Heat capacity anomalies at incommensurate-normal transition of �kermanite solid solution (Ca, Sr)2(Mg, Co, Zn, Fe)Si2O7

Iishi, Kazuaki; Mizota, Tadato; Fujino, Kiyoshi; Furukawa, Y.

doi:10.1007/bf00202243

Cited by 15 publications

(15 citation statements)

References 10 publications

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“…One can see that the specific heat of Ca 2 Ga 2 SiO 7 increases linearly from 0.629 JÁg À1 Á C À1 to 0.985 JÁg À1 Á C À1 over the temperature range of 20-300 C. A small peak was observed at 87 C for Ca 2 MgSi 2 O 7 crystals, which is associated with the incommensurate-normal phase transition, 16 above which, the specific heat was found to increase linearly from 0.889 JÁg À1 Á C À1 to 1.120 JÁg À1 Á C À1 . The specific heat of CNG is smaller than those of CMS and CGS, increasing linearly from 0.456 JÁg À1 Á C À1 to 0.598 J/gÁ C over the same temperature range.…”

Section: B Thermal Propertiesmentioning

confidence: 90%

Thermal and electromechanical properties of melilite-type piezoelectric single crystals

Shen

Zhang

Cao

et al. 2015

Journal of Applied Physics

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Melilite-type crystals, including Ca2Ga2SiO7, Ca2MgSi2O7, and CaNdGa3O7, were successfully grown by the Czochralski technique. Thermal properties were investigated and full matrices of electromechanical constants of these melilite crystals were evaluated by impedance method, with d14 being on the order of 5.3-9.3 pC/N. The relationship between microstructure and electromechanical properties of the three kinds of crystals was established, in order to explore the piezoelectric origin and further optimize the piezoelectric properties. The distortion of eight-fold antiprisms and the distortion/rotation of tetrahedrons were thought to contribute to the piezoelectric d14 and d36, respectively. In addition, the layered structure leads to strong anisotropic behavior, accounts for the high resistivity along Z direction in Ca2MgSi2O7, while the disordered structure accounts for the degraded resistivity in CaNdGa3O7. The properties at elevated temperature were investigated, where the elastic constants show high thermal stability over the range of 25-500 C, with minimal variation of 6%. Publication DetailsShen, C., Zhang, S., Cao, W. Melilite-type crystals, including Ca 2 Ga 2 SiO 7 , Ca 2 MgSi 2 O 7 , and CaNdGa 3 O 7 , were successfully grown by the Czochralski technique. Thermal properties were investigated and full matrices of electromechanical constants of these melilite crystals were evaluated by impedance method, with d 14 being on the order of 5.3-9.3 pC/N. The relationship between microstructure and electromechanical properties of the three kinds of crystals was established, in order to explore the piezoelectric origin and further optimize the piezoelectric properties. The distortion of eight-fold antiprisms and the distortion/rotation of tetrahedrons were thought to contribute to the piezoelectric d 14 and d 36 , respectively. In addition, the layered structure leads to strong anisotropic behavior, accounts for the high resistivity along Z direction in Ca 2 MgSi 2 O 7 , while the disordered structure accounts for the degraded resistivity in CaNdGa 3 O 7 . The properties at elevated temperature were investigated, where the elastic constants show high thermal stability over the range of 25-500 C, with minimal variation of 6%. V C 2015 AIP Publishing LLC. [http://dx

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Section: B Thermal Propertiesmentioning

confidence: 90%

Thermal and electromechanical properties of melilite-type piezoelectric single crystals

Shen

Zhang

Cao

et al. 2015

Journal of Applied Physics

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“…These behavioral trends are shown by all incommensurate X2ZT207 melilites and their solid solutions, except Ca2ZnSi207 (Louisnathan 1969;Iishi et al 1991). The reasons behind the anomalous changes in lattice parameters and Tc of Ca2ZnSizO7 is still unclear (Iishi et al 1991). Despite the direct correlation between the increasing tetrahedral sheet dimension and increasing To, no systematic variation in the c/a lattice parameter ratio is found as a function of composition, or analogously, as a function of transition temperature in incommensurate X2ZSi207 melilites (Fig.…”

