Calorimetric Investigations of Phase Transitions in KNO<sub>3</sub>Embedded Into Porous Glasses

Sieradzki, Adam; Komar, Jarosław; Rysiakiewicz-Pasek, E.; Ciżman, A.; Poprawski, R.

doi:10.1080/00150191003697393

Cited by 29 publications

(16 citation statements)

References 20 publications

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“…For the nanocomposites with pore sizes of 3.7 and 2.6 nm, the temperature region of the existence of the polar phase is broadened to 44 and 50 K, respectively. From a comparison of these results with the data obtained in [15] for sodium nitrate in porous glasses with the pore sizes one order of magnitude larger (which are also presented in Fig. 6), it can be seen that the broadening of the temperature region of the existence of ferroelec tricity increases with a decrease in the pose size.…”

Section: Discussion Of the Resultsmentioning

confidence: 64%

“…The influence of the confined geometry on the for mation of the ferroelectric phase in nanocomposites with KNO 3 particles has been observed in thin films [13], porous glasses [14,15] and MCM 41 matrices [16]. The size effects in nanocomposites with K 1 ⎯ x Ag x NO 3 and K 1 -x Na x NO 3 were studied in our previous works [17,18].…”

Section: Introductionmentioning

confidence: 95%

“…In all cases, for the nanostruc tured pure potassium nitrate and related mixtures, the authors have reported on a broadening of the temper ature region of the existence of the ferroelectric phase. Sieradzki et al [15] performed a differential scanning calorimetry investigation of KNO 3 in porous glasses during cooling and revealed a broadening of the tem perature region of the existence of the ferroelectric phase III from 15 K in the bulk sample to ~20 and 37 K for samples with pore sizes of 160 and 23 nm, respectively. This paper reports on the results of the investiga tion performed by the methods of linear and nonlinear dielectric spectroscopy and differential scanning calo rimetry of the nanocomposites based on KNO 3 embedded in the nanoporous silica matrices MCM 41 with pore sizes of 3.7 and 2.6 nm in comparison with those obtained for bulk potassium nitrate.…”

Section: Introductionmentioning

confidence: 98%

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Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

et al. 2012

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The temperature dependences of the linear dielectric permittivity, the third harmonic amplitude, and the heat capacity of nanoporous silica matrices MCM 41 with cellular channels (3.7 and 2.6 nm in diam eter) filled with KNO 3 have been investigated in comparison with those obtained for bulk potassium nitrate. Measurements have been performed during heating and cooling in the range from room temperature to 463 K. Anomalies corresponding to structural phase transitions have been observed. A significant broadening of the temperature region of the existence of the ferroelectric phase III of potassium nitrate upon cooling has been revealed. This broadening increases with a decrease in the size of pores. It has been shown that, in the nanocomposites with potassium nitrate, the ferroelectric phase can also be formed during heating. The effi ciency of observation of the third harmonic generation for studying nanocomposites with the ferroelectric phase has been demonstrated.

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Section: Discussion Of the Resultsmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 98%

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Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

et al. 2012

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“…The recent reports [3,4,18,19] carrying out for NCM on base of MCM-41 and porous glasses with average pore diameters 320 and 46 nm have shown that the decreasing of pore diameters results in broadening of temperature range where γ-phase is stable. The principle goal of this contribution was to study the dielectric properties of NCM on base of porous glasses with average pore diameters 320, 46 and 7 nm filled by KNO 3 in the wide frequency range 0.1 -10 7 Hz, to identify the relaxation processes taking place in a restricted geometry, to obtain their temperature dependences and the information concerning to PT in these NCM.…”

Section: Accepted Manuscriptmentioning

confidence: 98%

Dielectric response of potassium nitrate in a restricted geometry

Koroleva

Набережнов

Rysiakiewicz-Pasek

et al. 2016

Composites Part B: Engineering

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“…(2) Temperature of the g!a transition shifts to lower values. This corresponds to calorimetric and dilatometer measurements [6,8] performed for these NCMs. (3) There is a wide temperature interval where two or even all three crystal phases coexist.…”

Section: Neutron Diffraction Datamentioning

confidence: 99%

Phase transitions in nanostructured potassium nitrate

et al. 2014

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Dielectric properties and temperature evolution of the crystal structure of nanocomposites on the basis of porous glasses and KNO 3 embedded into the pores have been studied on heating and cooling. It is shown that the stability of the ferroelectric phase depends on nanoparticle sizes and temperature prehistory of sample preparation and measurement procedure. The temperature interval, where the ferroelectric phase exists, increases on decreasing of the nanoparticle size. In the composite of KNO 3 and porous glasses with the average pore diameters of 7 nm, the ferroelectric phase becomes stable down to 100 K after the first heatingÀcooling circle. IntroductionAt room temperature (RT) the bulk potassium nitrate (KNO 3 ) has the orthorhombic structure Pmnc (a-phase or phase II). At 403 K a reconstructive phase transition (PT) from the low-temperature paraelectric phase to the high-temperature paraelectric trigonal phase R 3 m (b-phase, phase I) occurs. On cooling from this b-phase KNO 3 transforms to another trigonal phase R 3 m (g-phase) at the temperature »397 K. This g-phase is ferroelectric and remains stable on cooling down to 378 K and below this temperature a transformation into the initial a-phase takes place. For thin films and ultradispersed particles, the situation changes essentially. For example, in paper [1] it has been shown that KNO 3 thin films exhibit ferroelectric properties at temperatures even below 273 K possibly due to different thermal expansion of film and substrate. Later on, similar changes in the g ! a PT temperature have been observed for KNO 3 powders and it was attributed to cooperative behavior. [2] It has been demonstrated [3] that thin films have address voltages between 2 and 6 V, depending on the thickness, switching times as fast as 20 ns and square hysteresis loops. It opens a possibility to use KNO 3 thin films as materials for production of non-volatile ferroelectric random access memory (FeRAM). [4] As for nanocomposite materials (NCMs) with KNO 3 , the studies [5À9] carried out for NCM on the basis of mesoporous molecular sieves MCM-41,[10] having an ordered

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Calorimetric Investigations of Phase Transitions in KNO₃Embedded Into Porous Glasses

Cited by 29 publications

References 20 publications

Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

Dielectric response of potassium nitrate in a restricted geometry

Phase transitions in nanostructured potassium nitrate

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Calorimetric Investigations of Phase Transitions in KNO3Embedded Into Porous Glasses

Cited by 29 publications

References 20 publications

Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

Dielectric response of potassium nitrate in a restricted geometry

Phase transitions in nanostructured potassium nitrate

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Calorimetric Investigations of Phase Transitions in KNO₃Embedded Into Porous Glasses