Sm2O3掺杂TiO2光催化剂的制备和性能

 采用溶胶-凝胶法制备了Sm2O3掺杂TiO2光催化剂,通过X射线衍射、程序升温脱附和漫反射紫外-可见光谱等手段对催化剂进行了表征,并以苯酚为光催化降解反应模型化合物考察了光催化剂的活性,测定了苯酚在TiO2和Sm2O3掺杂TiO2光催化剂上的吸附常数. 结果表明,Sm2O3掺杂TiO2光催化剂具有较强的紫外光吸收性能. Sm2O3掺杂使TiO2粒径减小,比表面积增大,同时导致氧脱附温度提高及脱氧量增大. Sm2O3掺杂有利于反应底物在催化剂表面的吸附,Sm2O3的最佳掺入量为Sm/Ti摩尔比=0.8%.     

La_(1-x)Ba_xCo_(0.8)Ni_(0.2)O_3复合氧化物的制备及其对CO催化燃烧性能

采用溶胶-冷冻干燥法制备了La1-xBaxCo0.8Ni0.2O3(x=0~0.4)催化剂粉体。用X射线衍射(XRD)、比表面测定仪(BET)和扫描电子显微镜(SEM)等分析手段对催化剂的结构和形貌进行了表征,并考察了催化剂的最佳焙烧温度和催化活性。研究表明,催化剂的最佳焙烧温度为600℃。掺杂Ba2+后,催化剂以钙钛矿相和BaCO3相共存,不能形成单一的钙钛矿型结构。催化活性测试表明,当x=0.2时,催化剂对CO的催化活性最高(T90%=126℃)。     

钕掺杂对（Ba0.6Sr0．4）TiO3／MgO陶瓷结构和性能的影响

采用X射线衍射、扫描电镜及介电性能测试,研究了Nd掺杂对42%(Ba0.6Sr0.4)TiO3/58%MgO(质量分数)复相陶瓷微结构和低频介电性能的影响.结果表明,添加O%～0.6%Nd203的材料均由(Ba,Sr)TiO3和Mgo两相组成,不含其他物相.随着Nd2O3掺杂量的增加,材料的晶粒尺寸变大,晶粒结合更加紧密.适量的Nd2O3掺杂可以获得适中的介电常数和较高的介电可调度,并使材料的介电损耗显著改善.0.4%(质量分数)的Nd2O3掺杂使材料的居里温度从-24.6℃迅速降低至-79.2℃,并改善了材料的温度稳定性.这时材料具有很好的介电性能,室温下(约25℃),100 kHz时介电常数为103.0,介电损耗为0.0005,2V·μm-1偏置电场下样品的介电可调度为9.15%(10 kHz),能够满足移相器的应用要求.     

掺杂Sm_2O_3的Y_2O_3-2TiO_2系微波介质陶瓷的性能研究

以具有中介电常数的新型Y2O3-2TiO2系微波介质陶瓷为基体,选用Sm2O3作为掺杂改性剂,通过传统固相法制备成陶瓷。重点研究了不同Sm2O3掺杂量对基体Y2O3-2TiO2微波介质陶瓷物相组成和介电性能的影响。采用X射线衍射和扫描电子显微镜分别对其物相组成和显微结构进行了分析,用阻抗分析仪和网络分析仪测试其介电性能。结果表明:掺杂Sm2O3未改变材料的主晶相,仍为A2B2O7烧绿石结构,Sm3+取代Y3+占据A位;掺杂有效降低了陶瓷的烧结温度,掺杂量为5%(质量分数)时,烧结温度为1330℃,材料的综合性能最佳,εr=23,tanδ=0.0046,Q×f=6713 GHz。     

Bi_2O_3掺杂对Ag(Nb_(0.8)Ta_(0.2))O_3陶瓷结构和介电性能的影响(英文)

