K0.5Na0.5NbO3 Ceramics Research Articles

High Temperature-Insensitive Electrostrain Obtained in (K, Na)NbO3-Based Lead-Free Piezoceramics.

Over the last decades, notable progress is achieved in (K, Na)NbO3 (KNN)-based lead-free piezoceramics. However, more studies are conducted to increase its piezoelectric charge coefficient (d33). For actuator applications, piezoceramics need high electric-field induced strain under low electric fields while maintaining exceptional temperature stability across a wide temperature range. In this study, this work developes Li/Sb-codoped KNN (LKNNS) ceramics with high electrostrain by defect engineering and domain engineering. A remarkable strain of 0.43%, along with a giant d33* value of 2177 pm V-1, is attained in the LKNNS ceramic at 20 kV cm-1. The ceramic exhibits a minimal performance decrease of less than 15% over a temperature range from room temperature to 150 °C. The exceptional strain is attributed to the presence of A-site vacancy-oxygen vacancy ( ) defect dipoles and the increase in nano-domains. The hierarchical domain configuration and defect dipoles impede the switched domains from reverting to their original state as temperature increases, furthermore, the elongated dipole moments of caused by rising temperatures compensate for strain reduction results in exceptional temperature stability. This study provides a model for designing piezoelectric materials with exceptional overall performance under low electric fields and across a wide temperature range.

Multi-iteration active learning for the composition design of potassium–sodium niobate ceramics with enhanced piezoelectric coefficient

The piezoelectricity of piezoceramics considerably depends on the doped compositions. However, the conventional trial-and-error approach to composition design is time-consuming and inefficient when searching for high-performance piezoceramics with various dopants. In this study, we introduce a data-driven framework to accelerate the design and discovery of lead-free (K,Na)NbO3 (KNN) materials with enhanced piezoelectric performance. The proposed framework integrates machine learning with feature engineering, surrogate-based optimisation, and experimentation in an active learning loop. Using feature engineering techniques, we demonstrated that the piezoelectric coefficient d33 of KNN materials can be predicted based on a set of elemental and atomic properties. We evaluated six machine learning models and found that support vector regression with a radial basis function kernel achieved high accuracy in predicting the d33 values of KNN ceramics. After three iterations of experimentation and optimisation, we identified an optimal composition with a relatively high d33 of ∼353 pC/N from thousands of possible compositions using a pure exploitation strategy. This study demonstrates an efficient and systematic approach to the composition design of KNN-based piezoceramics, which can be applied to investigate the diverse functional properties of other materials.

Effect of A and B-site ion doping on the structure and properties of KNN-based ceramic coatings

K0.5Na0.5NbO3 (KNN) ceramics have been widely studied for high Curie temperature (Tc) and good electrical properties. The structural and electrical properties of KNN ceramics were significantly improved by A-site and B-site doping modifications. In this paper, KNN-based ceramic coatings doped with Mn, and Sb were prepared by supersonic plasma spraying. The effects of doping ions at A-site and B-site on the microstructure, phase structure, mechanical properties, and electrical properties of KNN-based ceramic coatings were mainly analyzed. The results show that the surface of the three coatings KNN, K0.5Na0.5Nb0.94Sb0.06O3 (KNNS), and K0.49Na0.49Mn0.02NbO3 (KNMN) is relatively flat, uniform distribution of the elements. The surface roughness (Sa) is 3.85 μm, 3.88 μm, and 3.66 μm, respectively. Pores and cracks are present within the coatings, but the KNNS ceramic coatings have significantly fewer pores and cracks compared to the KNN and KNMN ceramic coatings. XRD results show that KNN-based ceramic coatings exhibit single perovskite structure, and both Mn and Sb are successfully introduced into the KNN ceramics without the generation of a second phase. XPS results showed that the valence states of the elements in the KNN ceramic coatings did not change. In KNMN and KNNS ceramic coatings, the valence state of the doped elements did not change. The addition of Mn2+ and Sb3+ reduced the oxygen vacancy in KNN ceramic coatings. Among them, the KNMN ceramic coatings microhardness increased by 45.3 HV0.2, remnant polarization (Pr) increased by 8.1 μC/cm2, the dielectric constant (εr) increased by 107, and dielectric loss greatly reduced, reaching 0.005. The KNMN ceramic coatings microhardness increased by 90.8 HV0.2, dielectric constant increased by 195, Pr increased by 16.7 μC/cm2, dielectric loss is 0.007. These findings demonstrate that doping with Mn2+ and Sb3+ has a positive impact on the performance of KNN ceramic coatings, with Sb3+ having a greater effect.

