The preparation method of sodium niobate nano rods with ferroelectric perovskite structure
Technical field
The present invention relates to the preparation field of nano material, specifically is a kind of preparation method of sodium niobate nano rods with ferroelectric perovskite structure.
Background technology
Ferroelectric research comes from 1920's sieve breath salt (Seignette salt, NaKC
4H
4O
64H
2The discovery of special dielectric properties O) begins, and its most basic characteristic is a kind of spontaneous residual polarization to have occurred, and the spontaneous polarization vector can freely turn under outer field action, thereby shows characteristics such as ferroelectric, piezoelectricity, pyroelectricity, electric light and acoustics.To the forties, ferroelectric phenomenological theory begins to set up and is tending towards ripe.At the beginning of the sixties, ferroelectric soft mode type theory begins to occur and be gradually improved.After this along with multi-disciplinary development and infiltration,, started the upsurge of studying ferroelectric low dimension architectural characteristic particularly to the development of the nano science eighties.This is because when particle scale reaches nanometer scale (1-100nm); Small-size effect that particle itself is had and surface effects physically show particularly importantly ferroelectric; This specific character at first becomes in low dimension systems such as film and can not ignore, and mainly shows as Tc, remnant polarization, coercive field and specific inductivity and changes along with the variation of thickness or annealing temperature.
The piezoelectric ceramics of ferroelectric system is mainly with Pb (Zr, Ti) O
3(PZT) be sill, its piezoelectric property is superior to other piezoceramic material greatly, and can regulate the electricity and the physical property of material through doping vario-property and technology controlling and process within a large range, to satisfy various application demands.Yet, obtain piezoelectricity, the ferroelectric ceramic(s) of industrial application at present, comprise relaxation ferroelectric ceramic, mainly be leaded pottery, wherein the content of plumbous oxide accounts for more than 60% of material total mass.It is thus clear that leaded piezoceramic material in material processing, accumulating, element manufacturing, use and offal treatment process thereof, all causes serious harm to the environment and the mankind easily.Therefore, leadless electronic stupaliths such as research and development piezoelectricity, ferroelectric ceramic(s) are the important directions and the hot subject of Recent study and exploitation.After calendar year 2001, parliament of European Union in 2003 and EU Committee have issued the instruction of " about forbidding in electrical equipment and electronics, using some objectionable impurities ".Instruction regulation is from July 1st, 2006, in the electric/electronic device product of newly putting on market, forbids or limit and use lead (Pb), cadmium (Cd), mercury (Hg), sexavalent chrome (Cr
6+), polybromodiphenyl ether (PBDE) and PBBs 6 kinds of objectionable impuritiess such as (PBB), the electrical and electronic product that comprises in process of production and possibly contain above-mentioned 6 kinds of objectionable impuritiess in the starting material.The U.S. has also worked out the rules of oneself in succession.China Ministry of Information Industry has also issued " electronics and IT products prevention and cure of pollution management method " in succession in February, 2006; In beginning implementing plan on March 1st, 2007. in order to preserve our planet and the human existence space; Prevent the pollution of environment; Guarantee implementation of sustainable development, during the last ten years, international and domesticly doing a large amount of work aspect the research and development of leadless electronic product and material.At present big, wide scolder of application quantity and ceramic condenser (comprising porcelain and electrode slurry) have been realized unleadedly basically in international and domestic electronic product is made, and materials such as other non-plumbum ferroelectric, piezoelectricity are also being made great efforts in the exploration always.
Leadless piezoelectric ceramics mainly comprises niobate lead-free piezoelectric ceramics, barium titanate (BT) based leadless piezoelectric ceramics, bismuth laminated leadless piezoelectric ceramic and bismuth-sodium titanate (BNT) based leadless piezoelectric ceramics etc.The BT based leadless piezoelectric ceramics is meant with BT to be that base perhaps improves its piezoelectric property through doping vario-property through solid solution second constituent element, to satisfy certain application requiring.But because the Tc of BT is lower, be difficult to improve through doping vario-property the piezoelectric property of material, stability is not as PZT, simultaneously must be than higher sintering temperature, and direct substitution lead base piezoelectric ceramics is difficulty relatively.With regard to present research situation, niobate lead-free piezoelectric ceramics is the leadless piezoelectric material material that application prospect is arranged most.Possibly can obtain big breakthrough with using in performance through this material system of doping vario-property.Come acceleration of sintering through doping of A position or the superfluous A room that forms of Nb, perhaps form sosoloid with it or prepare high performance lead-free piezoceramic material with Spark plasma sintering method through adding other uhligite component.The niobate ferroelectric material more and more shows its importance as environment-friendly material in practical application.
