Solid-state Reaction Process Research Articles

Multicolor-tunable Ca8MgBi(PO4)7: Ce3+, Tb3+, Mn2+ phosphors under dual-channel excitation

A series of color-tunable phosphors Ca8MgBi(PO4)7(CMBPO): Ce3+, Tb3+, Mn2+ have been prepared by high-temperature solid-state reaction process. The X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), photoluminescence excitation (PLE) and emission (PL) spectra were utilized to characterize the samples. Through the dual-channel excitation process, energy transfers (ET) occur simultaneously between Ce3+ → Tb3+ and Ce3+ → Mn2+. In addition, ETs process from Ce3+ to Tb3+/Mn2+ has been proved to be a resonance type, which is manifested by dipole–dipole/dipole-quadrupole interactions. Moreover, the emission band of CMBPO:0.20Mn2+ distributed in the red and far-red regions matches well with the red light wavelength required for phytochrome protein (PR and PFR), indicating that the phosphor can be used as a new type of red luminescent powder absorbed by plant photosensitive pigment and promoted plant growth. Importantly, the CMBPO:0.10Ce3+, 0.08Tb3+, zMn2+ can emit white light by properly tuning the ratio of Tb3+ and Mn2+ under ultraviolet (UV) excitation. The results suggested that the present phosphors can be a potential candidate for white light emitting diodes (WLEDs).

Influence of CaO–B2O3–SiO2 crystallizable glass on microstructure and microwave dielectric of LiMg0.9Zn0.1PO4 ceramics for LTCC substrate applications

The low temperature co-fired ceramic (LTCC) material was developed with the LiMg0.9Zn0.1PO4 ceramic added CaO–B2O3–SiO2 crystallizable glass via the traditional solid-state reaction process. The addition of CBS glass can reduce the sintering temperature of LiMg0.9Zn0.1PO4 ceramic from 950 °C to 850 °C without an obvious degradation of the microwave dielectric properties as the low-loss phases CaSiO3 and CaB2O4 phases were crystallized during sintering. The LiMg0.9Zn0.1PO4-15 wt% CBS2 glass composite sintered at 850 °C for 15 min exhibited the εrvalue was 6.7, the Q × f value was 40,100 GHz at 15 GHz, and the τf value was −44 ppm/°C. The LTCC green tape based on the optimized LiMg0.9Zn0.1PO4-CBS2 glass composite composition was obtained by the standard tape-casting process. Tapes with Ag conductor paste printed were laminated and co-fired at 850 °C which revealed the good compatibility between the ceramic and silver. The sintered ceramic demonstrated the CTE value of 8.5 ppm/°C (25 °C–300 °C), the maximum thermal conductivity of 5.6 W/M·K at 25 °C and the flexural strength of 180 MPa, indicating it was a promising LTCC substrate material.

Power generation characteristics of 0.50(Ba0.7Ca0.3)TiO3–0.50Ba(Zr0.2Ti0.8)O3/PVDF nanocomposites under impact loading

Power generation characteristics of 0–3-type 0.50(Ba0.7Ca0.3)TiO3–0.50Ba(Zr0.2Ti0.8)O3/PVDF nanocomposites, prepared using a melt-mixing process, under impact loading have been presented in this paper. A solid-state reaction process was utilized to prepare lead-free nanoceramic powder of 0.50(Ba0.7Ca0.3)TiO3–0.50Ba(Zr0.2Ti0.8)O3 (BCZT50) which was then milled by high-energy ball milling technique. The BCZT50 as filler distribution in the PVDF matrix was checked from scanning electron microscope and the formation of BCZT50 and BCZT50/PVDF nanocomposites were ascertained by X-ray diffraction method. The free dielectric constant ( $$\varepsilon_{33}^{T}$$ ), loss tangent (tanδ), piezoelectric coefficient (d33), piezoelectric voltage constant (g33), shore hardness (D), and figure of merit (FoM) were observed to increase while that of applied mechanical force (F3) decreases with the increase in filler concentration. Studies of voltage responses of all the BCZT50/PVDF nanocomposites due to impact loading using drop weight method have been carried out. A marked increment in the contact voltage due to different heights (applied mechanical energy) of impact was noticed as the concentration of filler particles was increased from 0 to 25% in the BCZT50/PVDF nanocomposites. The contact voltage and generated energy increase, respectively, from 5.37 to 11.62 V and 0.53 nJ to 6.8 nJ with the increase in BCZT50 content from 0 to 25% at a height of impact = 21 cm. In addition, the low value of tanδ (~ 10–2), high values of d33, g33, D and FoM along with better voltage responses (proportional to the applied mechanical energy) foreshadowing the prospect of BCZT50/PVDF nanocomposites a better non-lead option for structural health monitoring, piezo-sensing/detection, and/or energy harvesting applications.