Effects of doping with selected rare-earth elements (Eu3+, Dy3+, Eu3+/Dy3+) on the structural characteristics as well as electrical and luminescent properties of K0.5Na0.5NbO3

The effects of adding Eu3+, Dy3+, and Eu3+/Dy3+ rare-earth elements on the microstructural, optical and electrical properties of lead-free piezoelectric materials based on K0.5Na0.5NbO3 (KNN) were investigated. A series of fine powders were synthesized via a modified Pechini route utilizing citric acid. Relatively large amounts of rare-earth elements were successfully incorporated into the crystal lattice of KNN. A combination of X-ray diffraction, X-ray absorption spectroscopy, energy-dispersive X-ray and scanning electron microscopy were used to characterize the structure and chemical composition of the powders and sinters. XRD patterns indicated the formation of a single-phase orthorhombic structure in the co-doped sinter. X-ray absorption spectroscopy revealed the nominal 3+ valence states of Eu and Dy in KNN ceramic sinters. The Mott model and group symmetry theory were used to discuss the characteristics of Raman spectra obtained for the EuDy:KNN ceramics. The ceramics exhibited good dielectric permittivity (ε≃1300) and low dielectric loss (tan δ=0.03) in the temperature range of 170–240°C. The electrical properties of the ceramics showed that the basic mechanism of conduction and relaxation was thermal activation, and that small polaron hopping was responsible for charge carrying. The Eu3+ and Dy3+ ions displayed characteristic red and orange emissions in sinters when excited with light in the wide ultraviolet spectra range (380–420 nm).

High energy storage performance of (1-x)Ba0.5Sr0.5TiO3-xK0.5Na0.5NbO3 ceramics via a combined strategy of fine grains and multiphase polar nanoregions

Electrostatic dielectric capacitors have received great attention due to their ultrafast charging-discharging speed and ultrahigh power density. However, the low energy storage density and efficiency are the main obstacles to their practical applications. In this work, solid solution relaxor ceramics with different proportions of lead-free ferroelectrics Ba0.5Sr0.5TiO3 (BST) and K0.5Na0.5NbO3 (KNN) were prepared. Superior energy storage performance was achieved in the 0.7BST-0.3KNN ceramics with a breakdown strength (Eb) of 510 kV/cm, a recoverable energy storage density (Wrec) of 4.10 J/cm3, and an energy storage efficiency (η) of 80 %, which was fairly stable over the temperature range of 30–100 °C. Since multiple cations with different valence and radius coexist on the equivalent sites (A or B sites) of the solid solutions, the chemical disorder and the corresponding lattice distortion induced the coexistence of cubic, tetragonal, and orthorhombic phases, as well as the appearance of the multiphase polar nanoregions (PNRs), making the ferroelectric hysteresis loops linear. At the same time, ultrafine grains in the ceramics greatly improved the Eb. For achieving excellent energy storage performance, this work demonstrates a potential candidate of (1-x)BST-xKNN lead-free solid solution ceramics and a combined strategy of fine grains and multiphase PNRs.

Excellent triboelectric properties of P(VDF-TrFE) nanofibers incorporated with Bi-based oxide-modified KNN polycrystals

Recently, improving triboelectric nanogenerator (TENG) performance with inorganic nanofillers and crafting multifunctional nanofiber films via electrospinning have gained much attention. This paper explores the effect of electrospun composite nanofibers based on P(VDF-TrFE) (denoted as PT) with K0.5Na0.5NbO3 (KNN) polycrystals doped with bismuth-based (Bi-based) oxides [Bi(Ni0.5Hf0.5)O3 (BNH) and Bi(Mg0.5Zr0.5)O3 (BMZ)] on the output performance of TENG. TENGs with four types of [PT-PET, (PT/KNN)-PET, (PT/KNN-BNH)-PET, and (PT/KNN-BMZ)-PET] are compared, and the output increases progressively from pristine (Voc = 572 V and Isc = 13.4 μA) to PT/KNN-BMZ (Voc = 831 V and Isc = 39.2 μA). The maximum output performance is higher than that of most previously reported inorganic particle-modified films. Electrospinning provides a high applied voltage, enhancing dipole alignment, which aids in the formation of the β-phase. Additionally, modifying KNN ceramics with BNH and BMZ and using them as nano-fillers not only increases the β-phase of P(VDF-TrFE) but also elevates its dielectric constant, enhancing the capacitance of TENG, thereby yielding superior triboelectric performance. Furthermore, when different KNN/BMZ concentrations are compared, the (PT/4% KNN-BMZ)-PET TENG demonstrates the optimum triboelectric output performance, with 13.84 mW of peak power at a matched load of 40 MΩ. This work provides guidance for nanofiller choices for high-performance TENG preparation.

