The crystal structure of α-Na2Cr2O7 and the α–β phase transition

Panagiotopoulos, N. C.; Brown, Ian

doi:10.1107/s056774087300350x

Cited by 8 publications

(4 citation statements)

References 3 publications

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“…None contain discrete Mo20~ions, their structures being composed of octahedral (Ag ÷ salt), or octahedral-tetrahedral (Na ÷, K+, NH] salts) infinite chains. 3 (Panagiotopoulos & Brown, 1973). MgMo20 7 is, thus, the first dimolybdate which has been found to belong to a large class of compounds containing isolated X20 7 groups composed of XO 4 tetrahedra sharing corners.…”

Section: Discussionmentioning

confidence: 99%

“…la) with a Mo(1)-O(4)-Mo(2) angle of 160.7(3) °. According to Panagiotopoulos & Brown (1973)the Table 2. lb).…”

Section: Description Of the Structurementioning

confidence: 99%

“…(i) -x, -y, -z (iv) x, y -1, z(ii) x,~-y,~+ z(v) x-i,y-l,z (iii) -x, ½ + y, ½ -z (vi)x -1, y, z Conformation types of the X20 7 group fromPanagiotopoulos & Brown (1973): (a) staggered, (b) and (c) eclipsed. (a) View of the dimolybdate ion Mo20~-projected on the Mo(l), 0(4), Mo(2) plane; (b) projection down the Mo(l)-Mo(2) direction.…”

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confidence: 99%

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The crystal structure of magnesium dimolybdate

Stadnicka¹,

Haber²,

Kozłowski³

1977

Acta Crystallogr Sect B

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The structure of magnesium dimolybdate, MgMo207, monoclinic with space group P2/c and a = 8.111 (2), b = 5.700 (1), c = 15.002 (3) ,~, fl = 115.26 (2) °, Z = 4, was determined by the heavy-atom method and refined by full-matrix least squares to an R of 0.095 for 2558 counter reflexions. The Mo202-pyro-anion consists of two corner-sharing MoO 4 tetrahedra, which are twisted from the ideal eclipsed configuration by an average of 12.3 °. Mo207 groups form anionic sheets parallel to the (100) plane. Mg 2÷ ions are situated between the anionic sheets in a distorted-octahedral environment of O atoms. MgO 6 octahedra share one edge forming Mg2Oi0 units.

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Section: Discussionmentioning

confidence: 99%

“…la) with a Mo(1)-O(4)-Mo(2) angle of 160.7(3) °. According to Panagiotopoulos & Brown (1973)the Table 2. lb).…”

Section: Description Of the Structurementioning

confidence: 99%

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The crystal structure of magnesium dimolybdate

Stadnicka¹,

Haber²,

Kozłowski³

1977

Acta Crystallogr Sect B

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“…To find the appropriate frequency distributions, histograms were prepared for the scattered corrosion current density data, and suitable distribution was selected. In earlier literature Normal, log normal, Weibull, Gumbel, Gamma, 3-parameter lognormal distributions were used to analyse corrosion data of steel reinforcement in concrete/mortar (Firodiya et al, 2014;Karuppanasamy and Pillai, 2016;Okeniyi, 2016;Okeniyi et al, 2013;Omotosho et al, 2010;Panagiotopoulos and Brown, 1973;Pillai and Karuppanasamy, 2014). For the present study, the best fit distribution for the corrosion current density data of each sample was selected from the lognormal, Weibull and logistic distribution functions by the AD Gof test.…”

Section: Frequency Distribution Analysismentioning

confidence: 99%

Corrosion performance of steel reinforcement in concrete admixed with magnesium chloride and sulphate

Babu

Kondraivendhan

2020

ACMM

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Purpose Besides with a large amount of Na+ and Cl− ions in seawater, the presence of Mg+2 and SO4−2 ions builds more complex corrosion mechanism. This paper aims to investigate the corrosion of embedded reinforcement in concrete with the environment of both Cl− and SO4−2 anions associated Mg+2 cation. Design/methodology/approach The concrete specimens were prepared by using ordinary Portland cement (OPC), and OPC blended with metakaolin (MK) for water to cementitious material ratio (w/cm) 0.48 and 0.51. The concrete mixes were contaminated with the addition of MgCl2 alone and combined MgCl2 and MgSO4 in mix water. Reinforcement corrosion was evaluated by half-cell potential and corrosion current densities (Icorr) at regular intervals. Moreover, the influence of cementitious material type, salt type and w/cm ratio on electrical resistivity of concrete was also investigated. The statistical models were developed for electrical resistivity as a function of calcium to aluminium content ratio, compressive strength, w/cm ratio and age of concrete. Findings Although the corrosion initiation time increases in the concomitant presence of MgSO4 and MgCl2 as internal source compared to MgCl2, Icorr values are higher in both OPC and MK blended concrete. However, electrical resistivity decreased with addition of MgSO4. MK blended concrete performed better with increased resistivity, corrosion initiation time and decreased Icorr values. Originality/value This study reports statistical distributions for scattered Icorr of rebar in different concrete mixtures. Stepwise regression models were developed for resistivity by considering the interactions among different variables, which would help to estimate the resistivity through basic information.

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Aspects of the Stereochemistry of Four‐Coordination and Five‐Coordination

Favas

Kepert

1980

Progress in Inorganic Chemistry

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The crystal structure of α-Na₂Cr₂O₇ and the α–β phase transition

Cited by 8 publications

References 3 publications

The crystal structure of magnesium dimolybdate

The crystal structure of magnesium dimolybdate

Corrosion performance of steel reinforcement in concrete admixed with magnesium chloride and sulphate

Aspects of the Stereochemistry of Four‐Coordination and Five‐Coordination

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