A combined X-ray diffraction and Raman scattering study of the phase transitions in Sr1−xCaxTiO3 (x=0.04, 0.06, and 0.12)

Mishra, S. K.; Ranjan, Rajeev; Pandey, Dhananjai; Ranson, P.; Ouillon, R.; Pinan-Lucarré, Jean-Paul; Pruzan, Ph.

doi:10.1016/j.jssc.2005.06.036

Cited by 25 publications

(39 citation statements)

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“…Presence of short-range-order AFD distortion in the globally cubic phase has been earlier reported for some of the Ca-substituted ST ͑Sr 0.94 Ca 0.06 TiO 3 and Sr 0.88 Ca 0.12 TiO 3 ͒. 28 Figure 3 shows Rietveld plot of neutron powder-diffraction pattern of SPT-05 after refinement with the cubic structure. The refined lattice parameter with the neutron data was found to be 3.9048͑1͒ Å. Duran et al 15 have reported a similar value of the lattice parameter 3.9046͑1͒ Å of x = 0.05 ͑Ref.…”

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“…24͔͒ substituted ST is 3.899 Å. 28 Though the Ca concentration is only 1% higher than the Pr concentration in SPT-05, the decrease in the lattice parameter ͑0.006 Å͒ is three times more than the corresponding decrease ͑of 0.002 Å͒ brought about by 5% Pr substitution in ST. This discrepancy can be explained by assuming that some of the bigger sized Pr 4+ ions occupy the smaller sized Ti 4+ , thereby compensating partly for the decrease in the lattice parameter caused by Pr 3+ / Pr 4+ occupying the Sr 2+ site.…”

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confidence: 85%

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Onset of spontaneous electrostrictive strain below 520 K in Pr-dopedSrTiO3

et al. 2008

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Sr 0.95 Pr 0.05 TiO 3 ceramic is shown to exhibit anomalous value of cubic lattice parameter at room temperature. A combination of temperature dependent dielectric and synchrotron x-ray powder-diffraction study has revealed that the anomalous lattice parameter has contribution from spontaneous electrostrictive strain that sets in below 520 K. In analogy with the lead-based classical relaxor ferroelectrics, it is suggested that Pr-doped SrTiO 3 is a new class of high-temperature lead-free relaxor ferroelectric system. DOI: 10.1103/PhysRevB.78.092102 PACS number͑s͒: 77.84.Dy, 65.40.Ϫb, 77.22.Ϫd Ever since the discovery of quantum paraelectricity, 1 the polar properties of SrTiO 3 ͑ST͒ have been investigated extensively in pure and mixed forms.2-16 At low temperatures bulk ST is an incipient ferroelectric/quantum paraelectric. The onset of a ferroelectric state is suppressed by the groundstate quantum fluctuations of the soft mode.1 The resulting delicate dielectric state is highly susceptible to dopants and external perturbations. Since the dipolar correlation length of incipient ferroelectric systems grow substantially only well below room temperature, 13 the effect of perturbing fields, more particularly the local electric fields due to chemical substitutions, is expected to be more effective in bringing about a ferroelectric state at cryogenic temperatures. Studies in the past, on the two well-known quantum paraelectric systems, ST ͑Refs. 2-8, 17, and 18͒ and KTaO 3 , [19][20][21][22][23] have shown that ferroelectric correlations develop only at temperatures well below room temperature ͑300 K͒. In this scenario, unless something dramatic takes place, a ferroelectric state by chemical substitutions in quantum paraelectric systems is not expected to occur at high temperatures ͑near 300 K or above͒. Recently, contrary to this intuitive perception, ferroelectricity at 300 K was reported in Pr-doped ST ceramics. 15 Observation of maxima at ϳ500 K in the temperature dependence of permittivity ͓Ј͑T͔͒, and dielectric hysteresis at 300 K was considered as evidence in support of this claim.15 However, apart from these macroscopic measurements, so far there has been no report of microscopic ͑structural͒ evidence related to the onset of ferroelectricity in Pr-doped ST. In this Brief Report, we present the results of a temperature dependent synchrotron x-ray powder-diffraction ͑XRPD͒ study on a representative Pr-doped SrTiO 3 composition, Sr 0.95 Pr 0.05 TiO 3 ͑SPT-05͒. It is shown that the system exhibits spontaneous electrostrictive strain below 520 K, a phenomenon which is known for the well-known hightemperature relaxor ferroelectric systems, Pb͑Mg 1/3 Nb 2/3 ͒O 3 ͑PMN͒ and La-substituted Pb͑Zr 1−x Ti x ͒O 3 ͑PLZT͒.Ceramic specimen of Sr 0.95 Pr 0.05 TiO 3 ͑SPT-05͒ was prepared by standard solid-state reaction method. 16 Relative permittivity of platinum electroded ceramic pellet of SPT-05 was measured as a function of temperature with a HP 4192 impedance analyzer. Temperature dependent XRPD study up to 400°C was c...

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confidence: 85%

Onset of spontaneous electrostrictive strain below 520 K in Pr-dopedSrTiO3

et al. 2008

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“…A recently proposed phase diagram is reproduced in Figure 1, after Carpenter et al (2006a). For Ca-rich compositions, the sequence of transitions with falling temperature is Pandey, 1999, 2001a;Ranjan et al, 2000;Mishra et al, 2001;Ouillon et al, 2002;Ranson et al, 2005;Mishra et al, 2005Mishra et al, , 2006a, and there has been a further suggestion of monoclinic symmetry (Woodward et al, 2006). From an earth sciences perspective, the CST solid solution has…”

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confidence: 90%

Elastic and anelastic anomalies in (Ca,Sr)TiO3 perovskites: Analogue behaviour for silicate perovskites

Walsh

Taylor

Buckley

et al. 2008

Physics of the Earth and Planetary Interiors

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“…The first octahedral tilting instability with falling temperature is then associated with the R point of the Brillouin zone. The resulting superstructure has been widely reported to have I4/mcm symmetry [5,[8][9][10]13,16,20,[24][25][26][27], though an alternative Pm3m2Imma transition has been suggested for compositions 0.06pxp0.35 [18,19,21,22]. Ca-rich samples undergo a further I4/mcm2Pnma transition, which involves coupling of M and R point octahedral tilt systems [9,[13][14][15][25][26][27].…”

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confidence: 99%