Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy

Banerjee, Debashis; Sewak, R.; Dey, C.C.; Toprek, Dragan; Pujari, P. K.

doi:10.1016/j.mtcomm.2020.101827

Cited by 9 publications

(4 citation statements)

References 40 publications

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“…The structural parameters are optimized for all the polymorphs of HfO 2 within the parameterization of GGA by fitting Birch-Murnaghan equation of states [49], and the corresponding volume optimization curves are shown in figure 1. Our optimized lattice parameters are in good agreement with the previously reported experimental results (listed in table 1) [22][23][24][25]. Therefore, we have not optimized angles of the monoclinic structure but rather taken the experimental values from literature [22].…”

Section: Structural Propertiessupporting

confidence: 85%

“…A low temperature thermodynamically stable monoclinic (m) phase exists at ∼1200 • C, whilst tetragonal (t) phase and cubic (c) phase occurs, respectively, at 1700 • C and 2500 • C [22][23][24]. The high pressure transforms the m-HfO 2 to orthorhombic (o) phase [25]. The existence of a variety of polymorphic phases of HfO 2 has numerous industrial applications like ferroelectric material [26], scintillation counter [27], and resistive random access memory devices [28].…”

Section: Introductionmentioning

confidence: 99%

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Carrier concentration mediated enhancement in thermoelectric performance of various polymorphs of hafnium oxide: a plausible material for high temperature thermoelectric energy harvesting application

Kumar¹,

Kumar²,

Singh³

et al. 2022

J. Phys. D: Appl. Phys.

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The optimization of figure of merit by tuning carrier concentrations is an effective way to realize efficient thermoelectrics. Recently, the feasibility of high p-type carrier concentration (order of ~1022 cm-3) is experimentally demonstrated in various polymorphs of HfO2. In light of these studies, using the first-principles calculation combined with the semi-classical Boltzmann transport theory and phonon dynamics, we realized high thermoelectric performance in various polymorphs of HfO2 in a range of carrier concentrations at high temperatures. The phonon dispersion calculations confirm the dynamical stability of all polymorphs. The observed values of the Seebeck coefficient are 945.27 mV/K, 922.62 mV/K, 867.44 mV/K, and 830.81 mV/K for tetragonal (t), orthorhombic (o), monoclinic (m), and cubic (c) phases of HfO2, respectively, at 300 K. These values remain positive at all studied temperatures which ensures the p-type behaviour of HfO2 polymorphs. The highest value of electrical conductivity 2.34×1020  -1m-1s-1observed in c-HfO2 at 1200 K, and the lowest value of electronic thermal conductivity (0.37×1015 W/mKsobserved in o-HfO2 at 300 K. The lattice thermal conductivities at room temperature are 5.56 W/mK, 2.87 W/mK, 4.32 W/mK, and 1.75 W/mK for c-, m-, o- and t- HfO2, respectively which decrease to 1.58 W/mK, 0.92 W/mK, 1.12 W/mK, 0.53 W/mK at 1200 K for respective phases. The low lattice thermal conductivities lead to the high values of the figure of merit, i.e., 0.97, 0.87, 0.83, and 0.77 at 1200 K for the m-, o-, t-, and c- HfO2, respectively, at the optimized carrier concentrations (~1021 cm-3). The predicted optimized carrier concentrations for various phases are in close agreement with the experimental reports. The estimated high figure of merit can make HfO2 a potential material for thermoelectric energy harvesting applications at elevated temperatures.

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Section: Structural Propertiessupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Carrier concentration mediated enhancement in thermoelectric performance of various polymorphs of hafnium oxide: a plausible material for high temperature thermoelectric energy harvesting application

Kumar¹,

Kumar²,

Singh³

et al. 2022

J. Phys. D: Appl. Phys.

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“…From Table 2 it can be seen that the TDPAC parameters for the m-site and different osites are in good agreement with the previous values. 29,30 All the o-phases could be unambiguously distinguished by their very different characteristic EFGs produced at the respective o-sites. This shows the sensitivity of TDPAC spectroscopy to distinguish the local environment.…”

Section: Resultsmentioning

confidence: 99%

Comprehensive study on the origin of orthorhombic phase stabilization in Gd-doped HfO₂ and DFT calculations

Banerjee¹,

Dey²,

Kumar³

et al. 2023

Phys. Chem. Chem. Phys.

Self Cite

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“…HfO 2 exists in different polymorph phases-cubic (space group: Fm3m), tetragonal (P42/nmc), orthorhombic (Pca21), and monoclinic (P21/s) [13]. The monoclinic phase is stable from RT up to 2000 K. The tetragonal phase is observed at 2000 K-2900 K. The highest symmetry cubic phase is stabilized between 2900 K and 3100 K. [13] The orthorhombic phase is typically not a stable phase under normal pressure conditions [14]. Various synthesis methods have been explored to optimize the physicochemical properties of HfO 2 and tailor its application-specific attributes [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Impact of Europium and Niobium Doping on Hafnium Oxide (HfO2): Comparative Analysis of Sol–Gel and Combustion Synthesis Methods

Laganovska,

Vitola,

Einbergs

et al. 2023

Ceramics

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This study compares HfO2 ceramics synthesized using sol–gel and combustion methods, emphasizing the impact of the method of synthesis on the resulting properties of the material. The research findings illustrate morphological differences between sol–gel and combustion-derived HfO2. While sol–gel samples displayed irregular nanoparticles with pronounced boundaries, combustion samples revealed more homogeneous structures with particles tending towards coalescence. It was discerned that Eu3+ doping induced oxygen vacancies, stabilizing the tetragonal phase, while subsequent doping with Nb5+ significantly reduced these vacancies, which was also observed in photoluminescence analysis. Furthermore, combustion synthesis left fewer organic residues, with urea presence during synthesis contributing to residual organic components in the material. XPS analysis was used to evaluate the presence of oxygen-deficient hafnia sub-oxide in the samples. The study underscores the important role of tailored synthesis methods in optimizing the properties and applications of HfO2.

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Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy

Cited by 9 publications

References 40 publications

Carrier concentration mediated enhancement in thermoelectric performance of various polymorphs of hafnium oxide: a plausible material for high temperature thermoelectric energy harvesting application

Carrier concentration mediated enhancement in thermoelectric performance of various polymorphs of hafnium oxide: a plausible material for high temperature thermoelectric energy harvesting application

Comprehensive study on the origin of orthorhombic phase stabilization in Gd-doped HfO₂ and DFT calculations

Impact of Europium and Niobium Doping on Hafnium Oxide (HfO2): Comparative Analysis of Sol–Gel and Combustion Synthesis Methods

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Orthorhombic phases in bulk pure HfO2: Experimental observation from perturbed angular correlation spectroscopy

Cited by 9 publications

References 40 publications

Carrier concentration mediated enhancement in thermoelectric performance of various polymorphs of hafnium oxide: a plausible material for high temperature thermoelectric energy harvesting application

Carrier concentration mediated enhancement in thermoelectric performance of various polymorphs of hafnium oxide: a plausible material for high temperature thermoelectric energy harvesting application

Comprehensive study on the origin of orthorhombic phase stabilization in Gd-doped HfO2 and DFT calculations

Impact of Europium and Niobium Doping on Hafnium Oxide (HfO2): Comparative Analysis of Sol–Gel and Combustion Synthesis Methods

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Comprehensive study on the origin of orthorhombic phase stabilization in Gd-doped HfO₂ and DFT calculations