The effect of pressure on the ferroelastic phase transition in LnP5O14

Cai, Qing Rui; Lan, Guoxiang; Wang, Hua Fu; Guang, Hong

doi:10.1016/0022-3697(90)90057-m

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…Previous studies have indicated that the monoclinic-to-orthorhombic transition in RP 5 O 14 is second order, being gradual at first, but becoming quite pronounced nearer to the transition temperature. The generally accepted transition temperature of NdP 5 O 14 is ~ 420 K, while that of GdP 5 O 14 is ~445 K [4][5][6]10,25]. The results for NdP 5 O 14 from our study agree well with those previous reports, as evidenced by the rise in twinning fraction as a function of temperature ( Figure 10).…”

Section: Temperature Characteristics Of the Phase Transitionsupporting

confidence: 91%

“…To this end, we herein investigate the topological stability of all cage structures in two rareearth ultraphosphates, neodymium and gadolinium ultraphosphate, NdP 5 O 14 and GdP 5 O 14 . This includes a temperature-dependent profiling of these cages in the range T = 120 -480 K, given that rare-earth ultraphosphate crystal structures, RP 5 O 14 (R = lanthanide), are well known to undergo monoclinic-to-orthorhombic second-order phase transitions with transition temperatures rising with increasing lanthanide atomic number, from approximately 390 K (LaP 5 O 14 ) to 447 K (TbP 5 O 14 ) [3][4][5][6][7]. This temperature range naturally contains the typical environmental conditions of nuclear waste storage.…”

Section: Introductionmentioning

confidence: 99%

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Host-guest prospects of neodymium and gadolinium ultraphosphate frameworks for nuclear waste storage: Multi-temperature topological analysis of nanoporous cages in RP5O14

Cramer

Cole

2018

Journal of Solid State Chemistry

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Rare-earth ultraphosphate (RP 5 O 14) framework materials are potential host media for nuclear waste storage, since cages within their nanoporous structures have volumes that match well those of prospective guests such as uranium or plutonium ions. Good volume matches of host cages and guest compounds are nonetheless not the only structural requirement for ensuring viable nuclear waste storage. Host structures also need to be stable enough to withstand the typical environmental conditions of long-term storage of spent nuclear fuel. To this end, the nanoporous cage topologies of neodymium and gadolinium ultraphosphate, NdP 5 O 14 and GdP 5 O 14 , are investigated as a function of temperature. Topological analysis shows that, while both compounds are essentially isostructural, thus displaying the same type of cage structures, the cage volumes of NdP 5 O 14 are significantly larger than those of GdP 5 O 14 , with one stark exception. This exception concerns the smallest cage of NdP 5 O 14 , whose 8/4 topology lacks structural cross-linking that would otherwise give it much more strength. This 'squashed' cage appears to owe its origins to the specific nature of crystallogra phic twinning in NdP 5 O 14 , which causes strain that needs alleviating; squashing the 8/4 cage in NdP 5 O 14 would be the most susceptible option towards this end, since its cage manifests the weakest structural construct. GdP 5 O 14 succumbs to a gradual contraction of its 8/4 cage only with increasing temperature above 300 K; this is well below its second-order monoclinic-toorthorhombic phase transition at 420-430 K; which is 420 K for NdP 5 O 14. Fortunately, the volumes of heavy metal ions that arise from spent nuclear fuels do not match the size requirements of cages with 8/4 topology in RP 5 O 14 hosts needed for encapsulation; otherwise, radiation leakage of such containment would present a risk. Both NdP 5 O 14 and GdP 5 O 14 would therefore seem to offer good prospects as host media for nuclear waste storage.

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Section: Temperature Characteristics Of the Phase Transitionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Host-guest prospects of neodymium and gadolinium ultraphosphate frameworks for nuclear waste storage: Multi-temperature topological analysis of nanoporous cages in RP5O14

Cramer

Cole

2018

Journal of Solid State Chemistry

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“…66 It is reported that rare-earth ultraphosphates can undergo the second-order phase transition from monoclinic to orthorhombic crystal structures in the temperature range from 117 to 180 °C, and the transition temperature rises with increasing lanthanide atomic number. [67][68][69][70] Figure S6 shows the DSC data of the CUP powder sample. The exothermic peak at ∼200 °C can be attributed to the phase transition during the heating process.…”

Section: → ( ) + [ ]mentioning

confidence: 99%

Intermediate-Temperature Proton Exchange Membranes Based on Cerium Ultraphosphate Composited with Polybenzimidazole

Жолобко

Hurley

et al. 2022

J. Electrochem. Soc.

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We report the rational fabrication and structural, thermal, mechanical, and electrochemical characterization of a new type of intermediate-temperature (IT) polymer-inorganic composite (PIC) proton exchange membranes (PEMs) that are made of cerium ultraphosphate (CeP5O14—CUP) as the solid-state proton conductor composited with a high-temperature (HT) polybenzimidazole (PBI) as the polymeric binder. Flexible PBI-CUP PIC membranes with the thickness of ~135 μm and CUP mass fraction of up to 75 % were prepared by solution-casting without additional acid-doping (e.g., phosphoric acid). The proton conductivity of the fabricated IT-PIC-PEMs was up to 5.80 × 10-2 S cm-1 as measured from a prototype IT PEM fuel cell (PEMFC) operated at 200°C in the humidified hydrogen and air environment. This type of IT-PIC-PEMs also demonstrated sufficient mechanical strength and flexibility, excellent thermal stability (up to 350°C), and very good durability of the proton conductivity (within the test duration of 500 h). The present experimental study shows the promising future of the IT-PIC-PEMs for applications in various IT electrochemical processes including IT-PEMFCs, IT-electrolyzers, etc.

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