We report the successful integration of a bilayer ferroelectric aluminum-scandium-nitride (Al0.64Sc0.36N) thin film on an industrial-scale 200 mm silicon (100) wafer. Microstructural analysis revealed that both the bottom and top Al0.64Sc0.36N layers exhibit comparable characteristics. Wafer-scale ferroelectric and piezoelectric characterization of the individual layers showed similar average values for permittivity (epsilon), loss tangent (tan delta), and piezoelectric coefficients (d(33,f) and e(31,f)). Findings suggest that the bottom Al0.64Sc0.36N layer has a lower leakage current than the top layer in the bilayer configuration. We present a strategy for efficiently actuating both the top and bottom layers to generate a high equivalent longitudinal strain and transverse stress without requiring any complex or additional electrical circuitry. Upon excitation, the bilayer structure yields equivalent d(33,f) and e(31,f) values of >26.8 pm/V and >4.6 C/m(2), respectively, among the highest ever reported within bilayers of complementary metal-oxide-semiconductor (CMOS) compatible ferroelectric nitride thin films. Such high piezoelectric coefficients enable the broader adoption of lead-free ferroelectric materials for actuator applications.

For lead replacement in established Pb-based relaxor ferroelectric materials, substituted barium titanate is among the most promising candidates. The ceramic samples investigated in this study are B-site-substituted, with Zr or Nb partially replacing the central Ti ion in the perovskite lattice. Although these two material systems have been macroscopically well characterized by various techniques, local information on the ferroelectric domain structure is still missing. In this work, we probe the domain structure and local switchability across various compositions and temperatures using piezoresponse force microscopy. The results reveal that even though long-range ferroelectric order is effectively suppressed with increasing substitution, temporal stabilization of domains within a limited volume is still possible, indicating the presence of highly unstable polar nanoregions.

Raman spectroscopy was employed to investigate the topotactic phase transition in SrFeOx thin films for memristive device applications. This study provides direct spectroscopic evidence of local structural changes associated with the redox-driven phase transition. In support of our previous reports, which primarily focused on X-ray absorption spectroscopy, our current operando Raman analysis reveals that the formation of conductive filaments involves not only variations in oxygen content but also a distinct structural transformation within the perovskite lattice. Notably, a much smaller change in oxygen content is sufficient to trigger significant alterations in the electronic properties, leading to the formation of conducting pathways in these memory devices. The spatially resolved Raman intensity mapping further confirms the localized nature of this structural phase transition within the active region of the device.

The control of the coercive field and growth of abnormally oriented grains (AOGs) in wurtzite ferroelectric Sc x Al 1‐x N thin films is crucial for piezoelectric and ferroelectric applications. However, elevated Sc concentrations generally result in significant AOG growth and high leakage current, degrading piezoelectric and ferroelectric properties. Here, compositionally graded Sc x Al 1‐x N layered structures grown by sputtering are explored to effectively limit the AOG growth, compared to the 8–10% typically observed in conventional films, without requiring process optimization. Notably, a large built‐in electric field of ≈0.45 MV cm −1 , nearly 2.5 times larger than in graded PbZr x Ti 1‐x O 3 (PZT) and BaSr x Ti 1‐x O 3 (BST) systems, is achieved. This built‐in field induces unique features, including horizontal shifts in polarization‐electric field hysteresis loops, bi‐stable states in capacitance‐voltage characteristics, and highly asymmetric electrostrain behavior. Unlike other graded systems, this large built‐in field in the graded Sc x Al 1‐x N films arises primarily from polarization and chemical gradients. These findings offer a simplified, scalable and CMOS‐compatible strategy to overcome the AOG challenges and tune ferroelectric properties of Sc x Al 1‐x N thin films, providing the path for potential applications in advanced photonic and MEMS devices with improved performance and low‐power consumption.

