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In this work, CaWO4 ceramics with high Q×f levels were successfully sintered at temperatures lower than 950 °C with the additions of very small amounts of Li2CeO3 (i.e., 0.1–2.0 wt.%). CaWO4 + x wt.% Li2CeO3 ceramic samples were found to be consisted of a single sheelite phase with relatively high density levels and homogenous microstructures. The ceramic samples exhibited excellent microwave dielectric properties, for instance, the specimen with 0.5 wt.% Li2CeO3 sintered at 725 °C for 4 h showed the properties of er = 9.9, Q×f = 69000 GHz, and τf = −63 ppm/°C. Moreover, it was found that there was no apparent reaction between the ceramic sample and Ag electrode during the sintering process. Therefore, Li2CeO3 has been proofed to be a highly effective sintering additive of CaWO4 ceramics, which is a promising candidate material for low temperature co-fired ceramic (LTCC) technology.

A theory of the magnetoelectric effect in three-layer asymmetric structures composed of a piezoelectric layer and two magnetostriction layers with opposite magnetostriction signs is presented. The thickness ratio of the layers is obtained, at which this effect is maximum. It is shown that the sign of the magnetoelectric coefficient changes to opposite (with respect to the initial two-layer structure) with an increase in the third-layer thickness. It is established that the magnetoelectric coefficients of the structures with different arrangements of the layers with positive and negative magnetostriction have opposite signs.

0.67CaTiO3–0.33LaAlO3 (CTLA) microwave dielectric ceramic materials with the additives of H3BO3, Li2CO3 or H3BO3–Li2CO3 were prepared by a conventional solid-state reaction method. The effects of the sintering additives on the densification behavior, phase compositions, microstructures, and microwave dielectric properties of the CTLA ceramic samples were investigated. It was found that the binary additive of H3BO3–Li2CO3 effectively promoted the densification and lowered the sintering temperature of the CTLA ceramic samples without a significant decrease in their Q × f values. For example, with an addition of 0.2 wt% H3BO3–0.1 wt% Li2CO3, the optimal microwave dielectric properties of er = 45.5, Q × f = 31,771 GHz and a near-zero τf of 2.43 ppm/℃ were obtained in the CTLA ceramic sample sintered at only 1175 ℃, which is significantly lower (~ 225 ℃) compared to the sintering temperatures of conventionally sintered CTLA ceramics.

Low-loss (1−x)Li2TiO3–xLi3Mg2NbO6 (LT-LMN, 0.02 ≤ x ≤ 0.08) microwave dielectric ceramics (MDCs) with rock salt structures were fabricated via a traditional solid-state reaction route. Li3Mg2NbO6 was used as a Li2TiO3 compensator to improve temperature stability. Scanning electron microscope observations and X-ray diffraction analyses were used to investigate the microstructures and crystalline structures of the ceramics, respectively. We demonstrated a correlation between macroscopic “dark hole” phenomena and the microwave dielectric properties (MDPs) of LT-LMN ceramics by analysing the valence states of Ti ions and the content of oxygen vacancies using X-ray photoelectron spectra. We continuously added Li3Mg2NbO6 to pure Li2TiO3 to form MDCs, and found that at x = 0.04, (1−x)Li2TiO3–xLi3Mg2NbO6 ceramics achieved a near-zero resonance-frequency temperature coefficient (τf). 0.96Li2TiO3–0.04Li3Mg2NbO6 ceramics sintered at 1250 °C had excellent MDP values: appropriate permittivity (ϵr) = 19.12, high quality factors (Q × ƒ) = 70814 GHz (at 6.105 GHz), and τf = 2.6 ppm/°C. This indicates that LT-LMN ceramics are promising materials for high-selectivity microwave ceramic dielectric substrates.

In this work, Ba4Nd9.33Ti18O54 (BNT) microwave dielectric ceramic materials fabricated by a conventional solid-state reaction method was compositionally modified via the replacement of Ti4+ by (Al0.5Nb0.5)4+ and the addition of NdAlO3 to enhance the temperature stability ( τ f ) and quality factor (Q×f) of the BNT ceramic materials. In the ceramic samples of Ba4Nd9.33(Al0.5Nb0.5)xTi18-xO54 (BNANT), an increase in the concentration of (Al0.5Nb0.5)4+ (i.e., x from 0 to 1.6) effectively improved both the τ f (from 67.5 to 12.6 ppm/°C) and the Q×f (from 9260 to 10245 GHz) despite the fact that the excessively high concentration of (Al0.5Nb0.5)4+ (i.e., x = 1.6) severely deteriorated the Q×f, and the τ f was still not at a near-zero level. Therefore, NdAlO3 was introduced into the BNANT ceramic materials as a τ f compensator. In the binary system of (1-y)Ba4Nd9.33(Al0.5Nb0.5)1.2Ti16.8O54-yNdAlO3, a near-zero τ f level of −2.06 ppm/°C with Q×f = 13680 GHz and dielectric constant ( e r ) = 70 was achieved at y = 0.55.

