Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3-BaMnO3无铅压电陶瓷的结构与电性能

采用固相法制备了(0.8 -x)Na0.5 Bi0.5TiO3 -0.2K0.5Bi0.5TiO3-xBaMnO3(简称NBT-KBT-BM)无铅压电陶瓷,研究了不同BM含量(x=0,0.25％,0.50％,0.75％,1.00％,1.25％,物质的量分数)样品的物相组成、显微结构及电性能.结果表明:所制备的NBT-KBT-BM陶瓷样品均为单一的钙钛矿结构.与纯NBT-KBT陶瓷相比,掺BM陶瓷的烧结温度降低,相对密度ρr得到提高.随x的增加,材料的压电常数d33、平面机电耦合系数kp与机械品质因子Qm先增大后减小,而介电损耗tanδ以及退极化温度Td一直降低.BM的掺入降低了材料的矫顽场Ec,提高了剩余极化强度Pr,从而增强了铁电性.当x=0.75％时,陶瓷获得最佳性能:d33=167 pC/N,kp=0.269,Qm=133,εr=774,tanδ=2.93％.     

SnO_2掺杂对(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Zr_(0.1-x)Sn_x)O_3无铅压电陶瓷介电弛豫与电性能的影响

采用固相烧结法制备了(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Zr_(0.1-x)Sn_x)O_3(BCZTS)无铅压电陶瓷。研究了不同含量SnO_2(x=0,0.02,0.04,0.06,0.08)对BCZT无铅压电陶瓷相结构、压电性能、介电性能和铁电性能的影响,并利用XRD、SEM、准静态d33测试仪等表征样品。结果表明,所有样品均为单一钙钛矿结构。当掺杂x=0.02时,(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Zr_(0.1-x)Sn_x)O_3无铅压电陶瓷材料的综合性能优异:d33=553 p C/N,kp=49%,εr~7474(1 k Hz),tanδ~1.5%(1k Hz),Pr=6.06μC/cm~2,Ec=2 k V/cm,利用Curie-Weiss定律对该实验结果进行拟合,发现x=0.02的样品的介电弛豫特征更为明显。     

CuO掺杂对KNN-LS-BF无铅压电陶瓷性能的影响

采用传统固相合成法和制备工艺,在1040℃制备了{0.996 [0.95( Na0.5 K0.5)NbO3-0.05LiSbO3 ]-0.004FeBiO3}+x mol％ CuO(KNN-LS-BF+x mol％ CuO)无铅压电陶瓷,研究了CuO掺杂量对陶瓷结构和性能的影响.结果表明,CuO的低温促烧作用明显,微量CuO的掺入并没有改变陶瓷体系的相结构,但对陶瓷的压电和介电性能有明显影响.随CuO掺杂量的增加,陶瓷的d33、kp、εr均是先升高后降低,并在x=0.15时,d33、kp、εr分别达到最大值222 pC/N、0.36、1223.14;Qm也是先升高后降低,不过是在x=0.3时达到了最大值66.02.而tanδ则是先降低,在x=0.45达到最小值2.5％后又开始回升.在x=0.15时,所制备压电陶瓷有最好的综合性能:d33=222pC/N,kp=0.36,εr=1223.14,tanδ=3.3％,Qm =52.27.     

预烧温度对(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Hf_(0.1))O_3压电陶瓷电性能的影响

采用固相法分别在1100~1250℃的预烧温度下制备了(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Hf_(0.1))O_3(BCHT)无铅压电陶瓷,通过对所制备陶微观结构和电性能的测试,发现:所有样品均具有纯的钙钛矿结构;随预烧温度的增加,室温下样品逐渐由四方相向三方相转变,预烧温度在1150~1250℃时两相共存;样品的压电常数d33、剩余极化强度Pr均随预烧温度的升高呈现先减小后增加的趋势,相对介电常数ε_r、弥散系数γ呈现先增加后减小的趋势,而矫顽场Ec则逐渐降低。样品的综合性能在预烧温度1250℃处达到最佳值:d_(33)=525 pC/N,Pr=10.2μC/cm~2,E_c=1.30 kV/cm,ε_r=17699,γ=1.65,表明该材料具有良好的应用前景。     

