压致硼酸盐晶态物质的非晶化现象研究  

PRESSURE-INDUCED NONCRYSTALLIZATION IN Eu^(2+) ACTIVATED Sr-BORATES

作　　者：刘维娜[1] 刘宏建[2] 冯禹辰 孙淑兰[1] 苏文辉[2] 

机构地区：[1]中国科学院长春物理研究所,长春130021 [2]吉林大学固体物理教研室,长春130023

出　　处：《高压物理学报》1993年第3期167-176,共10页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金

摘　　要：本文用X射线衍射、Eu^(2+)的发射谱与激发谱、喇曼谱以及扫描电镜(SEM)颗粒形貌,研究了常压下合成的具有正交结构的SrB_2O_4(?)Eu^(2+)晶体在3.0-7.0GPa压力下的晶态非晶化现象。分析结果表明,压力导致晶粒细化和晶态非晶化。晶粒尺寸由常压下的微米量级细化为几十个纳米量级,随压力的变化为:2μm(0.1MPa),49.4nm(3.0GPa),29.7nm(5.0GPa),25.1nm(7.0GPa)。晶态与非晶态体积比随压力增加而减小,分别为:70/30(3.0GPa),63/37(5.0GPa),57/43(7.0GPa)。在压力下Eu^(2+)是处在晶态与非晶态两种不同的低对称的环境中。纳米级晶粒是以亚晶粒形式存在于微米级大晶粒中的,压致非晶态可能组成了纳米亚晶粒的界面区。High pressure-induced crystallization in disordered or noncrystalline matter is well known. Pressure-induced disordering or noncrystallizing in crystals, however, has been seldom found so far. In the present paper,under the pressure of 3. 0-7. 0GPa,the pressure-induced non-crystallization phenomena in Euz+ activated orthorhombic Sr-borates crystals were investigated by using X-ray diffraction,emission and excitation spectra of Eu2+,Raman spectra and SEM topography. After treating at 3. 0GPa,the X-ray diffraction spectra of the sample exhibit a new character in which a set of clearly widened peaks of the crystal were superposed on the diffuse peaks of noncrystalline state ; the intensity of the emission spectrum peaking at 370nm, which is given by 5d→4f transition of Eu2+ located in orthorhombic crystal,decreased and widened obviously,and a broad band of emission spectrum peaking at 440nm,which is given by Eu2+ located in noncrystalline state,was also observed; the excitation spectra for the two emission bands differed with each other considerably;the intensity of Raman peaks decreased and their half width increased; the particle size observed by SEM remained in the order of micrometer of orthorhombic crystal grain synthesized under normal pressure. As the pressure increasing,the width of X-ray diffraction peaks for the crystalline state increased, but the total diffraction intensity further decreased, while the total intensity of diffuse peaks for the noncrystalline state further increased ; the emission band peaking at 370nm was not observed,only a very low emission peak was recorded at 440nm; Raman peabs were further decreased and widened,too;the particle size observed by SEM did not vary apparently. Analyses from the experimental results of X-ray diffraction show the pressure effects in the fining of crystal grains,the noncrystallization of crystalline state,and the grain size reduction from the order of micrometer to nanometer. They are 2μm (0. 1MPa), 49. 4nm (3. 0GPa),29. 7nm(5. 0GPa),25. 1nm(7. 0GPa),res

关 键 词：压致非晶化 硼酸盐 晶态 非晶化 

分 类 号：O521.2[理学—高压高温物理]