Strontium-doping effects in solution derived lead-free ferroelectric K(0.5)Na(0.5)NbO3 thin films

Potassium sodium niobate, K0.5Na0.5NbO3 (KNN) is an environment-friendly lead-free alternative to highly efficient lead-based piezoelectrics. The poor functional properties of the KNN thin films prepared by chemical solution deposition are frequently related to the volatilisation of alkali species during processing, which hinders control over the stoichiometry, contributes to formation of secondary phases and deterioration of the microstructure. The problem can be overcome by adding alkalis in excess and/or by partial substitution of the A- and B- site atoms, such as in the case of the solid state synthesized KNN ceramics. Therefore, in this contribution, the influence of the alkaline-earth A- site dopant, Sr2+ on the microstructure, structure, and functional properties were examined for the solution-derived KNN thin films with alkaline excess. Liquid precursors of (K0.5Na0.5)1-ySryNbO3 (KNN-ySr) thin-films, where the Sr- dopant content was set at y = 0, 0.005, 0.01, were prepared from potassium and sodium acetates and niobium ethoxide in 2-methoxyethanol solvent with 5 mol% of potassium acetate excess. Strontium was introduced as acetate or nitrate. The approximately 250 nm thick KNN-ySr thin films on Pt/TiOx/SiO2/Si substrates were obtained by rapid thermal annealing at 650 oC for 5 min. According to X-ray diffraction analysis, all synthesized KNN thin films crystallize in pure perovskite phase with random orientation. The surface and cross-section microstructure analysis, performed by the field emission scanning electron microscopy, reveals that the KNN-ySr films consist of equiaxed grains, the average size of which gradually decreases from about 90 nm to a few tens of nm by increasing the Sr-dopant content. In the contribution we discuss the influence of the chemical modification on the functional response, i.e., dielectric properties versus frequency and temperature, polarisation – electric field dependence, leakage current and piezoelectric response of the as-prepared films

Ceramic packaging of PiezoMEMS devices

In the contributionthe design and the fabrication of two different types of ceramic packaging for PiezoMEMS devices ispresented. The first ceramic packaging is designed for housing the piezoelectric energy harvester. This packaging is made using LTCC technology and in the final application willintegrate piezoelectric device, electroniccircuit, storage capacitor and other components into the complex microsystem. The second packaging is developed for piezoelectric vibrating device as a part of water-purification system. In this case,the thick-film technology is used for electrical interconnection of piezoelectric actuators and for the hermetic watertight insulation of the system

CRYSTALLIZATION AND EVOLUTION OF MICROSTRUCTURE OF K 0.5 Na 0.5 NbO 3 -SrTiO 3 THIN FILMS PREPARED BY CHEMICAL SOLUTION DEPOSITION

