Neutron diffraction of α-calcium formate at 100 and 296 K

Burger, Nicoletta; Fueß, H.; Mason, Sax A.

doi:10.1107/s0567740877007444

Cited by 32 publications

(22 citation statements)

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“…Better agreements are found in the nearest-neighbour M2+-O distances, as are shown in Table 6; the mean discrepancies between the observed and calculated structures are only 0.03 A for both a-Ca(HCOO)2 and a-Sr(HCOO) 2, and 0.02 A for Ba(HCOO)2. Burger, Fuess & Mason (1977): x' = -y, y' = -x, z' = -z for the non-H atoms; x' =y,y' =-½-x,z' =½+ zforH(1),andx' = 1 +y,y'= -½ -x, z' = -½ + z for H(2).…”

Section: Reliability and Transferability Of The Potential Parametersmentioning

confidence: 99%

“…The space group of each structure was unchanged, and the formate ions were treated as rigid bodies. The structural parameters for a-Ca(HCOO)2 were taken from the neutron diffraction analysis (Burger, Fuess & Mason, 1977), and those for a-Sr(HCOO)2 and Ba(HCOO)2 were from the X-ray crystal analysis (Watanab6 & Matsui, 1978). The coordinates of H atoms in a-Sr(HCOO)2 and Ba(HCOO) 2 were calculated assuming planar formate ions with C-H = 1.08A.…”

Section: Derivation Of the Potential Parametersmentioning

confidence: 99%

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Energy analyses for the alkaline-earth formates

Matsui¹,

Watanabe²

1981

Acta Cryst Sect A

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The structures of the alkaline-earth formates have been investigated in terms of lattice energy calculations. The lattice energy E was approximated to be the sum of electrostatic and repulsive terms, where the repulsive potential used was in the form: (1/12) f(R~ + R~) 13 r -12 (r, interatomic distance;f, arbitrarily chosen standard force; R~, repulsive radius of an atom a). The potential parameters concerned were obtained with the structures of a-Ca(HCOO) 2, a-Sr(HCOO) 2 and Ba(HCOO)2. These potential parameters were successfully used for the determination of the structure of fl-Sr(HCOO)2, for the differentiation of the structures of a-Sr(HCOO) 2 and Ba(HCOO) 2, and for the interpretation of the large anisotropy of thermal vibrations in fl-Ca(HCOO) 2.

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Section: Reliability and Transferability Of The Potential Parametersmentioning

confidence: 99%

Section: Derivation Of the Potential Parametersmentioning

confidence: 99%

Energy analyses for the alkaline-earth formates

Matsui¹,

Watanabe²

1981

Acta Cryst Sect A

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“…At 300 K, calcium formate forms an orthorhombic crystal with two crystallographically inequivalent sites per unit cell. 20 The crystal structure consists of ''chains'' of Ca͑II͒ ions alternating with pairs of O atoms. Formate ions bind the chains into a compact spatial network.…”

Section: Methodsmentioning

confidence: 99%

Nuclear magnetic resonance polarization and coherence echoes in static and rotating solids

Tomaselli¹,

Hediger²,

Suter

et al. 1996

The Journal of Chemical Physics

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The mechanisms of defocusing and refocusing of spin order in extended dipolar coupled nuclear spin systems are investigated by experiments on static and on rotating solids. It is demonstrated that polarization or coherence echoes are possible also under magic-angle sample spinning. The dipolar interactions, averaged by the spinning, are recovered by rotor-synchronized multiple-pulse sequences. By a simple modification of the pulse sequences, it is possible to reverse the sign of the effective dipolar Hamiltonian and to induce the refocusing of polarization or coherence. The creation of multiple-spin order in the course of polarization evolution or free precession is monitored by a modified echo experiment. Experimental results for a polycrystalline sample of calcium formate are presented.

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“…All the crystals used for measurements were ground to spheres, the sizes of which are given in for the refinement * Burger, Fuess & Mason (1977). ].…”

Section: Methodsmentioning

confidence: 99%

“…As the first step of a programme, we reinvestigated the crystal structures of a-calcium formate, a-strontium formate, and barium formate, for although the crystal structures of these three compounds had been reported, it was felt that the accuracy of the result would not be sufficient. During the preparation of this manuscript, a paper on the neutron diffraction analysis of a-calcium formate at 100 and 296 K came to our notice (Burger, Fuess & Mason, 1977; hereafter referred to as BFM). It is still worthwhile to compare the positional parameters given by these authors with those obtained by us using Mo Ka radiation.…”

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confidence: 99%