General Approach to Well-Defined Perovskite MTiO₃ (M = Ba, Sr, Ca, and Mg) Nanostructures

Abstract

Well-defined perovskite MTiO 3 (M = Ba, Sr, Ca and Mg) nanostructures were successfully synthesized by a convenient hydrothermal method, employing MCl 2 as M source and titanate nanowire as Ti precursor. Different perovskite nanostructures such as nanoring, nanobowl, nanotube, and nanodisk were successfully prepared. Two types of growth mechanisms were proposed by investigating the formation processes of MTiO 3 nanostructures. The formation of MTiO 3 (M = Ba and Sr) undergoes a "nanowire-tube-ring" growth mechanism with a self-sacrifice of titanate nanowire framework rout, whereas the formation of CaTiO 3 and MgTiO 3 structures follows a simultaneous epitaxial growth of TiO 2 nanotube on titanate nanowire and self-nucleation of MTiO 3 (M = Mg and Ca) in the solution initially, and then a conversion of the nanowire and nanotube to MgTiO 3 /CaTiO 3 nanostructure process. The electrical properties of the perovskite MTiO 3 nanostructure including polarization-field hysteresis and capacitance-voltage characteristics were also investigated.

A surfactant-free route to synthesize Ba x Sr1−x TiO3 nanoparticles at room temperature, their dielectric and microwave absorption properties

“…Several chemical methods have been developed for the low-temperature preparation of micro-and nano-sized perovskite crystals such as molten salt synthesis [9][10], solvothermal and hydrothermal method [11][12][13][14][15][16][17], decomposition of bimetallic alkoxide precursors [18][19][20], microwave route [21][22][23][24], and biosynthesis [25]. Though these routes offer successful synthesis of perovskite nanoparticles with high quality and good crystalline, they usually require temperatures higher than 100°C or expensive reactants.…”

Innovative nanocrystal-based technologies for ceramic devices with novel electronic functions

“…In Fig. 7 is also shown relaxor-like dielectric properties obtained for a free-standing dense ceramic sheet consisting of BaTiO 3 NCs with a median size of 57 nm [39]. This experimental fact provides a promising clue in considering the NC structures to be constructed for realizing NC devices with novel, gigantic dielectric functions based on relaxor-type dielectric responses.…”

“…Examples of monodisperse BaTiO 3 and SrTiO 3 NCs with well-developed cube-like shapes are shown in Fig. 3; the BaTiO 3 nanocubes were synthesized by a soft solution chemical process using Ba(NO 3 ) 2 , Ti(OBu) 4 , BuOH and oleic acid at 135 ℃ under a strong NaOH basic condition [21], while the SrTiO 3 nanocubes were prepared from an aqueous solution containing Sr(OH) 2 , bis(ammonium lactate) titanium dihydroxide (TALH), hydrazine and oleic acid using a hydrothermal process at 200 ℃ under a strong NaOH basic condition [22]; the latter was modified from that proposed by Koumoto group [23].…”

“…8, establishing a procedure to generate spontaneous polarization at both surface regions of the BaTiO 3 nanocube sheet sandwiched with thin flexible conducting polymer sheets acting as electrodes is essential in the technology of fabricating this device. Any clear solutions for this problem have not been found yet, but the experimental results reporting the induced ferroelectricity in stained BaTiO 3 and SrTiO 3 thin films may provide some hints to solve the problems [45][46][47].…”

“…The early ceramic powder synthesis technology, based on solid-state reaction methods, has made a rapid advance by adopting the advantage of solution-phase synthesis methods, which allow production of ceramic powder with high purity and much homogeneous grain morphologies (size and shape). It is now possible to obtain various kinds of electronic ceramic powder with well-controlled particle sizes in the range from nanometer to micrometer by employing suitable solution methods, and one may easily find many reports on the synthesis of nanocrystalline particles of perovskite oxides, which are used in the largest quantity in the electroceramic industry [1][2][3][4]. As to the technology of fabricating device structures, since most electronic ceramic devices have been used in rather simple forms of disks and slabs unless their forms cannot give desired electronic functions, the development of techniques for making two-and three-dimensional functional structures with purpose of generating new electronic functions has little progressed.…”