V delu opisujemo študij kristalizacije in razvoja mikrostrukture tankih plasti na osnovi trdne raztopine 0,85 K0.5Na0.5NbO3 – 0,15 SrTiO3 (KNN-STO), pripravljenih s sintezo iz raztopin, na platiniziranih silicijevih podlagah. Raztopino KNN-STO smo pripravili iz kalijevega acetata KO2C2H3, natrijevega acetata NaO2C2H3, niobijevega etoksida Nb(OEt)5, titanovega propoksida Ti(OC2H4CH3)4 in stroncijevega nitrata Sr(NO3)2. Kot topilo smo uporabili 2-metoksietanol CH3OCH2CH2OH. Plasti smo segrevali po dvostopenjskem in štiristopenjskem postopku segrevanja, kar pomeni, da smo jih po stopnji pirolize segrevali do končne temperature po vsakem drugem, oziroma po vsakem nanosu raztopine s koncentracijo cM = 0,4 M na podlago. Plasti, pripravljene iz raztopin različnih koncentracij (0,1 M, 0,2 M, 0,4 M), smo segrevali do končne temperature po vsakem nanosu raztopine na podlago. Rentgenski difraktogrami plasti kažejo, da vse plasti, ki smo jih segrevali po opisanih postopkih do temperatur med 500 °C in 700 °C, kristalizirajo v perovskitni fazi s psevdo-kubično osnovno celico brez izrazite kristalografske usmerjenosti. Mikrostruktura plasti je odvisna od pogojev priprave. Plasti, pripravljene iz raztopine KNN-STO s koncentracijo 0,4 M z dvostopenjskim segrevanjem, imajo enakomerno mikrostrukturo z enakoosnimi zrni, velikimi ~20 nm, medtem ko je mikrostruktura plasti, pripravljenih s štiristopenjskim segrevanjem, heterogena z zrni velikosti od ~20 nm do ~100 nm. Mikrostruktura plasti, ki smo jih pripravili iz raztopin KNN-STO z različnimi koncentracijami in segrevali po vsakem nanosu, je heterogena, z zrni velikosti od ~50 nm do ~150 nm. Pogoji priprave tankih plasti KNN-STO vplivajo tudi na njihove dielektrične lastnosti. Plasti, pripravljene z dvostopenjskim segrevanjem, imajo večjo vrednost dielektrične konstante kot plasti, pripravljene s štiristopenjskim segrevanjem. Vrednost dielektričnosti se povečuje z naraščajočo temperaturo in časom segrevanja. Plast KNN-STO, pripravljena z dvostopenjskim segrevanjem pri temperaturi T=700 °C in času t=15 min ima največjo dielektričnost in nizke dielektrične izgube, in sicer 700 in 0,04 pri sobni temperaturi in pri frekvenci 100 kHz. Izmerili smo temperaturno in frekvenčno odvisnost dielektričnosti in dielektričnih izgub omenjenega vzorca in ugotovili, da kaže značilen relaksorski odziv, podobno kot volumenska keramika z enako kemijsko sestavo.The work describes the study of crystallization and evolution of microstructure of the 0,85 K0.5Na0.5NbO3 – 0,15 SrTiO3 solid solution based thin films, prepared by Chemical Solution Deposition, on platinized silicon substrates. The solution was synthesized from potassium acetate KO2C2H3, sodium acetate NaO2C2H3, niobium-pentaethoxide Nb(OEt)5, titanium-n-propoxide Ti(OC2H4CH3)4, strontium nitrate Sr(NO3)2, and the solvent 2-methoxyethanol CH3OCH2CH2OH. The films, deposited from the solution with the 0˙4 M concentration by spin-coating, were heated at different temperatures and times by the two-step and four-step rapid thermal annealing. Furthermore, we prepared the films from the solutions with different concentrations, namely 0,1 M, 0,2 M, and 0,4 M, and annealing after each deposition . According to X-ray diffraction analysis, the films crystallized in perovskite phase with a pseudo-cubic unit cell upon heating to temperatures between 500 °C and 700 °C. We observed no preferential orientation of the perovskite phase. The films, prepared by the two-step annealing have got granular and homogeneous microstructures with the grain size of ~20 nm, while the microstructures of the films, prepared by the four-step annealing, are quite heterogeneous with equiaxed grains ranging from ~20 nm to ~100 nm. The films, prepared from the solutions with different concentrations and annealing after each deposition, have got heterogeneous microstructures with the grain size from ~50 nm to ~150 nm. The dielectric permittivity of the KNN-STO films depends on the heating profile. The films, processed by the two-step annealing have got higher values of dielectric permittivity than the films prepared by the four-step annealing. In both cases, the permittivity increases with longer annealing time and higher annealing temperature. The highest dielectric permittivity was obtained for the films, prepared by the two-step annealing at 700 °C for 15 min, namely 700 at room temperature and 100 kHz. The temperature and frequency dependent dielectric measurements revealed the relaxor-like behaviour of the KNN-STO film, similar as the bulk ceramic with the same chemical composition

Dielectric dynamics of the polycrystalline Ba

Polycrystalline Ba0.5Sr0.5TiO3 films, with thicknesses between 90 and 600 nm, were prepared on alumina substrates at 900 °C by chemical solution deposition (CSD) and a dielectric spectroscopy investigation of the in-plane properties was performed. The 5-kHz permittivity ε′ shows a non-monotonic thickness dependence, reaching 1230 at room temperature for the 310-nm-thick film, whose grain size is ∼75 nm. Its 15-GHz-value and losses are 1105 and 0.05, respectively. The temperature of the permittivity maximum Tmax at 5 kHz decreases with increasing thickness from 277 to 250 K for the 170- and 600-nm-thick films, respectively, which has been linked to the residual biaxial stress. A hysteresis is observed in the permittivity ε′-electric field EDC characteristics in all the films up to ∼50 K above Tmax. Frequency dispersion in which permittivity decreases with increasing frequency is present below Tmax in films thicker than 90 nm. The high permittivity values of the thinnest films, which are among the highest reported in the (Ba,Sr)TiO3 films with grain sizes below 75 nm, are a direct proof of the optimized CSD processing conditions

