Pyroelectric Properties of SBN/BST by Powder-Sol Method

2013 ◽  
Vol 320 ◽  
pp. 190-195
Author(s):  
Lian Wei Shan ◽  
Wei Li ◽  
Ji Hua Wang ◽  
Zhong Li ◽  
Li Min Dong
Keyword(s):  
Room Temperature ◽  
Perovskite Phase ◽  
Tungsten Bronze ◽  
Fine Powder ◽  
Relative Dielectric Constant ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Zero Bias ◽  
Maximum Value ◽  
Average Grain Size

0.7BaO·0.3SrO·0.3Nb2O5·0.7TiO2 (SBN/BST) composite ceramics werefabricated using a Powder-Sol (P-S) method with Nb2O5fine powder suspended in the barium strontium titanate (abbreviated as BST) solsolution. By X-ray diffraction (XRD) investigations, it is found that thetetragonal tungsten bronze (TTB) phase and perovskite phase were co-present incompositions. The average grain size of BST and SBN phase is 140 nm and 2.2 μm,respectively. The room temperature relative dielectric constant is 1445 forthis sample measured at 1 kHz and zero bias. In the room temperature, thepyroelectric coefficient of the 0.7BaO·0.3SrO·0.3Nb2O5·0.7TiO2is 39 nc/cm2·°C. The maximum value of FDis about 2.4×10-5 Pa-1/2at 45°C.

Effect of SrO/BaO Ratio on the Phase Structure of the BSTN Composite Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 111-114 ◽  
Author(s):  
Zong Hui Zhou ◽  
Pi Yi Du ◽  
Gao Rong Han ◽  
Wen Jian Weng
Keyword(s):  
Grain Size ◽  
Phase Structure ◽  
Composite System ◽  
Perovskite Phase ◽  
Tungsten Bronze ◽  
Composite Ceramics ◽  
Crystal Lattices ◽  
Average Grain Size

The effect of SrO/BaO ratio on the phase structure of the (1-x)BaO.xSrO.0.7TiO2.0.3Nb2O5 composite ceramics was investigated by XRD and SEM. The results showed that the SrO/BaO ratio increased in the perovskite phase and kept almost constant in the tungsten bronze phase as the content of SrO increased in the composite system. The constant SrO/BaO ratio in the tungsten bronze phase was about 0.667. The crystal lattices of the perovskite phase in the composite system were larger and smaller respectively than that in pure (1-x)BaO.xSrO.TiO2 system when SrO/BaO ratio were respectively <0.667 and >0.667. The crystal lattices of the perovskite phases in both systems showed the same crystal lattices when SrO/BaO = 0.667. Affected by the SrO/BaO ratio required in the tungsten bronze phase in composite system, the contents and average grain size of the perovskite phase decreased, while the content of tungsten bronze phase increased as the SrO/BaO ratio increased.

Structure and Electrical Properties of BNKT-Based Ceramics

2018 ◽  
Vol 283 ◽  
pp. 147-153 ◽  
Author(s):  
Supalak Manotham ◽  
Pichitchai Butnoi ◽  
Pharatree Jaita ◽  
Tawee Tunkasiri
Keyword(s):  
Grain Size ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Tetragonal Symmetry ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Average Grain Size ◽  
Influence Of Temperature On ◽  
Polarization Electric Field ◽  
Xrd Patterns

In this work, the properties of lead-free 0.92(Bi0.5Na0.42K0.08)TiO3-0.08(BaNb0.01Ti0.99)O3 or 92BNKT-8BNbT ceramic has been investigated. The sample was fabricated by a solid-state reaction technique. The 92BNKT-8BNbT sample was well sintered and dense with high density value of 5.86 g/cm3. X-Ray diffraction (XRD) patterns showed a single perovskite phase with tetragonal symmetry and no impurity or secondary phases. The microstructure was analysed using a scanning electron microscopy (SEM). Average grain size was measured and calculated based on a mean linear intercept method. The ceramics had a cubic-like grain shape with an average grain size of 0.39 µm. The influence of temperature on the dielectric and ferroelectric properties of the ceramic was investigated. The dielectric curves exhibited broad transition peaks at Td and Tm, which were the characteristics of a diffuse phase transition. The polarization-electric field (P-E) hysteresis loop changed from well-saturated at room temperature (RT) to pinched-type loop at high temperature (HT) and the remanent polarization decreased from 21.25 µC/cm2 (at RT) to 5.96 µC/cm2 (at 150 °C).

scholarly journals Photo-acoustic properties of nanoTiO2:Er

2016 ◽  
Vol 5 (4) ◽  
pp. 196
Author(s):  
R. Palomino-Merino ◽  
R. Lozada-Morales ◽  
J. Martínez-Juárez ◽  
G. Juárez-Díaz ◽  
J. Carmona-Rodriguez ◽  
...  
Keyword(s):  
Room Temperature ◽  
Sol Gel ◽  
Acoustic Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Electron Dispersion ◽  
Er Doped ◽  
Spectroscopy Optical

Nanocrystalline Er-doped TiO2 was prepared by sol-gel at room temperature. X-ray diffraction, photoacoustic spectroscopy (optical absorption), transmission electron microscopy (TEM), and electron dispersion microscopy (EDS) were carried out on both as-prepared and thermally-annealed (air at 700 ºC) samples, revealing the anatase crystalline phase of TiO2. The samples exhibit an average grain size from 38 to 5.1 nm, as the nominal concentration of Er varies from 0 % to 7 %. The photoacoustic spectra evidence the absorption edge at 300 nm attributed to TiO2, as well as several electronic transitions which are atomic energy absorption-line levels characteristics of Er.

