Thermally induced phase transitions of barium oxalates

Christensen, A. Nørlund; Arnbjerg, Lene M.; DiMasi, Elaine; Cerenius, Yngve; Hauback, Bjørn C.

doi:10.1016/j.solidstatesciences.2011.04.013

“…The compounds with alkali and alkaline earth metal cations are screened in terms of the type of FMs, [CO 3 ] 2− , [C 2 O 4 ] 2− , [C 2 O 6 ] 2− , 1 [C 4 O 4 ] 2− , 2 [C 4 O 4 ] 2− , and [C 6 O 6 ] 2− . Totally, 29 selected structures [25–44] are screened with the formula A n CO 3 (A=Li, Na, K, Rb, Cs, n =2; A=Mg, Ca, Sr, Ba, n =1), A n C 2 O 4 (A=NH 4 , Li, Na, K, Rb, Cs, n =2; A=Ca, Ba, n =1), A n C 2 O 6 (A=K, Rb, n =2), A n C 4 O 4 (A=NH 4 , H, Li, Na, Rb, Cs, n =2; A=Ca, Ba, n =1), and Na 2 C 6 O 6 , as listed in Table 2.…”

Section: Resultsmentioning

confidence: 99%

“…TheC ÀOunits are obtained from primary crystal information without structure optimization. Thepolarization anisotropy was acquired from static polarization according to the following formula: [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] are screened with the formula [2] YVO 4 ,r utile (TiO 2 ), [45] respectively. Na 2 C 6 O 6 possesses the largest birefringence in reported crystals to the best of our knowledge.…”

Section: Process Of Design and Explorationmentioning

confidence: 99%

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

Tong

¹

,

Zhang

²

,

Yang

³

et al. 2020

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The main commercially used birefringent oxides a-BaB 2 O 4 and YVO 4 have the birefringences of 0.12 and 0.22. We propose atargeted high-throughput screening system to search birefringence-active functional modules (FMs) and large birefringent materials.Aseries of p-conjugated CÀOu nits 2À are discoveredt o be birefringence-active FMs.T heoretical and experimental studies on the crystals with C À Ounits confirm the feasibility of strategy.B ased on this,t he CÀOc ontaining compounds ranging from deep-ultraviolet to near-infrared region with large birefringence from 0.1 to 1.35 are found, and most of them break through the birefringent limit of oxides.T he (NH 4 ) 2 C 2 O 4 •H 2 Oc rystal is grown and its experimental birefringence is 0.248 at 546 nm, which is identified as apromising UV birefringent crystal. The A-site cations playsignificant roles in optical properties by influencing the density and arrangement of the CÀOunits.

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“…The compound Ba 3 (H 2 O) 4 (1,3,5-C 6 H 3 (CO 2 ) 3 ) 2 only began to release the coordinated H 2 O molecules at 75 °C . The hydrated barium oxalate Ba 2 (H 2 O) 7 (C 2 O 4 ) 2 only began to release the coordinated H 2 O molecules at 100 °C . The trihydrate of the weakly coordinating perchlorate anion, Ba(H 2 O) 3 (ClO 4 ) 2 , lost the coordinated H 2 O molecules to form anhydrous Ba(ClO 4 ) 2 when it was heated from room temperature to 150 °C at 10 °C min –1 .…”

Section: Resultsmentioning

confidence: 99%

“…95% complete in 33 min) . It is possible that the dehydrated salts Ba(B 12 H 12 ), Ba 3 (H 2 O) 4 (1,3,5-C 6 H 3 (CO 2 ) 3 ) 2 , Ba(C 2 O 4 ), Ba(ClO 4 ) 2 , Ba(H 2 O) 3 (Fe(CN) 5 NO), and/or BaCl 2 would undergo rapid rehydration in the presence of H 2 O( g ), but that is not known because these experiments were not described in refs and − (presumably because they were not performed).…”

Section: Resultsmentioning

confidence: 99%

Manifestations of Weak O–H···F Hydrogen Bonding in M(H₂O)_n(B₁₂F₁₂) Salt Hydrates: Unusually Sharp Fourier Transform Infrared ν(OH) Bands and Latent Porosity (M = Mg–Ba, Co, Ni, Zn)

