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水熱法制備一維鈦酸鍶鋇晶體及生長機(jī)理的研究

發(fā)布時(shí)間:2018-03-27 12:13

  本文選題:水熱法 切入點(diǎn):一維鈦酸鍶鋇晶體 出處:《西南石油大學(xué)》2015年碩士論文


【摘要】:鈦酸鍶鋇可以通過調(diào)節(jié)鋇和鍶的比例,改變居里溫度(106K-393K),同時(shí)調(diào)節(jié)材料的介電性能、光學(xué)性能以及壓電性能,作為功能材料廣泛的應(yīng)用于可調(diào)諧微波器件、移相器、紅外探測、動(dòng)態(tài)隨機(jī)儲(chǔ)存器等體積小而容量大的器件中。從材料的結(jié)構(gòu)知道,晶體形貌對(duì)材料的性能有著重要的影響,而一維材料在一維方向上具有優(yōu)異的物理化學(xué)性能,因此一維材料的制備引起廣泛的關(guān)注。 本文用鈦酸丁酯、乙酸鍶和乙酸鋇為基本原料,采用溶膠-凝膠法,通過控制抑制劑乙二醇甲醚的濃度制備出非晶態(tài)的凝膠和含有銳鈦礦TiO2晶相的凝膠,將兩種凝膠作為水熱前驅(qū)體,在相同的水熱條件下進(jìn)行水熱處理,水熱溫度為230℃,保溫12h,2mol/L的KOH作為礦化劑,填充度為85%,利用FTIR、XRD、SEM等對(duì)前驅(qū)體以及相對(duì)應(yīng)的水熱產(chǎn)物進(jìn)行表征,研究了前驅(qū)體的結(jié)晶狀態(tài)對(duì)水熱產(chǎn)物的物相以及形貌的影響。實(shí)驗(yàn)結(jié)果:采用非晶態(tài)的凝膠作為前驅(qū)體,其水熱產(chǎn)物是鈦酸鍶鋇納米粉體顆粒,采用含有銳鈦礦Ti02晶相的凝膠作為前驅(qū)體,其水熱產(chǎn)物是鈦酸鍶鋇納米粉體顆粒和一維鈦酸鍶鋇晶體,其中一維鈦酸鍶鋇晶體長度為40um~200um,直徑在1um左右,并且被大量粉體包覆著。用濃度為0.1%的六偏磷酸鈉、pH值為10左右的溶液作為分散劑,將水熱產(chǎn)物加入分散劑后,超聲波震蕩15min,再將混合溶液用600目篩網(wǎng)過濾,這樣對(duì)粉體與一維晶體進(jìn)行分離。 將鈦酸丁酯、乙酸鍶和乙酸鋇加入到過量的去離子水中,生成共沉淀物,另一種共沉淀物是將鈦酸丁酯加入去離子水中后,通過水浴加熱使溶液成溶膠,然后加入乙酸鍶和乙酸鋇形成共沉淀物,利用XRD對(duì)兩種共沉淀物進(jìn)行物相檢測,結(jié)果表明兩種沉淀物中都具有多種晶相,其中第一種沉淀物中含有銳鈦礦TiO2晶相,而第二種沉淀物中不含有銳鈦礦TiO2晶相。將兩種沉淀物作為前驅(qū)體,在相同的條件下進(jìn)行水熱處理,利用XRD、SEM對(duì)水熱產(chǎn)物進(jìn)行表征,結(jié)果顯示含有銳鈦礦TiO2晶相的沉淀物前驅(qū)體的水熱產(chǎn)物是一維鈦酸鍶鋇晶體和納米粉體顆粒的混合物,另一種沉淀物前驅(qū)體的水熱產(chǎn)物是單一的鈦酸鍶鋇納米粉體顆粒。對(duì)第一種沉淀物前驅(qū)體進(jìn)行不同時(shí)間的水熱處理,觀察一維鈦酸鍶鋇晶體的生長過程并對(duì)其水熱生長機(jī)理進(jìn)行初探。 將納米銳鈦礦TiO2晶體與非晶態(tài)凝膠混合作為前驅(qū)體,然后進(jìn)行水熱處理,水熱產(chǎn)物是鈦酸鍶鋇納米粉體顆粒和一維晶體的混合物;將納米銳鈦礦TiO2晶體與不含有銳鈦礦TiO2晶相的共沉淀物混合作為前驅(qū)體,然后進(jìn)行水熱處理,水熱產(chǎn)物是鈦酸鍶鋇納米粉體顆粒和一維晶體的混合物。用高倍透射顯微鏡以及電子衍射對(duì)一維鈦酸鍶鋇晶體進(jìn)行表征,結(jié)果顯示,一維鈦酸鍶鋇晶體呈單晶態(tài),生長晶面為(001),一維鈦酸鍶鋇晶體與銳鈦礦TiO2共格生長。 為了使水熱產(chǎn)物中的一維鈦酸鍶鋇晶體和粉末完全分離,采用兩步水熱法制備一維鈦酸鍶鋇晶體。第一步水熱時(shí)根據(jù)所查的文獻(xiàn)制備出一維的銳鈦礦TiO2,然后再將一維的銳鈦礦TiO2與過量的乙酸鍶和乙酸鋇混合作為水熱前驅(qū)體,再進(jìn)行第二次水熱反應(yīng),得到一維的鈦酸鍶鋇晶體、碳酸鍶和碳酸鍶鋇粉末顆粒混合物,將水熱產(chǎn)物經(jīng)過酸洗,便能去掉粉體而留下一維鈦酸鍶鋇晶體。
[Abstract]:Barium strontium titanate can be adjusted by the ratio of barium and strontium, change the Curie temperature (106K-393K), while adjusting the dielectric properties of materials, optical properties and piezoelectric properties, application as functional materials in a wide range of tunable microwave devices, phase shifter, infrared detection, dynamic random memory such as small volume and large capacity of devices know. From the material structure, has an important effect on crystal morphology of the material properties, and one-dimensional materials have excellent physical and chemical properties in one direction, so one-dimensional material preparation has attracted much attention.
In this paper, using tetrabutyl titanate, barium strontium acetate and acetic acid as raw materials by the sol-gel method, the concentration of inhibitors of ethylene glycol monomethyl ether was prepared by gel gel containing amorphous and anatase TiO2 crystal phase, two gel as hydrothermal precursor by hydrothermal treatment under hydrothermal conditions are the same under the hot water temperature is 230 DEG C, holding 12h, 2mol/L KOH as mineralizer, filling degree is 85%, the use of FTIR, XRD, the precursor and the hydrothermal products corresponding to SEM were characterized. The crystalline state of the precursor of hydrothermal products to study the phase and morphology of the impact experiments. Results: using amorphous gel as precursor, the hydrothermal products are barium strontium titanate nano powder particle, the anatase crystalline phase containing Ti02 