采用化学包覆法将Ho_2O_3包覆在纳米级钛酸钡粉体表面,通过烧结将Ho^(3+)扩散到钛酸钡晶粒中,调节其介电性能,研究了不同Ho^(3+)掺杂量对Ba Ti O3基陶瓷相组成、微观结构和介电性能的影响。X射线衍射和扫描电子显微镜分析结果表明:Ho^(...采用化学包覆法将Ho_2O_3包覆在纳米级钛酸钡粉体表面,通过烧结将Ho^(3+)扩散到钛酸钡晶粒中,调节其介电性能,研究了不同Ho^(3+)掺杂量对Ba Ti O3基陶瓷相组成、微观结构和介电性能的影响。X射线衍射和扫描电子显微镜分析结果表明:Ho^(3+)改性陶瓷样品均为赝立方相,Ho^(3+)的加入能抑制晶粒生长,改善陶瓷微观结构,有利于制备均匀的细晶陶瓷。透射电子显微镜观察显示,包覆层的厚度约为2 nm,包覆Ho_2O_3有助于陶瓷烧结过程中形成"核-壳"结构晶粒,能显著改善钛酸钡基陶瓷的介电温度稳定性,提高绝缘电阻。当Ho^(3+)掺杂量为2.0%时,陶瓷的相对介电常数为1 612,ΔC/C(-55~150℃)<±15%,满足EIA X8R电容器的温度特性。展开更多
This study focuses on the preparation of nanostructured holmium oxide via the decomposition of holmium acetate precursor utilizing the non-isothermal strategy. Thermogravimetric analysis(TGA) was used to follow up the...This study focuses on the preparation of nanostructured holmium oxide via the decomposition of holmium acetate precursor utilizing the non-isothermal strategy. Thermogravimetric analysis(TGA) was used to follow up the various thermal events involved in the decomposition process. Dehydration completes approximately at 150℃, which is followed by the decomposition of the anhydrous acetate leading to the formation of holmium oxide. Based on the TGA results the acetate precursor was heated non-isothermally at the temperature range of 150 e700℃. The obtained solids were characterized using powder X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), field-emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM). It is found that nanocrystalline Ho_2 O_3 starts to form at 500℃ and presents the only phase detected at the 500 e700℃ range. The electrical conductivity of the solids that form at the temperature range of 300 e700℃ was investigated. The obtained values were correlated with the observed structural modifications accompanying the heat treatment. The electrical conductivity of the Ho_2 O_3 samples prepared at 500, 600 and 700℃ reaches the values of 1.92 × 10^(-7), 1.61 × 10^(-7) and 8.33 × 10^(-8) Ω^(-1)cm^(-1) at a measuring temperature of 500℃, respectively. These values are potentially advantageous for high-resistivity devices.展开更多
文摘This study focuses on the preparation of nanostructured holmium oxide via the decomposition of holmium acetate precursor utilizing the non-isothermal strategy. Thermogravimetric analysis(TGA) was used to follow up the various thermal events involved in the decomposition process. Dehydration completes approximately at 150℃, which is followed by the decomposition of the anhydrous acetate leading to the formation of holmium oxide. Based on the TGA results the acetate precursor was heated non-isothermally at the temperature range of 150 e700℃. The obtained solids were characterized using powder X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), field-emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM). It is found that nanocrystalline Ho_2 O_3 starts to form at 500℃ and presents the only phase detected at the 500 e700℃ range. The electrical conductivity of the solids that form at the temperature range of 300 e700℃ was investigated. The obtained values were correlated with the observed structural modifications accompanying the heat treatment. The electrical conductivity of the Ho_2 O_3 samples prepared at 500, 600 and 700℃ reaches the values of 1.92 × 10^(-7), 1.61 × 10^(-7) and 8.33 × 10^(-8) Ω^(-1)cm^(-1) at a measuring temperature of 500℃, respectively. These values are potentially advantageous for high-resistivity devices.
