Structural Phase Transitions of a Molecular Metal Oxide

Abstract

The structural phase of a metal oxide changes with temperature and pressure. During phase transitions, component ions move in multidimensional metal–oxygen networks. Such macroscopic structural events are robust to changes in particle size, even at scales of around 10 nm, and size effects limiting these transitions are particularly important in, for example, high‐density memory applications of ferroelectrics. In this study, we examined structural transitions of the molecular metal oxide [Na@(SO3)2(n‐BuPO3)4MoV4MoVI14O49]5− (Molecule 1) at approximately 2 nm by using single‐crystal X‐ray diffraction analysis. The Na+ encapsulated in the discrete metal‐oxide anion exhibited a reversible order–disorder transition with distortion of the Mo–O molecular framework induced by temperature. Similar order–disorder transitions were also triggered by chemical pressure induced by removing crystalline solvent molecules in the single‐crystal state or by substituting the countercation to change the molecular packing.

Solvent-induced reversible high-temperature phase transition in crown ether clathrates

“…The N value is consistent with the ordered/disordered phase transition accompanied by structural changes or molecular dynamics. 52 However, it is completely different from compound 1·ACN in that compound 1 does not have any reversible heat anomalies upon heating and cooling in the DSC measurements (Fig. 1e), which indicates that compound 1 has not undergone a reversible phase transition.…”

Solvent-oriented structural diversity, sequential SCSC and low-temperature transformation in Cd-coordination polymers: unique turn-on–off sensing of Fe3+

“…25 To date, few examples of thermal-responsive materials at high and low temperatures are available, such as [Cu 2 (L-R)(DABCO)] n ·(solvent) x , 26 [(CH 3 ) 2 NH 2 ][Ni(HCOO) 3 ], 27 and [Na@(SO 3 ) 2 ( n -BuPO 3 ) 4 Mo V 4 Mo VI 14 O 49 ] 5− . 28 The thermal-responsive phase transition interval close to RT based on CPs is relatively infrequent. The thermal-induced switchable nature of Cd-1 , combined with reversible accurate crystal structure information, prompted its use for the construction of temperature stimulation response materials in the following works, such as temperature sensing elements and thermal-driven switchable devices.…”

Proton-Coupled Electron Transfer at the Surface of Polyoxovanadate-Alkoxide Clusters

“…Indeed, the extended structure of these materials results in competing H atom intercalation and the presence of defect sites that alter mechanisms of PCET postulated for the pristine assembly . To circumvent these challenges, the study of molecular models has become an attractive route to both understand reactivity and bonding as well as uncover design criteria for subsequent material development. , …”

“…14 To circumvent these challenges, the study of molecular models has become an attractive route to both understand reactivity and bonding as well as uncover design criteria for subsequent material development. 15,16 Polyoxometalates (POMs) stand out as a particularly intriguing family of compounds for understanding PCET at metal oxide surfaces. 17 Composed of multiple transition-metal centers linked together through bridging oxygen atoms, these molecular metal oxides exist on the continuum between small molecules and extended solids.…”