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Ferroelectric transition and polarization characteristics were explored for filled tungsten bronze Ba4Sm2Ti4Nb6O30 ceramics with pinched P–E hysteresis loops. Two dielectric permittivity peaks were observed at around 553 and 486 K on heating and cooling cycles, respectively, with a large thermal hysteresis (∼77 K), indicating the first-order ferroelectric phase transition behavior in the present ceramics. In addition, a low-temperature dielectric relaxation appeared at around 300 K, following the Vogel–Fulcher relationship, which is related to thermal activation related to the polarization in the ab plane. Pinched P–E hysteresis loops were detected in the temperature range of 293–453 K with two pairs of coercive fields, indicating certain polar reversal mechanism, while E1 corresponds to the reversal field needed for all the ferroelectric domains in the system, and E2 is the back switch field from the polar state to the nonpolar state. Therefore, (E1–E2)/2 is the effect coercive field for the polar domain induced by the field transition. Temperature dependence of the coercive fields E1, E2, and (E1–E2)/2 is fitted to the Vopsaroiu model with different activated energies obtained for different temperature ranges, based on which the polarization dynamics of the pinched hysteresis loops are discussed. [ABSTRACT FROM AUTHOR]

A-site high entropy Ba4(La0.2Nd0.2Sm0.2Eu0.2Y0.2)2Ti4Nb6O30 tungsten bronze ceramics were designed and prepared by a standard solid state sintering process. First-order ferroelectric transition occurs around 240 °C on heating, while around 136 °C on cooling. Pinched and asymmetric P–E hysteresis loops were observed within and below the thermal hysteresis temperature range of the ferroelectric transition. Pinched P–E hysteresis loops were attributed to the coupling between the ferroelectric transition and the commensurate/incommensurate modulation transition. The reason for the asymmetry of the hysteresis loop was the presence of an internal bias electric field. Different measuring procedures were designed to clarify the evolution of hysteresis loop asymmetry. The existence of oxygen vacancy and Eu3+/Eu2+ was identified by x-ray photoemission spectroscopy. The electric field cycling with elevated temperatures caused defect dipoles incline to align along the direction of spontaneous polarization leading to the internal bias electric field. Due to the A-site high entropy effect, dielectric strength of Ba4(La0.2Nd0.2Sm0.2Eu0.2Y0.2)2Ti4Nb6O30 ceramics is up to 300 kV/cm, which is increased by more than 50% than that with the single element in the A1-site. [ABSTRACT FROM AUTHOR]

Dense and strong calcite (CaCO3) ceramics were prepared by room‐temperature cold sintering with the aid of water and high pressure of up to 900 MPa. Under atmospheric pressure, calcite is barely soluble in water. However, the microstructure evolution and stress‐strain analysis during cold sintering revealed that the dissolution‐precipitation, plastic deformation, and pressure‐solution‐creep mechanisms played a crucial role in the densification and mechanical robustness of calcite ceramics, which was attributed to the significantly enhanced solubility of calcite in water under high pressure. The calcite ceramic cold sintered under 900 MPa from micron powder exhibited the highest relative density of 92.1% and best mechanical properties with compressive strength, flexural strength, hardness, and Young's modulus of 276.5 MPa, 52.5 MPa, 1.64 GPa, and 53.7 GPa, respectively. The as‐prepared calcite ceramic was stronger and harder than most stones and cement, indicating its promising application as novel building and biomimetic materials. The present study also provides a new strategy for densifying ceramics with low solubility by cold sintering. [ABSTRACT FROM AUTHOR]

MSO4 (M = Ca, Sr, Ba) ceramics with relative densities exceeding 96% were prepared by solid‐state sintering at low sintering temperatures of 625–875°C, and their structures and microwave dielectric properties at 10–19 GHz were characterized. MSO4 ceramics crystallized in orthorhombic symmetry with the space groups of Amma for CaSO4 and Pnma for SrSO4 and BaSO4. The optimal microwave dielectric properties were obtained with εr = 5.85, Qf = 57 000 GHz, τf,W = −98.8 ppm/°C for CaSO4, εr = 10.95, Qf = 15 500 GHz, τf,W = 101.6 ppm/°C for SrSO4, and εr = 9.42, Qf = 38 200 GHz, τf,W = −4.7 ppm/°C for BaSO4. The increased εr and τf,W while decreased Qf value in the order of CaSO4, BaSO4, and SrSO4 were attributed to the enhanced rattling effect of M2+. Besides, the temperature dependence of τf was weak for CaSO4 and BaSO4, whereas much stronger for SrSO4. As most low‐εr microwave dielectric ceramics are of large negative τf, the near‐zero τf of BaSO4 and positive τf of SrSO4 are rare, indicating they are potential candidates for millimeter‐wave communication as a temperature‐stable dielectric ceramic and a compensator for tuning negative τf to near‐zero, respectively. [ABSTRACT FROM AUTHOR]

(1) To explore attitudes and beliefs of neonatal nurses toward nursing care for dying neonates; (2) to estimate the influence of neonatal nurses' personal and professional characteristics on their attitudes towards end-of life care for dying infants. A cross-sectional design was used. A questionnaire was used to collect data from 80 neonatal nurses. Research setting was four level III NICUs at four medical centers around the central region of Taiwan. Research participants were neonatal nurses who had worked for at least 1 year in one of level III NICUs and had been directly involved with the care of dying infants. Research participants were 80 neonatal nurses (response rate 100%). Research findings identified eight barriers hindering neonatal palliative care practice. These barriers were insufficient communication due to the lack of an inservice educational program; the lack of available counseling help for neonatal clinicians; inability to express personal opinions, values and beliefs towards neonatal palliative care; insufficient staffing; the lack of unit policies/guidelines for supporting palliative care; the technological imperative; parental demands and personal beliefs about death and previous experience caring for dying infants. Further studies are needed to explore each barrier and to provide in-service neonatal palliative care educational programs that are needed to decrease these barriers. Keywords Neonatal palliative care * Neonatal nurses * Experience * Attitude * Belief * Dying infant, Introduction The World Health Organization [1] describes palliative care for children as the active total care of the child's body, mind, and sprit, as well as a means of providing [...]

Dielectric relaxations of charge-ordered Ln1.5Sr0.5NiO4 (Ln=La and Nd) ceramics were investigated over a broad temperature range. The giant dielectric constant (over 70 000) with a low dielectric loss of ∼0.1 was determined at high frequencies (up to 5 MHz) over a broad temperature range. There are two dielectric relaxations in the vicinity of charge ordering temperatures. The thermal activated small polaronic hopping between two charge ordering temperatures should contribute to the giant dielectric response in the present ceramics. Compared to other giant dielectric constant materials, the present materials have the notable advantage for high frequency applications. [ABSTRACT FROM AUTHOR]