SmFe_(12)基稀土永磁材料结构稳定性和磁性能的第一性原理计算

Structure Stabilities and Magnetic Properties of SmFe_(12)Based Rare Earth Permanent Magnet Materials:a First-Principles Calculation

采用第一性原理计算研究了Co,Ti,Y和Ce 4种元素替代对SmFe_(12)晶胞晶格常数、形成能(△E)和饱和磁矩的影响,阐明1∶12相晶格常数、结构稳定性和饱和磁矩与原子替代的定量关系。在SmFe_(12)晶胞中,随Co元素的添加,晶格常数a,c均增加,形成能升高,磁矩增大;随Ti元素的加入,晶格常数a增加、c减小,形成能降低,磁矩减小;随Y和Ce元素的添加,形成能降低,磁矩增大。Sm(Fe_(1-x-y)Co_(x)Ti_(y))_(12)在0.183≤x≤0.272,0.124≤y≤0.167区间内△E<0;当成分为Sm(Fe_(bal)Co_(0.13)Ti_(0.125))_(12)时,总饱和磁矩最大值为21.5μB。Y和Ce有助于提高1∶12相的稳定性,Y元素对1∶12结构稳定性的作用强于Ce。(Sm_(0.5)Y_(0.5))(Fe_(bal)Co_(0.24)Ti_(0.08))_(12)和(Sm_(0.5)Ce_(0.5))(Fe_(bal)Co_(0.14)Ti_(0.125))_(12)晶胞的总饱和磁矩分别达到30.2和25.4μB。

Quantitative relationship between Co,Ti,Y and Ce substitution and the lattice constants,formation energies and total saturation moments of the SmFe_(12)unit cell was investigated based on first-principles calculations.With the addition of Co element,all the lattice constants a and c,formation energy and magnetic moment of the Sm(Fe_(1-x-y)Co_(x)Ti_(y))_(12)unit cell increase.The lattice constant a increases with the addition of Ti element,while formation energy,magnetic moment and lattice constant c reduce.As Y or Ce element substitutes for Sm atom,the formation energy decreases,while the magnetic moment is higher.Formation energy of the Sm(Fe_(1-x-y)Co_(x)Ti_(y))_(12)unit cell is negative when 0.183≤x≤0.272 and 0.124≤y≤0.167.Moreover,the maximum saturation magnetic moment of 21.5μ_(B) can be obtained when x=0.13 and y=0.125.Addition of rare earth Y and Ce elements is helpful in stabling the 1∶12 phase,and adding Y element is more stable than Ce element.The maximum total saturation magnetic moments of(Sm_(0.5)Y_(0.5))(Fe_(bal)Co_(0.24)Ti_(0.08))_(12)and(Sm_(0.5)Ce_(0.5))(Fe_(bal)Co_(0.14)Ti_(0.125))_(12)are 30.2 and 25.4μ_(B),respectively.