SYNTHESIS AND X-RAY POWDER STUDY OF A NEW COMPOUND:Ba_6Ti_7Nb_9O_(42)

A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes in the hexagonal system -with unit cell parameters a=9.0527(4) A,c=11.790(1) A,and space group P63/mcm(193),z=1. The calculated and measured densities are 5. 293 g/cm3 and 5.285 g/cm3, respectively.     

SYNTHESIS AND CHARACTERIZATION OF A NEW COMPOUND:K6Ti0.67Nb15.33O42

A new compound K6Ti0.67Nb15.33O42 was prepared for the first time by solid state reaction in K2O-Ni2O3-Nb2O5 ternary system. The new compound was characterized by electron probe, X-ray powder diffraction and DTA. The result of X-ray powder diffraction shows that K6Ti0.67Nb15.33O42 crystallizes the hexagonal system with unit cell parameters a = 9. 1341(5) A ,c=12. 090(1)A . and space group P62/mcm(193 ).     

SYNTHESIS AND X-RAY POWDER DIFFRACTION DATA OF A NEW COMPOUND::K_6FeNb_(15)O(42)

A new compound K_5FeNb_(15)O_(42)(?) pre-pared for the first time by solid state reaction in K_2O-Fe_2O_3-Nb_2O_5ternary system.The XRD data of the titlecom pound was determined.K_6FeNb_(15)O_(42) crystallizes thehexagonal system with unit cell parameters a=9.1320(4)A,c=12.0670(9)A,and space group P63/mcm(193),z=1.The calculated and measured densities are 4.489g/cm~3 and 4.485 g.cm~3,respectively.     

SYNTHESIS AND X-RAY POWDER DIFFRACTION DATA OF A NEW COMPOUND:K_6FeNb_(15)O_(42)

A new compound K_6FeNb_(15)O_(42) was prepared for the first time by solid state reaction in K_2O Fe_2O_3-Nb_2O_5 ternary system. The X-ray powder diffraction data of the title compound was measured. K_6FeNb_(15) O_(42) crystallizes in the hexagonal system with unit cell parameters a=9.1320(4)(?),c=12.0670(9)(?), and space group P63/mcm(193), z=1. The calculated and mea sured densities are 4.489 g/cm~3 and 4.485 g.cm~3, respec tively.     

SYNTHESIS AND CRYSTAL STRUCTURE OF A NEW COMPOUND Sr6Sn2Nb8O30

A new compound Sr6Sn2Nb8O30 was found in the ternary system of SrO-SnO2-Nb2O5. The transparent colorless crystal with needle-like shape can be grown by flux method. The crystal structure of new compound was determined by X-ray diffraction, and its belongs to tungsten bronze structure. Sr6Sn2Nb8O30 crystallizes in orthorhombic system with unit cell parameters a= 17. 579 (DA,6= 17. 509(DA,c=7. 7880(5)A,Z = 4 and space group Cmm2.     

Preparation,structure and dielectric properties of tungsten bronze ferroelectrics in SrO-Eu<Subscript>2</Subscript>O<Subscript>3</Subscript>-TiO<Subscript>2</Subscript>-Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> system

Compounds Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 with filled tetragonal tungsten bronze structure were prepared,and the dielectric characteristics and ferroelectric transition were investigated.Both ceramics displayed weak frequency dependence in room temperature dielectric constant,which decreased from 125 to 118 for Sr4Eu2Ti4Nb6O30,from 206 to 195 for Sr5EuTi3Nb7O30 in the frequency range of 10 kHz to 1 MHz.The present ceramics showed a diffuse ferroelectric phase transition.The frequency independent transition temperature (Tm) indicated the above compounds had no relaxor property.The diffuseness (γ) was 1.45 and 1.64 for Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 respectively.The weak ferroelectric of the present materials are indicated from the P-E hysteresis loops,and a small 2Pr of 0.596 μC/cm2 and 0.068 μC/cm2 were observed for Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 respectively.     