Morphology and Interconnected Microstructure-Driven High-Rate Capability of Li-Rich Layered Oxide Cathodes.

A Li-rich layered oxide (LLO) cathode with morphology-dependent electrochemical performance with the composition Li1.23Mn0.538Ni0.117Co0.114O2 in three different microstructural forms, namely, randomly shaped particles, platelets, and nanofibers, is synthesized through the solid-state reaction (SSR-LLO), hydrothermal method (HT-LLO), and electrospinning process (ES-LLO), respectively. Even though the cathodes possess different morphologies, structurally they are identical. The elemental dispersion studies using energy-dispersive X-ray spectroscopy mapping in scanning transmission electron microscopy show uniform distribution of elements. However, SSR-LLO and ES-LLO nanofibers show slight Co-rich regions. The electrochemical studies of LLO cathodes are evaluated in terms of charging/discharging, C-rate capability, and cyclic stability performances. A high reversible capacity of 275 mA h g-1 is achieved in the fibrous LLO cathode which also demonstrates good high-rate capability (80 mA h g-1 at 10 C-rate). These capacities and rate capabilities are superior to those of SSR-LLO [210.5 mA h g-1 (0.1 C-rate) and 4 mA h g-1 (3 C-rate)] and HT-LLO [242 mA h g-1 (0.1 C-rate) and 22 mA h g-1 (10 C-rate)] cathodes. The ES-LLO cathode exhibits 88% capacity retention after 100 cycles at 1 C-rate. A decrease in voltage on cycling is found to be common in all three cathodes; however, minimal voltage decay and capacity loss are observed in ES-LLO upon cycling. Well-connected small LLO particles constituting fibrous microstructural forms in ES-LLO provide an enhanced electrolyte/cathode interfacial area and reduced diffusion path length for Li+. This, in turn, facilitates superior electrochemical performance of the electrospun Co-low LLO cathode suitable for quick charge battery applications.

Diffused phase transition, ionic conduction mechanisms and electric-field dependent ferroelectricity of Nb/Ce co-doped Pb(Zr0.52Ti0.48)O3 ceramics

In this work, polycrystalline ceramics of the Pb(Zr0.52Ti0.48)0.95Nb0.05O3 + 0.2 wt% CeO2 (PZT-NC) compound were fabricated by the conventional solid-state reaction process from oxide precursors. Firstly, XRD analysis and SEM observation associated with EDS mapping were used for characterizing the phase structure, grain morphology and element composition of the specimens, respectively. And then, the temperature dependence of the dielectric properties were studied for the specimens in a wide frequency range of 1 kHz–1 MHz. The diffused phase transition behavior were comprehensively characterized in terms of the modified Curie-Weiss law involved in diffuseness and diffusivity. The dielectric loss mechanisms were explained by space charge conduction and domain wall relaxation. Further, the temperature dependent AC conductivity of the specimens were analyzed at a low frequency of 1 kHz. The electrical conduction mechanisms in three temperature regions: room temperature∼250 °C, 250∼400 °C, and 400∼500 °C, were associated with three different kinds of charge carriers. Finally, the polarization switching properties of the specimens were measured with the applied electric field of 30–50 kV/cm. The linear variation of coercive field, remanent polarization and maximum polarization with the electric-field amplitude demonstrated the field dependent ferroelectricity. As profited from the co-doping effect of Nb/Ce applied in the B-/A-site of the perovskite structure, the PZT-NC ceramics achieved many optimized electrical properties, including a high d33 (443 pC/N) and Tc (312 °C), a large g33 (35 × 10−3 Vm/N) and Pr (∼24 μC/cm2), as well as a low Ec (∼10 kV/cm), which make it possible for prospective applications in piezoelectric/ferroelectric devices.

