Dielectric properties and phase transitions in [(CH3)2NH2]5Cd3Cl11 single crystals

Czapla, Z.; Dacko, S.; Krzewska, U.; Waśkowska, A.

doi:10.1016/0038-1098(89)90450-x

Cited by 22 publications

(8 citation statements)

References 3 publications

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“…The similar maxima in the same temperature region were observed in the "pure" DMACC crystals [3]. Moreover, they manifested clear frequency shift at much higher frequencies of measuring field (20 MHz-3.5 GHz).…”

Section: Resultssupporting

confidence: 76%

“…A maximal value of the dielectric permittivity was found to be along the c-axis. The dielectric measurements revealed the anomalies at the temperatures T 1 = 180 K and T 2 = 127 K. These anomalies were supposed to be related to the phase transitions (PTs) [3]. The investigations of the complex dielectric permittivity of DMACC crystal in the frequency range from 20 MHz to 42 GHz revealed the Debye-type dielectric dispersion in the c-cut with the two relaxation times [4].…”

Section: Introductionmentioning

confidence: 99%

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Dielectric and Birefringent Properties of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁Solid Solutions in the Region of Their Phase Transitions

et al. 2006

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On the basis of the optical and dielectric investigations of [(CH3)2NH2]5Cd2CuCl11 solid solutions the existence of phase transitions at T 1 = 175 K and T 2 = 117.5 K was confirmed. Both phase transitions were found to be shifted toward lower temperatures with respect to the corresponding transitions in the "host" [(CH 3 ) 2 NH 2 ] 5 Cd 3 Cl 11 crystals. It was found that the proton conductivity in [(CH3)2NH2]5Cd2CuCl11 crystals is realized through the Grotthus mechanism. The investigations of the birefringent properties confirmed existence of the structural changes at T0 = 320 K connected with the complex co-operative effect involving weakening of the hydrogen bonds and modification of the Jahn-Teller distortion with temperature.

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Section: Resultssupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Dielectric and Birefringent Properties of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁Solid Solutions in the Region of Their Phase Transitions

et al. 2006

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“…The two low-temperature anomalies correlate with clear λ-like anomalies of the heat-capacity characteristic of the phase transitions (the relevant results will be published elsewhere). Besides, one can note that phase transitions at temperatures close to T 1 and T 2 were observed in the host crystals of DMACC [1,4,5]. It is necessary to note that introduction of the copper ions into the structure of DMACC induces shifts of these PTs by 3.5 and 5 K, respectively.…”

Section: Resultsmentioning

confidence: 97%

“…A new crystalline compound with composition [(CH 3 ) 2 NH 2 ] 5 Cd 3 Cl 11 (DMACC) has been reported by Czapla et al [1]. X-ray structural investigations have shown that at room temperature the crystal is of orthorhombic symmetry (the space group Cmcm) [2].…”

Section: Introductionmentioning

confidence: 91%

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Electronic spectra of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁ crystals

Kapustianik

Batiuk

Czapla

et al. 2004

Physica Status Solidi (b)

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The temperature evolution of Cu 2+ ion environment in the solid solutions of ((CH 3 ) 2 NH 2 ) 5 Cd 2 CuCl 11 is studied on the basis of absorption spectroscopy data. For the detailed analysis of experimental data the special program package Crys Tool 1.0 based on quantum-mechanical models, first of all on the model of normalized spherical harmonics (NSH), has been employed. It has been found that similarly to the crystal of ((CH 3 ) 2 NH 2 ) 5 Cd 3 Cl 11 (DMACC) the investigated solid solution contains tetragonally distorted octahedral metal-halogen complexes of two types and the degree of their distortion is changed considerably at the temperatures of phase transitions (PTs). The parameters of crystal field, angular overlap model, as well as the copper-chlorine distances, show continuous changes at T 1 = 176 K that should be related to the second-order transition, whereas the jump-like anomalies of the spectral parameters at T 2 = 115 K (on cooling) are characteristic of the first-order PTs. Introduction of the copper ions into the structure of the host DMACC crystal induces the shifts of these PTs toward low temperatures by 3.5 and 5 K, respectively. The observed structural changes around T 0 = 313 K are connected with a complex co-operative effect involving weakening of the hydrogen bonds and modification of the Jahn-Teller distortion with temperature.

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Exciton–phonon interaction and Raman spectra of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁ crystals

Kapustianik

Batiuk

Czapla

et al. 2004

Physica Status Solidi (b)

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Temperature evolution of the exciton-phonon interaction (EPI) in ((CH 3 ) 2 NH 2 ) 5 Cd 2 CuCl 11 solid solution was studied on the basis of absorption spectroscopy data. The obtained values of effective phonon energies were compared with the data of Raman spectroscopy. It is shown that the σ(T) and E ′ parameters of Urbach's rule show the continuous anomalous change characteristic of the second-order phase transition at T 1 = 176 K. The anomalous behaviour of the EPI and other spectral parameters at T 0 = 310 -315 K was related to the complex co-operative effect involving weakening of the hydrogen bonds and variation of the Jahn-Teller distortion of metal-halogen polyhedra with temperature. This process takes place only within the copper-chlorine sublattice and due to this would be hardly related to the usual phase transition. At the same time, the considered temperature change of the tetragonal distortion of the metal-halogen octahedra is followed by nonfulfillment of Urbach's rule in the temperature range T ≥ T 0 .

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Dielectric properties and phase transitions in [(CH3)2NH2]5Cd3Cl11 single crystals

Cited by 22 publications

References 3 publications

Dielectric and Birefringent Properties of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁Solid Solutions in the Region of Their Phase Transitions

Dielectric and Birefringent Properties of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁Solid Solutions in the Region of Their Phase Transitions

Electronic spectra of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁ crystals

Exciton–phonon interaction and Raman spectra of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁ crystals

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Dielectric properties and phase transitions in [(CH3)2NH2]5Cd3Cl11 single crystals

Cited by 22 publications

References 3 publications

Dielectric and Birefringent Properties of [(CH3)2NH2]5Cd2CuCl11Solid Solutions in the Region of Their Phase Transitions

Dielectric and Birefringent Properties of [(CH3)2NH2]5Cd2CuCl11Solid Solutions in the Region of Their Phase Transitions

Electronic spectra of [(CH3)2NH2]5Cd2CuCl11 crystals

Exciton–phonon interaction and Raman spectra of [(CH3)2NH2]5Cd2CuCl11 crystals

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Dielectric and Birefringent Properties of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁Solid Solutions in the Region of Their Phase Transitions

Dielectric and Birefringent Properties of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁Solid Solutions in the Region of Their Phase Transitions

Electronic spectra of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁ crystals

Exciton–phonon interaction and Raman spectra of [(CH₃)₂NH₂]₅Cd₂CuCl₁₁ crystals