Dielectric capacitors used as energy storage components in electrical and electronic systems offer ultrafast charge and discharge rates but have long faced the challenge of insufficient recoverable energy storage density. These materials are either lead-based, and/or their processing involves hazardous chemicals and expensive equipment, which hampers their scalability and limits their industrial applicability. We report here thin films with enhanced energy density (61 J cm-3) and efficiency (70%) from chemical solution deposition that are lead-free, scalable, comparably cheap in production and equipment costs and possess properties comparable to those of other high energy density dielectrics produced by costly high-vacuum deposition methods. This lead-free high-performance dielectric demonstrates a step toward implementation of dielectric thin films produced through an affordable, industrially scalable process, achieving improved energy densities.

High energy density capacitors are essential in portable energy-autonomous devices for the Internet of Things (IoT). Capacitors based on perovskite ferroelectric thin films, where substitution breaks down ferroelectricity to the local scale, are interesting due to their improved energy density, efficiency and breakdown strength. For this work, Mn-substituted (1.5 %) Barium Zirconate Titanate (BaZrxTi1-xO3, BZT) thin films were prepared on Pt/Si substrates via a novel aqueous chemical solution deposition (CSD) process using entirely environmentally friendly chemicals. The thin films were investigated with Grazing incidence X-ray Diffraction (GI-XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and dielectric/ferroelectric characterization under application-relevant conditions. All thin films exhibit a highly crystalline and dense microstructure with a smooth surface. All compositions offer high energy density and efficiency, whereby the best results were obtained at 15 % Zr content, with a high recoverable energy density (11 Jcm_ 3 at 1.8 MVcm_ 1), high fatigue resistance, high frequency and temperature stability with deviations from the reference state (lowest value) of less than 3 % (106 cycles), 5 % (0.1-100 kHz) and 16 % (20-200 degrees C), respectively. These thin films are highly suitable as capacitors for IoT devices, and moreover, they are prepared using a green process.

Large-area deposition of Aluminium-Scandium-Nitride (Al1-xScxN) thin films with higher Sc content (x) remains challenging due to issues such as abnormal orientation growth, stress control, and the undesired crystal phase. These anomalies across the wafer hinder the development of high scandium-content AlScN films, which are critical for microelectromechanical systems applications. In this study, we report the sputter deposition of Al0.64Sc0.36N thin films from a 300 mm Al0.64Sc0.36 alloy target on 200 mm Si(100) wafers, achieving an exceptionally high deposition rate of 8.7 μm/h with less than 1

Abstract Perovskites at the crossover between ferroelectric and relaxor are often used to realize dielectric capacitors with high energy and power density and simultaneously good efficiency. Lead-free Bi0.5Na0.5TiO3 is gaining importance in showing an alternative to lead-based devices. Here we show that (1-x)Bi0.5Na0.5TiO3 – xBaZr y Ti 1-y O3 (best: 0.94Bi0.5Na0.5TiO3 -0.06BaZr0.4Ti0.6O3) shows an increase of recoverable energy density and electric breakdown upon chemical substitution. In thin films derived from Chemical Solution Deposition, we observed that polarization peaks at the morphotropic phase boundary at x = 0.06. While Zr substitution results in reduced polarization, it enhances both efficiency and electric breakdown strength, ultimately doubling the recoverable energy density and the metallization interface by lowering surface roughness. Our dielectric capacitor shows <3% deviation of energy properties over 106 cycles. A virtual device model of a multilayer thin film capacitor (7.25 mJ recoverable energy) was used to compare its performance to already in use multilayer ceramic capacitors.

Dielectric thin film capacitors are essential for miniaturized electronics and energy storage systems, offering ultrafast charge-discharge rates and high reliability. However, achieving high energy density, efficiency, and stability in lead-free systems remains challenging, particularly with scalable and cost-effective methods. Here, we demonstrate relaxor sodium niobate-based thin films with Bi and Mg substitution, synthesized via optimized chemical solution deposition. By tailoring crystallization temperature and heating rate, we achieved a recoverable energy density of 37 J cm-3 and an efficiency of 80% at 2.45 MV cm-1. The films exhibit exceptional thermal stability, with energy density variation below 10% up to 310 °C, and superior charge-discharge stability beyond 16 million cycles at high fields. Microstructural engineering, involving grain size reduction and enhanced granularity, was critical for achieving a high Weibull breakdown strength (2.29 MV cm-1) and reliability. These films outperform previously reported sodium niobate systems, surpassing lead-based alternatives in environmental sustainability and scalability. Our approach highlights the potential of sodium niobate-based thin films for high-performance dielectric capacitors in harsh environments, offering a scalable pathway for environmentally sustainable energy storage technologies.