Low-temperature fabrication of pyroelectric Ba0.8Sr0.2TiO3 thin films by a sol-gel process

2001 ◽  
Vol 16 (3) ◽  
pp. 778-783 ◽  
Author(s):  
Jian-Gong Cheng ◽  
Jun Tang ◽  
Shao-Ling Guo ◽  
Jun-Hao Chu
Keyword(s):  
Perovskite Phase ◽  
Sol Gel ◽  
Pyroelectric Coefficient ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Pure Perovskite Phase ◽  
Average Grain Size ◽  
Sol Gel Process ◽  
Columnar Grains ◽  
Uncooled Infrared Detectors

Ba0.8Sr0.2TiO3 films were fabricated with a 0.05 M solution by a sol-gel process at temperatures between 550 and 650 °C. Analysis by x-ray diffraction, Raman spectroscopy, and scanning electron microscopy revealed that the films annealed at 650 °C showed pure perovskite phase, tetragonal structure, and columnar grains with an average grain size of 150 nm. Electrical measurements performed on the films annealed at 650 °C showed two dielectric peaks in the dielectric constant–temperature curve, a remnant polarization of 1.4 μC/cm2, a coercive field of 18.3 kV/cm, and good insulating property. The measured pyroelectric coefficient for the films annealed at 650 °C was larger than 3.1 × 10−4 C/m2K at the temperatures ranging from 10 to 26 °C and reached the maximum value of 4.1 × 10−4 C/m2K at 16 °C. The excellent pyroelectric property rendered the Ba0.8Sr0.2TiO3 films annealed at 650 °C promising for uncooled infrared detectors and thermal imaging applications.

Effect of Sr/Ba Ratio on Dielectric Properties of BSTN Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 125-128 ◽  
Author(s):  
Zong Hui Zhou ◽  
Xin Cheng ◽  
Pi Yi Du ◽  
Jun Chang ◽  
Shi Feng Huang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Phase Composition ◽  
Dielectric Properties ◽  
Perovskite Phase ◽  
Tungsten Bronze ◽  
Dielectric Constants ◽  
Composite Ceramics ◽  
Impedance Analyzer ◽  
Applied Frequency ◽  
Two Phases

The phase composition of (1-x)BaO·xSrO·0.7TiO2·0.3Nb2O5 (BSTN) composite ceramics was analyzed by XRD, and the effect of Sr/Ba ratio on the dielectric properties of BSTN was investigated by impedance analyzer. The results showed that any sample with different x value contained two phases-the perovskite phase and the tungsten bronze phase. The dielectric constants of BSTN basically decreased while the tanδ increased with the increase in x value. Both dielectric constant and tanδ decreased with the applied frequency increased for the same x value. There were two Curie points for BSTN composite ceramics. The first one belonging to the perovskite phase decreased with the increase in x value, but the second one belonging to the tungsten bronze phase kept almost constant at about 300°C.

Flexural Strength of Superfine Grained Si2N2O-Si3N4 Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1477-1480
Author(s):  
Jun Ting Luo ◽  
Qing Zhang ◽  
Kai Feng Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Flexural Strength ◽  
Liquid Phase Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value ◽  
Average Grain Size ◽  
Main Fracture ◽  
Scanning Electron

The Si3N4- Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering(LPS) method. The sintering temperatures ranged from 1500°C to 1700°C. Microstructure and component of the composites were performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results show that sintered body consists of Si2N2O and β-Si3N4, with an average grain size about 1μm. The maximum value of flexural strength of the material is 680MPa when sintered at 1700°C. Transcrystalline cracking is the main fracture mechanism of the composites.

Deposition of Photoluminescent Nanocrystalline Silicon Films by SiF4-SiH4-H2 Plasmas

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Cicala ◽  
G. Bruno ◽  
P. Capezzuto ◽  
L. Schiavulli ◽  
V. Capozzi ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Silicon ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size

AbstractVisible photoluminescence at 1.62 eV has been observed at room temperature from fluorinated and hydrogenated nanocrystalline silicon (nc-Si:H,F) produced in a typical plasma enhanced chemical vapor deposition system. The use of SiF4-SiH4-H2 mixture, because of the H2 dilution and the presence of SiF4, favours the amorphous - crystalline transition through the etching process of the amorphous phase. The x - ray diffraction measurements give an average grain size of about 100 Å. The presence of these nanocrystals shifts the absorption edge of the films towards higher energy. An energy gap of 2.12 eV is estimated, although the hydrogen content in the material is only 4.5 at. %. The temperature dependence of the photoluminescence behaves similarly to that of porous silicon.