本文研究了Bi2O3掺杂对Ag(Nb0.8Ta0.2)O3陶瓷的结构和介电性能的影响。X射线衍射(XRD)结果表明,Bi2O3的掺杂可以使陶瓷中Ag+被还原并析出,且银析出的量随Bi2O3掺杂量的增加而不断增加,这可能源自于Bi3+对Ag+的取代。在一定范围内增大Bi2O3掺杂量可提高Ag(Nb0.8Ta0.2)O3陶瓷的室温介电常数,降低介电损耗,并使温度系数向负值方向移动。当Bi2O3的掺杂量约为3.5wt%时,样品具有较大的介电常数(ε=672)和较小的介电损耗(tanδ=7.3×10-4)。     

Ca、Ba掺杂Sm0.5Sr0.5CoO3作为中低温固体氧化物燃料电池阴极的结构与性能

通过X射线衍射(XRD)、热重、热膨胀、电导率以及电化学交流阻抗等测试技术研究了SmSr1-xAexCo2O6(x=0, 0.2, 0.4, 0.6, 0.8, 1; Ae=Ca, Ba)作为中低温固体氧化物燃料电池(IT-SOFC)阴极的结构与性能. 研究表明, 固相法合成的SmSr0.8Ae0.2Co2O6(Ae=Ca, Sr, Ba; 简写为SSAC)随着Ca、Ba掺杂量的增大晶体结构发生变化. 其中, 空间群为Pnma晶体结构的电极SSAC中, 晶胞参数随着Sr、Ca、Ba的顺序增大; SSAC晶体中的氧空位浓度随着Ca、Sr、Ba的顺序增大, SSAC热膨胀系数与Ae元素关系不大, 氧催化性能随着Ca、Sr、Ba的顺序降低. 由于载流子浓度降低, 使得Ba 掺杂Sm0.5Sr0.5CoO3(SSC)后电极的电导率降低. 由于导电活化能增大, 使得Ca掺杂SSC后电极的电导率也降低.     

Sm掺杂对TiO2薄膜光催化性能的影响

 采用溶胶-凝胶法、浸渍-提拉法制备了不同形式和不同含量Sm掺杂的锐钛矿晶型TiO2的光催化剂薄膜. 采用X射线衍射、UV-Vis光谱及电化学实验对所制得的TiO2光催化剂薄膜进行了表征,并通过甲基橙溶液的光催化降解实验评价了其光催化活性. 结果表明,与未掺杂的TiO2薄膜相比,Sm掺杂的TiO2薄膜的UV-Vis吸收光波长向长波方向移动,并且光照开路电压也相应提高; 适量Sm掺杂可以明显提高TiO2薄膜的光催化活性,最佳Sm掺杂量为x(Sm3+)=0.5%; 在各种掺杂形式中以表层Sm掺杂的Sm-TiO2(S)薄膜的光催化活性最好. 讨论了Sm掺杂提高TiO2薄膜光催化活性的机理.     

氮掺杂二氧化钛粉体的制备及掺杂机理研究

以钛酸四丁酯为钛源,尿素为氮源制备了N掺杂二氧化钛粉体。采用X射线衍射、透射电镜和紫外-可见吸收光谱对粉体晶粒尺寸、物相及光吸收性质进行了表征。结果表明,N掺杂有效抑制了二氧化钛晶粒的长大,并使TiO2光吸收效果大大提高。采用密度泛函方法对掺杂机理进行研究证明,N掺杂有效减小了TiO2带隙宽度,使吸收谱红移,相比替位氮掺杂,间隙氮掺杂更有利于提高光吸收效率。     

锰掺杂Ba0.6Sr0.4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料, 采用草酸盐共沉淀法制备了钛酸锶钡（Ba0.6Sr0.4TiO3, BST）纳米粉体. XRD和SEM分析结果表明, 该方法制备出立方相的Ba0.6Sr0.4TiO3粉体, 平均粒径小于100 nm, 具有较高的烧结活性. 用传统固相法制备了锰掺杂钛酸锶钡-钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3, BST-MT)复相陶瓷, 系统研究了掺杂0.1%-2.0%(x, 摩尔分数, 下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理. 结果表明, 当锰的掺杂量小于1.5%时, Mn作为受主掺杂取代占据钙钛矿ABO3的B位, 因此导致居里点略微向高温偏移和相变扩散的发生, 锰的掺杂导致晶格畸变, 促进了晶粒生长, 使晶界相比例下降, 因此介电损耗随着锰掺杂量的增大而减小; 当锰的掺杂量为1.5%时, 介电损耗达到最小值, 继续增大掺杂量, 介电常数下降, 介电损耗上升.     