Promoted osteogenesis by corona discharge poling induced in electroactive piezoelectric bioceramics

Rapid bone reconstruction and regeneration process is still a problem to be solved in the clinical orthopedic treatment. In vivo electric stimulation (ES) shows great promise in repair and regeneration of damaged tissues, and the piezoelectric characteristic of nature bone tissue make the electrical activity piezoelectricity biomaterials feasible and attractive in bone regeneration. Herein, we prepared a biocompatible lead-free piezoelectric ceramic K0.5Na0.5NbO3 (KNN) via solid phase sintering, which possesses wireless ES capability through corona discharge poling. Compared with the traditional piezoelectric ceramic polarization methods, corona discharge poling is a non-contact and biologically safer electrical poling method without electrodes or insulating liquids. The results of piezoelectricity, the water contact angle, the protein adsorption, surface potential characteristics of KNN ceramics and bone mesenchymal stem cells (BMSCs) behavior on ceramics, showed that after corona discharge poling the surface of KNN piezoelectric ceramic became hydrophilic, and positively charged, and the electrostatic effect formed by these charges promoted protein adsorption and BMSCs attachment and proliferation, which further promoted osteogenic differentiation. In conclusion, we used the corona discharge to polarize KNN piezoelectric ceramics and excellent biocompatibility of the ceramics was maintained after poling. Meanwhile, our work demonstrated the potential application of piezoelectric bio-ceramic materials in bone regeneration.

High‐performance KNN piezoceramics with reproducibility and chemical stability. Part II: Innovative melt‐reaction route

AbstractIn the first part, a means to synthesize high‐density homogeneous (K,Na)NbO3 (KNN) ceramics with high piezoelectric performance and chemical stability at low spark‐plasma sintering temperature was found. However, these properties could not be obtained reproducibly, thus this second part is focused on solving this issue. Here, instead of doing a fine pulverization of raw materials prior to the reaction, the powders are ultimately mixed in the molten state and quenched to keep a single stoichiometry. A fast quenching is found to promote a better homogenization of the KNN phase upon annealing. Additionally, the coarse‐ground KNN powder is pre‐annealed before fine pulverization to preserve its high crystallinity. This innovative procedure prevents the formation of parasitic phases, leading with it to high‐performance undoped KNN ceramics (d33 ≈ 145 – 154 pC/N, kp ≈ 47–48% and kt ≈ 35 – 42%), while achieving both high reproducibility and chemical stability.

The dissolution of potassium sodium niobate (KNN) in aqueous media towards sustainable electroceramics sintering

K0.5Na0.5NbO3 (KNN) is as a relevant lead-free piezoelectric material due to its piezoelectric performance and a high Curie temperature. Although high-sintering temperature is required for obtaining dense KNN ceramics, it favours alkalis volatilization with deleterious effects on the physical properties. Together with the need of more environmentally-friendly technologies for ceramic manufacturing, cold sintering (CSP), a low temperature sintering process, is a promising technique. CSP of incongruently dissolving materials (with different dissolution rates of constituents) is, however, a challenge. In this work, a systematic study of the interaction of KNN particles with water under different pH conditions and temperatures is used to elucidate the nature and mechanisms of KNN dissolution. The KNN dissolution follows the trend [K+] > [Na+] ≫ [Nb5+]. Differences are demonstrated between acidic, neutral, and alkaline conditions, with the latter exhibiting less incongruence. Acidic pH increases solubility of KNN and promotes the incongruence of dissolution. Oppositely, alkaline pH decreases solubility of KNN and prevents dissolution incongruence. The incongruence of KNN dissolution in aqueous media is quantified. These observations have implications for our understanding of powders dissolution and offer opportunities to control the stoichiometry of the powders, that might be the key for CSP of incongruently dissolving materials.

