Tunable negative thermal expansion and structural evolution in antiperovskite Mn₃Ga_1−xGe_xN (0 ≤ x ≤ 1.0)

Abstract

The negative thermal expansion (NTE) and structural evolution of antiperovskite compounds Mn3Ga1−xGexN (0 ≤ x ≤ 1.0) were systematically investigated. Our results indicate the crystal structure of Mn3Ga1−xGexN changes from cubic (C) to tetragonal (T4) with increasing Ge content by X‐ray diffraction (XRD).The negative thermal expansion from x = 0 (operation‐temperature range ▵T = 20 K) to x = 0.4 (▵T = 60 K) becomes broad and shifts to higher temperature, and then it became positive from x = 0.5 in Mn3Ga1−xGexN. Typically, Mn3Ga0.5Ge0.5N shows low thermal expansion behavior between 300 and 450 K (∆T = 150 K), and thermal expansion coefficient α is estimated to be 2 × 10−6 K−1. Furthermore, variable temperature XRD was measured to reveal the origin of NTE. The cubic I ‐ cubic II phases coexistence (x = 0.2) and cubic I ‐ tetragonal coexistence (x = 0.5, 0.6) was observed at low temperature. The tunable NTE is highly valuable for practical applications in precision devices.

Near‐Zero Thermal Expansion Ba1−xSrxZn2Si2O7‐Based Microwave Dielectric Ceramics for 3D Printed Dielectric Resonator Antenna with Integrative Lens

“…[ 23 ] Several NCTE materials, such as Hf/ZrWO 8 , [ 24 ] PbTiO 3 , [ 25 ] and MZrF 6 (M = Ca, Mn, Fe), [ 26 ] are widely used to acquire zero coefficient of thermal expansion (ZCTE). [ 27 ] Ternary BaO‐ZnO‐SiO 2 systems have many interesting properties, such as the coexistence of weak ferroelectricity and microwave dielectric properties in Ba 2 ZnSi 2 O 7 [ 28 ] and BaZnSiO 4 . [ 29 ] Moreover, BaZn 2 Si 2 O 7 ceramic undergoes a phase transition from monoclinic ( C 2/ c ) to orthorhombic ( Ccm 2 1 ) crystal structure at 280 °C.…”

Spray‐dry synthesis of β‐Cu1.8Zn0.2V2O7 ceramic fine particles showing giant negative thermal expansion

“…For this reason, many attempts have been made to use recently developed large negative thermal expansion (large NTE) materials. [3][4][5][6][7][8][9] Nevertheless, technical difficulties persist in the fabrication of NTE fine particles. Many reports of earlier studies [10][11][12][13] have described that the NTE function is drastically altered by fine particles: The magnitude of the negative coefficient of thermal expansion is degraded, although the temperature window for NTE is expanded.…”

“…The capabilities of such materials for suppressing thermal expansion are inadequate. For this reason, many attempts have been made to use recently developed large negative thermal expansion (large NTE) materials . Nevertheless, technical difficulties persist in the fabrication of NTE fine particles.…”