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Buscaglia MT Buscaglia V Viviani M Dondero G Röhrig S Rüdiger A Nanni P 《Nanotechnology》2008,19(22):225602
Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO(3) crystals (size ≈1?μm) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO(2) shell using a precipitation process. Calcination of the BaCO(3)@TiO(2) core-shell particles at 700?°C resulted in the formation of BaTiO(3) hollow particles (shell thickness of ≈70?nm) which retain the morphology of the BaCO(3) crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180° ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds. 相似文献
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Grain size dependence of dielectric properties of ultrafine BaTiO3 prepared by a sol-crystal method 总被引:1,自引:0,他引:1
T Takeuchi M Tabuchi K Ado K Honjo O Nakamura H Kageyama Y Suyama N Ohtori M Nagasawa 《Journal of Materials Science》1997,32(15):4053-4060
Ultrafine BaTiO3 prepared by a decomposition of an organometallic crystal with unity of Ba/Ti ratio (sol-crystal method) has
been characterized. While the as-prepared product resulting from the decomposition of the organometallic crystal at room temperature
was BaTiO3 with pseudo-cubic structure, the well-crystallized tetragonal polymorph was obtained by firing the as-prepared
product above 1000°C. Residual organic compounds, CO2-3 and OH- ions in the samples prevent the grain growth and tetragonal
distortion of BaTiO3. We obtained quite higher room temperature permittivity (3700) at 1 kHz for the sample fired at 1200°C
than that (630) prepared by conventional solid-state reaction starting from BaCO3 and TiO2. Such a high value was probably
due to the accomplishment of homogeneous cation stoichiometry, which was achieved by this preparation method via the organometallic
crystal with stoichiometric Ba/Ti ratio.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
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钛酸钡的制备研究进展 总被引:9,自引:0,他引:9
对钛酸钡粉末的制备方法进行了综合。传统的高温固相合成法已不能满足电子技术微型化和集成化发展对钛酸钡粉体提出的超细、高纯、单分散要求。从制备成本和操作过程来看,经过改进的共沉淀法、草酸盐法和水热法是制备高纯、亚微米级钛酸钡粉末的重要方法,在大规模生产中有较好的应用前景。在水热过程中,通过选择适当的钛源和水热条件,可以制备出高纯、单分散的亚微米级及纳米级钛酸钡粉体。低温直接合成法因其原料易得,过程简单,是一种在大规模生产上较有应用前景的制备纳米钛酸钡的方法。 相似文献
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固相反应法制备系列K2La2Ti3O10 总被引:5,自引:0,他引:5
通过固相反应法合成了一系列不同尺寸的钙钛矿型层状化合物KLa2Ti3O10考察了原料TiO2粒径对固相反应速率及产物尺寸、形貌的影响,得到了不同粒径下原料的最佳配比;以XRD,TEM等手段进行表征,研究制备过程可能的反应历程.结果表明:降低原料粒径,固相反应速率加快、温度降低,有利于合成小尺寸、比表面积大(可达11.83m2·g-1)的层状K2La2Ti3O10. 相似文献
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Supercritical fluid route for synthesizing crystalline Barium Strontium Titanate nanoparticles 总被引:1,自引:0,他引:1
Reverón H Elissalde C Aymonier C Bidault O Maglione M Cansell F 《Journal of nanoscience and nanotechnology》2005,5(10):1741-1744
