Fabrication of Novel Ceramics in the Rare-Earth Oxide and Silicon Nitride System and Their Evaluation for the Application to the Materials

稀土氧化物和氮化硅体系新型陶瓷的制备及其材料应用评价

基本信息

批准号：
14550671
负责人：
ITATANI Kiyoshi
金额：
$ 1.92万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The author fabricated four kinds of ceramics in the Si_3N_4-SiO_2-Y_2O_3 system, i.e., melilite-type structure (Y_2Si_3O_3N_4), wollastonite-type structure (YSiO_2N), cuspidine-type structure (Y_4Si_2O_7N_2) and apatite-type structure (Y_5(SiO_4)_3N), and evaluated the thermal and mechanical properties. Moreover, synthesis conditions of RE_2Si_3O_3N_4 (RE = La, Ce, Nd, Sm, Gd, Dy, Er and Yb) were examined using Si_3N_4 and RE_2O_3. The high-density ceramics in the Si_3N_4-SiO_2-Y_2O_3 system were fabricated from the powders by hot pressing technique. Relative densities of the hot-pressed ceramics in the Si_3N_4-SiO_2-Y_2O_3 system were 98% or higher. The magnitude of the flexural strength of these ceramics could be arranged as follows; YSiO_2N(249 MPa) > Y_2Si_3O_3N_4(193 MPa) > Y_4Si_2O_7N_2(177 MPa) > Y_5(SiO_4)_3N(144 MPa). Oxidations of Y_2Si_3O_3N_4 and YSiO_2N ceramics started at around 1100℃ and 1050℃, respectively ; oxidation of Y_4Si_2O_7N_2 ceramic started at around 800℃, whereas that of Y_5(SiO_4)_3N ceramic started at around 850℃. Synthesis conditions of RE_2Si_3O_3N_4 (RE = rare-earth metal) were examined using Si_3N_4 and RE_2O_3. Single phases of RE_2Si_3O_3N_4 were formed in the case of RE = Nd, Sm, Gd, Dy and Er. Among these compounds, only Gd_2Si_3O_3N_4 emitted the light by the irradiation of near-ultraviolet beam. The activators (RE'_2O_3) were doped to the Gd_2Si_3O_3N_4. In the case of Sm-doped Gd_2Si_3O_3N4, the excitation peak appeared at 300 nm, whereas the emission peak appeared at 601 nm. This phosphor emitted the red light. With increasing amount of Sm dopant, the emission intensity of Gd_2Si_3O_3N4 with 1 mol% of Sm dopant achieved 1.8. It was concluded that among four kinds of the composites in the Si_3N_4-SiO_2-Y_2O_3 system, the flexural strengths of YSiO_2N ceramics fabricated by hot pressing-techniques showed maximum (249 MPa), whereas 1 mol% of Sm-doped Gd_2Si_3O_3N_4 intensity showed maximum (relative intensity:1.8).

作者在SI_3N_4-SIO_2-Y_2O_3系统中制作了四种陶瓷系统，即Melilite-type结构（Y_2SI_3O_3N_4），Wollastonite-Type结构（YSIO_2N）（y_5（sio_4）_3n），并评估了热和机械性能。此外，使用si_3n_4和re_2o_3检查了RE_2SI_3O_3N_4（RE = LA，CE，SM，GD，GD，DY，ER和YB）的合成条件。 SI_3N_4-SIO_2-Y_2O_3系统中的高密度陶瓷是通过热按技术从粉末制造的。 SI_3N_4-SIO_2-Y_2O_3系统中热压陶瓷的相对密度为98％或更高。这些陶瓷的弯曲强度的大小可以如下排列； YSIO_2N（249 MPA）> Y_2SI_3O_3N_4（193 MPA）> Y_4SI_2O_7N_2（177 MPA）> Y__5（SIO_4）_3N（144 MPA）。 Y_2SI_3O_3N_4和YSIO_2N陶瓷的氧化分别在1100次和1050年左右开始； Y_4SI_2O_7N_2陶瓷的氧化始于800 r，而Y_5（SIO_4）_3N陶瓷的氧化开始于850左右。使用SI_3N_4和RE_2O_3检查了RE_2SI_3O_3N_4（RE =稀土金属）的综合条件。在RE = ND，SM，GD，DY和ER的情况下，形成了RE_2SI_3O_3N_4的单个阶段。在这些化合物中，只有GD_2SI_3O_3N_4通过近距离脉冲梁的照射发出光。激活器（RE'_2O_3）被掺杂到GD_2SI_3O_3N_4。在SM掺杂的GD_2SI_3O_3N4的情况下，兴奋峰出现在300 nm，而发射峰出现在601 nm处。该磷光发射红光。随着SM掺杂剂量的增加，GD_2SI_3O_3N4的发射强度为1 mol％的SM掺杂剂的发射强度达到1.8。得出的结论是，在SI_3N_4-SIO_2-Y_2O_3系统中的四种复合材料中，由热按压技术最大的YSIO_2N ceramics的弯曲强度（249 MPA），而1 mol的1 mol％sm-poped gd_2si_3o_3o_3o_4 Intentive则最大程度显示。