铅基钙钛矿型结构铁电薄膜的介电及热释电性能研究

用改进的溶胶－凝胶旋转涂履技术,在Ｐｔ／Ｔｉ／ＳｉＯ２／Ｓｉ基片上研制出了１－２μｍ厚,具有钙钛矿型结构的ＰｂＴｉＯ３、ＰＬＴ和ＰＺＴ铅基铁电薄膜。该类铁电薄膜具有良好的结晶特性、优异的介电和热释电性能。     

天然热释电材料电气石的微结构及对水的pH值影响机理的研究

以新疆产天然电气石为原料制备了电气石微粉,利用X射线衍射仪、扫描电镜、高分辨电镜、pH酸度计研究了电气石的物相、微结构特点和电气石对水酸度及其随温度变化的影响.结果表明,电气石单个微粒为单畴的铁电体,可视为电偶极子;利用电气石微粉可以使水的酸度呈弱碱性;电气石对水酸度的影响随温度的变化进一步佐证了电气石的热释电性,并探讨了电气石对水作用的可能机理.     

固相法制备钇掺杂的钛酸钡锶钙陶瓷的介电和热释电性能

采用固相反应法制备了Y掺杂 (Ba_0.6Sr_0.3Ca_0.1)_1-xY_xTi_0.999Mn_0.001O₃ (0≤x≤0.007)陶瓷, 重点研究了Y含量对BSCT基陶瓷的显微结构、介电性能和热释电性能的影响。结果表明: 随着Y含量的增加, BSCY_xTM陶瓷的平均晶粒尺寸逐渐减小, 介电常数、介电损耗、居里温度和热释电系数均呈现先增加后减小的趋势。当Y掺杂量为0.7mol%时, BSCY_xTM陶瓷的平均晶粒尺寸最小为3.1 μm, 且探测优值F_d较大, 最大值可达8.22×10^-5 Pa^-1/2(700 V/mm, 30℃), 高于采用溶胶-凝胶法制备的同组分陶瓷的探测优值5.91×10^-5 Pa^-1/2。     

热释电红外探测材料的研究进展

热释电红外探测材料主要分为热电堆型、热敏电阻型和热释电型，本文综述了热释电红外热探测材料的种类、性能和研究进展。     

梯度复合KTN薄膜的铁电和热释电性能研究

在Pt/Ti/SiO2/Si基片上采用Sol-Gel法制备了五组分成分梯度分布的KTa1-xNbxO3(x=0.55,0.525,0.50,0.425,040)热释电薄膜。测试结果表明,复合KTN薄膜具有钙钛矿型结构,0.5μmKTN薄膜在15℃至51℃温度范围内,频率1.0kHz时,平均相对介电常数εr=1075,平均介电损耗tanδ=0.011。在室温及120kV/cm下极化30m in后,0.5μm复合薄膜在15-51℃温度范围内热释电系数出现峰值,平均热释电系数为3.54×10-6C/(cm2.K),电压响应优值Fv=1.205×10-9C.cm/J,探测度优值Fd=3.768×1-7C.cm/J。该薄膜工作温度范围较宽,作为热释电材料开发应用前景十分广阔。     

热释电材料的一般解

利用Stroh公式,给出了热释电材料热弹性问题的一般解,此解适用于四对复共轭压电本征值和一对热本征值互不相等的情况.然后,讨论了压电本征值问题出现重根时退化热释电材料的通解,并给出相应通解的形式.当热本征值与一个或多个压电本征值相等时,给出了退化热释电材料热弹性问题特解的具体形式.最后,通过共线界面裂纹问题证明了退化热释电材料和非退化热释电材料一般解中的任意函数f_α(z_α)形式相同,只是其中的某些系数有所变化.     