Fe2O3掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3无铅压电陶瓷的制备与性能

采用固相合成法制备了Fe2O3掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3(简称BCZT)无铅压电陶瓷。借助XRD、SEM、阻抗分析仪等对该陶瓷的相组成、显微结构以及压电和介电性能进行了研究。结果表明,Fe2O3掺杂降低了BCZT无铅压电陶瓷的烧结温度并使居里温度Tc从85℃提高到95℃;当Fe2O3掺杂为0.02wt%～0.1wt%时,陶瓷样品均为ABO3型钙钛矿结构;少量Fe2O3掺杂促进了陶瓷晶粒的生长,但随着Fe2O3掺杂量进一步增加,陶瓷晶粒随之细化;当Fe2O3掺杂量为0.04wt%时,陶瓷样品具有最优综合电性能,其压电常数d33、机电耦合系数kp、机械品质因数Qm、介电损耗tanδ和介电常数εr分别为400 pC/N,0.40,51,0.023和3482。     

LiBiO2掺杂的低温烧结PSZT压电陶瓷

采用固相二步合成法,通过在预烧粉料中添加LiBiO2,制备出一种低温烧结的Pb0.95Sr0.05(Zr0.54Ti0.46)O3压电陶瓷材料。LiBiO2的添加具有降低烧结温度同时提高陶瓷性能的优点。实验结果表明:适量的LiBiO2掺杂,可形成过渡液相烧结,使烧结温度降低到950～1050℃,比未添加时的烧结温度低240～340℃。当w(LiBiO2)=1.0%,陶瓷达到最佳压电性能:压电应变常数d33=425 pC/N,平面机电耦合系数kp=57.62%,退极化温度Td=350℃,相对介电常数ε3T3/ε0=1543,介电损耗tanδ=0.0216,剩余极化强度Pr=35.51μC/cm2,体积密度ρ=7.45g/cm3。该材料可应用于低温共烧的叠层压电器件中。     

烧结温度对(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3无铅压电陶瓷结构和电学性能的影响研究

采用固相反应法成功制备出具有ABO3型钙钛矿结构的锆钛钡钙(Ba0.85Ca0.15) (Zr0.1Ti0.9) O3无铅压电陶瓷,研究了粉体预烧温度和陶瓷片烧结温度对(Ba0.85Ca0.15) (Zr0.1Ti0.9) O3陶瓷结构和电学性能的影响.结果表明:当预烧温度为1200oC、烧结温度为1400oC可获得具有优异电学性能的(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3无铅压电陶瓷,其电学性能分别为居里温度Tc＝97 ℃,最大介电常数εmax＝14920,剩余极化强度为Pr＝9.96 μC/cm2,矫顽场Ec＝7.20 kV/cm,压电常数d33＝543 pC/N,机电耦合系数kp＝52;,其高的电学性能可以和铅基压电材料相媲美,表明(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3陶瓷有望实现压电陶瓷的无铅化应用.     

BiAlO3改性对BF-BT压电陶瓷电性能与温度稳定性的影响

采用固相合成法制备了高温钙钛矿结构0.7Bi(Fe1-xAlx)O3-0.3BaTiO3+0.3%MnO2(BFAx-BT)无铅压电陶瓷。研究了BiAlO3改性对该体系陶瓷显微组织、电性能及温度稳定性的影响。结果表明:随BiAlO3含量的增加,陶瓷晶粒尺寸先增加后减小,压电性能的变化规律与晶粒尺寸变化一致,在x=0.01时,压电性能达到最大值d33=134 pC/N,kp=0.28。陶瓷弥散相变特征随BiAlO3含量的增加更加明显,适量BiAlO3添加显著增加了介电性能与压电性能的温度稳定性,特别是kp随温度增加在退极化温度前基本保持不变。     

Y_2O_3掺杂对(Ba_(0.85)Ca_(0.15))Zr_(0.1)Ti_(0.896)Sm_(0.004)O_3无铅压电陶瓷介电弛豫与电性能的影响

采用固相法制备了(Ba0.85Ca0.15)1-xYxZr0.1Ti0.896Sm0.004O3(BCZTS-Yx)无铅压电陶瓷.研究了Y2O3含量对BCZTS-Yx无铅压电陶瓷相结构、压电与介电性能的影响.结果表明:Y3+作为施主掺杂物占据A位。当0.004≤x≤0.006时,陶瓷存在三方相与四方相共存的准同型相界结构。当x=0.006时,陶瓷具有最佳的电性能,分别为d33=384 pC/N,kp=37.2%,εr~6775,tanδ~2.04%.利用Curie-Weiss定律对该实验结果进行拟合,发现x为0.006的样品的介电弛豫特征更为明显。     

