ad-free piezoelectric ceramics of a(Bi0.5Na0.5)TiO3-b(Bi0.5K0.5)TiO3-cBaTiO3 (BNBK) ternary system near the composition of MPB has been widely investigated in recent decades.
ad-free piezoelectric ceramics of a(Bi0.5Na0.5)TiO3-b(Bi0.5K0.5)TiO3-cBaTiO3 (BNBK) ternary system near the composition of MPB has been widely investigated in recent decades.
In present work, undoped and Co 2 O 3 -doped Ba 4 Eu 2 Fe 2 Nb 8 O 30 ceramics were fabricated by routine solid state method. Wide temperature range measurement shows two kinds of dielectric peaks. The low-temperatur...
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In present work, undoped and Co 2 O 3 -doped Ba 4 Eu 2 Fe 2 Nb 8 O 30 ceramics were fabricated by routine solid state method. Wide temperature range measurement shows two kinds of dielectric peaks. The low-temperature peak attributes to ferroelectric-paraelectric phase transition. The high-temperature peak is affected greatly by Co 2 O 3 additives. With increasing the content of Co 2 O 3 dopant the second peak vanished, indicating that it is related to space charge.
The precursors of CIS and CIGS thin films were prepared by one-step electrodeposition in alcohol solution and then annealed in Ar atmosphere at 550°C for 30min. The influences of deposition potentials and salt co...
An investigation of the properties of the blends of nylon 6(PA6) and poly(vinyl alcohol) (PVA) with varying degrees of hydrolysis was conducted. A near disappearance of the characteristics of the α-form PVA crystals,...
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Controlled Al doped Si3N4 single-crystal nanobelts were synthesized by catalyst-assisted pyrolysis of polymeric precursors. The Al-doping levels can be tailored by varying the Al concentration in the polymeric precurs...
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Controlled Al doped Si3N4 single-crystal nanobelts were synthesized by catalyst-assisted pyrolysis of polymeric precursors. The Al-doping levels can be tailored by varying the Al concentration in the polymeric precursors. The as-synthesized nanobelts were characterized by SEM, XRD, EDS, TEM and HRTEM. The single-crystal belts had perfect crystal structures with few defects such as dislocations and stacking faults. The nanobelts obtained are several tens nanometers in thickness, several hundreds nanometers in width. The growth direction of the Al doped α-Si3N4 nanobelts was [011]. The growth mechanisms of α-Si3N4 nanobelts were proposed to be solid-liquid-gas-sold (SLGS). The optical properties of Al doping Si3N4 nanobelts were measured. Current results suggested that the optical properties of the nanomaterials can be controlled by adjusting Al doping contents.
A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics we...
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A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.
Three novel dielectric ceramics Ba5LnZnNb9O30 (Ln= La, Nd and Sm) were synthesized and characterized in the BaO-Ln2O3-ZnO-Nb2O5 quaternary system, which formed the filled tungsten-bronze structures. The present cerami...
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Three novel dielectric ceramics Ba5LnZnNb9O30 (Ln= La, Nd and Sm) were synthesized and characterized in the BaO-Ln2O3-ZnO-Nb2O5 quaternary system, which formed the filled tungsten-bronze structures. The present ceramics exhibit high dielectric constant (εr) up to 310, low dielectric loss in the level of 10 3 at 1 MHz. Meanwhile, the temperature coefficients of the dielectric constant (τε) of Ba5LnZnNb9O3o varies from -1 390×10-6 to -1 220×10-6/℃as the radius of Ln3+ increases. The present ceramics are promising candidates for high dielectric constant and low loss dielectric ceramics.
A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) ...
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A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20―40 μm, while a thickness of the cell wall is about 1―2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property.
A novel and efficient methodology for obtaining highly active photocatalyst of bi phase TiO 2 with small particle size and high specific surface area was developed by solvent evaporation induced crystallization (SE...
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A novel and efficient methodology for obtaining highly active photocatalyst of bi phase TiO 2 with small particle size and high specific surface area was developed by solvent evaporation induced crystallization (SEIC) method at low temperature. The prepared TiO 2 powder was characterized with X ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface areas. The photocatalytic activity was evaluated by the photocatalytic oxidation of acetone in air. The results showed that the photocatalytic activity of the TiO 2 powder prepared by this method approached that of Degussa P25. This may be attributed to the fact that the prepared TiO 2 powder had larger specific surface areas (265 m 2·g -1 ) and smaller crystallite size (about 5 nm), but relatively low crystallinity, as compared with Degussa P25.
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