At present, the preparation about niobate particle and film mainly contains solid reaction process; Sol-gel process; Hydrothermal method; The microemulsion method; Glycerine thermal treatment and other method.Yet to the preparation of one dimension niobate nano material and the research of rerum natura; Relevant both at home and abroad work report is few; Hydro-thermal synthetic method is arranged, but the reaction time of hydrothermal method demand length, and the general time is 6-7 days; Only generally need through The high temperature anneal (generally greater than 500 ℃), the niobate nano material compound method of therefore seeking a kind of simple, low temperature is the focus of present material area research.
Summary of the invention
The invention provides a kind of preparation method of sodium niobate nano rods with ferroelectric perovskite structure, be employed in the hydrothermal method that tensio-active agent is participated in, original position is synthesized sodium niobate nano rods.
Technical scheme of the present invention is:
The preparation method of sodium niobate nano rods with ferroelectric perovskite structure is characterized in that: at first with Nb
2O
5Powder adds in the deionized water, stirs 20-30 minute down at 20-55 ℃, adds NaOH then in Nb
2O
5In the aqueous solution, at room temperature stirred 15-30 minute, add tensio-active agent again; Continue down to stir 20-30 minute at 30-55 ℃, be enclosed in mixing solutions in the autoclave then, controlled temperature reacted 2-72 hour down at 150-200 ℃; After reaction was accomplished, reactant was cooled to room temperature, through washing; Descended dry 8-14 hour at 75-85 ℃, get the white product powder
The preparation method of described nanometer rod is characterized in that: described tensio-active agent is selected oleic acid, X 2073 or sodium laurylsulfonate for use; Described Nb
2O
5, NaOH and tensio-active agent mol ratio be 2: 310-330: 2.5-10; The volumetric molar concentration of the described NaOH aqueous solution is 4-22mol/l; Described washing selects for use deionized water, ethanol to wash.
The present invention introduces tensio-active agent, has reduced the synthetic temperature, utilizes the guide effect of tensio-active agent, makes the structural unit preferred orientation self-organizing growth of sodium columbate, finally obtains the sodium columbate club shaped structure.
Description of drawings
Fig. 1 takes the sodium niobate nano rods photo that obtains behind the scanning electronic microscope observation.
Fig. 2 is a sodium niobate nano rods high power stereoscan photograph.
Fig. 3 is a sodium columbate XRD spectra of using Phlips X ' Pert type X-ray diffraction appearance to record.
Fig. 4 is the transmission electron microscope photo of sodium niobate nano rods.
Fig. 5 is the high-resolution electron microscopy photo at a nanometer rod edge.
Embodiment
With 0.5g (0.002mol) Nb
2O
5Powder (~200nm) join in the deionized water of 30ml, stirred 20 minutes down at 50 ℃, join above-mentioned Nb to 12.8g NaOH (about 0.32mol) then
2O
5In the aqueous solution, at room temperature stirred 20 minutes, 0.005mol tensio-active agent sodium laurylsulfonate is added; Continuation was stirred 30 minutes down at 50 ℃; Be enclosed in 125ml to mixing solutions then and have in the teflon-lined autoclave, reacted 24 hours down at 170 ℃, question response is accomplished postcooling to room temperature; Product finally got the white product powder down in dry 12 hours at 80 ℃ through deionized water and washing with alcohol.Product process ESEM and transmission electron microscope and X diffractometer characterize as follows.
Can find out by Fig. 1, the nanorod structure of sodium columbate, the low power stereoscan photograph can be found out its club shaped structure, and these excellent diameters mainly are distributed in 50-300nm, and length is at 1-4 μ m.
Fig. 2 is the stereoscan photograph to the sodium niobate nano rods high power, and the composition that further shows product is the nano bar-shape structure.
Fig. 3 is a sodium columbate XRD spectra of using Phlips X ' Pert type X-ray diffraction appearance to record to Fig. 1, can find out from spectrogram, and products therefrom is cubic structure (JCPDF 75-2102).
Fig. 4 is the transmission electron microscope photo that sodium niobate nano rods is taken, and the mean diameter that can draw these nanometer rod is about about 250nm, and length does not wait from one to several microns.
Fig. 5 is the high-resolution electron microscopy photo to a nanometer rod edge of Fig. 4 selection (seeing the square frame zone); Can find out on scheme interplanar distance 0.39nm corresponding (100) crystal face of cube phase sodium columbate, find out that further sodium niobate nano rods grows along [100] direction.There is one deck amorphous layer on the surface that can find out simultaneously rod, and this is a surfactant materials.