In this work, a novel additive-free microwave dielectric ceramic (MWDC) system of (1 − x)CaWO4−x(Li0.5Sm0.5)WO4 (CW-LSW, 0.12 ≤ x ≤ 0.20) for low temperature co-fired ceramic (LTCC) applications was successfully fabricated by a solid-state reaction route. The sintering temperature and composition effects on the microwave dielectric (MWD) properties, microstructures, and crystalline phases were investigated. The optimal sintering temperatures of the CW-LSW ceramics are ranging from 875 to 950 °C. When sintered at 900 °C for 3 h, the sample of 0.86CW-0.14LSW exhibited excellent MWD properties: er = 10.76, Q × f = 28,754 GHz, and τf = − 0.54 ppm/°C. Furthermore, it is found that the CW-LSW ceramics are well compatible with Ag electrode during the sintering process. Therefore, the findings suggest that CW-LSW ceramic materials are promising for LTCC applications.

CoFe2O4 (CFO) nanofibers (NFs) with tunable diameter and length are successfully synthesized via an electrospinning process. Each individual CFO NF was assembled with a large amount of small nanoparticles stacked one by one along the axis direction after high temperature heat treatment. The surface morphology and diameter of the NFs can be easily adjusted by controlling the solution concentration, content of PVP additives, electro-spinning voltage and post-annealing temperature. The grain size of CFO NFs is increased with increasing annealing temperature, and the magnetic properties of which also exhibit annealing temperature and grain size dependence. The controllable synthesis strategy for one-dimensional CFO NFs lays an alternative foundation for the application of CFO in nanoelectromagnetic and spintronic devices.

A model for the low-frequency magnetoelectric (ME) effect that takes into consideration the bending deformation in a ferromagnetic and ferroelectric bilayer is presented. Past models, in general, ignored the influence of bending deformation. Based on the solution of the equations of the elastic theory and electrostatics, expressions for the ME voltage coefficients (MEVCs) and ME sensitivity coefficients (MESCs) in terms of the physical parameters of the materials and the geometric characteristic of the structure were obtained. Contributions from both bending and planar deformations were considered. The theory was applied to composites of PZT and Ni with negative magnetostriction, and Permendur, or Metglas, both with positive magnetostriction. Estimates of MEVCs and MESCs indicate that the contribution from bending deformation is significant but smaller than the contribution from planar deformations, leading to a reduction in the net ME coefficients in all the three bilayer systems.

This work focuses on the nature of magnetic anisotropy in 2.5–16 micron thick films of nickel ferrite (NFO) grown by liquid phase epitaxy (LPE). The technique, ideal for rapid growth of epitaxial oxide films, was utilized for films on (100) and (110) substrates of magnesium gallate (MGO). The motivation was to investigate the dependence of the growth induced anisotropy field on film thickness since submicron films of NFO were reported to show a very high anisotropy. The films grown at 850–875 C and subsequently annealed at 1000 C were found to be epitaxial, with the out-of-plane lattice constant showing unanticipated decrease with increasing film thickness and the estimated in-plane lattice constant increasing with the film thickness. The uniaxial anisotropy field Hσ, estimated from X-ray diffraction data, ranged from 2.8–7.7 kOe with the films on (100) MGO having a higher Hσ value than for the films on (110) MGO. Ferromagnetic resonance (FMR) measurements for in-plane and out-of-plane static magnetic field were utilized to determine both the magnetocrystalline the anisotropy field H4 and the uniaxial anisotropy field Ha. Values of H4 range from −0.24 to −0.86 kOe. The uniaxial anisotropy field Ha was an order of magnitude smaller than Hσ and it decreased with increasing film thickness for NFO films on (100) MGO, but Ha increased with film thickness for films on (110) MGO substrates. These observations indicate that the origin of the induced anisotropy could be attributed to several factors including (i) strain due to mismatch in the film-substrate lattice constants, (ii) possible variations in the bond lengths and bond angles in NFO during the growth process, and (iii) the strain arising from mismatch in the thermal expansion coefficients of the film and the substrate due to the high growth and annealing temperatures involved in the LPE technique. The LPE films of NFO on MGO substrates studied in this work are of interest for use in high frequency devices.

