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Combinatorial sample synthesis schematic. (a) Thin film sample library deposited through cosputtering from two different materials which results in a compositional gradient perpendicular to a substrate temperature gradient. (b) Bulk sample library created by the heat treatment of a heterogeneous bulk interface where the diffusion of materials into each other results in a compositional gradient across the interface.
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Piezoelectric materials are commonplace in modern devices, and the prevalence of these materials is poised to increase in the years to come. The majority of known piezoelectrics are oxide materials, due in part to the related themes of a legacy of ceramists building off of mineralogical crystallography and the relative simplicity of fabricating oxi...
Contexts in source publication
Context 1
... gradient in composition has frequently been the target of HTE, and common approaches to achieve such a gradient include pressing pellets with graded powder content, or more commonly, as vapor phase and liquid phase deposition onto substrates. Figure 6 shows the most common forms of combinatorial sample preparation, by vapor phase deposition and diffusion across bulk interfaces. Many mature methods for producing combinatorial samples by deposition, growth, or synthesis exist. ...
Context 2
... of a material in a device fabrication facility optimizes the process for a single material. However, combinatorial gradients can be used to illuminate the effects of process variables on a single material. A common gradient studied in combinatorial experiments is the temperature used during the processing of the sample libraries (also shown in Fig. 6). For example, high-throughput methods have been utilized to accelerate investigation and optimization of the sintering temperature of 0.98[0:6BiFeO 3 -0:4PbTiO 3 ] -0:02Pb(Mg 1=3 Nb 2=3 )O 3 bulk ferroelectric ceramics. 109 Similarly, in thin films, the optimization of growth temperature in the Sr x Ba 1Àx Nb 2 O 6 family of ...
Citations
... Group III-V nitrides and II-VI oxides crystallizing in the wurtzite structure have emerged as attractive candidates for the piezoelectric applications mentioned above [11][12][13]. Indeed, these compounds were found to exhibit large polarizations, which accounts for a much stronger piezoelectric effect compared to other conventional III-V and II-VI materials [14,15]. ...
We present a computational study of the crystal structure and electric polarization of strained wurtzite III-V nitrides and II-VI oxides, performed in the context of density functional theory and the Berry phase method. The main goal is to investigate the degree to which the lattice parameters, piezoelectric polarization, and piezoelectric constant can be affected by compressive uniaxial strain along the hexagonal c-axis. We show that imposing such strain enhances the piezoelectric response, with both polarization and piezoelectric coefficient increasing from their equilibrium values. The internal parameter of the wurtzite structure also increases with uniaxial strain and eventually becomes equal to 0.5, resulting in a phase transition into the layered hexagonal structure. Furthermore, we discuss the physical origin behind the enhanced piezoelectricity, showing that the enhancement is caused by a strong increase in the response of the internal parameter to strain.
... [6,11] These, combined with excellent mechanical stiffness and ease of integration with semiconductors, make it technologically relevant for nonvolatile memories, acoustic resonators, and more. [8,12,13] However, the crystal structures of most nitride perovskites including LaWN 3 still remain elusive, [6,8,10,[14][15][16][17][18][19][20][21] which have led to conflicting predictions (e.g., R3c [10,11,[19][20][21]6,7] and Pna2 1 [17,20] ) and imposed an insurmountable barrier for exploring this important class of materials. ...
Nitride perovskite LaWN3 has been predicted to be a promising ferroelectric material with unique properties for diverse applications. However, due to the challenging sample preparation at ambient pressure, the crystal structure of this nitride remains unsolved, which results in many ambiguities in its properties. Here, the authors report a comprehensive study of LaWN3 based on high‐quality samples synthesized by a high‐pressure method, leading to a definitive resolution of its crystal structure involving nitrogen deficiency. Combined with theoretical calculations, these results show that LaWN3 adopts an orthorhombic Pna21 structure with a polar symmetry, possessing a unique atomic polarization along the c‐axis. The associated atomic polar distortions in LaWN3 are driven by covalent hybridization of W: 5d and N: 2p orbitals, opening a direct bandgap that explains its semiconducting behaviors. The structural stability and electronic properties of this nitride are also revealed to be closely associated with its nitrogen deficiency. The success in unraveling the structural and electronic ambiguities of LaWN3 would provide important insights into the structures and properties of the family of nitride perovskites.
