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The University of Hong Kong recently hosted an international conference on the governance of medical artificial intelligence (AI). The conference discussed the challenges and capabilities needed to effectively govern AI in healthcare and health-related research. Presenters highlighted the lack of specificity and contextual sensitivity in existing regulations and the need for a unified approach to AI governance that involves collaboration across disciplines and diverse stakeholders. The conference also addressed issues related to the governance of AI as a medical device and data governance, emphasizing the importance of involving stakeholders and promoting trustworthiness while balancing research and development. [Extracted from the article]

A series of textured (Nb0.5La0.5)xTi1‐xO2 (x = 0, 0.0025, 0.005, 0.01) ceramics were sintered in a nitrogen environment after magnetic slip casting (12 T). Component x ranges from 0.0025 to 0.01 while the degree of orientation increases from 0.49 to 0.88. (Nb0.5La0.5)0.01Ti0.99O2 ceramics in the parallel magnetic field's plane have a high permittivity ɛr ≈ 1.6 × 104 and the ultralow dielectric loss tanδ ≈ 0.0038 at 104 Hz. The temperature coefficient value of η ≤ ± 7.1% between 218–473 K, fulfilling the X9R requirements. The giant permittivity properties of textured ceramics are mainly derived from internal barrier layer capacitor impacts, electron hopping, and electron‐pinned defect‐dipoles polarization. The microstructure evolution of sintered ceramics was modified by texturing in a magnetic field, leading to higher activation energies of dielectric relaxations and resistance of grain boundaries and grains. This excellent performance is expected to show great potential in electronic devices' miniaturization and high‐density energy storage. [ABSTRACT FROM AUTHOR]

AgNbO3 (AN)-based lead-free antiferroelectric ceramics are widely studied for their use as dielectric capacitor materials. In this study, Eu3+-doped AN ceramics were prepared and the results show that Eu3+ diffused into the AN lattice. The ceramics were formed by M1 and M2 phases coexisting at room temperature, as distinct from the M1 (M: monoclinic) phase of pure AN. Electrical properties and structural characterization showed that the antiferroelectric stability of the ceramics increases with the increase in Eu3+ levels. At room temperature, Ag0.94Eu0.02NbO3 ceramic exhibited a good energy storage density of 5.3 J/cm3 and a high efficiency of 71.9%. When the temperature rises from room temperature to 140 °C, the efficiency of the sample decreases from 80.4% to 67.1% and Wr decreases from 2.1 to 2.0 J/cm3, which indicates that the sample has good temperature stability. The time constant (t0.9) of this sample was less than 60 ns and the power density (PD) was 51.3 MW/cm3, indicating excellent charge–discharge capabilities. This novel ceramic is expected to be used as a new dielectric capacitor material for pulsed power supplies. [ABSTRACT FROM AUTHOR]

Al 0.15 Nb 0.15 Ti 0.7 O 2 ceramics were synthesized via strong magnetic field alignment at 6 T and sintered under a nitrogen atmosphere. A ceramic prepared at 6 T by polishing it along the direction parallel to the magnetic field (parallel-6 T) with a brick-layered microstructure shows a colossal permittivity of ε r ≈ 8.2 × 104 and a low dielectric loss of tan δ ≈ 0.019 at 1 kHz, with impedance spectroscopy suggesting that the colossal permittivity is attributed to internal barrier layer capacitor effects. XRD results indicate that approximately 90 % of the grains are aligned along the magnetic field with a tilt angle less than 10°. The average width and length of the grains for parallel-6 T ceramics are 4.1 μm and 9.4 μm. Compared to non-magnetically treated Al 0.15 Nb 0.15 Ti 0.7 O 2 ceramics, the high grain boundary resistance (1.6 × 108 Ω cm) of the parallel-6 T ceramic can be responsible for this low dielectric loss. [ABSTRACT FROM AUTHOR]

