•Sr and Nb co-doped Pb(Zr,Ti)O3 ferroelectric ceramics were synthesized by a solid-state reaction method.•Rare phenomenon of coexistence of negative and positive electrocaloric effect was found in Sr and Nb co-doped Pb(Zr,Ti)O3 ferroelectric ceramics.•High electrocaloric coefficient of −0.25 K mm kV−1 and 0.43 K mm kV−1 were obtained.•Reason for the coexistence of negative and positive electrocaloric effect was discussed.The electrocaloric effect has been investigated in Sr and Nb co-doped Pb(Zr,Ti)O3 (PSNZT) ceramics synthesized by conventional solid state reaction. The coexistence of negative and positive electrocaloric effect was revealed in PSNZT ceramics. The electrocaloric response values of −0.38 K at 80 °C and 0.65 K at 180 °C were observed under an electric field of 1.5 kV/mm. The corresponding electrocaloric coefficient values were calculated to be −0.25 K mm kV−1 and 0.43 K mm kV−1 respectively. The mechanism of the coexistence of negative and positive electrocaloric effect was discussed.

•LSMO thin film was firstly grown on PLZST antiferroelectric ceramics by RF magnetron sputtering.•The magnetoresistance exhibits excellent thermal stability in a broad temperature range under 6T magnetic field.•The excellent magnetic and transport properties of LSMO/PLZST are mostly attributed to the diffusion between LSMO and PLZST.La0.7Sr0.3MnO3 (LSMO) polycrystalline thin films were deposited respectively on (Pb0.97La0.02)(Zr0.58Sn0.3025Ti0.1175)O3 (PLZST) ceramics and Si wafer by RF magnetron sputtering. Their microstructure, electric transport and magnetic properties were investigated. Compared with the LSMO thin films on Si, the films on PLZST show excellent electrical and magnetic transport properties. The resistivity of LSMO on PLZST reduced obviously compared to that of LSMO on Si. The LSMO films on PLZST show higher Curie temperature and metal-insulator transition temperature (TC = 340 K, TMI = 260 K). Meanwhile, the magnetoresistance exhibits excellent thermal stability in a broad temperature range even under 6T magnetic field.

In this paper, we prepared lead-free (1-x)BaTiO3-xBi(Zn0.5Ti0.5)O3 (x=0.04, 0.08, 0.10, and 0.14) ceramics by a conventional solid-state reaction technique. Pure perovskite structures and dense microstructures were demonstrated for all the compositions. Interestingly, it was found that the sintering temperature tended to decrease with increasing the Bi(Zn0.5Ti0.5)O3 content. It should be stressed that a low sintering temperature of 1050 °C was utilized for the composition of x=0.14. Moreover, the dielectric permittivity-temperature curve became more flat and the relaxor degree became stronger with the augment in Bi(Zn0.5Ti0.5)O3 content. We also conducted a detailed study on the energy storage performance for all the compositions from 25 °C to 180 °C.We found that relatively temperature-stable energy storage performance could be obtained in the compositions with x=0.08, 0.10 and 0.14 regardless of the evolution of dielectric constant during the test temperature range. In particular, due to a higher field of 12 MV m−1, the discharge energy storage densities of x=0.14 could reach 0.81 J cm−3, 0.80 J cm−3, 0.78 J cm−3, 0.72 J cm−3, and 0.67 J cm−3 with high efficiencies of 94%, 92%, 94%, 88% and 77% at 25 °C, 50 °C, 100 °C, 150 °C, and 180 °C, respectively. All these results demonstrate the (1-x)BaTiO3-xBi(Zn0.5Ti0.5)O3 ceramics are quite promising for temperature-stable energy storage applications.

The fatigue behavior of 0.05Pb(Mn1/3Sb2/3)O3–0.50PbZrO3–0.45PbTiO3 ceramics (abbreviated as PMS-PZT) is investigated. Special attention is paid to the effect of applied electric frequency on the evolution of polarization-electric field, strain-electric field hysteresis loops as well as the parameters of remnant polarization, internal bias field and coercive field extracted directly from the former hysteresis loops or calculated according to these loops. It is found that the fatigue behavior is different from that of donor doped Pb(Zr,Ti)O3 (PZT) ceramics demonstrated by the tendency of increasing remnant polarization, the decreased internal bias field, decreased asymmetry of polarization-electric and strain-electric loops with increasing fatigue duration when PMS-PZT ceramics fatigued at lower frequency (i.e. 5 Hz or 500 Hz). The dynamic of oxygen vacancies under the application of bipolar electric field is supposed to be associated with the abnormal fatigue behavior. In addition, no matter at which cyclic frequency samples fatigued, coercive field shows the tendency of decrease with increasing fatigue duration except for sample fatigued at 5 kHz in which coercive field first decreases and then increases. According to phase structure and the empirical Rayleigh analysis, phase transition during fatigue treatment is supposed to be account for the decrease of coercive field.