新化合物Sr_6CrNb_9O_(30)的合成及其结晶化学研究

在 Sr O- Nb2 O5- Cr2 O3 三元系统中 ,首次合成了新化合物 Sr6Cr Nb9O3 0 ,通过光学显微镜、化学分析、透射电镜、电子探针、X- ray衍射等手段对该化合物进行了研究 ,得到了晶体粉晶衍射数据 ,晶胞参数 a=b=1.75 0 8nm,c=0 .7748nm,晶体属正交晶系 ,空间群为 Cmm2 ,该化合物晶体具有钨青铜超结构     

中温烧结0.6Mg_4Nb_2O_9-0.4SrTiO_3复相陶瓷

采用传统固态反应方法制备0.6Mg4Nb2O9-0.4SrTiO3复合陶瓷。研究LiF掺杂对其烧结特性、相结构和微观形貌的的影响。通过X射线衍射(XRD)和扫面电镜(SEM)观察样品的相组成和显微结构。实验结果表明:1.5 wt%LiF添加,可将Mg4Nb2O9/SrTiO3陶瓷的致密化烧结温度从1300℃降至1100℃;XRD表明除主相Mg4Nb2O9、SrTiO3外,还有少量新相Sr(Ti1-xNbx)O3+δ生成。     

STRUCTURAL AND FERROELECTRIC PROPERTIES OF A NEW NIOBATE : Sr6FeNb9O30

A new niobate Sr_6FeNb_9O_(30) was synthesized in the ternary system SrO-Fe_2O_3-Nb_2O_5 for the first time. The crystal structure was determined by X-ray diffraction and dielectric measurement, and it belongs to orthorhombic tungsten bronze structure at room temperature with unit cell parameters a=1.7554(1) nm, b=1.7534 (1) nm, c=0.77870 (6) nm. Dielectric constants measurement show that Sr_6FeNb_9O_(30) has two phase transitions, paraelectric to ferroelectric at 185C and ferroelectric to ferroelastic at 70C.     

Microstructure and dielectric properties of BaTi4O9(f)/0.64 BaTi4O9+0.36 BaPr2Ti4O12 composites

The microstructure, dielectric properties and chemical state of Ti element on BaTi4O9 (f)/(0. 64 BaTi4O9-0. 36BaPr2Ti4O12 ) composites sample surface were characterized by X-ray diffraction (XRD) ,Transmission electron microscopy (TEM), LCR meter method and X-ray photoelectron spectroscopy (XPS).The results show that the system is composed of BaTi4O9 and BaPr2Ti4O12 two phases. Pr ions are distributed inthe BaTi4O9 grains and the segregation of Pr ions was observed on the grain boundaries of BaTi4O9/BaTi4O9.The content of Ti3 + and Ti2+ decrease in the BPT system composites due to the addition of BaTi4O9 fibers,which improved the dielectric properties of the system. BPT10 sample with 10 % BaTi4O9 fibers, has the bestdielectric properties in the system, its εr =64,tan δ = 1×10-4(at 1 MHz) , and it may be a potential candi-date for microwave dielectric ceramics.     

Synthesis and Dielectric Properties of New Niobate Ba_5BiTi_3Nb_7O_(30)

1　ＩｎｔｒｏｄｕｃｔｉｏｎＦｅｒｒｏｅｌｅｃｔｒｉｃｓｗｉｔｈｔｈｅｔｅｔｒａｇｏｎａｌｔｕｎｇｓｔｅｎｂｒｏｎｚｅｓｔｒｕｃｔｕｒｅａｒｅｔｈｅｉｎｔｅｒｅｓｔｉｎｇｃｏｍｐｏｕｎｄｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｈｉｇｈｅｌｅｃｔｒｏ ｏｐｔｉｃ ,ｐｉｅｚｏｅｌｅｃｔｒｉｃ ,ｎｏｎｌｉｎｅａｒｏｐｔｉｃａｌｅｆｆｉｃｉｅｎ ｃｉｅｓａｎｄｉｔｓｉｎｔｅｒｅｓｔｉｎｇｆｅａｔｕｒｅｓｆｒｏｍｔｈｅｖｉｅｗｐｏｉｎｔｏｆｐｈａｓｅｔｒａｎｓｉｔｉｏｎｓ[1- 3] .Ｔｕｎｇｓｔｅｎｂｒｏｎｚｅｓｔｒｕｃ…     