Microstructure Evolution in Bulk Nanostructured Copper during Repeated Cold Rolling

2012 ◽  
Vol 248 ◽  
pp. 43-47
Author(s):  
Lei Liu ◽  
Han Zhuo Zhang ◽  
Qin Lan Zhao
Keyword(s):  
Grain Size ◽  
Cold Rolling ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Maximum Value ◽  
Deformation Stages ◽  
Average Grain Size ◽  
Dislocation Interactions ◽  
Room Temperature Rolling

Room temperature rolling tests were performed on a bulk nanostructured Cu with an average grain size of 90 nm. The results indicated a high thickness reduction ( ) of 92% without crack and an increased {220} texture as the rolling processes continued. Microstructure evolution of the deformed nanostructured Cu could be characterized by several deformation stages. Grain growth and coalescence was prevalent in the early deformation stage, while grain boundaries were impaired and replaced by dislocation interactions when 24%. Microhardness of the deformed nanostructured Cu increased sharply to a maximum value of 1.61 GPa at 8% and then slightly decreased to 1.58 GPa at 92%.

Microstructure and Magnetic Properties of Fe(C) and Fe(O) Nanoparticles

2001 ◽  
Vol 704 ◽  
Author(s):  
Xiang-Cheng Sun ◽  
N. Nava ◽  
J. Reyes-Gasga
Keyword(s):  
Room Temperature ◽  
Arc Discharge ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Average Grain Size ◽  
Fe Nanoparticles ◽  
Carbon Coated

AbstractTwo types of iron (Fe) nanoparticles, carbon-coated Fe nanoparticles (Fe(C)) and pure α-Fe nanoparticles that coated with oxide layers (Fe(O)), have been successfully synthesized using modified graphite arc-discharge method. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HREM) and electron diffraction (SAED) analysis have been used to characterize these distinct structural morphologies. It is indicated that those two Fe nanoparticles have an average grain size of 15-20nm. The presence of carbon encapsulated α-Fe, γ-Fe and Fe3C phases are clearly identified by X-ray diffraction and SAED patterns in those Fe(C) particles. However, the evidence of pure α-Fe nanocrystal coated with oxide layer is also revealed by HR-TEM images and SAED patterns in these Fe(O) particles.Mössbauer spectra and hyperfine magnetic fields at room temperature for the assemblies of Fe(C) and Fe(O) nanoparticles further confirm their distinct nanophases that detected by XRD analysis and HRTEM observation. Specially, the assemblies of Fe(O) nanoparticles exhibit ferromagnetic properties at room temperature due to the stronger interparticle interaction and bigger magnetocrystalline anisotropy effects among these Fe(O) nanoparticles. Moreover, modified superparamagnetic relaxation is observed in the assemblies of Fe(C) nanoparticles, which is attributed to the nanocrystalline nature of the carbon-coated nanoparticles.

scholarly journals Structure, Dielectric and Multiferroic Properties of Bi0.85Nd0.15Fe0.98Zr0.02O3 in Ba and Ti Co-Doping

2021 ◽  
Author(s):  
Lizhu Zeng ◽  
Yuming Lu ◽  
Lujia Zhang ◽  
Xin Gong ◽  
Jianfeng Tang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Oxygen Vacancies ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Structure Transition ◽  
X Ray ◽  
Co Doping ◽  
Average Grain Size ◽  
Rhombohedral Perovskite Structure

Abstract Multiferroic (1- x)Bi0.85Nd0.15Fe0.98Zr0.02O3- xBaTiO3 (x = 0, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4) ceramics were synthesized by the conventional solid state reaction method. X-ray diffraction studies confirm the phase transition from rhombohedral perovskite structure to pseudocubic structure with the introduction of BaTiO3. The results of the refinement indicate the BaTiO3 is successfully doped into the crystal lattice. The microstructure analysis shows that the average grain size increases with the introduction of BaTiO3. An increase in remanant polarization has been achieved at room temperature as the BaTiO3 concentration increasing. A greatly reduced leakage current density of about two orders of magnitude is observed in x = 0.375 (J = 2.4×10− 7 A/cm2) ceramic. The dielectric properties have been enhanced by the addition of BaTiO3, which is attributed to the reduction in Fe2+ ions and oxygen vacancies. Due to the grain effect and structure transition caused by the doping of BaTiO3, the magnetization reveals a slight decrease while the coercive field for x = 0.325 (Hc = 1785.8 Oe) increases to 6.4 times of the undoped ceramic.

Sign in / Sign up

Export Citation Format

Share Document