title: Structural evolution and properties of solid solutions of hexagonal InMnO3 and InGaO3.
abstract: Solid solutions InMn(1-x)Ga(x)O(3) (0 ≤ x ≤ 1) have been investigated using magnetic, dielectric, specific heat, differential scanning calorimetry (DSC), and high-temperature powder synchrotron X-ray diffraction (HT-SXRD) measurements. It was found that samples with 0.5 ≤ x ≤ 1 crystallize in space group P6(3)/mmc with a ~ 3.32 Å and c ~ 11.9 Å, and samples with 0.0 ≤ x ≤ 0.4 crystallize in space group P6(3)cm with a ~ 5.8 Å and c ~ 11.6 Å at room temperature. HT-SXRD data revealed the existence of a P6(3)cm-to-P6(3)/mmc phase transition at about 480 K in InMn(0.6)Ga(0.4)O(3) and at 950 K in InMn(0.7)Ga(0.3)O(3). However, no dielectric, phonon, second-harmonic-generation, or DSC anomalies were found to be associated with these phase transitions. The phase transition should be improper ferroelectric from the symmetry point of view, but the above-mentioned experimental facts, together with the absence of ferroelectric hysteresis loops, revealed no evidence for ferroelectricity in the low-temperature P6(3)cm structure. We suggest that InMn(1-x)Ga(x)O(3) corresponds to a nonferroelectric phase of hexagonal RMnO(3) with P6(3)cm symmetry. The antiferromagnetic phase-transition temperature decreases from 118 K for x = 0 to 105 K for x = 0.1 and 73 K for x = 0.2, and no long-range magnetic ordering could be found for x ≥ 0.3. Specific heat anomalies associated with short-range magnetic ordering were observed for 0.0 ≤ x ≤ 0.5. InMn(1-x)Ga(x)O(3) with small Mn contents (0.8 ≤ x ≤ 0.98) has a bright-blue color.
authors.affiliation: International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
authors.forename: Dmitriy A
authors.initials: DA
authors.lastname: Rusakov
authors.forename: Alexei A
authors.initials: AA
authors.lastname: Belik
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kamba
authors.forename: Maxim
authors.initials: M
authors.lastname: Savinov
authors.forename: Dmitry
authors.initials: D
authors.lastname: Nuzhnyy
authors.forename: Taras
authors.initials: T
authors.lastname: Kolodiazhnyi
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yamaura
authors.forename: Eiji
authors.initials: E
authors.lastname: Takayama-Muromachi
authors.forename: Fedir
authors.initials: F
authors.lastname: Borodavka
authors.forename: Jan
authors.initials: J
authors.lastname: Kroupa