... Ferroelectric materials 1,2 have received a wide range of applications 3,4 due to thei reversible spontaneous polarization 5 enabling excellent pyroelectric 6 and piezoelectric properties. [7][8][9] In particular, (Pb(Mg 1/3 Nb 2/3 )O 3 ) 1−x -(PbTiO 3 ) x (PMN-PT) with a morphotropic phase boundary composition has been employed in microelectromechanical systems (MEMS) for sensing and energy storage applications, owing to its strong electromechanical coupling and high electrical permittivity. 10,11 On the other hand, the ferroelectric properties of a PMN-PT thin film strongly depend on its chemical, structural, and interfacial characteristics. ...
Ferroelectric thin-film bilayers of Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT)/PbZr 0.52 Ti 0.48 O 3 (PZT) were grown on a flexible substrate of mica using pulsed laser deposition. Growth of the bilayer was induced with a thin film of LaNiO 3 (LNO) single crystal, which was deposited on a mica substrate through van der Waals epitaxy. The LNO thin film also serves as the electrode for the bilayer device. The growth of the LNO thin film along the [Formula: see text] orientation adopts a “Stranski–Krastanov” mechanism, governed by the relaxation of elastic energy between LNO/mica. Compared with the single layers of PMN-PT or PZT, or the bilayer of PZT/PMN-PT, the PMN-PT/PZT bilayer exhibits enhanced ferroelectric properties, with remnant polarization up to 72 μC/cm ² . In addition, polarization in the PMN-PT/PZT bilayer exhibits excellent resistance against mechanical bending fatigue over 10 ⁸ switching cycles. Such improved performances are ascribed to spontaneous polarizations enhanced by the residual stress at the PMN-PT/PZT heterointerface, increased interfacial potential barrier against leakage, and suppressed diffusion of Nb or Mg across the interface.
... We have previously extensively optimized for nonequilibrium growth conditions (i.e., deposition temperature, process pressure, gas ratios) based on our past experience with related Al 1−x M x N alloys. 10,[19][20][21]24 We expect that additional optimization of growth parameters may be able to further increase the amount of Gd 3+ that can be incorporated into AlN. ...
Al1–xGdxN is one of a series of novel heterostructural alloys involving rare earth cations with potentially interesting properties for (opto)electronic, magnetic, and neutron detector applications. Using alloy models in conjunction with density functional theory, we explored the full composition range for Al1–xGdxN and found that wurtzite is the ground-state structure up to a critical composition of xc = 0.82. The calculated temperature-composition phase diagram reveals a large miscibility gap inducing spinodal decomposition at equilibrium conditions, with higher Gd substitution (meta)stabilized at higher temperatures. By depositing combinatorial thin films at high effective temperatures using radio-frequency cosputtering, we have achieved the highest Gd³⁺ incorporation into the wurtzite phase reported to date, with single-phase compositions at least up to x ≈ 0.25 confirmed by high-resolution synchrotron grazing incidence wide-angle X-ray scattering. High-resolution transmission electron microscopy on material with x ≈ 0.13 and x ≈ 0.24 confirmed a uniform composition polycrystalline film with uniform columnar grains having the wurtzite structure. Spectroscopic ellipsometry and cathodoluminescence spectroscopy measurements are employed to probe the optoelectronic properties, showing that the band gap decreases with increasing Gd content x and that this effect causes the ideal Gd substitution level for cathodoluminescence applications to be low. Expanding our calculations to other rare earth cations (Pr³⁺ and Tb³⁺) reveals similar thermodynamic stability and solubility behavior to Gd. From this and previous studies on Al1–xScxN, we elucidate that both smaller ionic radius and higher bond ionicity promote increased incorporation of group IIIB cations into wurtzite AlN. This work furthers the development of design rules for new alloys in this material family.
... Physical vapor deposition (PVD) methods are common for the deposition of libraries [11]. Specifically, sputtering and pulsed laser deposition (PLD) serve as preparation methods to find new materials that meet application needs for, e.g., photovoltaics [12], electrocatalysis [13], piezoelectricity [14], electrochromic displays [10], superconductivity [15] luminescence [16], and energy storage and conversion, like lithium batteries [17], and supercapacitors [18]. ...
We present a multi-head spray pyrolysis system and its application in high-throughput combinatorial synthesis for research of solid Li-ion conductors. Each spraying nozzle is fed with a separate precursor solution. The overlap of areas that are sprayed leads to unprecedented composition flexibility of the films obtained after pyrolysis. Thus, a library with a continuous composition spread of a Li-La-P-O model system is formed. The Li-ion conduction was determined on 169 cells of the library, using high throughput impedance measurements in a controlled environment. While the activation energies that were found were relatively small, Li-ion conduction was still low. This low mobility is hypothesized to originate from the sub-optimal occupation of Li sites in the non-stoichiometric materials' lattices, and/or porosity and tortuosity issues, which in turn, reduces their effective concentration and contribution to ion transport. In addition, porosity and tortuosity in sprayed electrolyte causes random orientation of the grains and grain boundaries in the solid followed by the random diffusion scattering of Li-ions and low Li-ions conductivity, despite low apparent activation energy of conduction.
