【作者】 张岚；

【导师】 喻佑华；

【作者基本信息】 景德镇陶瓷学院 ， 材料学， 2009， 硕士

【摘要】 钛酸锌陶瓷具有谐振频率温度系数小、介电常数高、品质因数高等优良的微波介电性能,同时具有较低的烧结温度（约1100℃）,是一种实用化的微波介质材料。但是在950℃以上,钛酸锌陶瓷中微波介电性能较好的钛铁矿型ZnTiO₃相易受热分解生成微波介电性能较差的尖晶石型Zn₂TiO₄相和金红石相,利用传统的固相烧结法很难制备出单一相ZnTiO₃陶瓷材料。为了解决钛酸锌陶瓷的这一难题,本文利用聚合物前驱体法从以下几个方面进行了研究。考察了在不同pH值下的前驱体溶胶的状态、乙二醇与柠檬酸（EG/CA）的摩尔之比以及柠檬酸与金属离子（CA/M）的摩尔之比对聚合物前驱体法制备的前驱体粉末形态的影响。利用表观形态的观测和X射线衍射分析得出:溶液的pH值为5-6左右;乙二醇与柠檬酸的摩尔比为2;柠檬酸与金属离子的摩尔比为2时,溶液无沉淀,溶胶所形成的凝胶无块状团聚现象,前驱体粉末合成的六方钛铁矿型ZnTiO₃相最佳。对前驱体粉末进行了TG/DTA的综合热分析,确定了样品的烧结特性,钛酸锌陶瓷中六方ZnTiO₃相的晶型转变温度为950℃左右。通过对不同预烧温度和不同钛锌摩尔比下的钛酸锌陶瓷样品进行X射线衍射（XRD）和扫描电镜（SEM）分析,得出六方钛铁矿型ZnTiO₃粉末其结晶温度为600℃左右,而ZnTiO₃粉末的最佳合成温度为800℃,最佳合成钛锌摩尔比为1:1,此时ZnTiO₃相的颗粒粒径平均尺寸为0.5-1μm左右。对ABO₃钛铁矿型六方ZnTiO₃相中A位Zn²⁺离子进行Mg²⁺、Co²⁺和Ni²⁺离子的置换取代研究。利用TG/DTA、XRD和SEM等测试技术研究Mg²⁺、Co²⁺和Ni²⁺离子分别掺杂不同的掺杂量对六方ZnTiO₃相的热稳定性和钛酸锌陶瓷物相、显微结构及微波介电性能的影响。研究表明:当Mg²⁺离子掺杂量x=0.1时,六方ZnTiO₃相的晶型转变温度有所升高;适量的Mg²⁺离子掺杂取代能够提高六方ZnTiO₃相的热稳定温度,细化ZnTiO₃晶粒及促进ZnTiO₃烧结体致密化程度的提高。研究Mg²⁺离子取代Zn²⁺离子的钛酸锌陶瓷微波介电性能发现:微波介电性能较好的(Zn_0.7Mg_0.3)TiO₃微波介质材料能在970℃下烧结,其微波介电常数ε_r约为23,品质因数Qf值约为45000,谐振频率温度系数τ_f=+14（ppm/℃）。研究Co²⁺离子和Ni²⁺离子分别取代Zn²⁺离子的钛酸锌陶瓷微波介电性能发现:在1040℃烧结温度下,能够制备出微波介电性能为:ε=25、Qf=59000、τ_f=-20（ppm/℃）的Zn_0.3Co_0.7TiO₃微波介电材料;在1050℃烧结温度下,能够制备出微波介电性能为:ε=23、Qf=55000、τ_f=-10（ppm/℃）的Zn_0.3Ni_0.7TiO₃微波介电材料。更多还原

【Abstract】 In the zinc titanate ceramics, zinc metatitanate behaves excellent microwavedielectric properties, which are, high dielectric constant, and high quality factors andrelatively small, temperature coefficient of resonant frequency and it can be sintered atlower temperature （1100℃） than traditional microwave dielectric ceramics. So thissystem microwave dielectric materials may be put into industrial production quickly. Butzinc metatitanate, ZnTiO₃, decomposes into zinc orthotitanate and rutile at 945℃, thepreparation of pure ZnTiO₃ has been unsuccessful by conventional solid-state reaction. Inorder to resolve this problem, some studies will be carried out as follows via PolymericPrecursor Method.Studied the impact of different pH value of the sol, the different molar ratio of EGand CA and the different molar ratio of CA and metal ion to patterns of ZnTiO₃ powdersvia Polymeric Precursor Method.Using the apparent shape observation and X-ray diffractionanalysis, it was found that when the pH value of solution is 5-6, the molar ratio of EG toCA is 2, the molar ratio of CA to metal ion is 2, the solution has no deposition, the gelform from sol has no phenomenon of lumpish reunite, the precursor synthesize quantityof ZnTiO₃ phase is the best.After the synthesis thermal analysis to the raw material of the zinc titanate ceramics,and has preliminary determined the sintering temperature curve of the zinc titanateceramics, the phase transition temperature of zinc metatitanate was 950℃. Themicrostructure of this ceramics , which sintered at different temperature or differentmolar ratios of Ti/Zn, was studied by X-ray diffraction analysis and scanning electronmicroscopy, and it was found that the zinc metatitanate was synthesized at 600℃, theoptimum temperature of synthesizing zinc metatitanate at approximately 800℃, and thespecimens have optimum of synthesizes zinc metatitanate when the molar ratio of Ti/Znis 1:1,which the diameter of grains were about 0.5-1μm.Using the similar radius ionics Mg²⁺, Co²⁺ and Ni²⁺ substituting the Zn²⁺ of zinctitanate, where Zn²⁺at the A-site of ilmenite-type titanates. The thermal stability, phases,microstructure and microwave dielectric properties of this ceramics, which has differentamounts of additions, was studied by X-ray diffraction analysis and scanning electronmicroscopy, and it was found that the phase transition temperature of zinc metatitanatewas increased when the substitution x=0.1, the proper amounts of Mg²⁺ ionic substitutioncan enhance the thermally stable temperature of zinc metatitanate crystals, and alsoincreased the densification of zinc metatitanate ceramics. After systematic studies ofMg²⁺ ion substitute the Zn²⁺ ion, we have achieved microwave dielectric material Zn_0.7Mg_0.3TiO₃possessing excellent properties which can be sintered at approximately970℃.The dielectric properties of the samples are indicated as below: dielectric constantvalues saturating at 23, the Qf value being 45000GHz, the temperature coefficient ofresonant frequency being +14 ppm/℃. After systematic studies of Co²⁺ ion and Ni²⁺substitute the Zn²⁺ ion respectively, we have achieved microwave dielectric materialZn_0.3Co_0.7TiO₃possessing excellent properties which can be sintered at approximately1040℃. The dielectric properties of the samples are indicated as below: dielectricconstant values saturating at 25, the Qf value being 59000GHz, the temperaturecoefficient of resonant frequency was -20 ppm/℃; we also achieved microwavedielectric material Zn_0.3Co_0.7TiO₃ possessing excellent properties which can be sintered atapproximately 1050℃. The dielectric properties of the samples are indicated as below:dielectric constant values saturating at 23, the Qf value being 55000GHz, the temperaturecoefficient of resonant frequency being -10 ppm/℃.更多还原