Enhanced piezoelectric activity with good thermal stability and improved electrical resistivity in Ta–Mn co-doped CaBi4Ti4O15 high-temperature piezoceramics

Aurivillius phase CaBi4Ti4-x (Ta2/3Mn1/3)xO15 (x = 0–0.1) high-temperature piezoelectric ceramics were fabricated using the conventional solid-state reaction process. The effects of the Ta–Mn co-doping level on the structure, piezoelectric properties and electrical conduction behaviours of the as-prepared CBT (CaBi4Ti4O15) ceramics were explored in detail. It was revealed that the Ta–Mn co-doping efficaciously enhanced the electrical performances of the CaBi4Ti4O15 ceramic, which may be due to optimisation of the crystal structure and a reduction in the oxygen vacancy concentration. The composition with x = 0.04 presented superior electrical properties with an outstanding piezoelectric constant (d33) of 24 pC/N accompanied by a high Curie temperature (TC) of 793 °C, an optimised dielectric loss (tanδ) of 1.5%, and an improved resistivity (ρ) of 4.96 × 108 Ω cm at 400 °C. Moreover, the ceramic exhibited impressive thermal stability with the d33 value maintaining 91.7% of its initial value at room temperature (25 °C) after being annealed at 600 °C for 2 h. The improved performance indicates that the Ta–Mn co-doped CaBi4Ti4O15 ceramic might be a promising candidate for piezoelectric device applications at elevated temperatures.

Effects of doping ions on the luminescence performance of terbium doped gadolinium polysulfide phosphor

Gd2O2S: Tb (GOS) phosphor screen has been widely used in digital X-ray imaging, and so far, numerous studies have been focused on the doping ions to improve the luminescence performance of the GOS phosphors. GOS: Tb, Dy phosphors were synthesized by the solid-state reaction process, and their phase composition, particle size, morphology and luminescence properties were characterized. The results showed that co-doping Dy3+ can promote the luminescence and the optimal doping concentration of Dy3+ ions were about 0.2%, however concentration quenching will occur when the doping concentration exceeded 0.5%. Ta5+ ion was also studied in the GOS: Tb and GOS: Tb; Dy phosphors prepared by the same method. The results showed that when the Ta5+co-doping concentration was 100ppm, the strongest emitted light intensity would be obtained for both phosphors. The photoluminescence spectra revealed a different influencing mechanism of Ta5+ ion comparing to Dy3+, which is by a strong energy transfer between Dy3+ and Tb3+.

Crystal structure, Raman spectra and microwave dielectric properties of novel temperature-stable LiYbSiO4 ceramics

Olivine−type structure microwave dielectric ceramics LiYbSiO4 with near-zero τf were fabricated by solid-state reaction process for the first time. The relationships among structural parameters, sintering behavior, vibrational modes and microwave dielectric properties for the ceramics were studied. The variation in εr could be correlated with Raman shift. The variation in Q×f values was inversely correlated to FWMH and average cation covalency. The τf values were explained with the bond valence sum of cations. Single phase LiYbSiO4 ceramics could be obtained at the range of 1100–1140 °C and showed promising microwave dielectric properties with εr = 7.36 – 7.42, Q×f = 19081 – 25276 GHz and τf = +4.52 – +8.03 ppm/°C.

Structure and ionic conductivity of cerium doped La9.33-xCexSi6O26 apatite-type lanthanum silicates

In this work, the effect of cerium doping on the structure and ionic conductivity of the apatite-type lanthanum silicates is presented. Ceramic samples with nominal composition of La9.33-xCexSi6O26 (x = 0, 0.1, and 0.2) are synthesized via a solid-state reaction process. They are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and complex impedance measurements. The study shows that the samples, having small amount of secondary phases of La2SiO5 and La2Si2O7, crystallize in the hexagonal apatite type structure with P63/m space group. The doping increases first the cell parameters for x = 0.1 before decreasing for x = 0.2. It also increases the grain size of the samples and reduces their porosity. The complex impedance measurements have been carried out in the temperature range 625–769 °C. The results are treated by separating the grain from the grain boundaries components and show that the ionic conductivity is remarkably improved by this kind of doping.

Low temperature synthesis of Lu3Al5-xGaxO12:Ce3+,Cr3+ powders using a sol-gel combustion process and its persistent luminescence properties

