Chemical potential induced phase transition in the metallic electrode attached to the ferroelectric Pb5Ge3O11 single crystal

Molak, A.; Matlak, M.; Koralewski, M.

doi:10.1016/j.physb.2006.03.094

Cited by 3 publications

(3 citation statements)

References 39 publications

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“…This latter possibility has already succesfully been applied in the case of the high-T C superconductor YBa 2 Cu 3 O 7À to indicate for the hole-type superconductivity mechanism in this material (see [62,63] for details). This example, together with the results of the papers [64][65][66][67][68][69][70][71][72], evidently show how important is the measurement of the chemical potential of the electronic subsystem of solids. Note 1.…”

Section: Discussionmentioning

confidence: 85%

“…A special attention should, however, be paid to the method, which allows measurement of the temperature dependence of the chemical potential of the electronic subsystem of solids by using the work function method [62][63][64][65], or the method of the galvanic cell [66,67], which works well for metallic samples. Another interesting method is the contact electrode method, which uses the chemical potential induced phase transition in the electron gas of the metallic contact electrode attached to the investigated sample [68][69][70][71][72]. The papers [62][63][64][65][66][67][68][69][70][71][72] experimentally demonstrate that the temperature behaviour of the chemical potential can successfully be applied to detect phase transitions in solids, and therefore, it is necessary to include it into the calculations presented in this article.…”

Section: Introductionmentioning

confidence: 99%

“…Another interesting method is the contact electrode method, which uses the chemical potential induced phase transition in the electron gas of the metallic contact electrode attached to the investigated sample [68][69][70][71][72]. The papers [62][63][64][65][66][67][68][69][70][71][72] experimentally demonstrate that the temperature behaviour of the chemical potential can successfully be applied to detect phase transitions in solids, and therefore, it is necessary to include it into the calculations presented in this article. It is important to stress that several of the derived relations can successfully be used to foresee whether the transition or characteristic temperature of a given material sample will increase or decrease under applied pressure or under doping (injection), without necessity to produce new samples.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamical relations at characteristic points

Matlak

2008

Phase Transitions

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We define the characteristic temperature T C of a material by using the behaviour of the specific heat in the vicinity of this temperature: C p,N ðT Þ ¼ fð1 À ðT=T C Þ, p, N Þ for T 5 T C and C p,N ðT Þ ¼ gððT=T C Þ À 1, p, N Þ for T 4 T C where p is the external pressure and N is the number of particles. The characteristic temperature T C ¼ T C ( p, N ) can e.g. be identified with the transition temperature in the case of continuous phase transitions or with one of the two characteristic temperatures T ð1Þ C (on heating) and T ð2Þ C (on cooling) in the case of discontinuous phase transitions. Using the idea of the characteristic temperature, we present a new method on how to calculate the Gibbs potential G ¼ G (T, p, N ) in the vicinity of the characteristic temperature, without it being a necessity to know the explicite expressions for f and g. This general and uniform approach allows to derive many thermodynamical relations connecting measurable quantities at the characterisic point as e.g. Clausius-Clapeyron equation and its analogs, valid for discontinuous phase transitions and 15 relations valid for both continuous and discontinuous phase transitions, 6 of them are new. As a special case of these latter relations, we find six relations valid for continuous phase transitions (Ehrenfest equation and its analogs). The derived relations result exclusively from the definition of the characteristic point and are independent from the underlying microscopical mechanism leading to phase transitions (as e.g. solid-liquid, liquid-vapour, magnetic, ferroelectric, structural and superconducting transitions) and therefore, they are generally valid. These relations can be very important for material science. Using some of them it is possible to predict (without performing additional experiments) whether the transition or characteristic temperature T C of a given material sample will increase or decrease under doping (injection) or applied pressure. Similar 24 thermodynamical relations can also be found with ease for systems described by the Helmholtz potential F ¼ F(T,V, N ).

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Section: Discussionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermodynamical relations at characteristic points

Matlak

2008

Phase Transitions

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Local disorder influence on electrical phenomena of pure and Ba‐doped Pb₅Ge₃O₁₁ crystals

Molak

Talik

Pawełczyk

et al. 2008

Physica Status Solidi (a)

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The relation between chemical composition, crystal structure and electrical features of lead germanate, (Pb5–x Bax)Ge3O11, pure and doped with Ba (x = 0, 0.10, 0.25) was studied. The O deficiency and GeO2 precipitation was found in the crystals studied. In the case of the Ba‐doped crystals, the XPS lines width (FWHM) variation suggests structural local disorder. The valence band is placed near 3 eV and it shows an exponential tail, which is ascribed to existence of energy levels correlated to defects. Both the valence band edge shift and the degree of disorder deduced from the change in the XPS lines width vary non‐linearly with the concentration of the Ba ions. The ac conductivity activation energy values Ea = 0.55–0.85 eV indicate electric conductivity of lead germanate is determined by local energy levels originated from point defects. The analysis of the imaginary part of the electric modulus M ″(T, f) exhibited the electronic relaxation process related to electric conductivity, for which the activation energy EM = 0.63–0.72 eV, and the characteristic times τ0 of the order of 10–13 s were evaluated. The crystal structure parameters and several of the electrical conduction parameters exhibit non‐monotonic dependence on the Ba concentration. It was deduced that Ba ions contributed to the mentioned phenomena by two opposite mechanisms. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Thermal Diffusivity and Critical Behaviour of Uniaxial Ferroelectric Pb₅Ge₃O₁₁

et al. 2008

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Chemical potential induced phase transition in the metallic electrode attached to the ferroelectric Pb5Ge3O11 single crystal

Cited by 3 publications

References 39 publications

Thermodynamical relations at characteristic points

Thermodynamical relations at characteristic points

Local disorder influence on electrical phenomena of pure and Ba‐doped Pb₅Ge₃O₁₁ crystals

Thermal Diffusivity and Critical Behaviour of Uniaxial Ferroelectric Pb₅Ge₃O₁₁

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Chemical potential induced phase transition in the metallic electrode attached to the ferroelectric Pb5Ge3O11 single crystal

Cited by 3 publications

References 39 publications

Thermodynamical relations at characteristic points

Thermodynamical relations at characteristic points

Local disorder influence on electrical phenomena of pure and Ba‐doped Pb5Ge3O11 crystals

Thermal Diffusivity and Critical Behaviour of Uniaxial Ferroelectric Pb5Ge3O11

Contact Info

Product

Resources

About

Local disorder influence on electrical phenomena of pure and Ba‐doped Pb₅Ge₃O₁₁ crystals

Thermal Diffusivity and Critical Behaviour of Uniaxial Ferroelectric Pb₅Ge₃O₁₁