Dielectric spectroscopy was carried out for reduced and stoichiometric La0.0025Nb0.0025Ti0.995O2 ceramics synthesized by sintering in different atmospheres. A giant permittivity (~1 × 104) was obtained at a frequency of 100 MHz and temperature range from 170 to 350 K. Three dielectric relaxation mechanisms were observed within the temperature range of 10‐300 K via dielectric spectroscopy. A low temperature dipole relaxation peak (in the temperature range of 10‐30 K) in the spectra was identified to be associated with the giant permittivity specifically measured at 100 MHz. The origin of such giant permittivity was attributed to dipole orientation polarization. Hopping polaron and interfacial effect contributed to giant permittivity. After annealing treatment, all the relaxation contributions were weakened. Low dielectric loss was attributed to high resistance of grain and grain boundaries. Annealing in ambient conditions led to decreased relaxation times which gives the signature of decreased concentration of oxygen vacancies and Ti3+. Dipoles which were related to oxygen vacancies and Ti3+, resulted in giant permittivity up to 100 MHz. [ABSTRACT FROM AUTHOR]

The (Bi 0.5 Nb 0.5 ) x Ti 1- x O 2 (BNTO, 0 ≤ x ≤ 0.05) ceramics were synthesized by a standard conventional solid-state reaction. The effects of sintering temperature and composition x on the crystal structure, microstructure, and dielectric properties of BNTO ceramics were investigated. A pure rutile phase is achieved as x ≤ 0.01, and secondary phase Bi 1.74 Ti 2 O 6.624 is detected as x ≥ 0.025. BNTO ceramic with x = 0.025 shows a high dielectric constant (155.1 k) and low dielectric loss (0.042) at 1 kHz (room temperature). Colossal permittivity is primarily related to Maxwell-Wagner effect, electron-pinned defect-dipoles or weak-binding electron. The low dielectric loss is argued to Bi ions which are doped into TiO 2 lattice and the formation of Bi 1.74 Ti 2 O 6.624 phase. [ABSTRACT FROM AUTHOR]

(Pb0.87Ba0.10La0.02)(Zr0.60Sn0.40-xTix)O3(PLBZST) (x = 0–0.20) bulk ceramics were prepared by the conventional solid state method, and the dependence of phase transformation, ferroelectric properties and energy storage properties on x values has been investigated. When x = 0.12, the unit cell volume significant change indicted the phase transformation of the ceramics. As x = 0.04–0.10, the PLBZST ceramics possess anti-ferroelectric phase with high recoverable energy storage density 0.8–1.3 j/cm3and when x = 0.12–0.20, the ceramics with ferroelectric phase have lower density values about 0.2–0.3 j/cm3. The phase switching electric field, saturation polarization and test temperature have an important influence on energy storage density and efficiency. As a result, the PLBZST bulk ceramics exhibit the largest recoverable energy density of 1.3 j/cm3with efficiency of 77.4% at 20°C. [ABSTRACT FROM AUTHOR]

(In0.5Nb0.5)0.005(Ti1‐xZrx)0.995O2 (INZT, x = 0‐0.10) ceramics were synthesized using a conventional sintering method, and the effects of Zr content on the microstructures, dielectric properties and electron‐pinned defect‐dipoles (EPDD) polarization of the resultant products were investigated. The solubility limit of INZT was x = 0.075, and a secondary ZrTiO4 phase appeared at x = 0.10. Ceramics with x = 0‐0.10 exhibited excellent dielectric properties, ie, colossal permittivity (CP, εʹ > 103) and low dielectric loss (tanδ < 0.1), over a wide range of frequencies (100‐106 Hz at 300 K) and temperatures (50‐350 K at 1 kHz). The dielectric spectra and XPS results confirmed that the CP property of the ceramics could be ascribed to their EPDD polarization. The activation energy (Ea) for EPDD polarization was continuously enhanced by increasing x values. EPDD relaxation parameters at different x values were revealed using Cole‐Cole equation fitting. Moreover, α, which characterize the relaxation time τ distribution, increased with x values, thus indicating that Zr was involved in and affected electron localized states. The high Ea, temperature Tp of the peak εʹʹ at 1 kHz, and dielectric relaxation time τp at 30 K were related to increases in hopping distance of electrons among defect clusters with Zr addition. [ABSTRACT FROM AUTHOR]

