From the massspectrometric measurements second law enthalpy values of ΔH0298 = 174 ± 6 kcal and ΔH0298 = 157 ± 6 kcal have been found for the reactions GdN (s) = Gd (g) + 1 2 N 2 (g) and HoN (s) = Ho (g) + 1 2 N 2 (g) respectively. When these enthalpies are combined with the known literature values for the enthalpy of vaporization of the metals, the standard enthalpies of formation of GdN (s),ΔH0f,
摘要 研究了钆和钬单氮化物的汽化,并通过克努森渗出质谱法测定了蒸气种类的分压。没有发现气态 GdN 或 HoN 的证据。氮化物通过分解成金属蒸气和分子氮而一致地蒸发。描述了钆和钬氮化物的汞齐法合成,并批判性地讨论了获得纯化学计量样品的困难。这些化合物的单晶已在密封的钼坩埚中通过升华生长。发现生长速率为 10-7 (HoN) 到 10-8 (GdN) cm/sec 的数量级。为了找出这些低值的原因,已经对这些化合物的平均蒸发冷凝系数进行了估计。这是通过将朗缪尔-克努森方程根据测量的蒸气压和晶体生长温度计算的最大通量与对应于实验测量的生长速率的通量进行比较来实现的。发现两种氮化物的平均蒸发-冷凝系数的数量级为 10-3,表明表面反应是晶体生长过程中的速率决定过程。从质谱测量中,已经发现反应 GdN (s) = Gd (g) + 1 2 N 2 (g) 和 HoN (s) 的第二定律焓值 ΔH0298
Magnetocaloric properties of TbN, DyN and HoN nanopowders prepared by the plasma arc discharge method
作者:K. P. Shinde、S. H. Jang、J. W. Kim、D. S. Kim、M. Ranot、K. C. Chung
DOI:10.1039/c5dt03528g
日期:——
We report for the first time the synthesis of nanopowders of TbN, DyN and HoN crystallized in a cubic structure by the plasma arc discharge (PAD) method and investigate their magnetocaloric properties for magnetic refrigeration applications.
Synthesis, structure and properties of RNiBN (R = rare-earth elements)
作者:Shi-jie Song、Bai-Zhuo Li、Qin-Qing Zhu、Zhi Ren、Guang-Han Cao
DOI:10.1016/j.jallcom.2023.172491
日期:2024.1
We report the structural and physical properties of new nitridoborates NiBN ( = Nd, Sm, Gd, Tb, Dy, Ho, and Er). These compounds crystallize in a tetragonal LaNiBN-type structure with two-dimensional NiB and N layers. The physical properties measurements indicate that they are antiferromagnetic metals. For = Gd and Ho, a successive magnetictransition was observed below N é el temperature, possibly
我们报告了新型硝基硼酸盐 NiBN(= Nd、Sm、Gd、Tb、Dy、Ho 和 Er)的结构和物理性质。这些化合物结晶为具有二维 NiB 和 N 层的四方 LaNiBN 型结构。物理特性测量表明它们是反铁磁金属。对于 = Gd 和 Ho,在 Néel 温度以下观察到连续的磁转变,这可能与 Ruderman-Kittel-Kasuya-Yosida 相互作用导致的自旋重新定向有关。在 = Er 和 Ho 化合物中测量到巨磁热效应,该效应与场诱导的从反铁磁态到铁磁态的一级变磁转变有关。我们的结果表明 NiBN(= Er 和 Ho)可能是低温磁制冷的有希望的候选者