In this work, (1-x)Li2TiO3-xLi4NbO4F ceramics were prepared by the conventional solid-state ceramic route. With the increase of Li4NbO4F content, the phase structure transformed from ordered monoclinic to disordered cubic. By increasing Li3NbO4F content, the temperature coefficient of resonant frequency (τf) was successfully adjusted closer to zero, while the dielectric constant (εr) and microwave quality factor (Qf) decreased to some degree. Outstanding microwave dielectric properties with a εr = 18.7, Qf = 61,388 GHz (6.264 GHz), and τf = 0.9 ppm/°C were obtained for 0.9Li2TiO3-0.1Li4NbO4F ceramics sintered at 1050 °C for 2 h, which indicated that these ceramics are suitable for practical applications in the field of microwave substrates and components.

Metal halide perovskites exhibit small exciton binding energy, which leads to a low electron–hole capture rate for radiative recombination and accordingly decreases the luminescence efficiency. Reducing the thickness of the perovskite film or the size of the perovskite crystal is found to be an effective method to spatially confine the electrons and holes to promote the bimolecular radiative recombination. Here, we fabricate CsPbBr3/Cs4PbBr6 nanocomposites, applicable for light emission diodes, by a simple self-assembly method. We effectively reduce the critical size of the CsPbBr3 nanocrystals in the CsPbBr3/Cs4PbBr6 nanocomposites by adding a certain amount of dimethyl sulfoxide into the perovskite precursor solution. Accordingly, the photoluminescence quantum yield of the CsPbBr3/Cs4PbBr6 nanocomposites increased from 56 to 91% due to the quantum size effect. In situ observation of the growth of CsPbBr3/Cs4PbBr6 nanocomposites reveals that the reduction of the CsPbBr3 crystal size is due to the change of the chemical reaction speed during the two-step growth process of the CsPbBr3/Cs4PbBr6 nanocomposites.

Polycrystalline rare-earth-substituted Bi5Ti3Fe0.7Co0.3O15 (BReFCT (Re = La, Nd and Ho)) ceramics were prepared by conventional solid-state reaction. The main four-layered Aurivillius structure was confirmed in the as-prepared ceramics by X-ray diffraction and Raman spectra analysis though a small amount of secondary phase consisting of magnetic Co and Fe elements was detected by SEM/EDS. The observed ferromagnetic behavior and magnetoelectric coupling response were attributed to the main Aurivillius phase. A maximum ME coefficient of 31.58 mVcm−1Oe−1 was achieved in BLaFCT ceramics. The magnetic and magnetoelectric coupling properties in BReFCT ceramics were discussed based on the radius difference of the rare earth ions and the induced distorted lattice structure. The enhanced magnetoelectric properties of the BReFCT ceramics are promising for novel magnetoelectric device applications.

(1 − x)Li0.5Sm0.5TiO3–xNa0.5Sm0.5TiO3 (LST-NST, x = 0.35 to 0.45) microwave dielectric ceramics with orthorhombic perovskite structure have been fabricated by a conventional solid-state reaction method. The densification behavior of the LST-NST ceramic samples was investigated by dilatometry analyses. The effects of the sintering temperature and composition on the microstructure and microwave dielectric properties of the ceramic samples were investigated in detail. Generally, 1180°C was found to be the optimal sintering temperature for the LST-NST ceramics. The optimal microwave dielectric properties of the LST-NST ceramics were achieved for the 0.63LST-0.37NST (x = 0.37) composition with er = 96.8, Q × f = 5102 GHz, and near-zero τf of − 4.35 ppm/°C.

Highly transparent and submicrometer-grained Yb:Y2O3 ceramics were obtained by hot-pressing method with ZrO2 sintering additive. Hot-pressing method provides extra driving force to promote the densification of Yb:Y2O3 transparent ceramics, resulting in high transmittance achieved. The transmittances of all samples were ranging from 80.5-81.8% at 1100 nm and 72.7-77.7% at 600 nm. The ceramic samples in this work were sintered at a low temperature of 1600 ℃ for 3 h, providing dense microstructures with average grain size less than 1μm, which are smaller than those of Yb:Y2O3 ceramics prepared by other traditional sintering techniques. The microhardness and fracture toughness were ranging from 8.16 to 7.99 GPa, and from 0.94 to 0.88 MPa·m1/2, respectively, which are higher than the comparison samples fabricated by pressureless sintering. The absorption cross-sections of the 1 at.% Yb-doped sample at 950 and 976 nm were 0.93 × 10-20 and 1.22 × 10-20 cm2, respectively. The fluorescence decay lifetime at 1032 nm was in the range of 0.79-1.36 ms. According to the available literature, this is the first report about Yb:Y2O3 transparent ceramics fabricated by hot-pressing sintering without any combined sintering process. The ceramics obtained may have potential use for solid-state lasers partly replacing single crystals.