Pb_(0.92)Sr_(0.08-x)Ba_x(Sb_(2/3)Mn_(1/3))_(0.05)Zr_(0.48)Ti_(0.47)O_3的制备与性能研究

采用传统固相烧结法制备了Pb_(0.92)Sr_(0.08-x)Ba_x(Sb_(2/3)Mn_(1/3))_(0.05)Zr_(0.48)Ti_(0.47)O_3(PSBSM-PZT)压电陶瓷样品。研究了不同Sr2+、Ba2+掺杂含量对样品的相结构、微观形貌、压电和介电性能的影响。结果显示:所有样品均为钙钛矿结构。而当x=0.02~0.06时,陶瓷样品组分位于准同型相界区(MPB)。由于位于准同型相界区域的陶瓷样品对于电畴的转向具有促进作用,所以处于MPB区域的陶瓷样品具有较大的压电和介电性能,但同时由于电畴转向带来的较大内摩擦和结构损耗,从而提高了材料的机械损耗和介电损耗。当x=0.02时的陶瓷样品获得最佳的综合性能:d33=346 pC/N,kp=0.58,Qm=1217,εr=1724,tanδ=0.774%。     

Crystal and molecular structures oftrans-dichloro-(ethylene) (4-methylpyridine)platinum(II) andtrans-dichloro(ethylene) (2,4,6-trimethylpyridine)platinum(II)

The crystal and molecular structures oftrans-[PtCl₂(C₂H₄)(4-MeC₅H₄N)] (I) andtrans-[PtCl₂(C₂H₄)(2,4,6-Me₃C₅H₂N)] (II) have been determined by single-crystal x-ray methods.I crystallizes in space groupP2₁/c witha= 4.991(1), b=21.658(3), c=10.675(3) Å, =110.17(2) °,Z=4;II is orthorhombic (Pbca) witha=10.295(6),b=12.393(8),c=20.370(10) Å,Z=8.Full-matrix least-squares refinements have given finalR factors of 0.053 (1520 reflections) forI and 0.042. (1412 reflections) forII. The intensities were recorded by counter methods, and only those reflections havingI>3(I) were used in the analyses.In both complexes, platinum is four-coordinate with the two chlorine atoms, the double bond of the ethylene, and the nitrogen atom of the substituted pyridine. The two structures are discussed in terms of the arrangement of the pyridine ligand with respect to the PtCl₂(C₂H₄) moiety.     

Synthesis, spectroscopy, and X-ray structures of fac-(CO)3(dppe)MnSC(S)H, fac-(CO)3(dppe)ReSC(S)H, fac-(CO)3(dppp)ReSC(S)H, and fac-(CO)3(dppb)ReSC(S)H

The monodentate dithioformato complexes, fac-(CO)₃(dppe)MnSC(S)H (1), fac- (CO)₃(dppe)ReSC(S)H (2), fac-(CO)₃(dppp)ReSC(S)H (3), and fac-(CO)₃ (dppb)ReSC(S)H (4), where dppe is 1,2-bis(diphenylphosphino)ethane, dppp is 1,3-bis(diphenylphosphino)propane, and dppb is 1,4-bis(diphenylphosphino)butane, were synthesized from the treatment of the corresponding hydrides, fac-(CO)₃ (P-P)MSC(S)H with CS₂. Compounds 1–4 crystallize in the monoclinic crystal system: for 1, space group = P2₁/c, a = 15.3139(3) Å, b = 9.7297(4) Å, c = 19.0991(6) Å, = 105.928(1), V = 2736.5 ų, Z = 4; for 2, space group = P2₁/c, a = 15.6395(8) Å, b = 9.8182(5) Å, c = 19.4153(11) Å, = 106.741(1), V = 2854.9(3) ų, Z = 4; for 3, space group = P2₁/n, a = 11.3570(10) Å, b = 19.465(2) Å, c = 15.5702(14) Å, = 104.776(2), V = 3328.3(5) ų, Z = 4; and for 4, space group = C2/c, a = 32.078(2) Å, b = 10.4741(6) Å, c = 19.0608(9) Å, = 94.315(2), V = 6386.1(6) ų, Z = 8.     

