Seed-induced Method Research Articles

Influence of CaZrO3 Nanocrystals on Phase Structure, Microstructure and Electrical Properties of BCZT Ceramics Prepared by Seed-Induced Method

Influence of CaZrO₃ Nanocrystals on Phase Structure, Microstructure and Electrical Properties of BCZT Ceramics Prepared by Seed-Induced Method

Effect of NaNbO3 Crystals on the Electrical Properties of Na0.47K0.47Li0.06NbO3 Ceramics Synthesised by Seed Induced Method

Effect of NaNbO₃ Crystals on the Electrical Properties of Na_0.47K_0.47Li_0.06NbO₃ Ceramics Synthesised by Seed Induced Method

Preparation and Characterization of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics by a BaTiO3 Seed-Induced Method

Preparation and Characterization of (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ Ceramics by a BaTiO₃ Seed-Induced Method

Synthesis of ZSM-5 aggregates by a seed-induced method and catalytic performance in methanol-to-gasoline conversion

A seed-induced method was applied to synthesize a series of ZSM-5 aggregates using silicalite-1 (S-1) as seeds. The samples were characterized by several techniques and studied in the methanol-to-gasoline (MTG) conversion reaction in a continuous fixed-bed reactor. The results showed that the molar ratios of Na 2 O/SiO 2 and H 2 O/SiO 2 in the precursors had great effects on the physicochemical and catalytic properties. The ZSM-5 aggregates with the highest crystallinity, external surface areas, micropore volumes, mesopore volumes and small primary crystal and aggregate sizes, obtained with the molar composition of 0.12Na 2 O–1SiO 2 –0.02Al 2 O 3 –25H 2 O-0.01Seed in the precursor, exhibited the highest stability.

Phase Structure, Microstructure and Electrical Properties of BCZT Ceramics Prepared by Seed-Induced Method

The effect of particle sizes of CaZrO3 (CZ) nanocrystal on the phase structure, microstructure and electrical properties of Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) was studied. The CaCO3 and ZrO2 were used as starting materials for CaZrO3 (CZ) seeds synthesized by the molten-salt method. The results were found that the CZ powder has a pure perovskite with the particle size about 370 to 460 nm. Then the CZ nanocrystals were mixed with the metal oxides BaCO3, CaCO3, ZrO2 and TiO2 by mixed oxide method. The phase structure, microstructure and electrical properties of BCZT ceramic were investigated as a function of particle size and concentration of CZ. The results indicated that all samples showed pure perovskite phase. The highest values of density, grain size, dielectric constant (εr) and piezoelectric coefficient (d33) were 5.50 g/cm3, 10.95 μm, 2992 and 446 pC/N, respectively which obtained at the CZ seed size 459 nm.

The Electrical Properties of BCZT Lead-Free Ceramics Induced by BaZrO<sub>3</sub> Seeds

Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics were produced by using the seed-induced method. The nano-particle BZ (BaZrO3) seeds were mixed with BaCO3, CaCO3, ZrO2 and TiO2 powder for preparing by the mixed oxide method. The XRD results indicated that all powder and sintered ceramic samples showed a pure perovskite phase with coexistence between rhombohedral and tetragonal phase. As the BZ seed content increased, the density of ceramics tended to decrease from 5.61 g/cm3 to 5.37 g/cm3. The average grain size of the ceramics was in the range of 12.15 -13.50 mm. The dielectric loss (tand) was less than 0.03 for all samples at room temperature (at 1 kHz). Other electrical properties, including dielectric constant (εr), remnant polarization (Pr), and piezoelectric charge coefficient (d33) values decreased with increasing BZ seed doping with relates to the decreasing grain size and density of BCZT ceramics. However, the values of coercive field (Ec) decreased and piezoelectric voltage coefficient (g33) increased with BZ seed doping.