Nowadays, wearable and flexible nanogenerators are of great importance for portable personal electronics. A flexible piezoelectric energy harvester (f-PEH) based on Bi3.15Nd0.85Ti3O12 single crystalline nanoplates (BNdT NPs) and polydimethylsiloxane (PDMS) elastomeric polymer was fabricated, and high piezoelectric energy harvesting performance was achieved. The piezoelectric output performance is highly dependent on the mass ratio of the BNdT NPs in the PDMS matrix. The as-prepared f-PEH with 12.5 wt% BNdT NPs presents the highest output voltage of 10 V, a peak-peak short-circuit current of 1 μA, and a power of 1.92 μW under tapping mode of 6.5 N at 2.7 Hz, which can light up four commercial light emitting diodes without the energy storage process. The f-PEHs can be used to harvest daily life energy and generate a voltage of 2–6 V in harvesting the mechanical energy of mouse clicking or foot stepping. These results demonstrate the potential application of the lead-free BNdT NPs based f-PEHs in powering wearable electronics

BACKGROUND We explored the role of MACC1-AS1 in hepatocellular carcinoma (HCC). MATERIAL AND METHODS Measurement of preoperative plasma levels of MACC1-AS1 was performed by qPCR, and the comparison between the HCC and Control group was performed by unpaired t test. The overexpression of TGF-ß1 in SNU-182 and SNU-398 cells was confirmed by qPCR. RESULTS MACC1-AS1 was overexpressed in HCC patients. In comparison to pretreatment level, distant recurrence (DR) was accompanied by increased levels of MACC1-AS1 in plasma, but this phenomenon was not observed in cases of local recurrence (LR) or non-recurrence (NR). In HCC cells, MACC1-AS1 positively regulated the expression of TGF-ß1. MACC1-AS1 overexpression resulted in increased invasion and migration rates of HCC cells, while siRNA silencing resulted in reduced rates. Moreover, TGF-ß1 overexpression reduced the effects of MACC1-AS1 siRNA silencing. CONCLUSIONS MACC1-AS1 is involved in the distant recurrence of HCC, and its actions are possibly mediated by TGF-ß1.

Novel perovskite ferroelectric (1-x)KNbO3-xBi(Ni1/2Ti1/2)O3 nanofibers were synthesized by electrospinning for the first time. The synthesized 0.99KNbO3-0.01Bi(Ni1/2Ti1/2)O3 nanofibers displayed the optimal photocatalytic activity with a hydrogen production rate of 0.57 μmol·h−1 for 20 mg under visible light radiation. By first principles calculations, a midgap of Ni 3d was formed between the O 2p states at the valence band maximum and the Nb 4d states at the conduction band minimum due to the addition of Bi(Ni1/2Ti1/2)O3, which may be the principal reason for the visible light response in this work. In addition, the hydrogen production rate of polarized 0.99KNbO3-0.01Bi(Ni1/2Ti1/2)O3 nanofibers was twice as high as that of unpolarization under visible light irradiation, indicating that the internal dipole field can accelerate the separation of photogenerated electron-hole pairs. This may provide a new viewpoint for improving the visible light response of perovskite-oxide ferroelectrics.

High-Q×f 0.95MgTiO3–0.05CaTiO3 (MT–CT) glass-free microwave dielectric ceramics with LiF (1–4 wt%) were fabricated by a conventional solid-state reaction method at medium temperatures. The effects of LiF additive on the phase compositions, microstructures, and microwave dielectric properties of the MT–CT ceramics were studied. The results showed that LiF effectively enhanced the densification and lowered the sintering temperature of the MT–CT ceramics without deteriorating the quality factor (Q×f) values significantly. The optimal microwave dielectric properties of er = 17.96, Q×f = 70572.4 GHz, and τf = –18.77 ppm/°C were achieved in the MT–CT ceramics with 2 wt% LiF sintered at 1150 °C, which is approximately 250 °C lower than the sintering temperature of conventional MT–CT ceramics.

Microwave dielectric ceramics of (1 − x)(Mg0.97Zn0.03)(Ti0.97Sn0.03)O3–x(Ca0.8Na0.1Sm0.1)TiO3 (MZTS–CNST, 0.05 ≤ x ≤ 0.08) were fabricated by a conventional solid-state reaction method. The effects of the sintering temperature and composition on the phases, microstructures, and microwave dielectric properties were studied. A relatively low sintering temperature of 1325 °C is needed for the MZTS–CNST ceramic samples. The optional microwave dielectric properties were achieved at x = 0.08 with er = 21.5, Q × f = 60,110 GHz, and a near-zero τf of 1.69 ppm/ °C.

