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Low-temperature heat capacity and magnetic properties of the R Ni X sub 2 compounds ( R =La, Ce; X =Si, Ge, Sn)

Journal Article · · Physical Review, B: Condensed Matter; (USA)
;  [1];  [2]
  1. Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (USA)
  2. Ames Laboratory, Iowa State University, Ames, Iowa 50011 (USA)

Heat-capacity (1.4--80 K) and magnetic-susceptibility (1.5--300 K) measurements were carried out for the series of six ternary intermetallic compounds with {ital R}Ni{ital X}{sub 2} composition ({ital R}=La, Ce and {ital X}=Si, Ge, and Sn). All of the LaNi{ital X}{sub 2} compounds exhibit normal metallic behavior with an electronic specific-heat coefficient in the range 5.2--5.6 mJ/mol K{sup 2} and Debye temperature decreasing from 451 K (LaNiSi{sub 2}) to 258 K (LaNiSn{sub 2}). The CeNi{ital X}{sub 2} compounds display anomalous behaviors. CeNiSi{sub 2} is an intermediate-valence compound at high temperatures with the cerium valence varying from 3.35+ at room temperature to 3.65+ at {ital T}=50 K, and becomes a spin fluctuator at low (around 3.3 K) temperature. The spin fluctuations can be quenched by an external magnetic field of about 5.3 T. Both CeNiGe{sub 2} and CeNiSn{sub 2} undergo two-step antiferromagnetic phase transitions at {ital T}{sub {ital N}}{sup II}=3.9 K and {ital T}{sub {ital N}}{sup I}=3.2 K, which are accompanied by sharp anomalies for all properties studied. The electronic specific constants (in units of mJ/mol Ce K{sup 2}) of the three Ce compounds were 45.3{plus minus}0.6 for CeNiSi{sub 2}, 97.6{plus minus}0.9 for CeNiGe, and 60.8{plus minus}0.7 for CeNiSn{sub 2}.

DOE Contract Number:
W-7405-ENG-82
OSTI ID:
5692209
Journal Information:
Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:13; ISSN PRBMD; ISSN 0163-1829
Country of Publication:
United States
Language:
English