Abstract A series of La+Nb co-doped TiO 2 (La 0.5 Nb 0.5) x Ti 1- x O 2 (0.25% ≤ x ≤ 5%) ceramics were prepared using a solid-state reaction method. Colossal permittivity (CP) (εʹ > 104) and low dielectric loss (tanδ < 0.05) were obtained when the ceramics were sintered at 1673 K in an N 2 atmosphere and annealed at 1073–1173 K in air. A pure rutile phase was achieved when x = 0.25% and secondary phase La 2 TiO 5 was detected when x ≥ 0.5%. The optimum dielectric performance of εʹ > 104 and tan δ < 0.05 within 1 Hz–2 MHz and 25–350 K was obtained for x = 0.5%. Three types of dielectric relaxations were observed through the dielectric-temperature spectrum: electron-pinned defect-dipoles (EPDD) polarization, electron hopping, and Maxwell–Wagner polarization. The CP (> 25 K at 1 kHz) was primarily related to EPDD polarization. The high activation energy of the grain boundary (E gb = 1.98 eV) is one of the reasons for the low tanδ in this study. Graphical abstract Image 1 Highlights • The (La 0.5 Nb 0.5) x Ti 1- x O 2 (0.25% ≤ x ≤ 5%) ceramics have been investigated. • For x = 0.5, ε r > 104 and tan δ < 0.05 within 1 Hz–2 MHz and 25–350 K. • The CP property was confirmed original from EPDD polarization. • High activation energy of the grain boundary is reason for low tanδ. [ABSTRACT FROM AUTHOR]

A series of Tl + Nb co-doped TiO 2 ceramics ((Tl 0.5 Nb 0.5 ) x % Ti 1- x % O 2 0.5 ≤  x  ≤ 10.0) were prepared by a solid-state reaction method under N 2 atmosphere. The evolution of their microstructures, and dielectric properties were systematically studied. The co-doped ceramics exhibited a tetragonal rutile structure wherein the Nb and Tl elements were homogeneously distributed. The cell volumes, grain size, and permittivity increased with doping x , whereas the impedance values of the grain and grain boundary decreased with an increasing x . The optimum dielectric performance ( ε r > 10 4 , tan δ  < 0.05) in the range of 10–10 6 Hz was obtained for x  = 1.5 with a corresponding grain boundary active energy of 0.86 eV. Four types of dielectric relaxation were observed at different temperature ranges: 10–30 K, 30–200 K, 200–350 K and 350–475 K; those dielectric relaxtions were respectively caused by electron-pinned defect-dipoles, electron hopping, oxygen vacancy hopping, and Maxwell–Wagner polarization. The colossal permittivity is primarily a result of the electron-pinned defect-dipole polarization. [ABSTRACT FROM AUTHOR]

In, Nb, and Zr co-doped TiO 2 ((In 0.5 Nb 0.5 ) 0.005 (Ti 1-x Zr x ) 0.995 O 2 ) (x = 0–0.80) ceramics were prepared by a solid-state reaction method, and their structures, dielectric properties, and response to DC bias were studied. The solubility limit was found to be near x = 0.10, and the excess added Zr was present in the form of secondary ZrTiO 4 phase. The mean grain size increased from 20.2 to 39.5 μm in the x = 0–0.10 range and then decreased to 5.2 μm for x = 0.20. Permittivity at 1 kHz exceeded 10 4 for the samples in the x = 0–0.20 range and then decreased to 570 for x = 0.40. For x = 0.20, the ceramic sample showed ε r ≈ 10 4 and tanδ ≤ 0.05 (20 Hz–100 kHz), as well as good temperature (−150 to 125 °C) and DC bias (0–875 v/cm) stability. The breakdown electric field increased from 940 v/cm for x = 0 to 5770 v/cm for x = 0.20. The excellent dielectric properties are attributed to the coexistence of smaller grains and the presence of insulating ZrTiO 4 in the sample. [ABSTRACT FROM AUTHOR]