Order–disorder in the α'-(Ca,Sr)<sub>2</sub>SiO<sub>4</sub> solid solution: a structural and statistical-thermodynamic analysis

Catti, M.; Gazzoni, G.; Ivaldi, Gabriella

doi:10.1107/s0108768184002652

Cited by 44 publications

(38 citation statements)

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“…The two mirror -related SiO 4 tetrahedra with 50% probability are disordered in this structure. We believe that Catti et al (1984)'s samples are the α´L phase and the disordered structure modeled is the average structure of the α´L phase. Catti et al (1984) did not observe superstructure reflections for their samples.…”

Section: Possibility Of Antiphase Domains In the α´L Phasementioning

confidence: 99%

“…We believe that Catti et al (1984)'s samples are the α´L phase and the disordered structure modeled is the average structure of the α´L phase. Catti et al (1984) did not observe superstructure reflections for their samples. It can be concluded that the superstructure reflections from their samples were diffused and could not be measured by the diffractometer due to the presence of small antiphase domains in their samples.…”

Section: Possibility Of Antiphase Domains In the α´L Phasementioning

confidence: 99%

“…The X -ray intensities of different antiphase domains are equal by Friedel's law if we neglect the effect of the anomalous dispersion. Catti et al (1984) synthesized single crystals of Ca 0.5 Sr 1.5 SiO 4 , CaSrSiO 4 , Ca 1.5 Sr 0.5 SiO 4 , and Ca 1.8 Sr 0.2 SiO 4 from SrCO 3 , CaCO 3 , and SiO 2 using SrF 2 and CaF 2 as flux. They heated the mixture to 1500 °C and then cooled it very slowly to room temperature.…”

Section: Possibility Of Antiphase Domains In the α´L Phasementioning

confidence: 99%

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Orientational ordering of three SiO4 tetrahedra in α´L-Ca1.5Sr0.5SiO4 that satisfies bond-valence requirements and avoids O-O repulsion

Itoh

Nishi

Kuribayashi

et al. 2009

Journal of Mineralogical and Petrological Sciences

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Section: Possibility Of Antiphase Domains In the α´L Phasementioning

confidence: 99%

Section: Possibility Of Antiphase Domains In the α´L Phasementioning

confidence: 99%

Section: Possibility Of Antiphase Domains In the α´L Phasementioning

confidence: 99%

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Orientational ordering of three SiO4 tetrahedra in α´L-Ca1.5Sr0.5SiO4 that satisfies bond-valence requirements and avoids O-O repulsion

Itoh

Nishi

Kuribayashi

et al. 2009

Journal of Mineralogical and Petrological Sciences

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“…Previous work was published on the strontium stabilized belite and on the α′-β transformations in strontium oxide-doped dicalcium silicate (41)(42)(43). Zirconium is the next highest concentration The strontium concentration detected in Clik 3 made of egg shell (544.5 ppm) is lower than those of Clik 2 and Clik 1ref.…”

Section: Discussionmentioning

confidence: 96%

High belite cement from alternative raw materials

Ghorab¹,

Rizk²,

Ibrahim³

et al. 2014

Mater. construcc.

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Three high belite laboratory clinkers were prepared from traditional and alternative raw materials. Reference clinker was obtained from 77% limestone, 11% sandy clays, 11% fatty clays and 1% iron scales. The fatty clays were replaced by red brick powder in the raw meal of the second clinker and were lowered to 2% with the replacement of 10% of the limestone by egg shells in the third clinker. The SEM examination revealed clear presence of crossed striae and twinning in the rounded belite grains of the reference clinker caused by the transformation of the α′-belite to the β polymorph. Striae were weaker in the second and third clinkers indicating a probable stabilization of the α '-belite polymorph.Compressive strength of the respective cements were attained first after 28 days and the early strength did not improve with increasing fineness. Higher compressive strength values were found for the cement prepared from second clinker. RESUMEN: Cementos con altos contenidos en belita obtenido a partir de materias primas alternativas.Se han preparado tres clinkeres de laboratorio con altos contenidos en belita a partir de materias primas tradicionales y alternativas. El clinker de referencia se obtuvo a partir de una mezcla de caliza, arcillas arenosas y grasas y limaduras de hierro. Las arcillas grasas fueron sustituidas por polvo de ladrillo rojo en la preparación del segundo clinker, y en el tercero el contenido de arcilla grasa fue de solo un 2% y parte de la caliza fue sustituida por cascara de huevo.El estudio realizado por SEM muestra superficies estriadas alrededor de los granos de belita que indican una transformación del polimorfo α´a la forma β-C 2 S, durante el enfriamiento. Esas estrías son menos marcadas en el segundo y tercer clinker, indicando, una estabilización del polimorfo α´-C 2 S.Los valores de resistencias a compresión de los correspondientes cementos, a 28 días de curado, no se ven incrementados por la finura de dichos cementos. Las mayores resistencias se obtuvieron en el cemento preparado a partir del clínker con polvo de ladrillo rojo.

