共查询到20条相似文献,搜索用时 0 毫秒
1.
Electrical and dielectric properties of Na_(1/2)La_(1/2)Cu_3Ti_4O_(12) ceramics prepared by high energy ball-milling and conventional sintering
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We report on the measurements of the electrical and dielectric properties of Na_(1/2)La_(1/2)Cu_3Ti_4O_(12)(NLCTO) ceramics prepared by high energy ball-milling and conventional sintering without any calcination steps. The x-ray powder diffraction analysis shows that pure perovskite-like CCTO phase is obtained after sintering at 1025?C–1075?C. Higher sintering temperatures result in multi-phase ceramics due to thermal decomposition. Scanning electron microscope observations reveal that the grain size is in a range of ~ 3 μm–5 μm for these ceramics. Impedance spectroscopy measurements performed in a wide frequency range(1 Hz–10 MHz) and at various temperatures(120 K–470 K) are used to study the dielectric and electrical properties of NLCTO ceramics. A good compromise between high ε(5.7 × 10~3 and 4.1 × 10~3 at 1.1 k Hz and 96 k Hz, respectively) and low tan δ(0.161 and 0.126 at 1.1 k Hz and 96 k Hz, respectively) is obtained for the ceramic sintered at 1050℃. The observed high dielectric constant behavior is explained in terms of the internal barrier layer capacitance effect. 相似文献
2.
3.
4.
5.
采用固相反应法制备了不同含氧量的BiFeOδ多晶陶瓷样品,利用HP4294A阻抗分析仪测量了样品的介电特性随频率和氧含量的变化,用正电子湮没寿命谱学的方法研究了样品中因氧含量的变化所引起的结构缺陷. 实验结果表明:引入氧空位和氧填隙离子缺陷都会使介电常数减小,而介电损耗则随氧含量的增加而增加,二者的变化范围均在10%—35%之间;对不同氧含量的BiFeOδ样品,介电常数和介电损耗随测量频率的增加而减小. 氧空位的引入使得局域电子密度变小,正电子平均寿命τm增加. 在氧含量δ=2.99时电子密度最大(ne=3.90×1023/cm3),继续增加氧含量对正电子寿命与局域电子密度的影响不大. BiFeOδ样品的介电常数和介电损耗随氧含量的变化可以在空间电荷限制电导的框架下来理解. 相似文献
6.
开展了固态脉冲形成线相关材料的研究,基于脉冲形成线的特性参数与材料介电性能之间的关联性,可实现固态脉冲形成线材料的筛选和评估。对不同类型材料介电性能的比较和固态脉冲形成线性能的分析表明:介电常数可调的微波陶瓷是制备固态脉冲形成线较为理想的材料。以Ba-Nb-Ti微波陶瓷制备的固态脉冲形成线可获得高压脉冲前沿5~6 ns,脉宽为13 ns,脉冲平顶为5~6 ns,击穿场强超过17.5 kV/mm。 相似文献
7.
采用氧化物固相反应法制备了锰掺杂改性的Ba(Zr0.06Ti0.94)O3陶瓷.研究了锰的掺杂量对Ba(Zr0.06Ti0.94)MnxO3 (BZTM)陶瓷的结构、介电和压电性能的影响.实验发现,当锰含量x<0.5 mol%时进入晶格,使材料压电性能提高,损耗减小,表现出受主掺杂的特性;当锰含量x>0.5 mo
关键词:
Ba(Zr
3 陶瓷')" href="#">Ti)O3 陶瓷
锰掺杂
介电性能
压电性能 相似文献
8.
TheDynamicBehaviourAnalysisofUp-ConversionLuminescenceinErP_5O_(14)GlassTheDynamicBehaviourAnalysisofUp-ConversionLuminescence... 相似文献
9.
非晶态HoP5O14的蓝绿波段上转换发光的分析 总被引:2,自引:0,他引:2
本文报道了脉冲DCM染料激光导致的非晶态HoP5O14的兰绿波段的上转换发光现象,从实验和理论上对其上转换发光的现象,机理和能道行了测量,分析和计算;结果表明对^5F3和S2能级,其上转换发光主要由离间能量传递机理导致;对5G4和(5G3G)5能级,则步进双光子吸收和离子间能量传递共同参与导致了它们的上转换发光。 相似文献
10.
Priyadarshini S. Sahoo Anuradha Panigrahi Sunanda K. Patri Ram N. P. Choudhary 《Central European Journal of Physics》2008,6(4):843-848
Polycrystalline samples of Ba4SrRTi3V7O30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique
and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31–500°C) and
frequency (1 kHz-1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic
structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples
and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest
that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355°C
for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of
temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature
coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization
study.
相似文献
11.
本文利用拉曼散射对非晶 La_(1-X)Nd_XP_5O_(14)及其晶化过程进行了研究。拉曼散射表明在非晶La_(1-X)Nd_XP_5O_(14)中仍保留着晶态 La_(1-X)Nd_XP_5O_(14)中具有的 PO_4~(3-)四面体结构单元。非晶La_(1-X)Nd_XP_5O_4在不同温度下晶化,其拉曼谱线的频率不同,这一现象可用应力模型给予解释。 相似文献
12.