Lu3Al5-xGaxO12:Ce3+,Cr3+ powders were prepared using a sol-gel combustion (SGC) process. To clarify the effects of the preparation method on the phase formation and luminescence properties, Lu3Al3Ga2O12:Ce3+,Cr3+ powders were also prepared at different calcination temperatures using a solid-state reaction (SSR) process for comparison with the SGC process. The photoluminescence spectra of the synthesized powders consisted of strong bands of Ce3+ and weak peaks of Cr3+ within the green and red regions, respectively. A Lu3Al3Ga2O12:Ce3+,Cr3+ single phase can be achieved even at a low temperature of 1100 °C for the SGC process, whereas it is formed at a higher temperature of 1500 °C for the SSR process. The green emission intensities of the Lu3Al3Ga2O12:Ce3+,Cr3+ powders prepared using the SGC process were significantly higher than those prepared using the SSR process. This behavior can be explained using a crystal structure, particle morphology, and uniformity of the dopant distribution. For the Lu3Al5-xGaxO12:Ce3+,Cr3+ powders prepared using the SGC process, increasing the Ga content caused an increase in the lattice constant, resulting in a blue-shift of the green band of Ce3+. The synthesized powders exhibited a persistent luminescence, which resulted from the trapping and de-trapping behaviors between the Ce3+ and Cr3+ ions. The longest persistent luminescence was observed for the Lu3Al3Ga2O12:Ce3+,Cr3+ powders prepared at 1700 °C using the SGC process, lasting approximately 40 min.

Frequency- and temperature-dependent dielectric features of multi-component electronic material: (Pb0.8Dy0.1Bi0.1)(Fe0.2Ti0.8)O3

A multiple cation containing sample as [(Pb0.8Dy0.1Bi0.1)(Fe0.2Ti0.8)O3] is fabricated by adopting the solid-state reaction process. The crystallographic structure, crystallite size, morphology, dielectric behavior, conductivity, polarization, impedance as well as electric modulus spectroscopy are experimentally observed for this fabricated composition. The crystal structure of the specimen is observed to be tetragonal from X-ray diffraction. The micrograph shows the presence of polycrystalline microstructure with uniform distributed grains. The impedance spectroscopy analysis as a function of temperature (100–450 °C) and frequency (1–1000 kHz) helps to signify the resistive and capacitive behavior of the compound. The nature of the prepared specimen and conduction mechanism is illustrated through AC conductivity study. The modulus analysis elucidates the existence of non-Debye dielectric relaxation nature in the synthesized compound. The compound possesses appreciable value of loss tangent and remnant polarization, i.e., 0.02 and 0.014 µC/cm2, with high value of dielectric constant at room temperature. The dysprosium doping entails stability with interesting electrical and dielectric properties. The preliminary capacitive characteristic has been elucidated, thus making it a stronger contender for functional device applications.

Oxygen nonstoichiometry and electrical properties of La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5)

The amount of interstitial oxygen (δ) in Sr-doped lanthanum nickel oxide (La2–xSrxNiO4+δ) as a function of Sr content has been investigated by the thermogravimetry analysis (TGA) and X-ray photoelectron spectroscopy (XPS). La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5) ceramics were prepared by the general solid-state reaction process and sintered in different ambient of argon, air or oxygen, respectively. An increase in the amount of Sr decreased δ in La2–xSrxNiO4+δ, while the Ni2+/Ni3+ ratio analyzed by Ni3p XPS decreased indicating that the oxidation state of Ni increased. Particularly when the sample was sintered in a low oxygen partial pressure condition such as in Ar ambient, the hole concentration strongly depended on the Sr content, suggesting that the hole generation seems mostly originated from Sr2+ substitution into the La3+ site.

Winning wide-temperature-range and high-sensitive thermometry by a multichannel strategy of dual-lanthanides in the new tungstate phosphors

Abstract Both high sensitivity and wide temperature range are vital guides for up-conversion (UC) thermometers. However, high sensitivities were limited to a very narrow temperature range in existing optical thermometers. Also, the highest sensitivity usually occurred at elevated temperatures, while the sensitivity at room temperature or below it is very low or scarce. To overcome such a state, a novel optical thermometer with high sensitivities over a wide temperature range was designed. Lanthanide-doped UC phosphors with LiCaYb(WO4)3 (LCYW) as a novel host, were synthesized by a solid-state reaction process. Temperature sensing properties were carried out by a fluorescence intensity ratio (FIR) technique. High sensitivities of 0.01–0.0191 K-1 over the temperature range of 288–663 K were obtained in LCYW:0.03Er phosphor, which originated from the energy levels of Er3+ (2H11/2/4S3/2). Then, the thermal coupling levels (TCLs) and non-thermal coupling levels (NTCLs) were used to study the temperature sensing properties by co-doping Tm3+ ion. Excellent temperature sensing sensitivities were achieved, which are the higher sensitivities of 0.01–0.0216 K-1 over the range of 253–663 K based on the same TCLs of 2H11/2/4S3/2 and the highest sensitivity of 0.0563 K−1 at 663 K based on the NTCLs of 4S3/2 (Er3+)/3F2,3 (Tm3+). Besides, a multichannel strategy that mentions both sensitivity and temperature range was provided. Thus, the resulting new sensor can be operated in the wide temperature sensing range of 163–663 K with sensitivities of 0.011–0.0563 K-1. All of the results suggest that the LCYW:Er/Tm UC phosphor could be a good candidate with its high sensitivities for optical thermometry and as a safety sign in low and high temperatures.