Lead-free sodium niobate (NN) thin films with varying barium titanate (BT) content and 1 mol% manganese were deposited on platinized silicon substrates by chemical solution deposition. Microstructural analysis reveals a change in nucleation mechanism, and X-ray diffraction and Raman spectroscopy confirmed a composition-driven antiferroelectric (AFE) to ferroelectric (FE) phase transition at 0.01 < x < 0.03, providing a stability interval for the AFE phase despite increasing the tolerance factor. The thin films show well-shaped ferroelectric response under applied electric field, indicating an irreversible field-induced phase transition. The composition with 7 mol% BaTiO3 showed the most promising energy storage properties (W-rec similar to 5.7 J/cm(3) and 68% efficiency (eta)), along with excellent thermal stability up to 120 degrees C and largely improved cyclic stability up to 5 * 10(6) bipolar cycles. These findings highlight the potential of NN-based thin films as lead-free candidates for energy storage, emphasizing the importance of stabilizing the AFE phase under electric fields for practical applications.

Dielectric thin films have garnered considerable attention in recent years, driven by their potential applications in advanced electronics and electrical systems. This interest is particularly due to their use in the growing trend toward miniaturization, where these films play can play an important role, enabling more compact and efficient devices. In this study, we deposited xNaNbO(3) - (1-x) Bi0.5Na0.5TiO3 (x = 0.22, 0.76) thin films on Pt/TiO2/SiO2/Si substrates using chemical solution deposition. We investigated the influence of different compositions of NaNbO3 and Bi0.5Na0.5TiO3 on energy storage and dielectric properties to evaluate the compatibility of the system. Solid solutions were successfully formed in both systems, exhibiting a pure perovskite phase and very low surface roughness. The Bi0.5Na0.5TiO3- and NaNbO3-based capacitors demonstrated dielectric breakdown strengths of 1.5 MV cm(-1) and 1.2 MV cm(-1), respectively, with recoverable energy densities of 18 J cm(-3) and 10 J cm(-3). Although the efficiencies were low around 60% and 50% at maximum field, as well as the polarization hysteresis at fields above 700 kV cm(-1) suggesting leakage current contributions, both systems showed impressive temperature stability and relative permittivity. The energy storage properties remained stable from 25 to 175 degrees C for x = 0.22 and from 25 to 275 degrees C for x = 0.76, with cyclic fatigue stability maintained up to 107 cycles. These results pave the way for integrating this binary material system into other BNT-substituted systems to enhance temperature and cyclic fatigue stability.

Dielectric capacitors for energy storage applications have garnered significant attention due to their fast charge-discharge rates, high volumetric energy and power densities, and excellent stability and reliability, making them ideal for various modern electronics and electrical systems. AgNbO 3 is an antiferroelectric material with promising dielectric and energy storage properties. However, thin films based on AgNbO 3 face challenges in terms of phase purity and achieving a dense microstructure. In this work, we report on AgNb 1-x Ta x O 3 thin films prepared via chemical solution deposition using two different solvents to reduce porosity, enhance densification, and produce smooth, crack-free films. A shift in relative permittivity towards room temperature with increasing Ta substitution was observed, aligning well with reported phase transition temperatures in bulk ceramics. Additionally, an excess of Ag was successfully used to eliminate natrotantite-like secondary phases in highly Ta-substituted thin films, leading to phase-pure AgNb 1-x Ta x O 3 thin films with improved dielectric properties.