Enhanced electromechanical response in (K, Na)NbO3-based ferroelectrics by phase boundary and nonstoichiometry engineering

Compositional fluctuation of the K and Na elements during the preparation process becomes a major issue for (K,Na)NbO3 (KNN) lead-free ceramics to maintain relatively stable electrical properties. The raw material Bi2O3 is more sensitive to high temperature. To improve electrical properties, it is more necessary to compensate the volatile Bi. In this work, the 0.96K0.48Na0.52Nb0.96Sb0.04O3-0.04Bi0.5*(1+x)Na0.5ZrO3 (x = −0.05, −0.02, 0.00, 0.02, 0.05, and 0.08) ceramics were selected as basis material. The excess Bi can increase the phase fraction of the T phase and decrease oxygen vacancy content, which effectively enhance the extrinsic contribution of the piezoelectric response. The electromechanical properties were optimized by excess Bi, and the optimal properties (d33 = 522 pC/N, kp = 58.9%, Tc = 235 °C) were obtained in the ceramic with x = 0.05. The present work provides new guidelines for enhancing the piezoelectric performance of KNN ceramics by a simple method, which can be applied to other lead-free piezoelectric ceramic systems.

Preparation and physicochemical properties of K0.5Na0.5NbO3 ceramics obtained using a modified wet chemistry method

A modified wet chemical method involving different chelating acids was applied to prepare a series of lead-free K0.5Na0.5NbO3 (KNN) piezoelectric ceramics. The microstructural, dielectric, spectral and ferroelectric properties of the obtained ceramics were investigated as part of a comparative study. Thermal characteristics specific to a phase transition were detected via high-temperature HT-XRD, FT-IR and EIS. The obtained sinters were dense and consisted of micro-sized grains. Sinters obtained from powders prepared from oxalic acid with the addition of tartaric acid exhibited lower dielectric constants and lower coercive field values than those synthesized using oxalic acid only (332 vs 399 and 10 vs 9.5 kV⋅cm−1, respectively) measured at room temperature. The KNN ceramics exhibited high conductivity (>10−3 S/cm at 600 °C), dielectric loss (∼200 at 1 kHz) and high remnant polarization (∼310−3 μC/cm2).

Flash Sintered Potassium Sodium Niobate: High-Performance Piezoelectric Ceramics at Low Thermal Budget Processing.

Alternative sintering technologies promise to overcome issues associated with conventional ceramic sintering such as high thermal budgets and CO2 footprint. The sintering process becomes even more relevant for alkali-based piezoelectric ceramics such as K0.5Na0.5NbO3 (KNN) typically fired above 1100 °C for several hours that induces secondary phase formation and, thereby, degrades their electrical characteristics. Here, an ability of KNN ceramics to be of high performance is successfully demonstrated, using an electric field- and current-assisted Flash sintering technique at 900 °C only. Reported for the first time, Flash sintered KNN ceramics have room-temperature remnant polarization Pr = 21 μC/cm2 and longitudinal piezoelectric coefficient d33 = 117 pC/N, slightly superior to that of conventional ones due to the reduced content of secondary phases. High-performance KNN ceramics Flash sintered at a low-thermal budget have implications for the development of innovative low carbon technologies, electroceramics stakeholders, and piezoelectric energy harvesters.

Influence of chemically synthesized powder addition on K0.5Na0.5NbO3 ceramic’s properties

A new strategy to produce lead-free K0.5Na0.5NbO3 (KNN) piezoceramics with reliable and improved piezoelectric performance is presented for the first time. KNN powders were synthesized using two distinct synthesis routes: a mechanochemical activation-assisted solid-state route (KNNSSR) and a sol–gel modified Pechini method (KNNchem). KNNchem powders were mixed with KNNSSR at different weight ratios (0, 3, 5, 10 and 20 wt%), and the mixtures were conventionally consolidated and sintered at 1130 °C for 2 h. It was found that KNNchem powders influence crystal phase, microstructure and piezoelectric properties of the sintered pellets. Gradually increasing KNNchem content promotes the conversion of the undesired phase present in KNNSSR into the stoichiometric one. It is also proved that the addition of KNNchem between 5 and 10 wt% improves piezoelectric properties, eventually leading to a d33 piezoelectric charge constant value of 113–115 pC/N. These values are among the highest reported for undoped KNN ceramics obtained by conventional sintering.