Structure of (chloranilato)bis(tri-n-butylphosphine)palladium(II)

(Chloranilato)bis(tri-n-butylphosphine)palladium(II), [Pd(C₆Cl₂O₄){P(C₄H₉)₃}₂] (chloranilic acid=2,5-dichloro-3,6-dihydroxy-p-benzoquinone): FW=718.02,P2₁/c,a=21.729(6),b=17.293(5),c=21.010(9) Å,=112.62(3)°,V=7287.42 ų,Z=8,D _c=1.309mg m^–3, Mo, =0.710730 Å,=0.76 mm^–1,F(000)=3008, finalR=0.087, 2594 observed reflections. Palladium is ligated by a distorted square planar P₂O₂ coordination sphere in the title compound. The two molecules per asymmetric unit differ in the arrangement of phosphine n-butyl chains, yielding two unique metal centers.     

Crystal structure of triphenylphosphine-(1-(di(trifluoromethyl)-hydroxymethyl)-cyclopentadienyl)-(1,2-di(carboxymethyl) ethylene-1-yl) ruthenium (0)

The structure of triphenylphosphine — (1 — (di(trifluoromethyl) — hydroxymethyl) — cyclopentadienyl) — (1,2 — di(carboxymethyl)ethylene — 1 — yl) — ruthenium (0) has been studied by single-crystal X-ray diffraction techniques. This compound, [C₅ H₄(CF₃)2 COH] Ru(PPh₃)C2(CO₂Me)₂H, crystallizes in the triclinic space groupP¯1 witha =10.131,b= 15.107,c= 10.798 Å, = 102.14, = 107.04, = 89.64° andZ = 2. The structure was refined by block-diagonal least-squares methods to a finalR value of 0.042, including hydrogen atoms. The compound contains a dicarboxymethylethylene ligand coordinated to ruthenium both through a ketonic oxygen and through a metal--carbon -bond. An intramolecular hydrogen bond is observed. Details of the structure are reported, and the structures of several Ru(0) complexes are compared.     

X-ray crystal structures ofcis-bis(diphenylphosphinamide)tetracarbonylmolybdenum(0) andtrans-bis(N-methyl diphenylphosphinamide)tetracarbonylmolybdenum(0)

The X-ray crystal structures ofcis-Mo(CO)₄(Ph₂PNH₂)₂,I, andtrans-Mo(CO)₄(Ph₂PNHMe)₂,II, are presented. ComplexI crystallizes in the monoclinic space groupP2₁/c(a=13.433(1),b=12.2719(8),c=17.318(2)Å;=109.79(1)°;V=2686.1(8)ų;Z=4). ComplexII crystallizes in the triclinic space groupP¯1 (a=6.9986(8),b=10.328(1),c=11.241(2)Å,=107.58(1)°,=91.76(1)°, =101.28(1)°,V=756.1(4)ų,Z=1). The molybdenum coordination geometry in each complex is a slightly distorted octahedron. The molybdenum-carbon bond lengths for the carbonyls trans to phosphorus in complexI are shorter than those the carbonyls trans to other carbonyls. The average molybdenum-phosphorus distance inI (2.525(5)Å) is similar to those in other diphenylphosphinamide complexes and longer than the molybdenum-phosphorus distance inII in 2.4585(7)Å). The distance between two nitrogen atoms incis Mo(CO)₄(Ph₂PNH₂)₂ (3.74(3)Å) is significantly larger than the sum of their van der Waals radii (3.10 Å) indicating that the two nitrogens are not hydrogen bonded.     

Structure of (N-(2-hydroxyphenyl)-salicylaldiminopiperidino) Ni(II) complex

The crystal and molecular structure of the title complex, C₁₈H₁₉N₂O₂Ni, has been determined by direct methods. The compound crystallizes in the monoclinic crystal system witha=22.973(1),b=5.212(1),c=27.076(1)Å, β=106.46(1)°, space groupC2/c,V=3109.1(6)ų, Z=8, andD _x=1.51g cm^?3. The nickel atom is in a slightly distorted square-planar environment of two oxygens [Ni(1)?O(1) 1.824(3) and Ni(1)?O(2) 1.856(3)Å] and two nitrogens [Ni(1)?N(1) 1.849(3) and Ni(1)?N(2) 1.932(3)Å] with O?Ni?N angles between 85.7(1) and 97.1(1)°. The nickel atom is 0.006 Å out of the plane of its ligands.     