The x(Ca0.8Na0.1Sm0.1)TiO3–(1 − x)(Sm0.5Nd0.5)AlO3 (CNST–SNA, 0.60 ≤ x ≤ 0.75) ceramic materials were prepared by a conventional two-step solid-state reaction route. The effects of the sintering temperature and composition on the phases, microstructures, and microwave dielectric properties were investigated. The optimal sintering temperature of the CNST–SNA ceramics was found at 1475 °C. The optimal microwave dielectric properties were achieved at x = 0.69 with er = 43.8, Q × f = 34303 GHz (at 5.968 GHz), and τf = − 1.64 ppm/°C.

CsPbBr3/Cs4PbBr6 nanocomposites recently were found to yield efficient luminescence. However, the formation mechanism of the nanocomposites is unclear, and large-scale and green synthesis is still challenging. Here, we develop a self-assembly reaction to fabricate CsPbBr3/Cs4PbBr6 nanocomposites efficiently and environmentally friendly. The transmission electron microscopy clearly shows CsPbBr3 nanocrystal is embedded in Cs4PbBr6 matrix, forming a CsPbBr3/Cs4PbBr6 composite structure. In situ characterization reveals that the CsPbBr3/Cs4PbBr6 nanocomposites are formed by a two-step reaction, driven by ion concentration difference. The self-encapsulation and separation of the CsPbBr3 NCs by the host Cs4PbBr6 result in the material exhibiting a high PLQY of 83% and narrow-band emission at 517 nm with a full width at half-maximum of only 21 nm. Further, we fabricate an on-chip white light-emitting diode (LED) using the as-synthesized CsPbBr3/Cs4PbBr6 nanocomposites as a green emitter and red K2SiF6:Mn4+ phos...

In this work, magnetoelectric thin film heterostructures of Pb(Zr 0.52 Ti 0.48 )O 3 /La 0.67 Sr 0.33 MnO 3 (PZT/LSMO) were epitaxially grown on SrTiO 3 (STO) substrates. aa -phase and r -phase in PZT layer could be observed simultaneously. Thickness dependent magnetoelectric effect of these heterostructures is investigated in detail. The results show that the r -phase in PZT layer will significantly improve the magnetoelectric voltage coefficient (α E31 ), and the amount of r -phase will decrease with increasing thickness of PZT layer. The maximum α E31 can reach 1153 mV/cm Oe for the sample with PZT thickness of 32 nm. This work will be of significance for tuning magnetoelectric effect via thickness ratio between ferroelectric and ferromagnetic layers.

Inorganic–organic hybrid perovskite solar cells have become of interest due to their high solar-to-electric power conversion efficiency and low fabrication costs. Recently, it is reported that chlorine doping is an effective means of improving the conversion efficiency and stability of these cells. However, the role played by chlorine and the chemical state of chlorine in the MAPbI3−xClx perovskite is still the subject of much debate. In the present work, we fabricate Cl-containing perovskite films by spin coating a mixed solution of CH3NH3Cl and CH3NH3I on PbI2 films in air. The chemical state of Cl in these films is investigated by X-ray diffraction and X-ray photoelectron spectroscopy. It is found that the Cl is present in different chemical states depending on the concentration of CH3NH3Cl used in the original synthesis. XPS depth profile results demonstrate that Cl is present throughout the samples rather than solely at the perovskite/TiO2 interface as has been reported previously. However, the Cl located at the interface is more stable during thermal treatment of the films. Photovoltaic characterization reveals that strong relationship between the chemical state of chlorine and photovoltaic performance exists.

High epitaxial (001)-, (110)- and (111)-oriented Ni ferromagnetic thin films were coherently grown on Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) (001), (110) and (111) substrates by magnetron sputtering. Reciprocal space mapping (RSM) results indicate that all of these films are partially relaxed. The mechanism of strain-induced magnetic anisotropy of these epitaxial thin films has been investigated in detail. The easy axis is induced toward out-of-plane (OOP) due to compressive strain, while the hard axis is along in-plane (IP) owing to tensile strain. (111)- and (110)-oriented Ni thin films show the strongest and the weakest magnetic anisotropy, respectively. The strain-induced magnetoelastic energy for (001)-oriented Ni thin film increases its anisotropic field and decreases its total free energy resulting in an enhanced magnetic anisotropy comparing with (110)-oriented one. The remarkable variation of magnetization in high epitaxial Ni thin film system reveals that the magnetic anisotropy can be modulated by changing the biaxial strain.