Determination of magnetic levitation force properties of bulk MgB2 for different permanent magnetic guideways in different cooling heights

Abstract In our study as different from the literature, the magnetic levitation force between a bulk MgB2 and two different permanent magnetic guideway (PMG) arrangements, which are Halbach and Conventional PMGs, were investigated in different cooling heights (CHs) and Field-Cooled (FC) condition at the temperatures of 37 K and 33 K. The cylindrical bulk MgB2 superconductor was fabricated by in-situ solid state reaction process with the diameter of 18 mm and the height of 5 mm. The XRD data indicates well developed MgB2 phase and the Jc value was obtained as 68 kA/cm2 at 30 K in the self-field. Experimental results show that MgB2 bulk above the Halbach PMG can exhibit better load capability at all the cooling heights between the bulk MgB2 and the PMG due to a more suitable magnetic field distribution. The maximum levitation force for Halbach PMG corresponds to 16.86 N whereas the conventional PMG shows 9.02 N at 37 K in cooling height of 77 mm. Additionally, the maximum levitation force increases while the CH increases because flux exclusion is more effective for larger CHs. It is considered that the experimental results obtained in study are very useful for future Maglev applications, because there are limited number of studies on magnetic levitation force of MgB2 bulk for different MgB2-PMG arrangements.

Microstructure and thermoelectric properties of higher manganese silicides fabricated via gas atomization and spark plasma sintering

Higher manganese silicides (HMS) powders were successfully prepared by a gas atomization technique. The gas atomized (GAed) powders showed spherical morphologies and a wide particle size distribution. No MnSi and Si phases were detected by XRD analyses, indicating that the high cooling rate during rapid solidification is effective in inhibiting the formation of second phases. When the GAed powders were consolidated by spark plasma sintering (SPS), the densified samples revealed almost the same phase composition as the powders and an isotropic feature. The contrast differences between different grains in backscattered electron images are believed to be associated with orientation differences. The HMS samples SPSed at different temperatures exhibited similar values of the Seebeck coefficient, but larger electrical conductivity and power factor were obtained in the sample SPSed at 1000 °C. Moreover, the HMS samples showed higher fracture toughness compared to those fabricated by a solid-state reaction and SPS process.

Electrical properties of, Na1−0.315K0.315Nb1−yTayO3 (0 ≤ y ≤ 0.05) system

Na0.685K0.315Nb1−yTay O3 (where y = 0, 0.01, 0.02, 0.03, 0.04, 0.05) based ceramics were synthesized by the conventional solid-state reaction process. The effects of (Ta) – doping on the phase structure and electrical properties of (NKNTaO3) were observed. The cell parameters were refined by High Score Plus software, using Rietveld method, The monoclinic Pm(6) space group was chosen in these refinements. X-ray diffraction analysis shows that the crystal structure of the ceramics, without and with Ta-doping possessed monoclinic symmetry. Among the prepared compositions, a break in the XRD peaks shifting tendency was observed at y = 0.03, and also maximum dielectric permittivity, loss tangent and electrical conductivity observed at the composition with y = 0.03.

Investigation of structural, optical and thermoelectric properties of 2H–MoTe2 and MoO3–TeO2 thin films