Effect of SrTiO<sub>3</sub> Nano-Crystals on the Dielectric Properties of Na<sub>0.47</sub>K<sub>0.47</sub>Li<sub>0.06</sub>NbO<sub>3</sub> Ceramics by Seed-Induced Method

A solid-state reaction method is generally used to fabricate ceramics. This work studies the influence of heterogenous nano-crystallites on electrical properties of lead free Na0.47K0.47Li0.06NbO3 (NKLN) ceramics by adding SrTiO3 nano-crystals as the initial phase of reaction. The lead-free piezoelectric ceramics were synthesized by the seed-induced method. The SrTiO3 nano-crystals used as seeds were prepared by molten salt technique. The seed content was varied from 0 to 10.0 mol%. The investigation reports microstructure and electrical properties of ceramics. The XRD showed a mixed tetragonal and orthorhombic phase structure. Tc decreasing with increased SrTiO3nano-crystal concentration.

Effects of NaNbO<sub>3 </sub>Crystals on Electrical Properties of K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> Ceramics

Lead-free (K0.5Na0.5)NbO3 (KNN) piezoelectric ceramics were studied and synthesized by the seed-induced method. NaNbO3 crystal was used as seed and prepared by molten salt synthesis (MSS). The average particles size of NaNbO3 seed crystal was about 1-3 mm. Then, the NaNbO3 seed was mixed with KNN powder and ball milled for 24 h. The mixed powder was calcined at 700-900 °C and sintered at 1100 °C. The phase structure and morphology of the ceramics were investigated by X-ray diffraction and scanning electron microscope and the electrical properties were studied. The results indicated that all samples showed a pure perovskite phase. The highest density of the ceramic was 93% compared to the theoretical density. The results showed that NaNbO3seed crystal improved piezoelectric properties of KNN ceramics.

Conversion of methanol to propylene over nano-sized ZSM-5 zeolite aggregates synthesized by a modified seed-induced method with CTAB

Nano-sized ZSM-5 zeolite aggregates with mesopores and high catalytic activity were prepared by a modified seed-induced method using silicate-1 as seeds without additional templates in the presence of a trace amount of CTAB.

Preparation of cobalt‐doped colloidal silica abrasives and their chemical mechanical polishing performances on sapphire

Cobalt (Co)-doped colloidal silica abrasives were synthesised by seed-induced growth method. Time-of-flight secondary ion mass spectroscopy was used to characterise the composition of the obtained abrasives. The morphology of the abrasives was measured by using scanning electron microscopy. The chemical mechanical polishing (CMP) performances of the Co-doped colloidal silica abrasives on sapphire substrates were investigated. Experiment results indicate that the Co-doped colloidal silica abrasives exhibit lower surface roughness and higher material removal rate (MRR) than that of pure colloidal silica abrasive under the same testing conditions. Furthermore, the inductively coupled plasma-atomic emission spectrometry and X-ray photoelectron spectroscopy were also used to investigate the acting mechanism of the Co-doped colloidal silica in sapphire CMP. Analysis results show that cobalt aluminate appears after polishing, implying the tribochemistry reaction occurs during CMP. The chemical reaction between element cobalt and sapphire surface during CMP can promote the chemical effect in CMP and lead to the increasing of MRR.

Preparation and Electrical Properties of Ba<sub>0.85</sub>Sr<sub>0.15</sub>Ti<sub>0.90</sub>Zr<sub>0.10</sub>O<sub>3</sub> Ceramics Doped Sn by Seed-Induced Method

Ba0.85Sr0.15Ti0.90Zr0.10O3 (BSZT) ceramics doped Sn was prepared by seed-induced method. The seed was prepared by molten salt method, NaCl-KCl (1:1 by mole) eutectic mixtures was used as the flux. The BSZT added seed with doped SnO were calcined at 1250 °C for 3 hrs and sintered at 1400 °C for 2 hrs, respectively. The phase formation and morphology of these samples were characterized via X-ray powder diffraction and scanning electron microscopy, respectively. From the above studies, it has been concluded that the maximum dielectric constant is 19147 at BSZT ceramics prepared by seed-induce method.

