Large Linear Negative Thermal Expansion In Nias-Type Magnetic Intermetallic Cr-Te-Se Compounds

A large linear negative thermal expansion (NTE) and expanded NTE temperature range (Delta T-NTE) were obtained in magnetoelastic CrTe1-xSex (0 <= x <= 0.15) compounds. For CrTe compound, its thermal expansion coefficient of volume (alpha(V)) was calculated to be -28.8 ppm K-1 with the temperature ranging from 280 to 340 K. Substituting Te with Se atoms, the NTE behavior and magnetic properties can be well manipulated. With increasing Se in CrTe1-xSex (0 <= x <= 0.15) compounds, the Delta T-NTE increases from 60 K (280-340 K for x = 0), to 80 K (240-320 K for x = 0.05), to 95 K (200-295 K for x = 0.1), and finally to 100 K (170-270 K for x = 0.15). Furthermore, a linear NTE remains independent of temperature for samples with x <= 0.1. The relationship between tunable NTE and magnetic properties was analyzed in detail, indicating that the NTE in CrTe1-xSex compounds originates from the magnetovolume effect (MVE).