XRD STUDY ON PIEZOELECTRIC CERAMIC OF PZSN SYSTEM

The structure of piezoelectric ceramic in Pb[(Zn_(1/3)Nb_(2/3)(Sn_(1/2)Nb_2/3](Zr,Ti)O_3 system is studiedthrough XRD and TEM analysis.The effects of substitutionof Ba~(2 ), Sr~(2 ).for Pb~(2 )and small amount of dopants such asMnO_2 and Sb_2O_3 on the structure are investigated.The dif-ference between unpolarized and polarized XRD patternsand the structure of ferroelectric domains is emphaticallystudied.The result shows that the samples are of the tetrago-nal pertovskite-type structure.The dopants change the tetrago-nallty of samples and grain size but have no effect on thecrystal phase.The effects of polarizing on the structure canbe proved from the deformation of unit cell in microscopicstate and rotation of 90°ferroelectric domains in microscopicstate.     

Synthesis and Characteristic of a New Niobate:Ba_5NaCo_0.5Nb_9.5O_30

A new niobate crystal was synthesized for the first time in BaO-Na2O-Co2O3 -Nb2O5 system by solid state reaction and the flux method. The new compound was studied by X-ray diffraction, electron probe. N-ray microanalysis, chemical analysis and SEM. The result of the X-ray diffraction shows that Ba5 NaCo0.5 Nb9.5 OK) belongs to tetragonal tungsten bronze structure with space group P4bm( 100) and lattice parameters a = b = 12.4453(2) A, c = 3. 9770 (3) A and Z = 1. The structure of the compound is different from that of Ba4Na2Nb10O30     

Preparation and properties of SrBi_(2.2) Ta_2O_9 thin film

1INTRODUCTION Ferroelectricfilmshaveattractedmuchatten tionduetotheirpotentialapplicationsinelectronic devices,suchaspyroelectricinfrareddetectors,opticalswitches,actuators,dynamicrandomac cessmemories(DRAMS)[1,2],andnon volatile randomaccessmemories(NVRAMS)[3,4].Re cently,thereisinterestinthestudyofbismuthlayerstructuredferroelectricmaterialsformemory applications.Inparticular,strontiumbismuthtan tanate(SBT),oneofthebismuthlayerstructuredcompounds,isapromisingcandidateforferroelec t…     

一种新的配合物烟酸锶的合成及表征

以碳酸锶为锶源,烟酸为配体合成了一种新的配合物Sr(C6H4NO2)2.3H2O。通过化学分析、元素分析、红外、热重和X-射线粉末衍射等手段对其组成、结构、性能进行了表征。结果表明烟酸以双齿桥式与Sr(Ⅱ)结合形成配合物;热分析结果显示该配合物的热分解过程包括失水、配体的氧化,最后完全分解为氧化物;分析测试结果表明该物质属于单斜晶系,晶胞参数为:a=16.282 5,b=13.345 4,c=35.285 7,β=111.682 7。     

锂离子电池负极材料 Na2Li2Ti6O14的嵌脱锂过程动力学研究

为了研究钛酸钠锂(Na2Li2Ti6O14)负极材料嵌脱锂的动力学行为,用溶胶-凝胶法合成 Na2Li2Ti6O14负极材料,采用 X 射线衍射法(XRD)和电子显微镜(SEM)分别对材料进行物相分析和微观形貌的观察.采用恒流充放电测试、循环伏安法(CV)和恒电流间歇滴定法(GITT)研究了 Na2Li2Ti6O14的电化学性能和嵌脱锂过程动力学.研究结果表明,制备的 Na2Li2Ti6O14材料纯度高,结晶度良好,循环稳定性好;由不同扫描速率的循环伏安法测出的 Na2Li2Ti6O14中锂离子在氧化、还原峰对应的化学扩散系数 Da和 Dc分别为7.3×10-11和7.8×10-11cm2/s;由恒电流间歇滴定技术测得的锂离子在 Na2Li2Ti6O14电极中的扩散系数为10-11~10-8cm2/s.     