Ce0.8Gd0.2-xPrxO1.9固溶体的合成与表征

利用X射线衍射(XRD)、拉曼光谱(Raman)、X射线光电子能谱(XPS)和交流阻抗谱对溶胶-凝胶法制备的稀土双掺杂固溶体Ce0.8Cd0.2-xPrxO1.9(x=0,0.02,0.10)的结构和导电性进行了研究.XRD结果表明,经800℃焙烧所得样品都形成了单相立方萤石结构,平均晶粒尺寸在23～30 nm之间;X...     

Bi4(Ti1/3Sn2/3)3O12掺杂BaTiO3基X8R陶瓷微观结构与介电性能

研究了Bi4(Ti1/3Sn2/3)3O12掺杂对钛酸钡基陶瓷微观结构和介电性能影响。结果表明,掺杂Bi4(Ti1/3Sn2/3)3O12后钛酸钡基陶瓷晶粒明显长大,同时烧结温度可由1 280℃降低至1 180℃。系统的介电性能和Bi4(Ti1/3Sn2/3)3O12的掺杂量有密切关系。当Bi4(Ti1/3Sn2/3)3O12的掺杂量从0.5mol%增加到2mol%,体系的居里峰被明显压低和展宽,当掺杂量为2mol%时居里峰变得不明显。当Bi4(Ti1/3Sn2/3)3O12的掺杂量从0.5mol%增加到2mol%,系统的居里温度由131℃升高至139℃。当Bi4(Ti1/3Sn2/3)3O12的掺杂量为1mol%时,钛酸钡基陶瓷介电常数为1 930,介电常数温度变化率为5%(-55℃),13%(134℃),-8%(150℃),满足X8R标准。     

Transformation of proton-conducting Perovskite-type into fluorite-type fast oxide ion electrolytes using a CO2 capture technique and their electrical properties

Fast oxide ion conducting Ce 1- x M x O 2-delta (M = In, Sm; x = 0.1, 0.2) and Ce 0.8Sm 0.05Ca 0.15O 1.825 were prepared from the corresponding perovskite-like structured materials with nominal chemical composition of BaCe 1- x M x O 3-delta and BaCe 0.8Sm 0.05Ca 0.15O 2.825, respectively, by reacting with CO 2 at 800 degrees C for 12 h. Powder X-ray diffraction (PXRD) analysis showed the formation of fluorite-type CeO 2 and BaCO 3 just after reaction with CO 2. The amount of CO 2 gained per ceramic gram was found to be consistent with the Ba content. The CO 2 reacted samples were washed with dilute HCl and water, and the resultant solid product was characterized structurally and electrically employing various solid-state characterization methods, including PXRD, and alternating current (ac) impedance spectroscopy. The lattice constant of presently prepared Ce 1- x M x O 2-delta and Ce 0.8Sm 0.05Ca 0. 15O 1.825 by a CO 2 capture technique follows the expected ionic radii trend. For example, In-doped Ce 0.9In 0.1O 1.95 (In (3+) (VIII) = 0.92 A) sample showed a fluorite-type cell constant of 5.398(1) A, which is lower than the parent CeO 2 (5.411 A, Ce (4+) (VIII) = 0.97 A). Our attempt to prepare single-phase In-doped CeO 2 samples at 800, 1000, and 1500 degrees C using the ceramic method was unsuccessful. However, we were able to prepare single-phase Ce 0.9In 0.1O 1.95 and Ce 0.8In 0.2O 1.9 by the CO 2 capture method from the corresponding barium perovskites. The PXRD studies showed that the In-doped samples are thermodynamically unstable above 800 degrees C. The ac electrical conductivity studies using Pt electrodes showed the presence of bulk, grain-boundary, and electrode contributions over the investigated temperature range in the frequency range of 10 (-2)-10 (7) Hz. The bulk ionic conductivity and activation energy for the electrical conductivity of presently prepared Sm- and (Sm + Ca)-doped CeO 2 samples shows conductivities similar to those of materials prepared by the ceramic method reported in the literature. For instance, the conductivity of Ce 0.8Sm 0.2O 1.9 using the CO 2 capture technique was determined to be 4.1 x 10 (-3) S/cm, and the conductivity of the same sample prepared using the ceramic method was 3.9 x 10 (-3) S/cm at 500 degrees C. The apparent activation energy of the area-specific polarization resistance for the symmetric cell (Sm,Sr)CoO 3- x |Ce 0.8Sm 0.2O 1.9|(Sm,Sr)CoO 3- x was determined to be 1 eV in air.     