Antiferroelectric-like double hysteresis loops in Ag-doped K0.5 Na0.5NbO3 ceramics

In this work, we report the effect of Ag+ doping on the microstructure, dielectric, ferroelectric, piezoelectric, and energy storage properties of the K0.5Na0.5NbO3 (KNN) ceramics for which (K0.5Na0.5)(1-x)AgxNbO3 (KNN-xAg) ceramics with x = 0, 0.01, 0.02 and 0.03 were prepared by the conventional solid-state method. The substitution of Ag+ changes the microstructure of KNN from inhomogeneous bimodal grain distribution to homogeneous densely packed grains with an average grain size of 0.5–2.25 μm. The phase transition (TC) of KNN shifts towards the lower temperature side with Ag+ doping. Antiferroelectric-type double PE loops were observed in Ag-doped KNN ceramics at room temperature, which has improved the energy storage and piezoelectric properties of KNN. For ceramics poled at 2 kV/mm for 30 min, a d33 value of ∼149 pC/N and kp ∼0.41 were obtained. These enhanced properties in Ag-doped KNN are due to the occurrence of double polarization hysteresis loops.

(K, Na)NbO3 lead-free piezoceramics prepared by microwave sintering and solvothermal powder synthesis

Low temperature and short processing time are favorable for fabricating (K, Na)NbO3 (KNN) lead-free piezoelectric ceramics with a drawback of easy alkali metal volatilization during the powder synthesis and sintering processes. This study revealed that microwave sintering (MS) in addition to microwave solvothermal synthesis (MSS) of powder can lead to short-time fabrication of KNN ceramics with high density and fine grains. It was found that when the concentration of KOH/NaOH exceeds 1 M, KNN powder with single perovskite structure can be synthesized successfully by MSS method, which can be densified by MS to a high relative density close to 97% at 1050 °C even using 2/9 shorter time than conventional sintering (CS) at the same temperature. Importantly, the MSed KNN ceramics show better piezoelectric and ferroelectric properties than CSed counterparts. Without any dopants, the piezoelectric coefficient (d33) of the MSed pure KNN ceramics is 132 pC/N, and the remnant polarization (Pr) is 26.3 μC/cm2. The results show that the MS method is a promising method for preparing KNN-based ceramics.

Enhanced piezoelectric property in Mn‐doped K0.5Na0.5NbO3 ceramics via cold sintering process and KMnO4 solution

AbstractThrough mixing the KMnO4 solution with K0.5Na0.5NbO3 (KNN) powders, cold sintering process (CSP) was employed to fabricate high‐density Mn‐doped KNN green pellets and ceramics. The microstructure, doping effect of Mn and electrical properties of these ceramics were studied in detail. Compared with conventional sintering (CS), the CSP supports the homogeneity of dopants and then promotes grain growth and ceramic densification; thus the Mn‐doped KNN ceramics prepared by CSP show the obviously higher density and larger grain size. Besides, the less alkalis volatilization and oxygen vacancies result in more Mn3+ but less Mn4+ in CSP ceramics compared to CS ones, which endows the pinning effect and good poling characteristics in CSP ceramics. All the previous results contribute to the high dielectric constant and remnant polarization in CSP ceramics, which support the enhanced piezoelectric coefficient and are much superior than Mn‐doped KNN ceramics prepared by CS. This work reveals that CSP can be a new doping strategy to perform chemical modification of electrical properties in KNN ceramics.

Real-Time Capturing of Microscale Events Controlling the Sintering of Lead-Free Piezoelectric Potassium-Sodium Niobate.

Sintering is a very important process in materials science and technological applications. Despite breakthroughs in achieving optimized piezoelectric properties, fundamentals of K0.5 Na0.5 NbO3 (KNN) sintering are not yet fully understood, facing densification versus grain growth competition. At present, microscale events during KNN sintering under reducing atmospheres are real-time monitored using a High Temperature-Environmental Scanning Electron Microscope. A two contacting KNN particles model satisfying the Kingery and Berg's bulk diffusion model is reported. Dynamic events like individual grain growth and grain elimination process are explored through a postanalysis of recorded image series. The diffusion coefficient for oxygen vacancies of 10-8 cm2 s-1 and average boundary mobility of 10-9 cm4 J-1 s-1 are reported for the KNN ceramics. Moreover, the local pore shrinkage is consistent with the Kingery and François's concept of pore stability except that pore curvatures are not all concave, convex or flat due to anisotropic grain-boundary energies. The global grain growth kinetics are described using parabolic and/or cubic laws. The effect of atmospheres and microstructure evolution on the intrinsic and extrinsic contributions to the dielectric response using Rayleigh's law is also explored. These results bring a new breath for KNN sintering studies in order to adapt the sintering process.

