Preparation of sodium contained aluminum higher borides and a search of higher hardness material

含钠铝高硼化物的制备及高硬度材料的探索

基本信息

批准号：
20560629
负责人：
OKADA Shigeru
金额：
$ 0.58万
依托单位：
Kokushikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

项目摘要

Single crystals of a new ternary boride NaAlB_<14> (orthorhombic, Imma) were obtained from the Na-Al-B system using a high-temperature Al self-flux under an Ar atmosphere. The reagents used to prepare the samples were NaF or Na_2B_4O_7 powder, crystalline boron powder and Al metal chips. The optimum conditions to obtain relatively large crystals were found to include soaking temperature 1573 K, soaking time 1 h, cooling rate 50 K/h and the atomic ratios (n=B/Na=1.0 to 4.0) of starting materials. The NaAlB_<14> crystal prepared had maximum sizes of approximately 7.3mm. The crystals were generally obtained in the form of plate-like crystals with well-developed {010} faces or trapezoidal-shape crystals. The values of Vickers microhardness are in the ranges of 23.3(1.0) and 28.4(0.6) GPa, respectively. Single crystals of quaternary compounds in the solid solution (Na_xRE_<1-x>)AlB_<14> (RE=Li, Mg, rare earths (Tb, Dy, Ho, Er, Tm, Yb, Lu)) were grown by the Na-RE-Al-B system using Al-self flux. The single crystals of LiAlB_<14>, NaAlB_<14>, MgAlB_<14> and (Na_xMg_<1-x>)AlB_<14> (0.21≦x≦0) were grown; the quaternary boride (Na_xLi_<1-x>)AlB_<14> and (Na_xRE_<1-x>)AlB_<14> (RE=rare earths) phases were not obtained at the single crystal growth experiment in the Na-Li-Al-B and Na-RE-Al-B systems. The homogeneity range for the solid solutions of (Na_xMg_<1-x>)AlB_<14> (0.21≦x≦0) crystals was studied by XRD and chemical analyses. The hardness values of (Na_xMg_<1-x>)AlB_<14> (0.21≦x≦ 0.08) crystals were in the range of 31.1(0.8) to 33.4(0.9) GPa. Magnetic susceptibility of as-grown (Na_xMg_<1-x>)AlB_<14> (x=1, 0.21≦x≦0) have been measured in the temperature range of 300 K to 2 K. The magnetic susceptibility of (Na_<0.21>Mg_<0.79>)AlB_<14> and (Na_<0.08>Mg_<0.92>)AlB_<14> crystals are diamagnetic and shown an increase at low temperatures indicative of small paramagnetic contributions which can normally be attributed to impurities or defects.

在AR大气下，使用高温Al自由升华从Na-Al-B系统中获得了新的三元硼化硼Naalb_ <14>（正骨，IMMA）的单晶。用于制备样品的试剂是NAF或NA_2B_4O_7粉末，结晶硼粉和Al金属芯片。发现获得相对较大晶体的最佳条件包括浸泡温度1573 K，浸泡时间1小时，冷却速率50 k/h以及原子比（n = b/na = 1.0至4.0）的起始材料。 Naalb_ <14>制备的晶体的最大尺寸约为7.3mm。通常以板状晶体的形式获得晶体，并具有发达的{010}面或梯形形状晶体。 Vickers显微硬度的值分别在23.3（1.0）和28.4（0.6）GPA的范围内。使用AL-B-B-By-Bystem生长了实心溶液（Na_xre_ <1-x>）Alb_ <14>（re = li，mg，稀土（TB，dy，ho，ho，ho，tm，yb，lu））中第四纪化合物的单晶。 lialb_ <14>的单晶，naalb_ <14>，mgalb_ <14>和（na_xmg_ <1-x>）alb_ <14>（0.21≦x≦0）；在Na-Li-Al-B和Na-Re-Al-B Systems的单晶生长实验中未获得第四纪结合（Na_xli_ <1-x>）Alb_ <14>和（Na_xre_ <1-x>）Alb_ <14>（re =稀土）。通过XRD和化学分析研究了（Na_xmg_ <1-x>）Alb_ <14>（0.21≦X≦0）的固体溶液的同质性范围。（Na_xmg_ <1-x>）Alb_ <14>（0.21 x x≦0）0.08）的硬度值在31.1（0.8）至33.4（0.9）GPA范围内。在300 k至2 K的温度范围内测量了Alb_ <14>（x = 1，0.21 = 1，0.21 = 1，0.21 = 1，0.21 = 1，na_xmg_ <1-x>）的磁敏感性在300 k至2 k的温度范围内。在低温下的增加表示通常归因于杂质或缺陷的小磁素贡献。