This study investigates lead-free BaTiO3 (BT) perovskite ceramics, unraveling the synergistic effects arising from simultaneous homovalent (Zr) and heterovalent (Nb) substitution. Focusing on piezoelectric, ferroelectric, and relaxor behaviors, this research employs a comprehensive suite of analyses, including temperature-dependent dielectric measurements, polarization-electric field hysteresis loops, and bipolar strain measurements. Significantly, our study unveils that the simultaneous substitution of Zr and Nb in the BT lattice induces room-temperature relaxor behavior at relatively low concentrations (5 % Zr and 3 % Nb), yielding higher permittivity and larger maximum polarization compared to single element (Zr or Nb) substituted BT relaxors. Bipolar strain measurements showcase substantial large-signal d(33)* values (similar to 250 pm/V) across a broad temperature range (-50 degrees C to 30 degrees C) for BT ceramics with simultaneous 5 % Zr and 2 % Nb substitution. This research advances understanding of homovalent and heterovalent substitution in BT ceramics and opens avenues for tailoring properties to suit specific applications.

Despite being applied with success in many fields of materials science, Raman spectroscopy is not yet determinant in the study of electroceramics. Recent experimental and theoretical developments, however, should increase the popularity of Raman spectroscopy in this class of materials. In this review, we outline the fields of application of Raman spectroscopy and microscopy in various electroceramic systems, defining current key bottlenecks and explaining promising recent developments. We focus our attention on recent experimental developments, including coupling Raman spectroscopy with other methodologies and modelling approaches involving both the model-based data interpretation and the ab initio calculation of realistic Raman spectra.

Ferroelectric materials can exhibit metastable phases when exposed to THz pulses, characterized by a polarization integration capability related to the amplitude and frequency of the pulses. These so-called "hidden" phases enable gradual switching of polarization that can be utilized in artificial synapses for nonconventional (neuromorphic) computing machines. In this work, we employ large-scale molecular-dynamics simulation based on an effective Hamiltonian approach, and we report on the discovery of hidden phases in Zr-and Nb-doped barium titanate (BaTiO3). We investigate the formation and the stability of those phases at different stimuli and temperatures (20 and 200 K). Our results shed light on the compositional dependence of the properties of these phases, demonstrating the potential of lead-free relaxor ferroelectrics for near-room-temperature neuromorphic computing.

Ruthenium dioxide (RuO2) thin films were synthesized by Chemical Solution Deposition (CSD) on silicon substrates using only water and acetic acid as solvents. The microstructure, phase purity, electrical and optical properties as well as the thermal stability of the thin films have been characterized. The microstructure of the thin films strongly depends on the annealing temperature: A smooth thin film was achieved at an annealing temperature of 600 °C. Higher annealing temperatures (800 °C) led to radial grain growth and an inhomogeneous thin film. A very low resistivity of 0.89 µΩm was measured for a 220 nm-thick thin film prepared at 600 °C. The resistivity of the thin films increases with temperature, which indicates metallic behavior. Phase purity of the thin films was confirmed with X-ray Diffraction (XRD) measurements, X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. Transmission and reflectivity measurements indicate that RuO2 efficiently blocks the UV-VIS and IR wavelengths. The optical constants determined via spectroscopic ellipsometry show high absorption in the near-IR region as well as a lower one in the UV-VIS region. The thermal stability was investigated by post-annealing, confirming that the thin films are stable up to 750 °C in synthetic air.

Within this work the effect of the B content on the microstructure, phase composition and mechanical properties of CVD Ti(B,N) coatings is investigated. Ti(B,N) coatings with B contents from 0 (fcc-TiN) to similar to 5, similar to 15, similar to 30, similar to 45 and 66 (h-TiB2) at.% have been deposited by CVD. The elemental composition of the coatings was confirmed by ERDA and their microstructure was investigated using XRD and SEM. With increasing B content, a transition from a fcc to a h-dominated structure via dual-phase fcc/h-Ti(B,N) was observed, which was accompanied by a decreasing grain size from the mu m to nm range. Combinatorial use of Raman spectroscopy, XPS and APT measurements indicated B-rich grain boundary segregations and the formation of increasing amounts of h-Ti(B,N)(2) clusters embedded within an fcc-Ti(B,N) matrix up to B contents of similar to 30 at.%, while for -45 at.% B the matrix was predominantly composed of h-Ti(B,N)2. Complementary ab initio calculations predicting the phase formation confirmed the interpretation of the experimental results. In terms of the mechanical properties, nanoindentation measurements and micromechanical testing revealed a rise in hardness from similar to 18 to similar to 41 GPa and an increasing fracture stress and toughness from similar to 7 to -13 GPa and similar to 4.6 to -5.5 MPam(1/2), respectively, by increasing the B content up to similar to 30 at.%. In contrast, a significant drop in hardness, fracture stress and fracture toughness was observed at similar to 45 at.% B. Thus it can be concluded, that both h-TiB2 and dual-phase fcc/h-Ti(B,N) coatings with maximized B content yield superior properties over TiN and consequently improved performance.