Pure and well-crystallized Barium Strontium Titanate (BST) nanoparticles with controlled Ba/Sr ratio have been successfully synthesized under supercritical conditions using a continuous-flow reactor in the temperature range of 150-380 degrees C at 26 MPa. To synthesize the Ba0.6Sr0.4TiO3 composition, alkoxides, ethanol and water were used. The resulting nanopowder consists of fine particles with an average particle size of 23 nm. The results show that the Ba/Sr ratio of this powder can be accurately controlled from the composition of precursor. The characterization of the as-synthesized Ba0.6Sr0.4TiO3 solid-solution and the dielectric properties of the sintered ceramics are here reported. 相似文献
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Ph值对BaTiO3水悬浮液性质的影响 总被引:1,自引:0,他引:1
研究了pH值对BaTiO3水悬浮液的颗粒带电特性、颗粒尺寸分布及流变特性的影响。找到了制备高分散的、稳定的BaTiO3悬浮液的最佳pH值。 相似文献
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BaTiO3纳米晶机械力化学合成 总被引:11,自引:0,他引:11
在氮气保护下,采用高能球磨BaO,锐钛矿型TiO2混合粉体,机械力化学法成功地合成了BaTiO3纳米晶,并讨论了反应机制。发现在一定操作参数条件下,粉磨初期为无定形形成期(15h以前),混合物颗粒粒度减小,晶格畸变,转变为无定形;粉磨中期为固相反应期(15-30h),BaO与TiO2在机械力的作用下产生固相反应生成BaTiO3,同时BaTiO3晶粒长大;粉磨后期又转入动态平衡期(30h以后),固相反应基本结束,已生成的BaTiO3的晶粒生长与粉磨引起的晶粒减小处于动态平衡;XRD,SEM,TEM研究表明:合成BaTiO3纳米晶体的晶粒尺寸为10-30nm。 相似文献
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粒度对纳米掺杂BaTiO3陶瓷结构和性能的影响 总被引:1,自引:0,他引:1
制备了纳米掺杂BaTiO3陶瓷,研究了纳米掺杂剂和BaTiO3的粒度对BaTiO3陶瓷的微观结构和介电性能的影响.结果表明,小粒度、高分散的纳米掺杂剂更易对BaTiO3颗粒实现均匀包裹,有效地抑制晶粒生长并形成更多的壳-芯晶粒,大比表面积使更多高活性的表面原子与BaTiO3发生原子输运形成传质,导致晶粒壳/芯比增大,从而提高其介电性能.纳米掺杂陶瓷的平均晶粒尺寸和四方率与BaTiO3粒度几乎成正比.随着BaTiO3粒度的减小,立方晶粒壳增大而四方晶粒芯减小,陶瓷由四方晶相向赝立方晶相转变,居里峰被显著压制,从而改善介电温度特性.同时,晶粒的壳与芯之间失配产生的内应力随之增加,使居里点向高温方向移动. 相似文献
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水热法制备BaTiO3粉体 总被引:15,自引:0,他引:15
水热法制备的陶瓷粉体结晶度高,团聚少,烧结活性闹,得到了越来越广泛的重视。本文报道了水热法制备BaTiO3粉体的研究结果,给出BaTiO3粉体晶粒组成、粒度和结晶形貌与反应温度、前驱物形式以及Ba、Ti摩尔比之间的关系,选择较高的反应温度,使用强碱性溶液以及较高m(Ba).m(Ti)比的前驱物,有利于钙钛矿型BaTiO3晶粒的形成。采用新制的Ti(OH)4胶体为前驱物,在Ba(OH)2水溶液水热反 相似文献
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表面疏水性纳米TiO2颗粒的制备及光催化性能 总被引:3,自引:1,他引:2
在70℃水解钛酸四丁酯(TBOT)时加入十二烷基硫酸钠(SDS),无需热处理就能得到准球形锐钛矿结构的纳米TiO2.这种TiO2粉具有强疏水性,漂浮于水溶液的表面,可通过过滤手段与溶液分离.应用透射电子显微镜和X射线衍射仪对TiO2粉进行了形貌观察和晶体结构的测定.研究了反应体系pH值的变化对TiO2粉结构的影响.FT-IR光谱证明在酸性条件下SDS分子吸附于TiO2颗粒的表面.颗粒尺寸增大引起Rama峰、紫外吸收峰的红移,表现出量子尺寸效应.在对罗丹明B的光催化降解反应中,表面吸附SDS的TiO2粉显示出很强的光催化活性,在50 min内催化降解了100%罗丹明B. 相似文献
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Shujun Zhang Thomas R Shrout Hajime Nagata Yuji Hiruma Tadashi Takenaka 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(5):910-917
Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280 degrees C and 262 degrees C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224 degrees C and 162 degrees C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (approximately 40 microC/cm2) was larger than that of BNBK79 (approximately 29 microC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed. 相似文献
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溶胶-凝胶法在纳米粉体制备中的应用 总被引:7,自引:2,他引:7
溶胶-凝胶法是制备纳米粉体的一种低温工艺,具有制品纯度高、化学均匀性好、颗粒细、可容纳不容性组分和不沉淀组分、掺杂分布均匀、合成温度低、成分容易控制、工艺设备简单等优点。本文介绍了溶胶-凝胶法的概念、工艺原理及其在TiO2、ZrO2、BaTiO3、Al2O3等纳米粉体制备方面的应用,提出了溶胶-凝胶法制备纳米粉体的局限性及发展方向。 相似文献
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