中温烧结Mg_4Nb_2O_9-CaTiO_3陶瓷相结构的研究

采用传统固态反应方法制备了(1-x)Mg4Nb2O9+xCaTiO3[(1-x)MN-xCT]复合陶瓷。探讨了烧结温度、组分x对Mg4Nb2O9/CaTiO3复合材料相结构的影响。通过XRD和EDS进行物相分析。实验结果表明:V2O5添加能够有效降低Mg4Nb2O9/CaTiO3陶瓷的烧结温度;(1-x)MN-xCT复相的形成主要取决于烧结温度和x的含量。1150℃烧结、0.5≤x≤0.7范围内,形成了Mg4Nb2O9/CaTiO3复相,无新相生成,但元素在不同相之间发生了扩散。     

Synthesis mechanism of Pr doped BaTi4O9 powder by sol-gel process

Pr Doped BaTi4O9 gel was prepared by sol-gel method using Ti(OC4H9)4, Ba(CH3COO)2, CH3COOH and CH3OCH2CH2OH as raw materials. Through analyzing dry gel thermal treated at different temperatures, the possible synthesis mechanism of Pr doped BaTi4O9 powder was discussed. At first, Ti(OC4H9)4 hydrolyzes and three dimensional networks form, in which Ba2 and CH3COO- are mostly in the form of ions; organic solvent is gradually volatilized through calefaction at 700 ℃, then the offspring is turned into BaTi5O11. With the temperature increasing to 850 ℃, BaTi5O11 begins resolving partly and forming BaTi4O9, and at 1000℃ Ba4Ti13O22 forms partly, but BaTi4O9 is the main crystal phase. BaTi5O11 and Ba4Ti13O30 decomposes completely at 1200℃ and forms single-phase BaTi4O9. The infrared (IR) analysis also shows that the absorbing peak of Ti-O bond is not in the characteristic absorption range of Ti-O-Ti (700-900 cm-1), but slightly shifted to the higher end (908 cm-1). It is probably because that doping Pr enters into the crystal lattice and causes the abnormal absorption of Ti-O bond.     

一维链状化合物｛(C2H10N2)[Mo3O10]｝n的水热合成、晶体结构与表征

在水热条件下合成了一维链状结构多金属氧酸盐化合物{(C2H10N2)[Mo3O10]}n,并用IR、TG-DSC和单晶X-ray衍射等手段进行了表征。结果表明,化合物属于单斜晶系,P21/n空间群,晶胞参数a=0.808 40(2)nm,b=1.446 50(3)nm,c=0.891 50(2)nm,α=90°,β=98.140(2)°,γ=90°,V=1.031 97(4)nm3,Z=4,Dc=3.282g/cm3,R1=0.027 9,wR2=0.072 9。化合物分子结构单元由一个质子化乙二胺和一个[Mo3O210-]阴离子构成。[Mo3O210-]中相邻的MoO6八面体相互作用形成一维无限链状结构,毗邻的单链相互缠绕形成双链结构。热性质研究表明,标题化合物热稳定性较好,在290℃才开始有热失重的发生。同时,又将该化合物修饰到电极上,研究了其电化学行为。     

Eu~(2+),Eu~(3+)掺杂对Sr_2MgSi_2O_7荧光粉发光性能的影响

采用高温固相法分别制备Eu2+和Eu3+掺杂的Sr2MgSi2O7荧光粉.在356nm近紫外光激发下,Sr2MgSi2O7:Eu3+荧光粉呈多峰红光发射,主峰位于590nm、615nm、650nm和700nm,分别对应于Eu3+离子5D1→7FJ(J=1,2,3,4)能级的跃迁.在371nm近紫外光激发下,Sr2MgSi2O7:Eu2+荧光粉发射峰介于425~550nm之间,呈蓝光发射,主峰位于476nm,对应Eu2+的4f65d1→4f7跃迁.随着Eu2+浓度的增大,发射峰强度先增大后减弱.