Multiferroic Bi 5 Ti 3 Fe 1− x Co x O 15 (BFCT- x , where x = 0, 0.1, 0.3, 0.5, 0.7) ceramics were synthesized via a conventional solid-state reaction process and their microstructural, ferroelectric, magnetic and magnetoelectric coupling properties were investigated in detail. All samples show layered perovskite Aurivillius phase with an orthorhombic structure. The highest remanent polarization (2 P r ) (35 μC/cm 2 ) has been observed in BFCT-0 ceramic while the BFCT-0.3 ceramic shows the highest remanent magnetization ( M r ) (0.13 emu/g) and magnetoelectric coefficient (11.47 mV cm −1 Oe −1 ). The enhancement of magnetic properties and the magnetoelectric coupling of these ceramics are attributed to the structural distortion caused by Co substitution which subsequently led to ferromagnetic interactions via the Dzyaloshinskii-Moriya interaction.

(1-x)CaTiO3-x(Li0.5Sm0.5)TiO3 (0.7 ≤ x ≤ 0.8, CLST) ceramics with an orthorhombic perovskite structure were fabricated by a conventional solid-state reaction method. The effects of composition variation on the microwave dielectric properties were studied in detail. The permittivity (er) and quality factor (Q × f) value decreased with an increase in the x value, and the temperature coefficient of the resonant frequency (τf) reached nearly zero. Raman and infrared reflection spectroscopy were employed to reveal the relationship between vibrational modes and microwave dielectric properties. The Raman spectra fitted with the Lorentzian model indicated that the dielectric loss deteriorates with an increase in the x value are the result of the lowered A-site cation ordering degree. The harmonic oscillator model was used to fit the infrared reflection spectra, and the obtained complex dielectric response was extrapolated down to the microwave region. The infrared reflection spectra show that the vibrational modes related to A-site cations at lower frequencies (i.e.

A highly strained tetragonal (T)-like BiFeO 3 (BFO) phase interspersed between two rhombohedral ( R )-like phase regions in BFO films grown on LaAlO 3 substrates was confirmed by transmission electron microscopy (TEM). The typical width of the T-like phase was about 5–35 nm and the areal fraction of the T-like phase was estimated to be 35%. A lattice misalignment of 3.8° between adjacent R- and T-like phases was observed in both high-resolution TEM images and selected-area electron diffraction patterns. Superlattice reflection spots were observed along the [110] direction in the R-like phase, which were attributed to the antiphase tilting of oxygen octahedra about the pseudocubic [111] axis of the R-like phase. A structural phase transition from the T-like phase to the R-like one at around 435 °C was observed by TEM during in situ heating and cooling experiments.

This report is on strain control of magnetic order parameters in 50 nm epitaxial NiFe2O4 (NFO) films grown on (001), (110), and (111) SrTiO3 (STO) single-crystal substrates by pulsed laser deposition. The related in-plane strains for NFO films on (001), (110), and (111) STO substrates are found to be ―1.36 %, 1.35 %, and 1.52 %, respectively, where the lattice mismatch between film and substrate is as high as 6.7 %. Our analysis of magnetization and ferromagnetic resonance on all the NFO films reveals the presence of a uniaxial anisotropy field, which is perpendicular to the film plane. The anisotropy field decreases with the increase of strain in NFO films. Specifically, NFO films on STO (111) and STO (001) have the lowest and highest uniaxial anisotropy fileds of 1.4 kOe and 6.1 kOe, respectively. These experimental values of anisotropy field are a factor of 5–10 times smaller than those of the calculated ones due to the film defects induced by the high lattice mismatch. The studies of magnetic anisotropy of spinel ferrite films are of interest for spintronics and microwave devices.

We prepared (1−x)CaTiO3–xLaAlO3 (0 ≤ x ≤ 1) microwave dielectric ceramics using a conventional two-step solid-state reaction method, and investigated microwave dielectric properties of the ceramics in terms of A/B-site ionic-parameters. Ionic-parameters such as ionic polarizability, A-site bond valence, and ionic rattling were linked to the microwave dielectric properties. As the LaAlO3 content x in the (1−x)CaTiO3–xLaAlO3 ceramics increased from 0.3 to 0.7, the dielectric constant gradually decreased, which was attributed to the decrease of polarizability deviation and suppression of the cation rattling. The temperature coefficient of the resonant frequency decreased as the content of LaAlO3 increased because of the increase of A-site cation bond valence. The quality factor value (Q × f) increased as LaAlO3 content increased because of the enhancement of the order degree of B-site cation. A significant deterioration of the temperature coefficient of the resonant frequency and Q × f value was observed at the composition x = 0.5. These decreases were attributed to a phase transition from orthorhombic crystal (for x ≤ 0.5) to rhombohedral crystal (for x > 0.5).