高性能PZNFTSI陶瓷热释电材料与小面积红外探测器的研制

本探讨了小面积红外热释电探测器的探测率与热释电材料性能参数之间的关系，制备了热释电系数高达５．１×１０＾－４Ｃ·ｍ＾－２℃＾－１的ＰＺＮＦＴＳＩ型陶瓷热释电材料，并用其制作了一系列φ０．３ｍｍ的小面积探测器，性能最高达５．９×１０＾８ｃｍＨｚ＾１／２Ｗ＾－１，远远超过同样尺寸的ＬｉＴａＯ３晶体探测器。探测率Ｄ＾＊的测量结果与理论预测值符合得较好，克服了晶体热释电材料在小面积应用时的局限，为进一步     

热释电陶瓷

在严格地定义热释电效应、一级和二级热释电系数的基础上,从应用要求出发对不同材料包括单晶(如TGS、LiTaO_3、LiNbO_3、Ba_2NaNb_5_(15).Sr_(0.5)Ba_(0.5)Nb_2O_6)、陶瓷(如PZT、PZT95/5、PbTiO_3、改性PZT、PLT等)的热释电性能作了比较。介绍了热释电陶瓷材料在红外传感器、红外探测器以及红外摄象等方面的应用。     

Dielectric and pyroelectric properties of Ba-modified lead lanthanum zirconate stannate titanate ceramics

(Pb_0.97−xLa_0.02Ba_x)(Zr_0.75Sn_0.12Ti_0.13)O₃ ceramics in the composition range 0.1 ≤ x ≤ 0.16 were prepared by conventional solid state reaction process. On increasing Ba content from 0.1 to 0.16 mol, the specimens underwent phase transition from the first order to the second order and the Curie temperature decreased from 85 to 35 °C. With x = 0.16, the specimen showed good pyroelectric properties for practical applications. When a 500 V/mm dc bias field was applied, the specimen showed the maximum pyroelectric coefficient of 5800 μC/m² K and figure of merit of 58 × 10⁻⁵ Pa^−0.5 at Curie temperature.     

Effects of grain size on pyroelectric and dielectric properties of Pb0.9La0.1TiO3 ceramics

Pyroelectric and dielectric properties of Pb0.9La0.1TiO3 ceramics with grain sizes in the range of 1.3–6.0 m were investigated. The temperature stability of the pyroelectric coefficient at room temperature was improved as the grain size became smaller. The pyroelectric coefficient of Pb0.9La0.1TiO3 at room temperature reached the lowest value near the grain size of 2.7 m. Above 2.7 m, the relationship between the pyroelectric coefficient and the grain size could be explained by the increase of 90° domain switching. However, below 2.7 m, the relationship was not clear. The variation of the relative dielectric constant of Pb0.9La0.1TiO3 with the grain size showed a similar relationship with that of the pyroelectric coefficient. The variation of the pyroelectric figure of merit on voltage responsivity as a function of the grain size was similar to that of the pyroelectric coefficient because the pyroelectric coefficient varied more strongly than the relative dielectric constant. © 1998 Chapman & Hall     

Dielectric and pyroelectric properties of monovalent-lithium modified trivalent-samarium doped barium strontium sodium niobate tungsten bronze structured ceramics

The dielectric and pyroelectric properties of trivalent-samarium doped barium strontium sodium niobate tungsten bronze structured ceramics are further modified with monovalent-Lithium. Ba_1.6−(3/2)y Sr_2.4Sm _y Li _x Na_(2−x)Nb₁₀O₃₀ was studied for y = 0.1 and x in the range of 0 ≤ x ≤ 1. The BSSLNN ceramics can be indexed by typical orthorhombic structure and these orthorhombic (mm2) peaks are assigned to standard file No. C73-1214. Tolerance factor and average electronegativity difference has been determined for BSSLNN ceramics. Pyroelectric and DC resistivity properties of BSSLNN ceramics are reported. x = 1 composition was found to be optimum among the series for possible pyroelectric applications.     

