Pr_（2－x）Sr_xNiO_（4±δ）的合成、结构和电磁性质

Synthesis,Crystal Structure,Electrical and Magnetic Properties of Pr_(2-x)Sr_xNiO_(4±δ)

用固相法合成了Ｐｒ＿（２－ｘ）Ｓｒ＿ｘＮｉＯ＿（４±δ）（０．０≤ｘ≤１．０）系列Ｋ＿２ＮｉＦ＿４型化合物，研究了其结构，红外光谱，电磁性质。当０．０≤ｘ＜０．１和ｘ＝１．０时以正交晶系结晶；当０．１≤ｘ＜１．０时以四方晶系结晶；Ｎｉ离子平均价态在＋２至＋３价之间。当ｘ值较小时，样品中含有过量的氧。ＮｉＯ＿６八面体中Ｎｉ￣（３＋）的Ｊａｈｎ－Ｔｅｌｌｅｒ畸变引起ｃ／ａ值在ｘ＝０．５处出现极大，在７７～２５０Ｋ之间，样品磁性质符合居里－外斯定律，并表现出反铁磁相互作用。

A series of solid soItition Pr_(2-x)Sr_xNiO_4(0.00≤x≤1. 00)were synthesized withthe nickel valence being +2 to +3.The mixed oxides crystallized in orthorhombic(0.00≤x<0.10 and x=1.00)or tetragonal system(0.10≤x<1.00).The crystal parameter ratioc/a shows a maximum at x = 0.5 caused by Jahn-Teller distortion in octahedral site of thelow-spin Ni￣(3+) ions. The magnetic susceptibilities of the mixed oxides follow the Curie-Weissrule at temperatures 77～250K. An antiferomagne exchange interaction was observed in allthe samples.The change of electrical properties in the system of x>0.5 is attributed to thechange of electronic configuration of Ni￣(3+) from to .