The microstructure and electrical properties of 3-0 type composite of Na0.5Bi2.5Nb2O9-based bismuth layered piezoceramics modified by Al2O3 addition are investigated. The darker and plate-like grains, locating at the grain boundaries, are confirmed to be pure α-Al2O3 by high resolution transmission electron microscope, not a Bi2AlNbO7 pyrochlore phase. This 3-0 type Na0.5Bi2.5Nb2O9-Al2O3 composite piezoceramics have a large piezoelectric constant d33 of 15.2pC/N with good temperature stability up to 600 °C, and good ferroelectric properties with a relatively large remnant polarization of ~11.6 μC/cm2. These demonstrate that designing a 3-0 type composite structure would be an effective approach to tailor the microstructure and improve the electrical properties of bismuth layered piezoceremics for their potential applications at temperature up to 600 °C.

Crack-free Yttrium iron garnet (Y3Fe5O12, YIG) thin films were successfully deposited on Si/SiO2 substrates by RF magnetron sputtering, through controlling the annealing temperature and cooling rate during post-annealing process. The annealing condition dependences of crystallinity, microstructures and magnetic properties of YIG films were investigated. With the increase of the annealing temperature, the saturation magnetization of YIG films increases and the coercive field decreases, while the ferromagnetic resonance (FMR) linewidth becomes wider. The films annealed at 750 °C with cooling rate of 1 °C/min are crack-free and present excellent comprehensive performances, the corresponding coercive field is 32 Oe and the FMR linewidth is 57 Oe at 9.4 GHz. These results indicate that high-quality crack-free YIG films with excellent magnetic properties can be achieved on Si/SiO2 substrates by controlling the annealing process, which makes it more convenient to fabricate low-loss microwave integrated devices.

•The preparation of YIG films by Chemical Solution Deposition are demonstrated.•Well-crystallized and crack-free YIG films can be obtained on Si substrate by CSD.•YIG films can be crystallized in 750 °C with good magnetic performances.•It's beneficial to large-scale production of YIG films on Si integrated devices.Yttrium Iron Garnet (YIG) films were prepared on Si substrates by Chemical Solution Deposition (CSD) technique using acetic acid and deionized water as solvents. Well-crystallized and crack-free YIG films were obtained when annealed at 750 °C and 850 °C respectively, showing a low surface roughness of several nanometers. When annealed at 750 °C for 30 min, the saturated magnetization (Ms) and coercive field (Hc) of YIG films were 0.121 emu/mm3 (4πMs = 1.52 kGs) and 7 Oe respectively, which were similar to that prepared by PLD technique. The peak-to-peak linewidth of ferromagnetic resonance (FMR) was 220 Oe at 9.10 GHz. The results demonstrated that CSD was an excellent technique to prepare high quality yttrium iron garnet (YIG) films on silicon, which could provide a lower-cost way for large-scale production on Si-based integrated devices.

•LCMFO thin films have been deposited on Si substrates by CSD process.•The magnetization and Curie temperature reduced dramatically with Fe ion doping.•The resistance was very sensitive to Fe ion doping.•An enhanced magnetoresistance (−94%) was observed in the sample of x=0.05.The La0.7Ca0.3Mn1−xFexO3 (LCMFO: 0≤x≤0.10) thin films were synthesized by chemical solution deposition process on Si substrates. The structure, magnetic and transport properties have been investigated systematically. With the increase of Fe ion doping concentration, from x=0 to x=0.10, no apparent structural change was observed. While, the magnetization and Curie temperature were reduced dramatically, from 168 emu/cm3 and 231 K for x=0–18 emu/cm3 and 81 K for x=0.10, indicating that Fe ion suppressed the double-exchange mechanism and enhanced the anti-ferromagnetic ordering. Meanwhile, the resistance was very sensitive to Fe ion doping and an enhanced magnetoresistance (−94%) was observed in the sample of x=0.05.