熔盐法制备Ca0.9La0.2/3Cu3Ti4O12陶瓷粉体及其介电性能研究

以CaCO3,CuO,TiO2,La2O3为反应物,NaCl,KCl为熔盐,通过熔盐法分别在700、750、800、850℃条件下合成Ca0.9La0.2/3Cu3Ti4O12陶瓷粉体。利用XRD和SEM分别对陶瓷粉体的物相结构和微观形貌进行了分析,并对其介电性能进行了测试。实验结果表明,随着合成温度的升高,陶瓷粉体的钙钛矿相含量逐渐增大,与传统固相法相比,熔盐法制备的粉体无团聚现象,耗时少。Ca0.9La0.2/3Cu3Ti4O12粉体制备的陶瓷在1 000℃烧结、测试频率在100 Hz~10 kHz时,获得优良的介电性能:介电常数大大超过104,介电损耗在0.1~0.47之间。     

新钽酸盐Ba3TiTa4O15的结构与介电性能

在BaO Ta2O5系统通过掺Ti4＋合成了新钽酸盐Ba3TiTa4O15,用粉晶XRD对其结构进行了分析,并测试了其烧结体的介电特性.结果表明:Ba3TiTa4O15在室温下属于填满型四方钨青铜结构,晶胞参数a=1.256 27(6)nm, c=0.395 86(4)nm; Ba3TiTa4O15在－35 ℃从铁电相转变为顺电相.     

SDC和SSC在低温常压电化学合成氨中的性能研究

用溶胶—凝胶法制备了Ce0.8Sm0.2O2-δ(SDC)和Sm0.5Sr0.5CoO 3-δ（SSC）超细粉体,采用XRD、TEM和SEM等对粉体进行了观察和表征。分别以Ni-SDC和SSC为阴极, 磺化聚砜质子交换膜为电解质, Ni- SDC金属陶瓷为阳极,银-铂网做集流体组成单电池,在25℃～120℃温度范围内研究了其电导率随温度变化关系及在电化学合成氨中的性能。结果表明：在25℃～120℃温度范围内,使用Ni-SDC和SSC为阴极均有氨气生成,而SSC对电化学合成氨的性能优于Ni-SDC, 在80℃时氨产率达到了6.5×10-9 mol•s-1•cm-2。     

Hydrotherrnal synthesis, structure and property of nano-BaTiO3-based dielectric materials

A series of Ba1-xSrxTi1-yZryO3 (0≤x≤0.5, 0≤y≤0.4) and Ba1-xZnxTi1-ySnyO3 (0≤x≤0.3, 0≤y≤0.3) solid solutions were synthesized by Iow-temperature/Iow-pressure hydrothermal method below 170℃, 0.8 MPa. XRD pattern and cell parameters-composition figures of these prepared powders demonstrated that they are completely miscible solid solutions based on BaTiO3. Furthermore, TEM showed that they have a shape of uniform, substantially spherical particles with an average particle size of 70 nm in diameter. The sintered ceramics of those powders doped by Sr2+ and Zr4+ or Zn2+ and Sn4+ have dielectric constant twelve times higher than and dielectric loss 1/6 those of pure BaTiO3 phase at room temperature.     