Dielectric dynamics of the polycrystalline Ba 0.5

Polycrystalline Ba0.5Sr0.5TiO3 films, with thicknesses between 90 and 600 nm, were prepared on alumina substrates at 900 °C by chemical solution deposition (CSD) and a dielectric spectroscopy investigation of the in-plane properties was performed. The 5-kHz permittivity ε′ shows a non-monotonic thickness dependence, reaching 1230 at room temperature for the 310-nm-thick film, whose grain size is ∼75 nm. Its 15-GHz-value and losses are 1105 and 0.05, respectively. The temperature of the permittivity maximum Tmax at 5 kHz decreases with increasing thickness from 277 to 250 K for the 170- and 600-nm-thick films, respectively, which has been linked to the residual biaxial stress. A hysteresis is observed in the permittivity ε′-electric field EDC characteristics in all the films up to ∼50 K above Tmax. Frequency dispersion in which permittivity decreases with increasing frequency is present below Tmax in films thicker than 90 nm. The high permittivity values of the thinnest films, which are among the highest reported in the (Ba,Sr)TiO3 films with grain sizes below 75 nm, are a direct proof of the optimized CSD processing conditions

A 12-gene pharmacogenetic panel to prevent adverse drug reactions: an open-label, multicentre, controlled, cluster-randomised crossover implementation study

© 2023Background: The benefit of pharmacogenetic testing before starting drug therapy has been well documented for several single gene–drug combinations. However, the clinical utility of a pre-emptive genotyping strategy using a pharmacogenetic panel has not been rigorously assessed. Methods: We conducted an open-label, multicentre, controlled, cluster-randomised, crossover implementation study of a 12-gene pharmacogenetic panel in 18 hospitals, nine community health centres, and 28 community pharmacies in seven European countries (Austria, Greece, Italy, the Netherlands, Slovenia, Spain, and the UK). Patients aged 18 years or older receiving a first prescription for a drug clinically recommended in the guidelines of the Dutch Pharmacogenetics Working Group (ie, the index drug) as part of routine care were eligible for inclusion. Exclusion criteria included previous genetic testing for a gene relevant to the index drug, a planned duration of treatment of less than 7 consecutive days, and severe renal or liver insufficiency. All patients gave written informed consent before taking part in the study. Participants were genotyped for 50 germline variants in 12 genes, and those with an actionable variant (ie, a drug–gene interaction test result for which the Dutch Pharmacogenetics Working Group [DPWG] recommended a change to standard-of-care drug treatment) were treated according to DPWG recommendations. Patients in the control group received standard treatment. To prepare clinicians for pre-emptive pharmacogenetic testing, local teams were educated during a site-initiation visit and online educational material was made available. The primary outcome was the occurrence of clinically relevant adverse drug reactions within the 12-week follow-up period. Analyses were irrespective of patient adherence to the DPWG guidelines. The primary analysis was done using a gatekeeping analysis, in which outcomes in people with an actionable drug–gene interaction in the study group versus the control group were compared, and only if the difference was statistically significant was an analysis done that included all of the patients in the study. Outcomes were compared between the study and control groups, both for patients with an actionable drug–gene interaction test result (ie, a result for which the DPWG recommended a change to standard-of-care drug treatment) and for all patients who received at least one dose of index drug. The safety analysis included all participants who received at least one dose of a study drug. This study is registered with ClinicalTrials.gov, NCT03093818 and is closed to new participants. Findings: Between March 7, 2017, and June 30, 2020, 41 696 patients were assessed for eligibility and 6944 (51·4 % female, 48·6% male; 97·7% self-reported European, Mediterranean, or Middle Eastern ethnicity) were enrolled and assigned to receive genotype-guided drug treatment (n=3342) or standard care (n=3602). 99 patients (52 [1·6%] of the study group and 47 [1·3%] of the control group) withdrew consent after group assignment. 652 participants (367 [11·0%] in the study group and 285 [7·9%] in the control group) were lost to follow-up. In patients with an actionable test result for the index drug (n=1558), a clinically relevant adverse drug reaction occurred in 152 (21·0%) of 725 patients in the study group and 231 (27·7%) of 833 patients in the control group (odds ratio [OR] 0·70 [95% CI 0·54–0·91]; p=0·0075), whereas for all patients, the incidence was 628 (21·5%) of 2923 patients in the study group and 934 (28·6%) of 3270 patients in the control group (OR 0·70 [95% CI 0·61–0·79]; p <0·0001). Interpretation: Genotype-guided treatment using a 12-gene pharmacogenetic panel significantly reduced the incidence of clinically relevant adverse drug reactions and was feasible across diverse European health-care system organisations and settings. Large-scale implementation could help to make drug therapy increasingly safe. Funding: European Union Horizon 2020