Crystal and molecular structures of trans-bis(acetonitrile)bis(bipyridine)ruthenium(II) perchlorate and trans-diamminebis(bipyridine)ruthenium(II) perchlorate

The structures of trans-[(MeCN)₂(bpy)₂Ru](ClO₄)₂(I) andtrans-[(NH₃)₂(bpy)₂Ru](ClO₄)₂(II) have been determined by single crystal X-ray diffraction methods. (I) forms monoclinic crystals in the space groupP2₁/c witha=8.399(2),b=10.406(2),c=15.590(3) Å,=93.78(2)° andZ=2 atT=293 K. The final refinement gaveR=0.040 for 2448 reflections withF _o ² >3(F _o ² ). (II) crystallizes in the triclinic space groupP¯1 witha=1.702(1),b=8.439(2),c=10.525(2) Å,=107.56(2),=104.63(1), =100.89(2)° andZ=1 atT=293 K. Refinement using 1878 reflections withF _o ² >3(F _o ² ) produced a finalR value of 0.036. Both of these structures have the ruthenium atom located on a crystallographic inversion center. The bipyridine ligands in both structures are in the bowed conformation as a means of circumventing the steric problems associated with the trans arrangement of the bipyridine ligands. The Ru-N(monodentate) distance is longer for the ammonia complex (2.106(3) Å) than for the acetonitrile complex (2.008(4) Å); there are no significant differences in the distances and angles of the two Ru(bpy)₂ frameworks.     

X-ray structures of tris(0-cyclohexyl-dithiocarbonato)bismuth(III) and tris(0-benzyl-dithiocarbonato)bismuth(III)

The crystal structures of two Bi tris xanthates are reported, namely [Bi(S₂CO-c-C₆H₁₁)₃ J and [Bi(S₂COCH₂C₆H₅)₃]. They exist as centrosymmetric dimers, owing to the presence of bridging xanthate ligands, with seven-coordinate Bi atoms. The presence of a stereochemically active lonepair of electrons in each structure distorts the coordination geometry defined by seven S atoms and causes the elongation of some of the Bi-S bond distances. Crystals of both compounds are triclinic, space groupP¯1 with unit cell dimensions for [Bi(S₂CO-c-C₆H₁₁)₃]:a=12.417(3),b=13.571(3),c=9.681(4) Å;=102.30(2),=109.21(2), =66.23(2)° andZ=2; and for [Bi(S₂COCH₂C₆H₅)₃]:a=14.747(2),b=15.966(2),c=5.991(1) Å;=95.08(1),=98.51(1), =104.92(1)° andZ=2. The structures were refined by a full-matrix least-squares procedure to finalR=0.045 using 4274 reflections for [Bi(S₂CO-c-C₆H₁₁)₃] and toR=0.027 using 3993 reflections for [Bi(S₂COCH₂C₆H₅)₃].     

Crystal structure of bis(4-dimethylaminopyridinium) tribromocuprate(I) and bis(4-dimethylaminopyridinium) tetrabromocuprate(II)

The synthesis and crystal structures of two copper bromide salts of the 4-dimethylaminopyridinium (4DMAP⁺) cation are reported. The Cu(I) salt, (4DMAP)₂CuBr₃, crystallizes in the monoclinic space group C2/c, with a = 11.724(2), b = 11.055(3), c = 15.763(3) Å, = 107.64(3)°, and Z = 4. It contains isolated planar 4DMAP⁺ cations and trigonal planar CuBr₃ ^2– anions. Small distortions from idealized D _3h symmetry are observed for the anion. For the Cu(II) salt, (4DMAP)₂CuBr₄, a triclinic cell is observed with a = 8.2373(2), b = 9.2428(2), c = 14.4391(1) Å, = 93.760(1), = 94.576(1), = 105.249(1)°, and Z = 2. This compound contains discrete planar 4DMAP⁺ cations and flattened tetrahedral CuBr₄ ^2– anions. Small distortions are observed for ideal D _2d symmetry.