Square modulated differential thermal analysis

Valero, Constantino; Martín‐Olalla, José María; Romero, Francisco Sacristán

doi:10.1016/s0040-6031(02)00545-2

Cited by 17 publications

(25 citation statements)

References 20 publications

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“…In a very recent paper [9], we reported a preliminary analysis of the specific heat and latent heat of a 90% deuterated sample of TGSe using the technique "Square Modulated Differential Thermal Analysis" (SMDTA) [10], which has been proved to be very useful in the investigation of first-order phase transitions. The high sensitivity of the equipment and the very small temperature variation rate used to perform the measurements (lower than 0.1 K h −1 ) made it possible to observe in detail the kinetics of the transformation and to obtain information about growth or destruction of domains in ferroelastic and ferroelectric phase transitions [11,12].…”

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confidence: 99%

Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

2006

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Abstract. -The phase transition in a 90% deuterated sample of TGSe has been investigated by calorimetric and dielectric measurements. As a consequence of the presence of an internal crack in the sample, the transition takes place in two stages separated by an interval where the paraelectric and the ferroelectric phases coexist without latent heat contribution. From the latent heat, the specific heat excess and the Curie law for the dielectric constant, it is shown that the transition follows a 2-4-6 Landau potential, whose coefficients are determined. This potential describes completely all the data, including those corresponding to the coexistence interval.Introduction. -Compositional changes affect very significantly most ferroelectric phase transitions and their effects are particularly important if the transition is close enough to a tricritical point, so that the first-or second-order nature could be modified. Triglycine selenate [(NH 2 CH 2 COOH) 3 H 2 SeO 4 ], here-after TGSe, is a well-known uniaxial ferroelectric material belonging to the triglycine sulphate (TGS) family. It undergoes a typical order-disorder phase transition at about T ∼ 295 K, the space group of the lower-temperature phase being P2 1 and that of the higher-temperature phase P2 1 /m. [1,2]. Recently, we performed a calorimetric study on the phase transition showing that the specific heat of the ferroelectric phase follows a classical tricritical Landau potential whose coefficients have been determined [3].The effect of deuteration on the dielectric properties of phase transition in TGSe has been previously investigated [4][5][6]. It has been found that the thermal hysteresis as determined from dielectric-constant measurements increases when the deuteration increases, which indicates that the transition becomes first order.Concerning the thermal properties of partially deuterated TGSe, the specific heat and the latent heat of a 62% deuterated sample and under the effect of γ-irradiation have been measured [7,8]. The specific heat behaviour was found to follow the predictions of a 2-4-6 Landau potential and the latent heat was evaluated to be 168 J mol −1 . In a very recent paper [9], we reported a preliminary analysis of the specific heat and latent heat of a 90% deuterated sample of TGSe using the technique "Square Modulated Differential Thermal Analysis" (SMDTA) [10], which has been proved to be very useful in the investigation

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confidence: 99%

Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

2006

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“…Except around the M transition cd and cr match to each other within experimental resolution. We have shown previously that a difference between cd and cr is an evidence of a first-order phase transition [12]. Martensitic phase transitions are known to show athermal behaviour, so that there is a distribution of transition temperatures and the latent heat spreads over a wide temperature interval.…”

Section: Resultsmentioning

confidence: 98%

“…Specific heat data are obtained from [12]: where m is the mass of the sample and  is the thermal resistance of the fluxmeters obtained by calibration. When no kinetic process is present, both branches results are equivalent.…”

Section: Methodsmentioning

confidence: 99%

“…We previously developed a method called Squared Modulated Differential Thermal Analysis (SMDTA) which was able to characterize continuous (second-order) and discontinuous (firstorder) phase transitions [12,13] even in the neighborhood of a tricritical point where the challenges grow because the specific heat is expected to diverge. This paper introduces an improvement of the SMDTA technique that allows the measurement of the heat capacity during a first-order phase transition.…”

Section: Introductionmentioning

confidence: 99%

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Experimental method to determine specific heat capacity and transition enthalpy at a first-order phase transition: Fundamentals and application to a Ni-Mn-In Heusler alloy

et al. 2021

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“…To compute the enthalpy change due to the latent heat during this phase transition, we integrate the DTA trace respect to an appropriate baseline (dashed lines in Figure 3) calculated from specific heat data [21]. The computed transition enthalpy is represented in Figure 7.…”

Section: Specific Heatmentioning

confidence: 99%

Thermo-magnetic characterization of phase transitions in a Ni-Mn-In metamagnetic shape memory alloy

Romero

Martín‐Olalla

Blázquez

et al. 2021

Journal of Alloys and Compounds

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Square modulated differential thermal analysis

Cited by 17 publications

References 20 publications

Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

Phase coexistence in highly deuterated ferroelectric triglycine selenate: Landau description

Experimental method to determine specific heat capacity and transition enthalpy at a first-order phase transition: Fundamentals and application to a Ni-Mn-In Heusler alloy

Thermo-magnetic characterization of phase transitions in a Ni-Mn-In metamagnetic shape memory alloy

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