Low temperature heat capacity Study of Fe(PO3)3 and Fe2P2O7

Shi, Quan; Zhang, Liying; Schlesinger, Mark E.; Boerio‐Goates, Juliana; Woodfield, Brian F.

doi:10.1016/j.jct.2013.02.001

Cited by 31 publications

(18 citation statements)

References 51 publications

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“…The distributions discussed above are just a few of the possible distributions that result in a linear heat capacity similar to what has been reported in the literature [3,23,34,44,51,52].…”

Section: B Resultant Heat Capacitysupporting

confidence: 73%

Lattice vacancies responsible for the linear dependence of the low-temperature heat capacity of insulating materials

Schliesser

Woodfield

2015

Phys. Rev. B

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The linear dependence on temperature (γT) of the heat capacity at low temperatures (T < 15 K) is traditionally attributed to conduction electrons in metals; however, many insulators also exhibit a linear dependence that has been attributed to a variety of other physical properties. The property most commonly used to justify the presence of this linear dependence is lattice vacancies, but a correlation between these two properties has never been shown. We have devised a theory that justifies a linear heat capacity as a result of lattice vacancies, and we provide measured values and data from the literature to support our arguments. We postulate that many small Schottky anomalies are produced by a puckering of the lattice around these vacancies, and variations in the lattice caused by position or proximity to some form of structure result in a distribution of Schottky anomalies with different energies. We present a mathematical model to describe these anomalies and their distribution based on literature data that ultimately results in a linear heat capacity. From these calculations, a quantitative relationship between the linear term and the concentration of lattice vacancies is identified, and we verify these calculations using values of γ and vacancy concentrations for several materials. We have compiled many values of γ and vacancy concentrations from the literature which show several significant trends that provide further evidence for our theory.

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Section: B Resultant Heat Capacitysupporting

confidence: 73%

Lattice vacancies responsible for the linear dependence of the low-temperature heat capacity of insulating materials

Schliesser

Woodfield

2015

Phys. Rev. B

Self Cite

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show abstract

“…For the poor conducting LFP, this finding probably suggests the existence of electronic states in defects as recently also found and discussed for other iron phosphates by Shi et al [10][11][12]. The obtained spin wave gap D of approximately T = 13 K is equivalent to reported values for similar materials, e.g., …”

Section: Low Temperature Region (2 To 10) Ksupporting

confidence: 85%

“…For that temperature region we found that a sum of one Debyeand, in contrast to other iron phosphates [10][11][12], only one Einstein-function (equations (3)- (5)) is sufficient to fit the experimental data with adequate accuracy.…”

Section: Temperature Region From (70 To 300) Kmentioning

confidence: 92%

“…The electronic term is linear in T whereas the lattice contribution can be described by an odd-power series in T. For an antiferromagnetic material like LFP, magnetic spin waves also contribute to the heat capacity, and the magnetic term may be modeled by the function b asw T 3 e (ÀD/T) , where b asw and D are adjustable parameters denoting the spin-wave stiffness and the spin-wave gap, respectively [11,28,29].…”

Section: Low Temperature Region (2 To 10) Kmentioning

confidence: 99%

“…However, the theoretical results only represent the vibrational energy/entropy contribution, hence, expected electronic and especially magnetic contributions from the known antiferromagnetic transition of LFP near T = 50 K [7][8][9] were not taken into account. The magnetic transition should add a considerable amount to the thermodynamic functions as had been demonstrated by Shi et al for different iron phosphates using low temperature heat capacity measurements [10][11][12]. It is evident that the availability of reliable thermodynamic data is crucial for any rational design of electrode materials and optimization of electrochemical processes in batteries and therefore an improvement of the data basis is highly desirable.…”

Section: Introductionmentioning

confidence: 99%

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