Bulk ceramic samples of the perovskite series (1-x)(0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3))-xCaZrO(3) with 0 <= x <= 0.2 were prepared using the conventional solid-state route. It is shown that careful characterization of Bi2O3 raw materials is essential to avoid deviations from the nominal composition. X-ray diffraction analysis reveals formation of perovskite main phase, and a relaxor-like response of the relative permittivity over temperature was observed. Flattening of the permittivity-temperature curves is observed with increasing CaZrO3 fraction, while maintaining low dielectric losses over a wide temperature range. Samples with x = 0.2 exhibit a temperature stable permittivity of epsilon(r) approximate to 600 (Delta epsilon(r)'/epsilon(r,mid)' approximate to 10 % between -80 degrees C and 300 degrees C) along with small dielectric losses (tan delta < 0.02 between -55 degrees C and 265 degrees C) at 1 kHz. These attributes qualify these compositions as suitable high temperature capacitor dielectric materials.

Niobium pentoxide (Nb2O5) based thin films are predominantly used in optical filters, solar cells, electrochromic devices, sensors and microelectronic devices. The temperature-dependent thermophysical properties of Nb2O5 films are crucial for the performance and reliability of such devices. Within this work, for the first time, the ther-mal properties of sputter deposited Nb2O5 films are correlated with their structural properties at different length scales. Thermal measurements were carried out by time-domain thermoreflectance, yielding a thermal conductiv-ity of 3.0 +/- 0.3 W/mK at 25 degrees C for crystalline Nb2O5 films, which decreases to 2.6 +/- 0.2 W/mK at 450 degrees C. In contrast, amorphous Nb2O5 films had a thermal conductivity of 2.2 +/- 0.2 W/mK below 275 degrees C. Above 275 degrees C, an abrupt increase in thermal conductivity up to a maximum value of 2.8 +/- 0.2 W/mK at 325 degrees C was recorded. The average and local structure are determined by in-situ high-temperature X-ray diffraction and in-situ high-temperature Ra-man spectroscopy, respectively. These characterization techniques together enable to cross-correlate structural and thermal properties of Nb2O5 thin films highlighting the observed peculiarity of the thermal conductivity. This substantial increase in thermal conductivity cannot be linked to any macroscopic phase change but rather to a local phase rearrangement near the crystallization temperature, evidenced by temperature-dependent Raman spectra analysis. This study serves as a guide to engineering future Nb2O5 based thin film devices and for their reliability optimization.

Barium titanate (BT) based materials are at the forefront of materials being searched as possible candidates for the replacement of lead-based compositions in applications ranging from piezoelectrics to energy storage de-vices. Computational methods are very promising to increase the efficiency of materials discovery, provided that finite temperature properties can be realistically computed using, for example, molecular dynamics (MD). In this work, we present a systematic increase of the quality of MD simulations via an alternative way to calculate anhar-monic contributions to the potential energy surface (PES) of barium titanate. A large number of first-principles calculations are performed, which are subsequently used to parametrize an effective Hamiltonian. To test the ef-fects on various physical properties, MD simulations for the determination of transition temperatures, hysteresis, and permittivity of BT are shown. Furthermore, measurements were performed on BT single crystals to compare them directly with the MD simulations. It is observed that by incorporating a large number of anharmonic couplings, the description of the local minima in the PES becomes more accurate than in previous simulations. This leads to a better prediction of phase transition temperatures and shows the importance of anharmonic couplings in barium titanate. The presented approach can be directly adapted for other perovskite structures.