Influence of seed nano-crystals on electrical properties and phase transition behaviors of Ba0.85Sr0.15Ti0.90Zr0.10O3 ceramics prepared by seed-induced method

This work studied the effects of seed nano-crystal on the electrical properties and the phase transition behaviors of Ba0.85Sr0.15Ti0.90Zr0.10O3 (BSZT) ceramics. The BSZT ceramics were prepared by the seed-induced method. The seed nano-crystal were prepared by the molten salt technique, and NaCl-KCl (1:1 by mole) eutectic mixtures were used as the flux.[1] The ceramic powders were prepared by using a conventional method which added seed nano-crystals at various ratios. Results indicated that seed nano-crystals enhanced the electrical properties of ceramics. The sample with a 20 wt. % seed nano crystals has excellent value of dielectric constant (µ r ) of 34698 at maximum temperature. The phase transition temperature was observed at 60°C. The morphology was found that the grain size increasing significantly with an increased of seed nano crystals. The relaxor ferroelectric phase transition behavior was shown by a diffuseness parameter (³). An increase in the BSZT-seed showed a decreased in ³ value from 1.61 to 1.44. Thus the ferroelectric of the BSZT ceramics can be confirmed by hysteresis loop.

Preparation of Zn-modified nano-ZSM-5 zeolite and its catalytic performance in aromatization of 1-hexene

The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZn/HNZ5 and yZn/Al–HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity (WHSV) of 2.0 h–1 in the aromatization procedure of 1-hexene. Compared with xZn/HNZ5, yZn/Al–HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brønsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.

Effect of Zn2+ and Nb5+ Co-Doping on Electrical Properties of BCZT Ceramics by the Seed-Induced Method

The effects of Zn2+ and Nb5+ co-doping (x mol%ZN) on the electrical properties of lead-free Ba0.90Ca0.10Zr0.10Ti0.90O3-Seed ceramic systems, where x = 0.0–1.0 mol% have been studied. The ceramics were prepared using the solid state reaction technique. The phase of the samples showed pure perovskite structure. The density values of the ceramics were in the range of 4.86–5.78 g/cm3. The maximum dielectric constant was 40893 for 0.8 mol% ZN. The highest values of Pr ∼ 5.85 μC/cm2, d33 ∼ 381 pC/N and kp ∼ 38% were obtained for the sample of 0.4 mol% ZN.

Nano-crystallite oriented self-assembled ZSM-5 zeolite and its LDPE cracking properties: Effects of accessibility and strength of acid sites

Nano-crystallite oriented self-assembled ZSM-5 zeolite (NS-Z5) is successfully synthesized with high yield of 85% by a facile salt-aided seed-induced method within 1.5h at TPABr (tetrapropylammonium bromide)/SiO2 ratio of 0.1. The systematic and thorough characterizations, involving morphology, textural/structure property, and acidity, indicate that NS-Z5 particle is composed of oriented-assembled high-crystalline zeolite MFI nano-crystallites and possesses abundant accessible strong acid sites due to its large/rough external surface. The strong acidity of NS-Z5 sample results from its high crystallinity and few framework defects benefiting from the introduction of seeds. The catalytic evaluations both in batch and in thermogravimetric reactors demonstrate the important roles of the accessibility and strength of acid sites on low-density polypropylene cracking. This paper provides a facile method for preparation of hierarchical high-crystalline ZSM-5 nano-zeolite and confirms the significance to synchronously maintain large amount and high strength of accessible acid sites on large molecule conversion.

Nanosized ZSM-5 zeolites: Seed-induced synthesis and the relation between the physicochemical properties and the catalytic performance in the alkylation of naphthalene

ZSM-5 nanocrystals with Si/Al ratios in the range of 30–80 have been synthesised successfully by a seed-induced method. The physicochemical properties of the ZSM-5 nanocrystals were characterised by XRD, SEM, N2 adsorption, FT-IR, TG/DTG, 27Al MAS NMR, NH3-TPD and Py-IR. The catalytic activities of HZSM-5 with different Si/Al ratios (H-ZN-x) were evaluated at a temperature of 400°C and a weight hourly space velocity (WHSV) of 0.5h−1 by the methylation of naphthalene. The H-ZN-65 (Si/Al=65) catalyst exhibited the highest activity (naphthalene conversion of 74.3%), which is attributed to the strong acidity and large external surface area of the zeolites. H-ZN-30 (Si/Al=30) showed higher selectivity for the β and β′ site of dimethylnaphthalene, which is associated closely with the intermediate acidity and shape selectivity of ZSM-5 with its large micropore volume (0.154cm3/g).