... Binary III-V nitrides such as GaN, AlN, InN and their alloys with wurtzite crystal structures have already revolutionized optoelectronic, electronic, and electromechanical technologies, including (In,Ga)N light emitting diodes (LEDs) in solid state lighting [18,19], (Al,Ga)N radio-frequency (RF) transistors in military applications [20,21], and (Al,Sc)N piezoelectric resonator microelectromechanical systems (MEMS) in telecommunications [22,23]. All these transformative results were largely dependent on the use of chemical alloying to facilitate tuning of band offsets and other materials properties, and growth of epitaxial heterostructures to improve materials quality and enable spatial variations in electronic structure [24][25][26]. ...
Zinc Tin Nitride (ZnSnN2) is one of the emerging ternary nitride semiconductors considered for photovoltaic device applications due to its attractive and tunable material properties and earth abundance of constituent elements. Computational predictions of the material properties sparked experimental synthesis efforts, and currently there is a number of groups involved in ZnSnN2 research. In this article, we review the progress of research and development efforts in ZnSnN2 across the globe, and provide several highlights of accomplishments at the National Renewable Energy Laboratory (NREL). The interplay between computational predictions and experimental observations is discussed and exemplified by focusing on unintentional oxygen incorporation and resulting changes in optical and electronic properties. The research progress over the past decade is summarized, and important future development directions are highlighted.
The value and impact that ceramic coatings have had in the development of modern mechanical systems and protection of components exposed to harsh environments are often overlooked and understated. Modern equipment must be capable of withstanding substantial attrition, impact damage, erosion and corrosion that degrades materials across a variety of applications. Ceramic coatings enable a robust protective barrier for underlying substrates that outperforms most alternative film barrier materials (i.e. polymers, metals, glasses). In this work, a comprehensive review of modern ceramic coatings for barrier protection against mechanical wear and chemical attack is discussed in detail over a large breadth of relevant topics and case studies. This review highlights many critical aspects including various coating functionalities, design architectures, processing effects, material classes and promising future directions for engineering high-performance ceramic coating.
Multivalent ternary nitride materials, which combine two metal cations with a nitrogen anion in equal amounts and charge balanced stoichiometry, tend to have relatively simple structures and promising properties for a broad range of applications. Historically, discovery of such new nitrides has been a bulk synthesis endeavor, following chemical intuition. In the past decade experimental synthesis of theoretically predicted materials, including as thin films, has changed this approach. In this perspective, we discuss progress in the experimental synthesis of theoretically predicted multivalent ternary nitrides, with the focus on Zn- and Mg-based materials. First-principles theoretical calculations predicted structures and properties of many new Zn-M-N and Mg-M-N materials and offered insights into the effects of cation ordering. Thin film and bulk experiments were used to synthesize some of these predicted multivalent ternary nitride compounds such as Zn3MoN4, Zn2SbN3, and Zn2NbN3, as well as MgZrN2, Mg2NbN3, and Mg2SbN3, and many others. These multivalent ternary nitride success stories should inspire experimental synthesis of other underexplored materials predicted by theoretical calculations.
Piezoelectric materials are known to mankind for more than a century, with numerous advancements made in both scientific understandings and practical applications. In the last two decades, in particular, the research on piezoelectrics has largely been driven by the constantly changing technological demand, and the drive toward a sustainable society. Hence, environmental-friendly “lead-free piezoelectrics” have emerged in the anticipation of replacing lead-based counterparts with at least comparable performance. However, there are still obstacles to be overcome for realizing this objective, while the efforts in this direction already seem to culminate. Therefore, novel structural strategies need to be designed to address these issues and for further breakthrough in this field. Here, various strategies to enhance piezoelectric properties in lead-free systems with fundamental and historical context, and from atomic to macroscopic scale, are explored. The main challenges currently faced in the transition from lead-based to lead-free piezoelectrics are identified and key milestones for future research in this field are suggested. These include: i) decoding the fundamental mechanisms; ii) large temperature-stable piezoresponse; and iii) fabrication-friendly and tailorable composition. Strategic insights and general guidelines for the synergistic design of new piezoelectric materials for obtaining a large piezoelectric response are also provided.