Lacroix

¹

,

Bukovsky

²

,

Lozinšek

³

et al. 2018

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Eight M(H2O) n (Z) salt hydrates were characterized by single-crystal X-ray diffraction (Z2– = B12F12 2–): M = Ca, Sr, n = 7; M = Mg, Co, Ni, Zn, n = 6; M = Ba, n = 4, 5. Weak O–H···F hydrogen bonding between the M(H2O) n 2+ cations and Z2– resulted in room-temperature Fourier transform infrared (FTIR) spectra having sharp ν(OH) bands, with full widths at half max of 10–30 cm–1, which are much more narrow than ν(OH) bands in room temperature FTIR spectra of most salt hydrates. Clearly resolved νasym(OH/OD) and νsym(OH/OD) bands with Δν(OH) as small as 17 cm–1 and Δν(OD) as small as 11 cm–1 were observed (Δν(OX) = νasym(OX) – νsym(OX)). The isomorphic hexahydrates (R3̅) have two fac-(H2O)3 sets of H2O ligands and nearly octahedral coordination spheres. They exhibited four resolvable ν(OH) bands, one νasym(OH)/νsym(OH) pair for H2O ligands with longer O(H)···F distances and one νasym(OH)/νsym(OH) pair for H2O ligands with shorter O(H)···F distances. The ν(OH) bands for the three H2O molecules with shorter, slightly stronger O(H)···F hydrogen bonds were broader, more intense, and red-shifted by ca. 25 cm–1 relative to the bands for the three other H2O molecules, the first time that such small differences in relatively weak O(H)···F hydrogen bonds in the same crystalline hexahydrate have resulted in observable IR spectroscopic differences at room temperature. For the first time room temperature ν(OH) values for salt hexahydrates showed the monotonic progression Mg2+ > Co2+ > Ni2+ > Zn2+, essentially the same progression as the pK a values for these metal ions in aqueous solution. A further manifestation of the weak O–H···F hydrogen bonding in these hydrates is the latent porosity exhibited by Ba(H2O)5,8(Z), Sr(H2O) n,m (Z), and Ca(H2O)4,6(Z). Finally, the H2O/D2O exchange reaction Co(D2O)6(Z) → Co(H2O)6(Z) was ca. 50% complete in 1 h at 50 °C in N2/17 Torr H2O(g).

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“…TheC ÀOunits are obtained from primary crystal information without structure optimization. Thepolarization anisotropy was acquired from static polarization according to the following formula: [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] are screened with the formula…”

Section: Process Of Design and Explorationmentioning

confidence: 99%

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

Tong

¹

,

Zhang

²

,

Yang

³

et al. 2020

View full text Add to dashboard Cite

The main commercially used birefringent oxides a-BaB 2 O 4 and YVO 4 have the birefringences of 0.12 and 0.22. We propose atargeted high-throughput screening system to search birefringence-active functional modules (FMs) and large birefringent materials.Aseries of p-conjugated CÀOu nits 2À are discoveredt o be birefringence-active FMs.T heoretical and experimental studies on the crystals with C À Ounits confirm the feasibility of strategy.B ased on this,t he CÀOc ontaining compounds ranging from deep-ultraviolet to near-infrared region with large birefringence from 0.1 to 1.35 are found, and most of them break through the birefringent limit of oxides.T he (NH 4 ) 2 C 2 O 4 •H 2 Oc rystal is grown and its experimental birefringence is 0.248 at 546 nm, which is identified as apromising UV birefringent crystal. The A-site cations playsignificant roles in optical properties by influencing the density and arrangement of the CÀOunits.

show abstract

Thermally induced phase transitions of barium oxalates

Cited by 7 publications

References 17 publications

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

Manifestations of Weak O–H···F Hydrogen Bonding in M(H₂O)_n(B₁₂F₁₂) Salt Hydrates: Unusually Sharp Fourier Transform Infrared ν(OH) Bands and Latent Porosity (M = Mg–Ba, Co, Ni, Zn)

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

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Thermally induced phase transitions of barium oxalates

Cited by 7 publications

References 17 publications

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

Manifestations of Weak O–H···F Hydrogen Bonding in M(H2O)n(B12F12) Salt Hydrates: Unusually Sharp Fourier Transform Infrared ν(OH) Bands and Latent Porosity (M = Mg–Ba, Co, Ni, Zn)

Series of Crystals with Giant Optical Anisotropy: A Targeted Strategic Research

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Product

Resources

About

Manifestations of Weak O–H···F Hydrogen Bonding in M(H₂O)_n(B₁₂F₁₂) Salt Hydrates: Unusually Sharp Fourier Transform Infrared ν(OH) Bands and Latent Porosity (M = Mg–Ba, Co, Ni, Zn)