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“…The structural relationships among the five phases: a, a~, a~., /3, and 7 of calcium orthosilicate, the atomic mechanisms of transformation and their connections with equilibrium solid-phase relations are O 1986 International Union of Crystallography extensively studied topics (see, among others, Eysel & Hahn, 1970;Saalfeld, 1975;Barnes, Fentiman & Jeffery, 1980;Catti, Gazzoni & Ivaldi, 1984). In particular, the structural aspects involved in the transformation into the 3' form, stable at room temperature, are of relevant interest.…”

Section: Introductionmentioning

confidence: 99%

Crystallographic relations between the β and γ forms of (Ca₂,Ca_1.8Sr_0.2)SiO₄

Gazzoni¹,

Chiari²

1986

Acta Crystallogr Sect B

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coordinated cations, can account for practically any stoichiometry in the composition range between CaUO4 and CaUO3.5o. The given explanation is not only in agreement with all known experimental data, but also with the results of Thornber & Bevan (1970), who studied mixed oxides of the type MO2 (fluorite)-M203, which can accommodate large departures in stoichiometry in fluorite-related structures. The defect complex in these compounds, which enables the variation in composition, is equivalent to type A ordering, one of the possible ways of reducing CaUO4.There is a perfect intrinsic order in the arrangement of O vacancies in both types of microdomains and the observed disorder is only a result of more than one energetically equivalent possibility of stacking the reduced layers along the original inversion triad. If the nearest-neighbour interaction between reduced layers could be extended to the next-nearest neighbours at sufficiently low temperatures, a complete three-dimensional ordering would be achieved. As the favoured alternation of both types of ordering can only be explained on the basis of the most convenient charge balancing during reduction, it is obvious that this kind of ordering is conditioned by the possibility of U taking on a whole series of different ionization states with close ionization energies. AbstractCrystal associations of/3 and 3' forms of synthetic (Ca2,CalsSro2)SiO4 showing a paramorphosis relationship are studied by optical microscopy and X-ray diffraction. The mutual crystallographic orientation is unequivocally established. The cell parameters are: (a sin/3)~ = 5.48, a~ = 5.08; b~ = 6.74, by = 6.76; c~ = 9.30, cv = 11.23/~,. On the basis of experimental evidence the structural relationships

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Order–disorder in the α'-(Ca,Sr)₂SiO₄ solid solution: a structural and statistical-thermodynamic analysis

Cited by 44 publications

References 3 publications

Orientational ordering of three SiO4 tetrahedra in α´L-Ca1.5Sr0.5SiO4 that satisfies bond-valence requirements and avoids O-O repulsion

Orientational ordering of three SiO4 tetrahedra in α´L-Ca1.5Sr0.5SiO4 that satisfies bond-valence requirements and avoids O-O repulsion

High belite cement from alternative raw materials

Crystallographic relations between the β and γ forms of (Ca₂,Ca_1.8Sr_0.2)SiO₄

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Order–disorder in the α'-(Ca,Sr)2SiO4 solid solution: a structural and statistical-thermodynamic analysis

Cited by 44 publications

References 3 publications

Orientational ordering of three SiO4 tetrahedra in α´L-Ca1.5Sr0.5SiO4 that satisfies bond-valence requirements and avoids O-O repulsion

Orientational ordering of three SiO4 tetrahedra in α´L-Ca1.5Sr0.5SiO4 that satisfies bond-valence requirements and avoids O-O repulsion

High belite cement from alternative raw materials

Crystallographic relations between the β and γ forms of (Ca2,Ca1.8Sr0.2)SiO4

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Order–disorder in the α'-(Ca,Sr)₂SiO₄ solid solution: a structural and statistical-thermodynamic analysis

Crystallographic relations between the β and γ forms of (Ca₂,Ca_1.8Sr_0.2)SiO₄