configurational entropy through the introduction of unique atomic species can produce novel materials with desirable mechanical and electrical properties. From thermal transport perspective, large differences between elemental properties such as mass interatomic force reduce rate at which phonons carry heat thus conductivity. Recent advances in synthesis are enabling fabrication entropy-stabilized ceramics, opening door for understanding implications...
We report the initial observation of surface plasmon resonance (SPR) in a conducting metal oxide thin film. The SPR phenomenon has been observed by attenuated total reflection near-infrared radiation and is agreement with electron energy loss spectroscopy measurements. To date, only metals are known to exhibit noble have practical application. According theory should be observable any conductor. This theoretical prediction verified present study. compositions many oxides systematically...
Cold sintering is an unusually low-temperature process that uses a transient transport phase, which most often liquid, and applied uniaxial force to assist in densification of powder compact. By using this approach, many ceramic powders can be transformed high-density monoliths at temperatures far below the melting point. In article, we present summary cold accomplishments current working models describe operative mechanisms context other strategies for densification. Current observations...
Abstract Entropy‐stabilized oxides (ESOs) provide an alternative route to novel materials discovery and synthesis. It is, however, a challenge demonstrate that the constituent elements in entropy‐stabilized crystal are homogeneously randomly dispersed among particular sublattice, resulting true solid solution with no evidence of local order or clustering. In this work, we present application analysis extended X‐ray absorption fine structure (EXAFS) on prototype ESO composition Mg x Ni Co Cu...
Ferroelectric materials are well‐suited for a variety of applications because they can offer combination high performance and scaled integration. Examples note include piezoelectrics to transform between electrical mechanical energies, capacitors used store charge, electro‐optic devices, nonvolatile memory storage. Accordingly, widely as sensors, actuators, energy storage, components, ultrasonic in consumer electronics products. Because these functional properties arise from...
We demonstrate ferroelectricity in Mg-substituted ZnO thin films with the wurtzite structure. Zn1−xMgxO are grown by dual-cathode reactive magnetron sputtering on (111)-Pt // (0001)-Al2O3 substrates at temperatures ranging from 26 to 200 °C for compositions spanning x = 0 0.37. X-ray diffraction indicates a decrease c-lattice parameter and an increase a-lattice increasing Mg content, resulting nearly constant c/a axial ratio of 1.595 over this composition range. Transmission electron...
The need for improved functionalities in extreme environments is fuelling interest high-entropy ceramics
Ferroelectric wurtzites have the potential to revolutionize modern microelectronics because they are easily integrated with multiple mainstream semiconductor platforms. However, electric fields required reverse their polarization direction and unlock electronic optical functions need substantial reduction for operational compatibility complementary metal-oxide (CMOS) electronics. To understand this process, we observed quantified real-time switching of a representative ferroelectric wurtzite...
Abstract High‐entropy materials defy historical design paradigms by leveraging chemical disorder to kinetically stabilize novel crystalline solid solutions comprised of many end‐members. Formulational diversity results in local crystal structures that are seldom found conventional and can strongly influence macroscopic physical properties. Thermodynamically prescribed flexibility provides a means tune such Additionally, kinetic metastability possible atomic arrangements, including both...
A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency from 2.44 to 2.88 GHz (16% tuning) while achieving 1-dB bandwidth 400 MHz. The insertion loss 5.1 dB at zero 3.3 full bias, return exceeded 13 over range. intercept was found be 41 dBm.
Tunable lowpass and bandpass lumped-element filters employing barium-strontium-titanate (BST)-based capacitors are presented. A new metallization technique is used, which improves the quality factor of tunable BST by a two. The filter has an insertion loss 2 dB tunability 40% (120-170 MHz) with application 0-9 V DC bias. (BPF) 3 57% (176-276 0-6 DC. third-order intercept point BPF was measured to be 19 dBm two tones around 170 MHz.
The temperature and thickness dependence of permittivity (Ba,Sr)TiO3 has been investigated. films were deposited by liquid-source metalorganic chemical vapor deposition onto Pt/SiO2/Si, with thicknesses ranging from 15 to 580 nm. dielectric response was measured 100 520 K. As film decreased, the maximum constant at which occurred peak in became more diffuse. A model incorporating a independent interior nonferroelectric surface cannot account for these dependencies. To appropriately...
The evolution of polariton features with increasing thickness in p-polarized (TM) reflectance spectra indium tin oxide (ITO) thin films deposited on BK7 glass reveals the nature plasmons conducting without interference from band-to-band transitions or tendency very to form islands, both which are complicating factors noble metals Au and Ag. Although dependence energy, film thickness, angle incidence is complex, these accurately described by three-phase (substrate/overlayer/ambient) Fresnel...
Density functional theory calculations were carried out for three entropic rocksalt oxides, (Mg0.1Co0.1Ni0.1Cu0.1Zn0.1)O0.5, termed J14, and J14 + Li Sc, to understand the role of charge neutrality electronic states on their properties, probe whether simple expressions may exist that predict stability. The average lattice constants ternary structures provide good approximations random structures. For Bader charges are transferable between binary, ternary, Sc Li, in can be estimated from...
This work introduces oxidative molecular layer deposition (oMLD) as a chemical route to synthesize highly conductive and conformal poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via sequential vapor exposures of molybdenum(V) chloride (MoCl5, oxidant) ethylene dioxythiophene (EDOT, monomer) precursors. The growth temperature strongly affects PEDOT's crystalline structure electronic conductivity. Films deposited at ∼150 °C exhibit textured structure, with {010} planes aligned parallel...
This manuscript reports the temperature dependence of ferroelectric switching in Al0.84Sc0.16N, Al0.93B0.07N, and AlN thin films. Polarization reversal is demonstrated all compositions strongly dependent. Between room 300 °C, coercive field drops by almost 50% samples, while there was very small remanent polarization value. Over this same range, relative permittivity increased between 5% 10%. confirmed piezoelectric coefficient analysis chemical etching. Applying intrinsic/homogeneous models...
In this report we demonstrate fluorine-doped CdO as a model infrared plasmonic material by virtue of its tunable carrier density, high mobility, and intense extreme-subwavelength plasmon–polariton coupling. Carrier concentrations ranging from 1019 to 1020 cm–3, with electron mobility values 473 cm2/V·s, are readily achieved in epitaxial films over thickness range spanning 50 500 nm. concentration is reactive sputtering an Ar/O2 atmosphere trace quantities CF4. Infrared reflectometry...