All-inorganic cesium lead halide perovskite materials, such as CsPbBr3 and CsPb2Br5, have drawn immense attention recently due to their potential applications in optoelectronics. However, unlike the extensively-studied CsPbBr3, many of the fundamental properties of CsPb2Br5 remain unclear, such as its electronic structure and photoluminescence (PL) mechanism. In this work, we developed a novel environmentally friendly chemical method to synthesize CsPb2Br5, where only water and ethanol were used as solvents. The optical property and electronic structure of CsPb2Br5 were then examined both experimentally and theoretically. For the first time we found that the band-edge emission of CsPb2Br5 was not in the visible range as reported in the literature but rather located in the ultraviolet range. By monitoring the PL property during phase conversion between CsPb2Br5 and CsPbBr3, we propose that previously-reported visible emission might be due to the involvement of CsPbBr3 during sample preparation. Overall, this study presents a novel green method for the preparation of CsPb2Br5 and clarifies the optical properties and electronic structure of CsPb2Br5.

The interactions between electric and magnetic subsystems in a ferroelectric-ferromagnetic composite occur through mechanical forces. Here we discuss results of a systematic investigation on the strength of the magnetic response of the composite to an applied electric field, known as the converse magnetoelectric (CME) effect, and its dependence on the ferroic order parameters and volume fraction for the two phases. Studies were carried out on composites of lead zirconate titanate and 2-30-mu m-thick nickel zinc ferrite (NZFO) films grown by liquid phase epitaxy on lattice matched (100) and (111) MgO substrates. Ferromagnetic resonance was utilized to determine the strength of CME from data on electric field E induced shift in the resonance frequency and its dependence on ferrite film orientation and thickness as well as MgO substrate thickness. The CME coupling coefficient A was found to be a factor of 2 to 4 higher in samples with NZFO films with (100) orientation than for (111) films. A decrease in A was measured with increasing ferrite film thickness and a very significant enhancement in the strength of CME was measured for decreasing MgO thickness. A model for CME that takes into consideration the influence of nonferroic MgO substrate was developed, and estimated A values are in very good agreement with the data. The results presented here are also of importance for a new class of electric field tunable ferrite microwave devices. Public domain – authored by a U.S. government employee

We present a strong non-Ohmic transport characteristic in an individual Y3Fe5O12 (YIG) nanofiber at low temperature. The structural characterization reveals that the nanofiber consists of a multitude of nanoparticles stacked along the nanofiber axis. The non-Ohmic conductive behavior manifests itself by a strong input current dependence and the nonlinear I–V curves with a critical temperature around 160 K. The current measured at temperatures lower than 160 K follows the Simmons tunneling model, and the tunneling through the grain boundary is proposed to interpret the non-Ohmic feature in an individual YIG nanofiber. However, the observed resistance follows a T−1/4 variation in the high temperature range (> 160 K), suggesting a variable range hopping conduction.

Epitaxial Ni films with various thicknesses were grown on (0 0 1)-oriented 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–PT) substrates. Electric field tuning (E-tuning) of ferromagnetic resonance field (Hr) was utilized to investigate the magnetic response of Ni films along different film directions. Butterfly-like Hr vs E curves are shown when magnetic field is applied along film edge. While the combination of both loop-like and butterfly-like Hr vs E curves are observed for Ni film with thicknesses of 180 nm and 240 nm, and merely loop-like curves can be seen for film thicknesses of 330 nm and 510 nm, as magnetic field is applied along film diagonal. These interesting phenomena are assumed to be related to ferroelectric and ferroelastic domain switching in PMN-PT, film strain status, as well as magnetic anisotropy in Ni film. This work demonstrates the feasibility of control of anisotropic magnetic response via electric field in multiferroic heterostructure.

We report the cation distribution in CoFe2O4 (CFO) nanofibers (NFs) fabricated by electro-spinning technique for different annealing temperatures in the range of 700–850 °C. Both X-ray photoelectron spectroscopy (XPS) and Raman spectra of CFO NFs have confirmed that the Co2+ and Fe3+ ions are distributed both in octahedral and tetrahedral sites, forming a mixed spinel ferrite. The analysis of XPS spectra reveals that the Co2+ ions have a tendency to occupy the tetrahedral sites with increasing the annealing temperature, whereas the Fe3+ ions are preferred to migrate to the octahedral sites with a high possibility. Besides, the redistribution of Co2+ ions towards the normal spinel is confirmed by comparing the relative peak areal intensity ratio of A1g(2) and T2g(2) modes associated with the vibrational modes of tetrahedral and octahedral. The effects of the cationic redistribution of the magnetic properties were also discussed.