gel as precursor, the hydrothermal products are barium strontium titanate nano powder particle and one-dimensional barium strontium titanate crystal, which One dimensional barium strontium titanate crystal length is 40um ~ 200um, 1um in diameter, and a powder coated with a concentration of 0.1%. Six sodium phosphate solution, pH value is about 10 as dispersant, the hydrothermal products after adding dispersant, ultrasonic 15min, and then the mixed solution with 600 mesh sieve, so the powder and one-dimensional crystal separation.
The tetrabutyl titanate, barium strontium acetate and acetic acid into deionized water to excess, generating a total sediment, another is the coprecipitate of butyl titanate into deionized water, with water bath heating the solution sol, then adding barium strontium acetate and acetic acid to form precipitates, two co precipitate phase detection using XRD and the results show that two kinds of sediments have a variety of crystal phase, wherein the first precipitate containing anatase TiO2 crystal phase, while the second sediments do not contain anatase TiO2 crystal. The two kinds of precipitates as precursor, hydrothermal treatment, in the same conditions by using XRD, SEM on hydrothermal products the characterization results show, hydrothermal products precipitate precursor containing TiO2 anatase crystalline phase is a mixture of one-dimensional strontium barium titanate crystal and nano powder particles, another precipitate precursor hydrothermal products is single A barium strontium titanate nanopowder was prepared. Hydrothermal treatment of the precursor of the first precipitate at different time was carried out to observe the growth process of one-dimensional strontium barium titanate crystal and its hydrothermal growth mechanism.
The nano anatase TiO2 crystal mixed with amorphous gel as precursor, followed by hydrothermal treatment, the hydrothermal product is a mixture of barium strontium titanate nano powder particles and one-dimensional crystals; nano anatase TiO2 crystal mixed with anatase crystalline phase does not contain TiO2 precipitates as precursor, followed by hydrothermal treatment the hydrothermal product is a mixture of barium strontium titanate nano powder particle and one-dimensional crystal. The one-dimensional barium strontium titanate crystals were characterized by high-resolution transmission microscopy and electron diffraction showed that one-dimensional barium strontium titanate crystals are single crystalline, the growth of crystal plane (001), barium strontium titanate and anatase crystal one-dimensional TiO2 lattice growth.
In order to make the hydrothermal products in one-dimensional strontium barium titanate crystal and powder separation to prepare one-dimensional barium strontium titanate crystal by two step hydrothermal method. The first step is to check the hot water document prepared anatase TiO2 one-dimensional, then the one-dimensional anatase TiO2 with excess acetic acid and acetic acid mixed barium strontium as the hydrothermal precursor, then second hydrothermal reaction by barium strontium titanate crystal one-dimensional, strontium carbonate and strontium barium carbonate powder mixture, the hydrothermal products after pickling, can remove the powder and leave one-dimensional barium strontium titanate crystal.

【學(xué)位授予單位】:西南石油大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2015
【分類號(hào)】:TQ132.35;O78

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