稀土元素Sm、Eu、Gd对Nb掺杂的TiO2压敏电阻电性能的影响

研究了稀土元素Sm、Eu、Gd对于Nb掺杂的TiO₂基压敏电阻电学性能的影响. 几种稀土元素的掺杂量均为体系总量的2%(原子比), 其它原料的掺入量固定不变. 实验样品在1380 ℃烧结, 保温4 h. 实验发现, Sm、Eu、Gd等稀土元素可以有效降低TiO₂基压敏电阻的压敏电压, 但对于非线性系数的影响不很明显. 对于Sm、Eu、Gd掺杂, 实验得到的压敏电压值分别为12.7、14.7和16.1 V. 通过对试样的阻抗分析发现, Sm、Eu、Gd掺杂对于压敏电阻的介电性能有显著影响, 单独掺杂Sm或Gd的试样具有很低的介电常数和介电损耗, 并且具有很高的电阻率.     

Ba0.97Ce0.8Ho0.2O3-α陶瓷的离子导电性及其燃料电池性能

The perovskite-type-oxide solid solution Ba0.97Ce0.8Ho0.2O3-α was prepared by high temperature solidstate reaction and its single-phase character was confirmed by X-ray diffraction. The ionic conduction of the sample was investigated using electrical methods at elevated temperatures, and the performance of the hydrogen-air fuel cell using the sample as solid electrolyte was measured, which were compared with those of BaCe0.8Ho0.2O3 - α. In wet hydrogen, BaCe0.8 Ho0.2 O3 - α almost exhibits pure protonic conduction at 600-1000 ℃, and its protonic transport number is 1 at 600-900 ℃ and 0.99 at 1000 ℃. Similarly,Ba0.97Ce0.8Ho0.2O3-α exhibits pure protonic conduction with the protonic transport number of 1 at 600-700 ℃, but its protonic conduction is slightly lower than that of BaCe0.8Ho0.2O3-α, and the protonic transport number are 0.99-0.96 at 800-1000 ℃. In wet air, the two samples both show low protonic and oxide ionic conduction. For Ba0.97Ce0.8Ho0.2O3-α, the protonic and oxide ionic transport numbers are 0.01-0.11 and 0.30-0.31 respectively, and for BaCe0.8Ho0.2O3-α, 0.01-0.09 and 0.27-0.33 respectively. Ionic conductivities of Ba0.97Ce0.8Ho0.2O3-α are higher than those of BaCe0.8Ho0.2O3-α under wet hydrogen and wet air. The performance of the fuel cell using Ba0.97Ce0.8Ho0.2O3-α as solid electrolyte is better than that of BaCe0.8Ho0.2O3-α. At 1000 ℃, its maximum short-circuit current density and power output density are 465 mA/cm2 and 112 mW/cm2, respectively.     

Effect of TiO2 on electron paramagnetic resonance, optical transmission and dc conductivity of vanadyl doped sodium borate glasses

Glass systems with composition xTiO2.(30 - x)Na2O.70B2O3 (series I) and xTiO2.(70 - x)B2O3.30Na2O (series II) containing 2 mol% V2O5 have been prepared (0 < or = x < or = 7, mol%) by normal melt-quenching. The electron paramagnetic resonance (EPR) spectra of VO2+ ions have been recorded in the X-band (approximately 9.13 GHz) at room temperature. Spin Hamiltonian parameters, gparallel, gperpendicular, Aparallel, Aperpendicular, the dipolar hyperfine coupling parameter (P) and the Fermi contact interaction parameter (K) have been calculated. The increase in Deltagparallel/Deltagperpendicular with increase in TiO2 content in series I shows that the octahedral symmetry of V4+O6 complex is reduced, whereas in series II the octahedral symmetry is improved with increase in x. The decrease in P, in both the series, indicates that the 3dxy orbit expands with increase in mol% of TiO2. The molecular orbital coefficients, alpha2 and gamma2 have been calculated by recording the optical transmission spectra in the range 500-850 nm. alpha2 and gamma2 increase with increase in x in both the series, which indicates that, the covalency of the vanadium oxygen bonds decreases. The dc conductivity sigma, decreases and activation energy, W increases with increase in TiO2:Na2O ratio whereas with increase in TiO2:B2O3 ratio the variation in sigma and W is within experimental error.