Ultrasound is one of the most frequently used imaging modality in medicine due to its safety, portability and real time imaging.With the development of ultrasound imaging technology,3D ultrasound is more and more popular in clinical practice,as it can provide more diagnostic and therapeutic information than 2D ultrasound in many applications. One of the most important applications of 3D ultrasound is to diagnose congenital anomalies of the fetus in obstetrics and gynecology.

A low temperature sintering method was used to avoid the relatively high sintering temperatures typically required to prepare 0.67CaTiO 3 –0.33LaAlO 3 (CTLA) ceramics. Additionally, CeO 2 was introduced into the CTLA ceramics as an oxygen-storage material to improve their microwave dielectric properties. 0.67CaTiO 3 –0.33LaAlO 3 ceramics co-doped with B 2 O 3 –Li 2 O–Al 2 O 3 and CeO 2 were prepared by a conventional two-step solid-state reaction process. The sintering behavior, crystal structure, surface morphology, and microwave dielectric proprieties of the prepared ceramic samples were studied, and the reaction mechanism of CeO 2 was elucidated. CTLA+0.05 wt% BLA+3 wt% CeO 2 ceramics sintered at 1360 °C for 4 h exhibited the optimal microwave dielectric properties: dielectric constant ( e r )=45.02, quality factor ( Q×f )=43102 GHz, and temperature coefficient of resonant frequency ( τ f )=2.1 ppm/°C. The successful preparation of high-performance microwave dielectric ceramics provides a direction for the future development and commercialization of CTLA ceramics.

0.67CaTiO 3 –0.33La(Al 1− x Ga x )O 3 (0≤ x ≤0.4) (CTLAG) ceramics with pure perovskite structure were prepared by a conventional two-step solid-state reaction process. The effect of Ga 3+ substitution for Al 3+ on the microwave dielectric properties of the ceramics was subsequently investigated. As Ga content increased, the ionic polarizability increased and led to an increase of the dielectric constant ( e r ). Meanwhile, both the tolerance factor ( t ) of CTLAG ceramics and A-site bond valence were considered to have effect on the temperature coefficient of the resonant frequency ( τ f ) with the increase of Ga content. Results also showed that the quality factor ( Q × f ) varied with increasing Ga 3+ content because of not only intrinsic factor but also extrinsic factors such as the bimodal grain size distribution, the variation of relative density, and the packing fraction. Excellent microwave dielectric properties with e r ≈45.81, Q × f ≈34,152 GHz, and τ f ≈3.09 ppm/°C were achieved for 0.67CaTiO 3 –0.33La(Al 0.9 Ga 0.1 )O 3 ceramics sintered at 1420 °C for 4 h.

The scaling behavior of dynamic hysteresis was investigated in Bi3.15Nd0.85Ti3O12 bulk ceramics at a frequency of 1–1000 Hz and an external electric field amplitude of 79–221 kV/cm. The scaling behavior at low amplitude (E 0 ≤ 114 kV/cm) takes the form of $$\langle A \rangle \propto f^{ - 0.013} E_{0}^{0.7}$$ for low frequency (f ≤ 200 Hz) and $$\langle A \rangle \propto f^{ - 0.013} E_{0}^{0.22}$$ for high frequency (f > 200 Hz), where $$\langle A \rangle$$ is the area of hysteresis loop and f and E 0 are frequency and amplitude of external electric field, respectively. At high amplitude (E 0 > 114 kV/cm), we obtain $$\langle A \rangle \propto f^{0.011} E_{0}^{1.163}$$ at low frequency and $$\langle A \rangle \propto f^{ - 0.015} E_{0}^{0.7}$$ at high frequency. At low E 0, the contribution to the scaling relation mainly results from reversible domain switching, while at high E 0 reversible and irreversible domain switching concurrently contribute to the scaling relation.

Nowadays, wearable and flexible nanogenerators are of great importance for portable personal electronics. A flexible piezoelectric energy harvester (f-PEH) based on Bi3.15Nd0.85Ti3O12 single crystalline nanoplates (BNdT NPs) and polydimethylsiloxane (PDMS) elastomeric polymer was fabricated, and high piezoelectric energy harvesting performance was achieved. The piezoelectric output performance is highly dependent on the mass ratio of the BNdT NPs in the PDMS matrix. The as-prepared f-PEH with 12.5 wt% BNdT NPs presents the highest output voltage of 10 V, a peak-peak short-circuit current of 1 &mu, A, and a power of 1.92 &mu, W under tapping mode of 6.5 N at 2.7 Hz, which can light up four commercial light emitting diodes without the energy storage process. The f-PEHs can be used to harvest daily life energy and generate a voltage of 2&ndash, 6 V in harvesting the mechanical energy of mouse clicking or foot stepping. These results demonstrate the potential application of the lead-free BNdT NPs based f-PEHs in powering wearable electronics