CaBi4Ti4O15–Bi4Ti3O12 (CBT–BIT) ceramics were synthesized using a solid state reaction method. The X-ray diffraction (XRD) analysis revealed the existence of bismuth layered perovskite phase with orthorhombic crystal structure. High-resolution transmission electron microscopy (HRTEM) confirmed the alternate arrangement of CBT part and BIT part along c axis in the intergrowth structure. CBT–BIT ceramics showed excellent thermal stability of the dielectric loss (tan δ), but the relaxation of dielectric loss in the 100 Hz to 1 MHz frequency range had been observed. Meanwhile, an enhanced piezoelectric constant (d33) value of 15 pC/N was observed without degradation even the temperature up to 650 °C. The dc resistivity (ρdc) of CBT–BIT performed a high value of 5.68×1014 (Ω cm) at room temperature (RT). In addition, the ρdc values of CBT–BIT within the temperature range of 100–450 °C were close to those of CBT and kept almost one hundred times higher than those of BIT.

•The phase transition behaviors were strongly dependent on MgO concentration.•The FR(LT)–FR(HT) phase transition temperature obviously shifted toward a lower temperature with increasing MgO addition.•The FR(HT)–cubic paraelectric (PC) phase transition changed to a higher temperature with increasing MgO addition.•The distortion of BO6 oxygen octahedron caused by B-site replacement of Mg2+ ions is proposed to explain the observed behaviors.•Superior room-temperature pyroelectric properties were obtained in 0.1 wt% MgO-modified PZTN 95/5 ceramics during FR(LT)–FR(HT) phase transition.The phase transition behaviors of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics doped with different MgO concentrations (0–0.2 wt%) were systematically investigated by Raman and dielectric measurements. Raman results showed that the phase transitions were strongly dependent on MgO concentration. It was found that the low temperature rhombohedral (FR(LT))–high temperature rhombohedral (FR(HT)) ferroelectric phase transition shifted toward a lower temperature with increasing MgO concentration up to 0.1 wt%, while the FR(HT)–cubic paraelectric (PC) phase transition changed to a higher temperature. The Raman results were in good agreement with phase transition determined by dielectric measurements. Moreover, it was indicated that the changes of Raman active modes were related to distortion of BO6 octahedra during the phase transitions. Then, the distortion of BO6 octahedron caused by B-site replacement of Mg2+ ions was proposed to explain the observed behaviors. In addition, the effects of MgO doping on the dielectric, ferroelectric and pyroelectric properties were also discussed.

Grain size effect on phase transition, dielectric and pyroelectric properties of BST ceramics under DC bias field was reported for the first time. With the grain size increased by one order of magnitude, phase transition diffuseness parameters δ and γ decreased from 282 to 63 and 1.64–1.33, respectively. This resulted in the dielectric constant maximum increased by 65%, the pyroelectric coefficient maximum and corresponding figure of merit were quadrupled and tripled, respectively. The physical essence of the great size effect can be attributed to a combination of surface effect, mechanical stress effect and extrinsic effect of grain boundary. A well understanding of the grain size effect and its mechanism will be useful for the BaTiO3-based ceramics and other ferroelectrics.

•Novel ferroelectric/gyromagnetic ferrite PST/YIG layered film on Si is reported.•The composite film shows excellent magnetic and electric tunability.•Large magnetic tunability of μr (92.1%) and electrical tunability of 75% is obtained.•It shows potential applications in magnetically and electrically tuning devices.•It provides the basic study on YIG-based magneto-electric material from bulk to film.We report on a novel ferroelectric/gyromagnetic ferrite layered composite thin film with two degrees of tuning freedoms. The structure was prepared by layered growth of Y3Fe5O12(YIG) ferrite, LaNiO3(LNO) electrode and (1 0 0) orientated Pb0.4Sr0.6TiO3 (PST) ferroelectric films on Si substrates by RF magnetron sputtering. LNO not only exists as an electrode, but also provides a buffer layer for the orientation growth of PST film. The PST/YIG composite thin films exhibited large magnetic tunability of μr (92.1%@600 Oe), low FMR linewidth (ΔH) of 160.7 Oe@9.1 GHz and high electrical tunability (η) of 75%@360 kV/cm, which shows potential applications in magnetically and electrically tuning devices.