Structural and dielectric properties of pure potassium sodium niobate (KNN) lead free ceramics

Lead free KNN (K0·5Na0·5NbO3) ceramics was obtained via the conventional solid state sintering technique. The ceramics synthesized was characterized for their phase transition analysis, crystal structure, morphology and electrical properties. The powder X-ray diffraction (XRD) patterns confirmed single phase of KNN with orthorhombic crystal system at room temperature. Scanning electron microscopy (SEM) of the sintered KNN revealed the existence of densification and comparable size of the grains. Two phase transitions were observed in ϵr-T graph: orthorhombic to tetragonal at TO-T (~236 °C) and tetragonal to cubic at TT-C (~440 °C) for 1 kHz frequency. The decrease in the net polarization of the material with the increase in frequency leads to the decrease in the value of ϵr and tanδ. Three characteristic Raman peaks observed at (~262 cm−1, ~617 cm−1 and ~858 cm−1) correlate the structure and ferroelectric properties of KNN materials. These promising outcomes demonstrate that KNN-based lead-free ceramic composition is potential candidate to substitute lead-based materials for various applications.

Defect-mediated domain-wall motion and enhanced electric-field-induced strain in hot-pressed K0.5Na0.5NbO3 lead-free piezoelectric ceramics

Since the extrinsic contribution is the key to electric-field-induced strain in ferroelectrics, engineering the interaction between defect and domain-wall motion has been an effective approach for enhancing the strain performance. While acceptor doping has been frequently employed in the lead-free (K, Na)NbO3 (KNN) system, the individual influence of intrinsic defects is still ill-understood. In this work, pure KNN ceramics with various concentrations of intrinsic defects were prepared by hot-pressing at different temperatures. Meanwhile, the microstructure, electrical properties, and defect chemistry were systematically investigated. An enhanced normalized strain d33* of 320 pm/V with good temperature stability was obtained in the KNN sample hot-pressed at 1000 °C, which is two times larger than that of reported normally sintered KNN. Besides, an asymmetric bipolar strain was found accompanied by the presence of offset polarization. The phenomena can be explained by a qualitative model involving unswitchable domains and intrinsic defects. The present study could enable further understanding of defect engineering and demonstrate a possible manipulation of intrinsic defects to enhance the strain performance of KNN-based piezoceramics.

Reversible and color controllable emissions in Er3+/Pr3+-codoped K0.5Na0.5NbO3 ceramics with splendid photochromic properties for anti-counterfeiting applications

It is highly significant to develop multi-mode optical anti-counterfeiting materials to efficiently fight against counterfeit products. In this study, we chose ferroelectric K0.5Na0.5NbO3 (KNN) with excellent photochromism properties as the host and rare-earth Er3+ and Pr3+ ions as dopants to prepare the Er3+/Pr3+-codoped KNN ceramics. The color-tunable emissions can be obtained from red-orange-yellow to green by controlling the excitation wavelength. Upon 980 nm excitation, the synthesized ceramics does not only have superior upconversion (UC) emission behaviors but also have good luminescence modulation properties based on the photochromism properties. It is found that the KNN:0.003Er3+/0.003Pr3+ sample with the optimal UC emission features shows a highest ΔRt value of 74.52% when irradiated by 390 nm light for 5 min, whereas the KNN:0.005Er3+/0.003Pr3+ ceramics also exhibit a high ΔRt value of 66.81% under 395 nm light irradiation. According to the XPS and EPR results, one knows that the mechanism of luminescence modulation is closely related to defects and traps caused by the oxygen vacancies. Furthermore, the optical information writing and erasing test is conducted, exhibiting a good reproducibility and fatigue resistance. These results reveal that the designed ceramics are appropriate for the anti-counterfeiting applications.