Comprehensive studies on dielectric properties of p-methoxy benzylidene p-decyl aniline with function of temperature and frequency in planar geometry: A potential nematic liquid crystal for display devices
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pankaj Kumar Tripathi Kunwar Vikram Mithlesh Tiwari and Ajay Shriram 《中国物理 B》2021,30(6):64208-064208
The dielectric properties of the nematic mesophase, p-methoxy benzylidene p-decyl aniline(MBDA), measured in planar geometry with a function of frequency and temperature are investigated in detail. The complex dielectric permittivity(ε' and ε') is also studied at a bias voltage of 10 V for planar aligned sample cell of nematic mesophase. The dielectric permittivity with bias voltage attains a higher( 2 times) value than that without bias voltage at a temperature of 56℃,which is due to the fact that the linking group of nematic molecules is internally interacted with an applied bias voltage.This is supported by observing an enhanced dielectric permittivity of nematic liquid crystal(LC) in the presence of bias voltage, which can be fully explained as the increasing of the corresponding dipole moment. The dielectric relaxation behaviors of nematic LC are also demonstrated for planar aligned sample cell. The remarkable results are observed that the relaxation frequency shifts into low frequency region with the increase of the bias voltage applied to the planar aligned sample cells. The dielectric relaxation spectra are fitted by Cole–Cole nonlinear curve fitting for nematic mesophase in order to determine the dielectric strength. 相似文献
13.
从理论上证明了介电松弛过程在介电谱上等效于电子松弛过程,认为室温下105Hz处特征损耗峰起源于耗尽层处本征缺陷所形成的电子陷阱.在-130—20℃范围内测量了三种配方ZnO陶瓷的介电频谱,发现ZnO压敏陶瓷室温下105Hz处的特征损耗峰在低温下分裂为两个特征峰,认为它们起源于耗尽层中的本征缺陷(锌填隙或/和氧空位)的电子松弛过程.发现ZnO-Bi2O3二元系陶瓷特征峰仅仅由锌填隙引起,而ZnO-Bi2关键词:
ZnO压敏陶瓷
本征缺陷
介电谱
热处理 相似文献
14.
本文研究了DCM染料激光激发下的HoP5 O1 4 非晶在 370~ 5 80nm兰绿波段的上转换发光的动力学过程 ,发现离子间能量传递上转换和步进双光子吸收两种机理都共同参与导致了它们的上转换发光 ,而激发光频率的稍微改变会使其上转换动力学发生很大变化。 相似文献
15.
Neeraj 《Phase Transitions》2013,86(8):615-626
Silica (SiO2) nanoparticles in different wt/wt% ratios were dispersed in a novel room temperature ferroelectric liquid crystal mixture. Dielectric relaxation spectroscopy (50 Hz–1 MHz) and electro-optic responses were investigated. Dielectric permittivity gradually decreases by about 40% up to 1 kHz with increasing SiO2 concentration in the chiral smectic C phase. However, an increase of up to 1.5% has been observed for all the silica-doped samples above 2 kHz. We noticed an increase in optical transmission with increasing SiO2 concentration from 0.01 to 0.1 wt/wt%. 相似文献
16.
This paper reports the ultraviolet up-conversion luminescence of the noncrystalline HoP_5O_(14) at room temperature induced by 532nm pulsed laser for the first time and gives some simple analysis. 相似文献
17.
Sunanda Kakroo Arvind Kumar S.K. Mishra Vijay Singh Pramod K. Singh 《Phase Transitions》2016,89(3):211-220
In the present work, lead-free piezoelectric ceramics (Na0.5Bi0.5)TiO3 –xCuO–yNiO (for x = 0.0, 0.02, 0.04 and 0.06) have been prepared by a conventional solid-state reaction method. An investigation of CuO and NiO doping in bismuth sodium titanate (BNT) and a study of the structure, morphology, and dielectric and ferroelectric properties of the NBT–CuNi system have been conducted. Phase and microstructural analysis of the (Na0.5Bi0.5)TiO3 (NBT) based ceramics has been carried out using X-ray diffraction and scanning electron microscopy (SEM) techniques. Field emission scanning electron microscopy (FE-SEM) images showed that inhibition of grain growth takes place with increasing Cu and Ni concentration. The results indicate that the co-doping of NiO and CuO is effective in improving the dielectric and ferroelectric properties of NBT ceramics. Temperature-dependent dielectric studies have also been carried out at room temperature to 400 °C at different frequencies. The NBT ceramics co-doped with x = 0.06 and y = 0.06 exhibited an excellent dielectric constant ?r = 1514. The study suggests that there is enormous scope of application of such materials in the future for actuators, ultrasonic transducers and high-frequency piezoelectric devices. 相似文献
18.
Preparation and characterization of Sr_(0.5)Ba_(0.5)Nb_2O_6 glass-ceramic on piezoelectric properties
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We studied the influence of heat treatment time on the optical, thermal, electrical, and mechanical properties of strontium barium niobate(Sr_(1-x)Ba_xNb_2O_6; hereafter SBN) piezoelectric glass-ceramics with tungsten bronze-type structure,which have good piezoelectric properties and are important lead-free piezoelectric materials. We found that the best heat treatment time is 4 h. The properties of the prepared materials are better than that of SBN ceramics and the glass-ceramic growth is faster than the SBN crystal when the heat treatment time of the SBN piezoelectric glass-ceramic is controlled,reducing the preparation costs greatly. 相似文献
19.
It is found that the core-shell structured grains are easy to produce for fine grain doped BaTiO3 ceramics in the sintering process. We study the influence of the core-shell structure on the Curie-Weiss temperature and dielectric properties of BaTiO3 ceramics by using effective medium approximation (EMA). Considering the second approximation, the dielectric properties of fine grain doped BaTiO3 ceramics are consistent with experimental data. 相似文献
20.
The phase transition and electrical properties of Ba(Ti0.9Sn0.1)O3 ceramics with B2O3 added were investigated to explore the effect of B2O3 addition on enhanced densification and dielectric constant of these ceramics. With increasing B2O3 content, a linear reduction of ferroelectric to paraelectric transition temperature was observed. In addition, higher B2O3 concentrations enhanced a ferroelectric relaxor behavior in the ceramics. Changes in this behavior were related to densification, second-phase formation and compositional variation of the ceramics. 相似文献