Easy synthesis of two-dimensional chalcogenide materials sach as MoTe2 and WTe2 is an important challenge for researchers. In this paper, we are showed that using Mo and Te oxides percursors as inexpensive initial materials and spray pyrolysis method, the MoO3–TeO2 thin film binary compounds, and the important two-dimensional structure of 2H–MoTe2 are prepared. . In this method, through the preparation of thin films of the MoO3–TeO2 binary composition by changing the molar concentration of Mo and Te in a solid-state reaction process, with molar ratios (a) MoO3 (0.05 M) -TeO2 (0.15 M), (b) MoO3 (0.1 M) -TeO2 (0.1 M) and (c) MoO3 (0.15 M) -TeO2 (0.05 M), we can obtain the 2H–MoTe2 phase. After synthesis of MoO3–TeO2 and 2H–MoTe2 compounds, structural and optical characterization of thin films, as well as thermoelectric properties of the prepared thin films were studied before and after annealing at T = 500 °C. X-ray diffraction results showed that the structure of thin films before annealing is amorphous structure, and after annealing at T = 500 °C for synthesis c: MoO3 (0.15 M) -TeO2 (0.05 M), the two-dimensional structure of 2H–MoTe2 was formed. The images of the field emittion scanning electron microscope (FE-SEM) showed that the morphology of the nanoparticles is the pseudo-spherical shape, rod and polygon, indicating the presence of particles in different phases at before annealing and flat – like form after annealing. The results of UV–Vis spectrometry showed that the energy gap of thin films varied in the range of 2.3–2.87 eV. The nanoparticle bonding structure was also studied by FT-IR spectroscopy. Studies on the thermoelectric properties of thin films before and after annealing showed that for synthsis (c): MoO3 (0.15 M) -TeO2 (0.05 M) with formation of the 2-H-MoTe2 phase, the seebeck coefficient was larger than other samples, and the majority carrier are holes. Also, ZT increases with decreasing molar concentration of TeO2 and reached to 1.32 at room temperature for synthesis c: MoO3 (0.15 M) -TeO2 (0.05 M).

Spinel MnFe2O4 nanoparticles (MFO-NPs) for CO2 cyclic decomposition prepared from ferromanganese ores

Ferromanganese ores with high contents of Mn and Fe are abundant worldwide. In this study, spinel-type MnFe2O4 nanoparticles (MFO-NPs) were first synthesized via a novel solid-state reaction process followed by ball-milling, magnetic separation, and nano-grinding. The synthetic MFO-NPs presented a stable spinel structure, fine granularity, and large specific surface; these characteristics highlight their potential in the preparation of thermochemical catalysts. We additionally conducted H2 reduction (HR) and CO2 decomposition reaction (CDR) cyclic tests to investigate the catalytic performance of MFO-NPs. The MFO-NPs showed excellent recyclability and thermal stability during CO2 decomposition; moreover, oxygen-defect MFO-NPs were able to completely decompose CO2 into carbon quantum dots. The mechanism of CO2 decomposition on the MFO-NPs’ surfaces was analysed in detail by XRD, SEM, TEM, TG, Raman, XPS.

Dielectric, ferroelectric, and strain properties of lead-free (1−y)BNT–yST ceramics

Lead-free ceramics (1−y) (Bi1/2Na1/2)TiO3–ySrTiO3 (1−y)BNT–yST with y = 0, 0.1, 0.20, 0.25, 0.28, 0.30, and 0.32 were synthesized via a solid-state reaction process. A uniform grain morphology was obtained, and the mean grain size was around 2.0 μm for y = 0, which decreased slightly for y > 0. The undoped compound displayed a crystal structure with rhombohedral symmetry, and increasing amounts of ST gradually transformed the material to cubic phase. The maximum dielectric constant temperature (Tm) was observed to decrease from 305 °C for sample y = 0 to 135 °C for sample y = 0.30. Remnant polarization (Pr) decreased with increasing ST, and the ferroelectric loops narrowed. The coercive field (Ec) was also observed to decrease with enhanced ST content; however, Ec and Pr increased for y = 0.30. The electric field-induced strain gradually increased up to y = 0.28 but decreased for y > 0.28. The loops of strain became slimmer and saturated with increasing ST ratio to attain the maximum dynamic strain of 624 pm/V.

Nano-grass like AlOOH as an Al source for synthesis of Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes with high ionic conductivity

The lithium-ion conductor Li1.3Al0.3Ti1.7(PO4)3 (LATP) is prepared by a solid-state method using nano-grass-like AlOOH as the Al source. The nano AlOOH precursor, obtained by a hydrothermal method, makes it easier for Al atoms to replace Ti atoms in the LiTi2(PO4)3 structure during the solid-state reaction process, which creates a large amount of lithium vacancies and lithium gaps, leading to the easier migration of Li+ ions in the obtained LATP conductor. Moreover, the as-prepared LATP has high crystallinity and high relative density (96.06%), which are beneficial for reducing the grain boundary resistance as well as improving the total ion conductivity. The influences of sintering temperature and holding time on the ionic conductivity and morphology of the LATP conductor are also discussed systematically. The total ion conductivity of LATP reaches to as high as 3.44 × 10-4 S cm-1 when the samples are sintered at 950 °C for 6 h. This work provides a new method for the preparation of LATP with high ion conductivity, which is of great significance for all-solid-state lithium-ion battery application.