Section: Lattice Parameter Systematicsmentioning

confidence: 90%

“…This increase in misfit causes an increase in To. These behavioral trends are shown by all incommensurate X2ZT207 melilites and their solid solutions, except Ca2ZnSi207 (Louisnathan 1969;Iishi et al 1991). The reasons behind the anomalous changes in lattice parameters and Tc of Ca2ZnSizO7 is still unclear (Iishi et al 1991).…”

Section: Lattice Parameter Systematicsmentioning

confidence: 96%

“…All incommensurate melilites ((Caa xSrx)2CoSi2OT, Ca2Mgl_xZnxSi207, Ca2Mgl-xFexSi2OT, CazMgl-xCoxSi207 in Fig. 3) have figure is the phase transition temperature determined by adiabatic calorimetry (Iishi et al 1991). The solid lines are the least squares fits to the data.…”

Section: Lattice Parameter Systematicsmentioning

confidence: 98%

“…For the c lattice parameter (b), the data have been fit in three regions separate regions were fit. Region 2 corresponds to the temperature range over which premonitory changes in the structure occur (see text) (Iishi et al 1991). Error bar is one standard deviation and indicates the average errors on the data.…”

Section: Lattice Parameter Systematicsmentioning

confidence: 99%

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Atomic displacements in the normal-incommensurate phase transition in Co-åkermanite (Ca2CoSi2O7)

1994

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Abstract. New in-situ high-temperature X-ray powder diffraction data on the normal-incommensurate phase transition in Co-fikermanite (Ca2CoSi207) are presented. Evidence for the phase transition is found in the abrupt change in the thermal expansivity of the c lattice parameter at 220 ~ C. In addition, the c lattice parameter exhibits premonitory effects of the phase transition through the leveling out of the thermal expansivity at temperatures from 87 to 220 ~ C.The c/a ratio for XzZSi207 incommensurate melilites is shown to be constant for a wide variety of compositions. Correlation of the trends in mean atomic positions with c/a ratio and the sigmoidal variation in the c/a ratio for CazCoSi20 7 provide insight into the atomic displacements occurring in the melilite structure as a function of temperature. Three temperature regimes are discussed in detail (i.e. temperatures well above To, temperatures just above Tc, and temperatures below T~). The atomic displacements occurring in each temperature regime are correlated with the changes in anisotropy and orientation of the atomic displacement ellipsoids for each site, as well as spectroscopic evidence for the increasing number of Z-and T-site environments.

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Stimulated emission (4F3/2 → 4I11/2 channel) with LD and Xe-flashlamp pumping of tetragonal, incommensurately modulated Ca2MgSi2O7:Nd3+(Na+) - a new disordered laser crystal

et al. 2010

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Non‐centrosymmetric tetragonal crystalCa2MgSi2O7:Nd3+(Na+) with incommensurately modulated melilite‐type structure is presented as a new laser crystal. By LD and Xe‐flashlamp pumping its CW and free‐running pulsed stimulated emission of the 4F3/2 → 4I11/2 generation channel of Nd3+ lasant ions was excited. (© 2010 by Astro Ltd., Published exclusively by WILEY‐VCH Verlag GmbH & Co. KGaA)

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Heat capacity anomalies at incommensurate-normal transition of �kermanite solid solution (Ca, Sr)2(Mg, Co, Zn, Fe)Si2O7

Cited by 15 publications

References 10 publications

Thermal and electromechanical properties of melilite-type piezoelectric single crystals

Thermal and electromechanical properties of melilite-type piezoelectric single crystals

Atomic displacements in the normal-incommensurate phase transition in Co-åkermanite (Ca2CoSi2O7)

Stimulated emission (4F3/2 → 4I11/2 channel) with LD and Xe-flashlamp pumping of tetragonal, incommensurately modulated Ca2MgSi2O7:Nd3+(Na+) - a new disordered laser crystal

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