Phase transition, crystal water and low thermal expansion behavior of Al2−2x(ZrMg)xW3O12·n(H2O)

Negative thermal expansion and broad band photoluminescence in a novel material of ZrScMo2VO12

“…Those with larger A 3+ (A = Lu, Er, Yb and Y) cation size crystallize in an orthorhombic structure and are highly hygroscopic and NTE can only be observed after complete removal of crystal water914. The same happens for ZrMgW 3 O 12 20. On the other hand, those with smaller A 3+ cation size crystallize in a monoclinic structure and transform to orthorhombic structure at elevated temperatures (above 473, 780, 658, 610 K for A = Al, Fe, Cr and In, respectively)1113 and the NTE is only possible at the high temperature phase.…”

“…From the curves of linear thermal expansion, we can figure out that ZrScMo 2 VO 12 is an excellent NTE material without hygroscopicity and phase transition in the investigated temperature range because either hygroscopicity or phase transition would result in abnormal changes of the linear thermal expansion curves during temperature increasing920. In order to confirm this, we performed the differential scanning calorimetry (DSC) and thermogravimetry (TG) measurements.…”

“…It was demonstrated that the relative length change of a material is very sensitive to crystal water releasing during temperature increasing920. From the curves of linear thermal expansion, we can figure out that ZrScMo 2 VO 12 is an excellent NTE material without hygroscopicity and phase transition in the investigated temperature range because either hygroscopicity or phase transition would result in abnormal changes of the linear thermal expansion curves during temperature increasing920.…”

“…Since then, plenty of NTE materials has been discovered, such as open framework structure oxides A 2 M 3 O 12 (A = transition metal, M = W, Mo)891011121314, AMgM 3 O 12 (A = Zr, Hf. M = W, Mo)151617181920 and ZrV 2 O 7 2122, cyanides M(CN) 2 (M = Zn, Cd) and Ag 3 [Co(CN) 6 ]2324, fluorides ScF 3 and ZnF 2 2526, anti-perovskite manganese nitrides Mn 3 AN (A = Zn, Ga and Ge, etc. )272829303132, perovskite structure PbTiO 3 33, BiNiO 3 34 and LaCu 3 Fe 4 O 12 35, and high quartz structure beta-Li 2 Al 2 SiO 6 36, beta-LiAlSiO 4 37, and keatite38, etc.…”

Near-Zero Thermal Expansion and Phase Transitions in HfMg1−xZnxMo3O12

“…In recent years, a number of novel NTE materials have been designed based on the basic structure of A 2 M 3 O 12 family, including those with a general formula ABM 3 O 12 where A is tetravalent Hf 4+ or Zr 4+ and B is bivalent cation Mg 2+ or Mn 2+ , and M is W or Mo or a combination of them (Suzuki and Omote, 2004; Baiz et al, 2008; Gindhart et al, 2008; Marinkovic et al, 2008; Song et al, 2013; Li et al, 2014, 2016, 2017; Ge et al, 2016a; Liu et al, 2018) and those with a formula ABM 2 XO 12 where A and M are the same as in ABM 3 O 12 , B is a trivalent cation and X is P 5+ or V 5+ (Chen et al, 2016; Cheng et al, 2016b, 2017; Ge et al, 2016b,c). The most distinct characteristics of the materials with formula ABM 2 XO 12 are that they exhibit NTE over a wide temperature range and intense photoluminescence in the visible range.…”