title: Temperature-Induced Irreversible Phase Transition From Perovskite to Diamond But Pressure-Driven Back-Transition in an Ammonium Copper Formate.
abstract: The compound [CH3 CH2 NH3][Cu(HCOO)3] undergoes a phase transition at 357 K, from a perovskite to a diamond structure, by heating. The backward transition can be driven by pressure at room temperature but not cooling under ambient or lower pressure. The rearrangement of one long copper-formate bond, the switch of bridging-chelating mode of the formate, the alternation of N-H⋅⋅⋅O H-bonds, and the flipping of ethylammonium are involved in the transition. The strong N-H⋅⋅⋅O H-bonding probably locks the metastable diamond phase. The two phases display magnetic and electric orderings of different characters.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Shang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
authors.forename: Sa
authors.initials: S
authors.lastname: Chen
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
authors.forename: Bing-Wu
authors.initials: BW
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China. zmw@pku.edu.cn.
authors.forename: Zhe-Ming
authors.initials: ZM
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China. gaosong@pku.edu.cn.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
keywords: ammonium copper formate; magnetism; metal-organic frameworks; perovskite; phase transitions