Mn掺杂BST陶瓷的本征热释电性能研究

采用柠檬酸溶胶-凝胶法制备了不同锰掺杂含量的BST陶瓷。研究表明,利用柠檬酸溶胶-凝胶法制备BST陶瓷粉末可以降低BST陶瓷的烧结温度至1250℃,Mn掺杂能明显降低BST陶瓷的铁电性,适量掺杂Mn可以获得具有介电常数适中、介电损耗较小,且室温下具有良好热释电性和探测率优值的BST陶瓷。1%Mn掺杂的BST陶瓷在室温下本征热释电系数γint=610nC/(cm2.K),低频下的探测率优值Fd=88.4×10-6Pa-1/2,可以满足制作热释电探测器的要求。讨论了Mn掺杂BST陶瓷的电畴翻转机制     

Polar glass ceramics — A new family of electroceramic materials: Tailoring the piezoelectric and pyroelectric properties

Grain oriented multicomponent polar glass-ceramics have been prepared by crystallizing the glasses in a temperature gradient. Inexpensive, large area piezoelectric and pyroelectric devices can be fabricated by this method, and by adjusting the composition of the glasses and crystallization conditions, it is possible to tailor the properties to meet device requirements. Based on the growth characteristics and the connectivity pattern of the crystallites, the piezoelectric, pyroelectric and dielectric properties of glass-ceramic composites can be predicted. Two examples discussed in this paper are piezoelectric glass-ceramics which are not pyroelectric, and pyroelectric glass-ceramics which are not piezoelectric.     

BN基复合陶瓷高温力学性能

BN陶瓷因SiO2的引入而使材料的力学性能得到了改善,但依旧存在强度低的不足,为此,本研究将通过在基体中引入高强度、高模量的SiAlON相作为增强相来进一步提高材料的力学性能.以BN、SiO2、AlN为原料,采用热压工艺制备出BN基复合陶瓷.通过高温力学性能测试和扫描电镜(SEM)观察,研究了AlN添加量对复合陶瓷高温力学性能和断裂行为的影响.研究表明:复合陶瓷的高温弯曲强度随着温度的升高而呈先升高后降低的趋势,并在1 300℃达到最大值,而强度的升高主要是由于升温过程中内应力的缓解所致.对于添加体积分数5%AlN的复合陶瓷,在1 300℃时其高温弯曲强度达到376.7 MPa,与室温条件下的弯曲强度相比提升了52.5%,当温度升至1 500℃时其高温弯曲强度为272.0 MPa,具有良好的高温力学性能.     

Dielectric and pyroelectric properties of triglycerol-gelatin films

The dielectric and pyroelectric properties of triglycerol-gelatin thick films were studied as a function of temperature and frequency. The films exhibited a strong dispersion in the dielectric permittivity accompanied by a high dielectric loss near room temperature. The pyroelectric current measured by the static Byer-Roundy method is heavily dominated by the thermally stimulated currents. Measurements performed on prepoled samples using the dynamic technique of A.G. Chynoweth (1956) clearly proved the presence of a true, reversible pyroelectric response in the examined films. The value of the pyroelectric coefficient of the films was found to be comparable to that of polyvinylidene fluoride (PVDF)     

制备工艺对Fe掺杂PZN-PZT热释电陶瓷性能的影响

采用传统氧化物反应法(一步法)和前驱体法(两步法)合成铁掺杂改性的0.075Pb(Zn_(1/3)Nb_(2/3))O_3-0.925Pb(Zr_(0.95)Ti_(0.05))O_3(PZN-PZT)热释电陶瓷,研究制备方法对PZN-PZT热释电陶瓷的微观形貌、相结构及电学性能的影响。XRD结果表明,采用一步法制备的陶瓷不如两步法,前者存在钙钛矿相和少量焦绿石相,后者能有效抑制焦绿石相的生成,陶瓷为纯菱方钙钛矿相。SEM分析进一步证实了两步法能够制备出晶粒分布均匀、晶型饱满的致密陶瓷。结合介电、铁电及热释电性能分析可知,单一钙钛矿结构和均匀紧凑的晶粒结构对陶瓷材料电学性能的增强起着重要的作用。